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Bibliography of the Maurice Lamontagne Institute

Jean-Denis DUTIL

LAMBERT, P., G. VERREAULT, B. LÉVESQUE, V. TREMBLAY, J.-D. DUTIL, P. DUMONT, 2011. Détermination de l'impact des barrages sur l'accès de l'anguille d'Amérique (Anguilla rostrata) aux habitats d'eau douce et établissement de priorités pour des gains en habitat. Rapp. Tech. Can. Sci. Halieut. Aquat., 2921, 53 p .

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American eel (Anguilla rostrata) experience a marked decline in the St. Lawrence River. Access to freshwater is impaired by an ever growing number of dams some of which are used for hydropower and cause mortalities to downstream migrants. A model is proposed to prioritize mitigation schemes in the Rimouski River (Quebec), a 1376 km long mid-size watershed on which 23 barriers higher than 1 m occur. A diffusion rate of 20 km2 year-1 over a 20 year period was applied in the model. The impact of each barrier was simulated by reducing movements upstream at the barrier, survival among eels blocked downstream, and survival of eels at the barrier during the downstream migration. Model outputs have stressed the prime importance of a single dam located near the estuary in determining the colonization process whereas mitigating other dams in the watershed did not significantly improve spawning escapement. Setting priorities among watersheds poses additional challenges. There are differences in growth, fecundity and size at maturity among watersheds and these have an effect on egg production associated with spawning escapement. Size at maturity within a watershed was found to correlate with the observed back-calculated growth rate of eel from age 1 to age 10 in the watershed. OMMER (Obstacle Mitigation Model for Eel in Rivers) is a valuable tool to compare a range of management scenarios aimed at mitigating upstream and downstream passage at barriers, though its extension to other watersheds is currently limited by the availability of relevant data for a diversified set of habitats and watersheds.

TREMBLAY, V., C. COSSETTE, J.-D. DUTIL, G. VERREAULT, P. DUMONT, 2011. Évaluation de la franchissabilité amont et aval pour l'anguille aux barrages = Assessment of upstream and downstream passability for eel at dams. Rapp. tech. can. sci. halieut. aquat. ; Can. Tech. Rep. Fish. Aquat. Sci., 2912, 83 p .

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The American eel (Anguilla rostrata) population has experienced a marked population decline. Habitat loss resulting from dam construction to improve the control and use of freshwater discharge is one of the factors involved. There are some 5600 dams in rivers draining to the St. Lawrence in Quebec. Their passability to eels migrating upstream and downstream has been assessed using the dams database of the Centre d’expertise hydrique du Québec. Eighteen percent of the dams are used for supplying water and 13 % for hydroelectricity, but more than 50 % are used for recreational purposes. Although the majority of the dams are less than 3 m in height and are made of concrete or earthfill, dams present a great variety of physical characteristics and are used for all kinds of purposes. Passability ranks were assigned to each category of dam based on three assessment criteria: the height of the dam, the materials used in its construction, and its use. Passability to upstream migrants was also assessed from photographs for a subset of dams. The two methods (statistical analysis and the use of photographs) may yield different results, but the two methods were consistent to identify the impassable dams. This analysis shows overall that the problem of passability is more significant for upstream passage than it is for downstream passage. Once added to a geospatial analysis tool (GIS) which locates dams and calculates the surface area of habitats lost in each watershed, passability ranks will assist managers in setting priorities for mitigation.

DUTIL, J.-D., S. PROULX, P.-M. CHOUINARD, D. BORCARD, 2011. A hierarchical classification of the seabed based on physiographic and oceanographic features in the St. Lawrence. Can. Tech. Rep. Fish. Aquat. Sci., 2916, 79 p .

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A hierarchical framework has been proposed to classify marine waters surrounding North America into 24 different marine ecoregions based on large-scale oceanographic features. One of those ecoregions (Acadian-Atlantic) includes shelf waters from the Strait of Belle Isle (Canada) down to Cape Cod (U.S.A.) and encompasses the St. Lawrence estuary and Gulf. The present report aims at proposing a hierarchical classification of the seafloor at the scale of the megahabitat for the St. Lawrence estuary and Gulf as a basis for mapping and describing marine habitats for conservation and integrated management purposes. Information on salinity, temperature, dissolved oxygen, depth, slope, and variability in landscape and sediments were aggregated using a grid made up of 100 km2 cells. Based on that information, cluster analyses were conducted grouping cells into 13 different megahabitats. Four megahabitats described the deep waters, and areas outside channels formed 9 megahabitats: four in the southern Gulf and five in the northern Gulf. These groups of cells were spatially coherent. The tool proposes a novel way of making validated and integrated data available to end users. Potential applications include the screening of areas considered for inclusion in a network of protected areas and a quantitative assessment of surface areas for each class of habitat. the method can also be applied to describe the habitats of species at risk.

P.-M. CHOUINARD, J.-D. DUTIL, 2011. The structure of demersal fish assemblages in a cold, highly stratified environment. ICES J. Mar. Sci., 68(9): 1896-1908 .

Fish are a major component of marine ecosystems, with many species co-occuring in the same habitats. Potential interactions among species and with the environment can be studied through the identification of species assemblages. Data from bottom trawl surveys (2004–2008) conducted in the estuary and northern Gulf of St Lawrence were analysed using multivariate methods (cluster, multidimensional scaling, and detrended canonical correspondence analysis) to describe the structure and composition of demersal fish assemblages, including rare and smaller non-commercial species. The spatial variability in environmental conditions that characterizes the study area has a significant impact on the composition of fish assemblages in the region. In all, 35 taxa were classified as key, and 6 main fish assemblages were described, based on catch in numbers. These assemblages had a coherent spatial distribution in the study area, associated with either depth, salinity and temperature, or dissolved oxygen. The analyses showed overall strong correlations between species abundance and prevalent environmental conditions and explained 18.4 % of the variance in species abundance data and 79.2 % of the variance in the species–environment relationship.©2011 Oxford

LEMIEUX, H., J.-C. TARDIF, J.-D. DUTIL, P.U. BLIER, 2010. Thermal sensitivity of cardiac mitochondrial metabolism in an ectothermic species from a cold environment, Atlantic Wolffish (Anarhichas lupus). J. Exp. Mar. Biol. Ecol., 384: 113-118 .

To produce energy, mitochondria use oxidative phosphorylation, a multistep process involving several integrated reactions influenced by temperature. In order to identify which step in the process was most sensitive to temperature in a cold-temperate ectothermic species, we measured the thermal sensitivity of mitochondrial oxidative phosphorylation, as well as the thermal sensitivity of each individual step in this process, in mitochondria isolated from the heart of Atlantic wolffish (Anarhichas lupus). The thermal sensitivity of oxidative phosphorylation (coupled, ADP-stimulated), measured in the presence of pyruvate and malate as substrates, and those of Complexes II and IV activities were the same over the whole range of assay temperatures (5 to 35 °C). In contrast, the thermal sensitivity of Complexes I and III, ATPase, pyruvate dehydrogenase and citrate synthase could not be correlated with the thermal sensitivity of oxidative phosphorylation. The first step in the process of oxidative phosphorylation to be negatively affected by increased temperature was shown to be Complex III, followed by the Complex I. This occurred at temperatures above the tolerance limit and well above the range of temperatures occupied by the species. Our results identify specific steps within the electron transport system as potential control point limiting the capacity of Atlantic wolffish cardiac mitochondrial metabolism in response to changes in temperature.©2009 Elsevier B.V.

DUTIL, J.-D., C. DION, L. GAMACHE, R. LAROCQUE, J.- F. OUELLET, 2010. Ration and temperature effects on the condition of male adolescent molter and skip molter snow crab. J. Shellfish Res., 29(4): 1025-1033 .

This study examined the effects of ration and temperature on the molt of male adolescent snow crab Chionoecetes opilio (O. Fabricius, 1788). In one experiment, crabs were exposed to 1 of 4 treatments, 2 levels of ration and 2 levels of temperature. In a second experiment, all crabs were fed and a 4-level factor was addressed in which temperature was held constant as in experiment 1 (2 levels) or switched from one level to the other. Food consumption declined significantly and at a similar rate over time at both temperatures, several weeks before molt took place. Larger crabs molted to morphometric maturity in a greater proportion with no influence of ration or temperature. Smaller crabs also molted earlier than larger crabs. Temperature had a marked effect on the timing of molt, with crabs kept at a higher temperature molting 1 mo earlier and crabs exposed to shifted temperatures, molting midway between the two other groups. Body density decreased markedly at ecdysis, but was also influenced by ration and temperature particularly in nonmolters; the effect of ration on body density in nonmolters was highly significant. Ration also had a major effect on the size of muscle and digestive gland and their moisture content. Unfed nonmolters were in poor condition, particularly at a higher temperature, whereas molted crabs had large digestive glands associated with high moisture contents, irrespective of treatment. Timing of the migration of snow crabs to shallow and potentially warmer waters in the spring in the Gulf of St. Lawrence might be determined in part by molt requirements. Cold temperatures provide an energetic advantage during the premolt period, when food consumption decreases, but high temperatures result in an earlier molt and a fast recovery during the early postmolt eriod.©2010 Journal of Shelfish Research.

DUTIL, J. -D., S. PROULX, S. HURTUBISE, J. GAUTHIER, 2010. Recent findingl on the life history and catches of wolffish (Anarhichas sp.) in research surveys and in the Sentinel Fisheries and Observer Program for the Estuary and Gulf of St-Lawrence Nouvelles données sur la biologie et les captures de loups (Anarhichas sp.)dans les relevés de recherche, et dans les Pêches sentinelles et le Programme des observateurs pour l’estuaire et le golfe du Saint-Laurent. DFO, Canadian Science Advisory Secretariat, Science Advisory Report, 2010/126, 81 p .

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The three species of wolffish that inhabit the eastern Canadian Coast are considered as being at risk. Two species are listed as threatened (Anarhichas denticulatus, Anarhichas minor) whereas the third species (Anarhichas lupus) is listed as being of special concern. Since 2000 and 2001 when the status of those species was first assessed, the Department of Fisheries and Oceans has taken steps to facilitate their recovery. From a research and monitoring perspective, concrete actions included collecting more data and better data on which to base conservation measures in the future, as well as supporting research on life history, distribution and habitat associations of all three species. The present report reviews recent projects and publications on wolffish based on material collected in the Estuary and Gulf of St. Lawrence and addressing the following topics: fish species assemblages to which wolffish are associated, use of shelters by juvenile spotted wolffish, diving and towed camera surveys, metabolism, growth and reproductive biology, including new tools for fish identification and critical reviews of fish identifications on research surveys. Catch and effort data were aggregated using a grid made up of 100 km2 square cells. The probability of catching wolffish of a given species in a set and within a cell (relative occurrence) was calculated as the ratio of the number of sets in which a species was recorded and the total number of sets made. This method allows the mapping of catch and effort for numerous time series based on data from different programs in both the whole study area (research surveys and Sentinel Fisheries using bottom trawls and a random stratified design) or in specific areas within the Gulf. The method also allows an estimate of surface areas occupied by each species and lends itself to matching area of occupancy and characteristics of the habitat. The data suggest no temporal trend in abundance. Wolffish represent a small biomass compared to other demersal species, with northern wolffish being very rare. The west coast of Newfoundland appears to be a hot spot for the distribution of spotted and striped wolffish in the Gulf.

OUELLET, J.-F., DUTIL, J.-D., T. HURLBUT, 2010. Wolffish (Anarhichas sp.) landings in the estuary and Gulf of St. Lawrence(1960-2009)recorded in commercial fisheries statistics Débarquements de loups (Anarhichas sp.) dans l’estuaire et le golfe du Saint–Laurent (1960-2009) selon les statistiques de pêche commerciale. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2010/125, 38 p .

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Commercial landings data for the wolffishes (Anarhichas denticulatus, Anarhichas minor and Anarhichas lupus) were compiled from Northwest Atlantic Fisheries Organization (NAFO) and Zonal Interchange File Format (ZIFF) files for NAFO divisions 4RST. In both datasets, the landing data were not broken down by species for the period from 1960 to 2004, which precludes species-specific analyses. Since 2005, most landing reports have identified the species landed but fishermen have only been permitted to land Atlantic wolffish (A. lupus). The NAFO statistics indicate that wolffish landings in NAFO divisions 4RST averaged 216 metric tons per year during the period 1960–1998 and the ZIFF statistics indicate an average of 100 metric tons per year during the time period 1985-2009. The reported landings of wolffish occurred mainly during fishing activities directed toward Atlantic cod (Gadus morhua) and 3 species of flatfish. In the ZIFF statistics, the majority of the landings were from division 4R (80.7% of total landed catch in weight, with 13.1% from 4S and only 6.1% from 4T). Subdivisions 4Rb, 4Rc and 4Rd were the hotspots with an average landed catch of 2,112 kg per year per 1,000 km2 for the three species and three sub-divisions combined. Throughout the time series covered by the NAFO statistics (1960–1998) hook and line gears, primarily longlines, were the most important gears followed by bottom trawls. In the ZIFF statistics, which cover a more recent time period than the NAFO statistics (i.e., 1985–2009), longlines and gillnets collectively contributed two thirds of the total number of reports of wolffish landings with longlines accounting for as much as 72.0% of the total landed catch in weight. There was a significant negative trend in LPUE over the period from 1985 to 2009 in 4RST; a similar pattern was observed in the three sub-divisions where longline landings and LPUE were greatest (4Rb, 4Rc, and 4Rd).

LAROCQUE, R., J-D. DUTIL, S. PROULX, M. THORNE, P.-M. SCALLON-CHOUINARD, M.-H. GENDRON, J. PLOURDE, T. SCHMITT, 2010. Contribution à la description de l'habitat des loups de mer (Anarhichas spp.) près de la péninsule gaspésienne par vidéo remorquée et relevés acoustiques multifaisceaux. Rapp. tech. can. sci. halieut. aquat., 2902, 51 p .

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This report presents the results of several initiatives that examine the potential habitat of wolffish (Anarhichas spp.) in the Gulf of St. Lawrence and in particular near the Gaspé peninsula. The habitat features were examined at different spatial scales: by towed video, multibeam acoustic surveys and an examination of historical catch data. High-resolution bathymetry and backscatter coupled with information extracted from video allowed for a detailed description of environments known to be used by wolfish. Features believed to be favourable to wolfish were identified on both survey sites, including shelters and glacial scours. The resulting information is presented within the attached multimedia DVD-ROM. The complimentary nature of these methods and the management implications for a species at risk are discussed.

NOZERES, C., D. ARCHAMBAULT, P.-M. CHOUINARD, J. GAUTHIER, R. MILLER, E. PARENT, P. SCHWAB, L. SAVARD, J.-D. DUTIL, 2010. Guide d'identification des poissons marins de l'estuaire et du nord du golfe du Saint-Laurent et protocoles suivis pour leur échantillonnage lors des releves par chalut entre 2004 et 2008 ; Identification guide for marine fishes of the estuary and northern Gulf of St. Lawrence and sampling protocols used during trawl surveys between 2004 and 2008. Can. Tech. Rep. Fish. Aquat. Sci., 2866, 168 p .

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The annual survey that scientists conduct on large research trawlers is an important source of information on the status of marine resources harvested in the estuary and northern Gulf of St. Lawrence. The main objective of the survey is to estimate the abundance and biomass of five commercially important species, i.e., Atlantic cod (Gadus morhua), Greenland halibut (Reinhardtius hippoglossoides), Acadian (Sebastes fasciatus) and deepwater (Sebastes mentella) redfish, and northern shrimp (Pandalus borealis). For several years, biologists have sought to improve the integration of stock status and ecosystem information, which has required a greater effort to better describe catches of other species of fish and invertebrates. The long-used sampling and observation protocol has evolved into a much more complex, detailed model. However, in implementing this protocol, difficulties have been encountered in accurately identifying ten or so species caught at each trawling station. This report provides a guide to the identification of fish species likely to be caught in surveys in the estuary and northern Gulf of St. Lawrence. This visual guide is designed as a practical tool for training staff and ensuring the quality of data collected. This report also describes the sampling and examination protocol for fish catches used for surveys conducted aboard the CGSS Teleost between 2004 and 2008 and presents a brief descriptive analysis of fish catches during this period.

LACHANCE, A.-A., J.-D. DUTIL, R. LAROCQUE, G. DAIGLE, 2010. Shelter use and behaviour of juvenile Spotted Wolffish (Anarhichas minor) in an experimental context. Environ. Biol. Fishes, 88: 207-215 .

Laboratory experiments were conducted to assess shelter use and behaviour of juvenile Spotted Wolfish, Anarhichas minor, using time-lapse video. Information about the behaviour of Spotted Wolffish and its habitat utilization is sparse due to the great depth at which this species lives. Four experiments were conducted using one or two fish per tank, with and without a shelter. The positions and movements of fish in the tanks and interactions between fish were monitored over 24-h periods. In experiments in which no shelter was available, Spotted Wolffsih spent very little time exploring the water column. They did not show fidelity to a particular area on the bottom of the tank and exhibited few signs of aggressiveness to each other. When a shelter was made available, fish spent most of their time in the shelter or close to the shelter. The presence of a single shelter did not enhance aggressive behaviours in fish kept in pairs. When day and night observations were compared, no clear diel pattern emerged. The Canadian recovery plan for Spotted Wolffish calls for research aimed at describing their use of demersal habitats. The present study suggests that shelter availability might be an important feature of the habitat requirements of juvenile Spotted Wolffish.©2010 Springer

MacGREGOR, R., J.M. CASSELMAN, W.A. ALLEN, T. HAXTON, J.M. DETTMERS, A. MATHERS, S. LAPAN, T.C. PRATT, P. THOMPSON, M. STANFIELD, L. MARCOGLIESE, J4.-D. DUTIL, 2009. Natural heritage, anthropogenic impacts, and biopolitical issues related to the status and sustainable management of American eel : a retrospective analysis and management perspective at the population level. Am. Fish. Soc. Symp., 69: 713-739 .

We examine historical, archaeological, and current patterns in American eel Anguilla rostrata use, abundance, and distribution to improve understanding of current population- level status. Our research indicates that distribution and abundance has changed significantly in response to the cumulative impacts of fishing, turbine mortality, and major loss of freshwater habitat. The 1950–1970 peaks in dam construction and turbine mortalities, together with the unprecedented North American harvests in the 1970s, have lead to a perilous synergy of effects at the population level. Based on our findings, we call for coordinated conservation and management actions for American eel across North America. Preservation of life cycle diversity and coordinated conservation actions are required across the range to ensure continued and improved societal benefits, protect the legacy of cultural and natural heritage values, restore ecological services, and reinstate the benefits to biodiversity provided by this unique and important species. Finally, we describe key elements and recent progress in recovery planning.©2009 American Fisheries Society

DUTIL, J.-D., P. DUMONT, D.K. CAIRNS, P.S. GALBRAITH, G. VERREAULT, M. CASTONGUAY, S. PROULX, 2009. Anguilla rostrata glass eel migration and recruitment in the estuary and Gulf of St Lawrence. J. Fish. Biol., 74: 1970-1984 .

This study describes catches of Anguilla rostrata glass eels and associated oceanographic conditions in the St Lawrence Estuary and Gulf. Ichthyoplankton survey data suggest that they enter the Gulf primarily in May, migrate at the surface at night, and disperse broadly once they have passed Cabot Strait. T hey arrive in estuaries beginning at about mid-June and through the month of July. Migration extends west up to Quebec City, in the freshwater zone of the St Lawrence Estuary, 1000 km west of Cabot Strait. Anguilla roslrata glass eels travel between Cabot Strait and receiving estuaries at a straight-line ground speed of c. 10–15 km day-1. Catches of fish per unit effort in estuaries in the St Lawrence system are much lower than those reported for the Atlantic coast of Canada. Low abundance of A. rostrata glass eels in the St Lawrence system may be due to cold surface temperatures during the migration period which decrease swimming capacity, long distances from the spawning ground to Cabot Strait and from Cabot Strait to the destination waters (especially the St Lawrence River), complex circulation patterns, and hypoxic conditions in bottom waters of the Laurentian Channel and the St Lawrence Estuary.©2009 The Fisheries Society of the British Isles

DUTIL, J.-D., C. NOZÈRES, P.-M. SCALLON-CHOUINARD, L. VAN GUELPEN, D. BERNIER, S. PROULX, R. MILLER, C. SAVENKOFF, 2009. Poissons connus et méconnus des fonds marins du Saint-Laurent. Naturaliste can., 133(2): 70-82 .

[Abstract only available in French]
Des relevés effectués au moyen de chaluts benthiques entre 2004 et 2008 dans le bas Saguenay, l'estuaire maritime et le nord du golfe du Saint-Laurent ont permis d'identifier à l'espèce plus d'un million de poissons. Les captures ont été largement dominées par quatre espèces de prédateurs d'intérêt commercial: le flétan du Groenland, deux espèces de sébaste et la morue franche, mais on a dénombré plus d'une centaine d'espèces dont la moitié peuvent être considérées rares sur les fonds chalutés. Les espèces les plus abondantes dans les captures étaient également celles qui furent répertoriées dans une plus forte proportion des stations échantillonnées. Les espèces inusitées possèdent une distribution soit boréale, soit méridionale, et fréquentent généralement le plateau continental ou même le talus continental au-dessus de la plaine abyssale dans l'Atlantique. Les données issues de ces relevés ne fournissent qu'une vision partielle des communautés de poissons dans le Saint-Laurent: les poissons pélagiques et estuariens étaient mal représentés dans nos échantillons, les fonds rocheux ou escarpés n'étant généralement pas chalutables. Ce vaste territoire d'environ I5O 000 km2 est peuplé d'une faune variée.©2009 La Société Provancher d'histoire naturelle du Canada Certains poissons sont communs, d'autres représentent des visiteurs occasionnels en provenance des profondeurs de l'Atlantique, mais tous sont fascinants. Encore aujourd'hui, l'écologie d'un grand nombre de ces espèces reste mal connue.

MacGREGOR, R., J.M. CASSELMAN, W.A. ALLEN, T. HAXTON, J.M. DETTMERS, A. MATHERS, S. LaPAN, T.C. PRATT, P. THOMPSON, M. STANFIELD, L. MARCOGLIESE, J.-D. DUTIL, 2009. Natural heritage, anthropogenic impacts, and biopolitical issues related to the status and sustainable management of American Eel : a retrospective analysis and management perspective at the population level. Pages 713-739 in A.J. Haro, K.L. Smith, R.A. Rulifson, C.M. Moffitt, R.J. Klauda, M.J. Dadswell, R.A. Cunjak, J.E. Cooper, K.L. Beal & T.S. Avery (eds.). Challenges for diadromous fishes in a dynamic global environment (Am. Fish. Soc. Symp., 69) .

We examine historical, archaecological, and current patterns in American eel Anguilla rostrata use, abundance, and distribution to improve understanding of current population-level status. Our research indicates that distribution and abundance has changed significantly in response to the cumulative impacts of fishing, turbine mortality, and major loss of freshwater habitat. The 1950-1970 peaks in dam construction and turbine mortalities, together with the unprecedented North American harvests in the 1970s, have lead to a perilous synergy of effects at the population level. Based on our findings, we call for coordinated conservation and management actions for American eel across North America. Preservation of life cycle diversity and coordinated conservation actions are required across the range to ensure continued and improved societal benefits, protect the legacy of cultural and natural heritage values, restore ecological services, and reinstate the benefits to biodiversity provided by this unique and important species. Finally, we describe key elements and recent progress in recovery.©2009 American Fisheries Society

DUTIL, J.-D., R. LAROCQUE, S. VALOIS, E. MAYRAND, B. SAINTE-MARIE, 2009. Spatial, annual and seasonal patterns in the condition and muscle size of snow crab. Mar. Biol., 156(9): 1903-1916 .

The extent of spatial (depth and locality) and temporal (season and year) variabilities in condition and relative muscle size (a direct proxy of growth) were examined in male and female adult and non-adult snow crabs Chionoecetes opilio. Condition, determined from the relative size of the digestive gland and moisture content of the muscle and digestive gland, and muscle size, determined as the ratio of merus muscle mass over merus volume, separated as diVerent processes in a principal component analysis. Snow crabs showed a wide range of condition and muscle size values. Overall, the condition was better in non-adult than in adult crabs, with adult females being in worst condition, and muscle size was larger in males than in females. Condition variability was greater for seasonal compared to annual samples, probably reXecting annual molt cycles. In contrast, the muscle size variability was greater for annual compared to seasonal samples, possibly as a result of changing crab abundance and competition intensity during recruitment pulses. Condition and muscle size increased through summer in males and immature females, although to diVerent extents depending on instar, but did not change in adult females. Both condition and muscle size were highly variable at the investigated spatial scales. Condition and muscle size had a signiWcant eVect on gonad size, once the eVect of crab size was removed, suggesting a direct link between these two parameters and reproductive capability.©2009 Springer

MAYRAND, E., J.-D. DUTIL, 2008. Physiological responses of rock crab Cancer irroratus exposed to waterborne pollutants. J. Crust. Biol., 28(3): 510-518 .

This study investigates the impact of waterborne xenobiotics on the rock crabCancer irroratus. Male rock crabs were caged at two polluted sites for five weeks. One site was highly polluted while the other was slightly polluted mainly by metals. A control group was caged in a raceway tank supplied with clean sea water. The activity of branchial ATPases was increased in crabs exposed to pollution, presumably to compensate for the competition of metals with electrolytes and to facilitate the transport of metals out of the cytoplasm. The rock crab was characterized as having high basal levels of glutathione in the digestive gland (˜ 3500 nmol GSH equivalents/g dry weight). Exposure to waterborne pollutants failed to trigger an increase in glutathione concentration, but over time in crabs caged at the highly polluted site it elicited a 26 % increment in the relative mass of the digestive gland which is an important site for glutathione synthesis. Neither cytochrome C oxidase, nor lactate dehydrogenase activity in the merus muscle was affected by pollution. By the end of the experiment, somatic growth rate was highest in the control crabs though the crabs caged at the polluted sites also maintained a positive energy balance. Gonadal growth was delayed at the highly polluted site but the size of the gonads caught up with that of the controls by the termination of the experiment.©2008 The Crustacean Society

LAROCQUE, R., M.-H. GENDRON, J.-D. DUTIL, 2008. A survey of wolffish (Anarhichas spp.) and wolffish habitat in Les Méchins, Quebec. Can. Tech. Rep. Fish. Aquat. Sci., 2786, 35 p .

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Atlantic wolffish (Anarhichas lupus) and spotted wolffish (A. minor) are respectively listed as a species of special concern and as a threatened species under the Species at Risk Act (SARA) in Canada. The objectives of this work were to gather information on a near-shore wolffish population in the St. Lawrence estuary in eastern Quebec, to evaluate methods related to wolffish studies, and to assess the feasibility of wolffish release and in situ monitoring. The local A. lupus distribution was found to be vertically limited by temperature, with wolffish avoiding the surface layer affected by the Gaspé Current. The numbers of fish on the deeper reefs was relatively constant over the two years of the study, with many specimens spending long periods in the same shelters. Winter survival following a fish-release experiment was confirmed by scuba observations. Migration may explain the apparent low success rate of the release effort. Fish pairings and egg masses were observed, and this led to an evaluation of the role of coastal reefs in the life history of Anarhichas spp. A non-intrusive method for measuring fish was used by scuba divers and is described. The use of a high-resolution multibeam sonar survey as a tool for scuba divers and habitat-related work is also discussed.

SMOKOROWSKI, K.E., J.D. DUTIL, 2008. Workshop to compare methods to quantify the productive capacity of fish habitat impacted by hydro operations, October 15-16, 2007, Calgary, Alberta ; Atelier national sur la comparaison de méthodes pour quantifier l'impact de projets hydroélectriques sur la capacité de production de l'habitat du poisson, 15 et 16 octobre 2007, Calgary (Alberta). DFO, Canadian Science Advisory Secretariat, Proceedings Series ; MPO, Secrétariat canadien de consultation scientifique, Série des comptes rendus, 2008/002, 35 p .

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A one and a half day peer review meeting was held in Calgary, Alberta October 15-16, 2007, to provide a scientific review of methods used to measure productive capacity of habitat impacted by hydroelectric operations and development. Participants included national representatives of Fisheries and Oceans Canada (DFO) Science and Habitat Management, industry, academia, and environmental non-government organizations. The purpose of the meeting was to provide a science review of methods obtained from the primary literature, industry and elsewhere for evaluating the productive capacity of fish habitat for projects impacted by hydro. The objectives were as follows: 1. Review list of summarized methods and assess for completeness (i.e., identify missing methods); 2. Group methods according to general approach; 3. Evaluate the applicability of methods to DFO mandate and across systems and development scenarios. Identify systems and referral scenarios not covered; 4. Review, revise, and reach consensus on proposed criteria for evaluating the methods; 5. Select candidate methods for review using agreed-upon criteria; 6. Review selected methods according to criteria to ensure standard application of criteria against any future proposed or amended method; 7. Develop a plan to complete work beyond the workshop. The list of methods was reviewed for completeness and some additions were suggested. The methods were eventually grouped according to use and applicability for assessment and monitoring, and the only development scenario considered to be missing an appropriate method was how to assess the creation of reservoirs. However, no method handled connectivity of habitats or the impacts on estuaries, and all methods lacked adequate scientific validation of predictions. The criteria for evaluating methods were examined, modified, and consensus was reached, however, it was felt that the criteria should not be used to assess new proposed methods outside of a formal peer review process, particularly for large-scale projects. One method was reviewed under the criteria and was considered relatively robust for use in the referral assessment process. There was general agreement that the ‘holy grail’ of creating a national standard method or suite of methods was not feasible at this time. Because of the large spatial scale of hydropower impacts (whole watersheds), specific methods for measuring no-net-loss of productive capacity need to be peer-reviewed on a site-by-site basis in the future. The proceedings will be published on the Canadian Science Advisory Secretariat website and the summary of methods will be published as a Canadian Technical Report of Fisheries and Aquatic Sciences.

DUTIL, J.-D., C. JABOUIN, R. LAROCQUE, G. DESROSIERS, P.U. BLIER, 2008. Atlantic cod (Gadus morhua) from cold and warm environments differ in their maximum growth capacity at low temperatures. Can. J. Fish. Aquat. Sci., 65: 2579-2591 .

Maximum growth rate of Atlantic cod (Gadus morhua) was determined at a range of temperatures representative of cod benthic habitats (1-13 °C) using wild animals obtained from a cold environment (southern Gulf of St. Lawrence stock, SG) and a mild environment (Bay of Fundy stock, BF). SG cod performed well over a broader range of temperatures than BF cod. Growth in mass was greater for SG than BF cod at any temperature below 7 °C. SG cod consumed twice as much food as BF cod at 1 and 3 °C. At 1 °C, growth in mass was positive for SG cod but negative for BF cod, whereas growth in length did not differ from 0 for both SG and BF cod. Liver size represented a larger proportion of body mass in SG cod at both low and high temperatures, and citrate synthase activity in the intestine exhibited a strong inverse relationship to temperature. The maximum growth capacity of SG cod was comparable with that of cod of similar size in various other stocks in the Atlantic. These observations are not consistent with the view that intensive size-selective fishing practices have resulted in a significant loss of innate growth capacity in SG cod.©2008 NRC Canada

BLIER, P.U., J.-D. DUTIL, H. LEMIEUX, F. BÉLANGER, L. BITETERA, 2007. Phenotypic flexibility of digestive system in Atlantic cod (Gadus morhua). Comp. Biochem. Physiol., A: Mol. Integr. Physiol., 146(2): 174-179 .

This study examined the restoration of the digestive capacity of Atlantic cod (Gadus morhua Linnaeus) following a long period of food deprivation. Fifty cod (48 cm, 1 kg) were food-deprived for 68 days and then fed in excess with capelin (Mallotus villosus Müller) on alternate days. Ten fish were sampled after 0, 2, 6, 14 and 28 days and the mass of the pyloric caeca, intestine and carcass determined. Two metabolic enzymes (cytochrome c oxidase and citrate synthase) were assayed in white muscle, pyloric caeca and intestine, and trypsin activity was measured in the pyloric caeca. A delay of 14 days was required before body mass started to increase markedly, whereas most of the increase in mass of both the pyloric caeca and intestine relative to fish length occurred earlier in the experiment. By day 14, the activities of trypsin and citrate synthase in the pyloric caeca as well as citrate synthase in the intestine had reached maxima. The growth of the digestive tissues and restoration of their metabolic capacities thus occur early upon refeeding and are likely required for recovery growth to take place. The phenotypic flexibility of the cod digestive system is therefore remarkable: increases in trypsin activity and size of pyloric caeca resulted in a combined 29-fold increase in digestive capacity of the fish during the refeeding period. Our study suggests that Atlantic cod are able to cope with marked fluctuations in food availability in their environment by making a rapid adjustment of their digestive capacity as soon as food availability increases.© 2006 Elsevier Inc.

SCALLON-CHOUINARD, P.-M., J.-D. DUTIL, S. HURTUBISE, 2007. Liste des espèces de poissons inventoriés dans l’estuaire maritime du Saint-Laurent entre 1930 et 2005. Rapp. tech. can. sci. halieut. aquat., 2719, 64 p .

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Data concerning species of fish that inhabit the lower St. Lawrence Estuary, i.e., the section between Ile Rouge and Pointe des Monts, are fragmentary particularly for those species not harvested commercially. There is no account of each species distribution in the area, not to mention their life history. The present report provides an exhaustive list of fish species reported in the lower St. Lawrence Estuary. Three sources of information were examined, primary publications and reports, and two data bases, DFO’s At-Sea Observer Program data base (landings, 1991-2005) and DFO’s annual groundfish and northern shrimp abundance survey for the estuary and northern Gulf of St. Lawrence area (1978 - 2003). The lower St. Lawrence Estuary has a diversified fish fauna: reliable or multiple data sources have recorded and confirmed 99 species. These species belong to 80 different genus and 41 different families. Many of those species may reside in the study area whereas others are rare or occasional visitors or transit through the area en route to freshwater or the Gulf of St. Lawrence. Only 25 of those species were reported for the Manicouagan marine protected area during the same period

SYLVESTRE, E.-L., D. LAPOINTE, J.-D. DUTIL, H. GUDERLEY, 2007. Thermal sensitivity of metabolic rates and swimming performance in two latitudinally separated populations of cod, Gadus morhua L.. J. Comp. Physiol. B, 177: 447-460 .

Atlantic cod populations live in a wide thermal range and can differ genetically and physiologically. Thermal sensitivity of metabolic capacity and swimming performance may vary along a latitudinal gradient, to facilitate performance in distinct thermal environments. To evaluate this hypothesis, we compared the thermal sensitivity of performance in two cod stocks from the Northwest Atlantic that differ in their thermal experience: Gulf of St Lawrence (GSL) and Bay of Fundy (BF). We first compared the metabolic, physiological and swimming performance after short-term thermal change to that at the acclimation temperature (7 °C) for one stock (GSL), before comparing the performance of the two stocks after short-term thermal change. For cod from GSL, standard metabolism (SMR) increased with temperature, while active metabolism (AMR, measured in the critical swimming tests), EMR (metabolic rate after an exhaustive chase protocol), aerobic scope (AS) and critical swimming speeds (Ucrit and Ub-c) were lower at 3 °C than 7 or 11 °C. In contrast, anaerobic swimming (sprint and burst-coasts in Ucrit test) was lower at 11 than 7 or 3 °C. Factorial AS (AMR SMR-1) decreased as temperature rose. Time to exhaustion (chase protocol) was not influenced by temperature. The two stocks differed little in the thermal sensitivities of metabolism or swimming. GSL cod had a higher SMR than BF cod despite similar AMR and AS. This led factorial AS to be significantly higher for the southern stock. Despite these metabolic differences, cod from the two stocks did not differ in their Ucrit speeds. BF cod were better sprinters at both temperatures. Cod from GSL had a lower aerobic cost of swimming at intermediate speeds than those from BF, particularly at low temperature. Only the activity of cytochrome C oxidase (CCO) in white muscle differed between stocks. No enzymatic correlates were found for swimming capacities, but oxygen consumption was best correlated with CCO activity in the ventricle for both stocks. Overall, the stocks differed in their cost of maintenance, cost of transport and sprint capacity, while maintaining comparable thermal sensitivities.©2007 Springer-Verlag

DUTIL, J.-D., E.-L. SYLVESTRE, L. GAMACHE, R. LAROCQUE, H. GUDERLEY, 2007. Burst and coast use, swimming performance and metabolism of Atlantic cod Gadus morhua in sub-lethal hypoxic conditions. J. Fish Biol., 71(2): 363-375 .

Prolonged swimming capacity (critical swimming speed, Ucrit, protocol) and metabolism were measured for 14 Atlantic cod Gadus morhua exposed to seven oxygen levels within the non-lethal range normally encountered in the Gulf of St Lawrence (35 to 100 % saturation). Burst-and-coast swimming was triggered earlier (at lower speeds) in hypoxia, and burst-and-coast movements were more frequent in hypoxia than in normoxia at low speeds. Furthermore, the metabolic scope beyond the metabolic rate at which Atlantic cod resorted to burst-and-coast movements decreased gradually as ambient oxygen concentration dropped. Overall, fewer burst-and-coast movements were observed in hypoxia while the distance swum in burst-and-coast mode remained c. 1 % of the total distance swam in all tests. Oxygen availability had no effect on the rate of increase in metabolic rate with increasing velocity <50 cm s-1, but limited swimming performances and metabolic rate at higher speeds. The prevailing low oxygen tensions on the bottom in the deep channels may impair the swimming capacity of Atlantic cod in the estuary and northern Gulf of St Lawrence. ©2007 Crown in Right of Canada

LAPOINTE, D., H. GUDERLEY, J.-D. DUTIL, 2006. Changes in the condition factor have an impact on metabolic rate and swimming performance relationships in atlantic cod (Gadus morhua L.). Physiol. Biochem. Zool., 79(1): 109-119 .

In the field, Atlantic cod face seasonal changes in food availability that in turn lead to changes in condition. To examine the physiological consequences of these changes in condition, we measured routine metabolic rate (RMR) to estimate standard metabolic rate (SMR), active metabolic rate (AMR), aerobic scope, critical swimming speed (Ucrit), cost of transport, sprint performance, time to exhaustion, and postexhaustion metabolic rate (EMR) for 24 Atlantic cod from the Gulf of St. Lawrence. Cod were measured at their initial condition (condition factor of 0.676 ± 0.076) and after 9 wk of feeding (condition factor of 0.923 ± 0.096). These levels of condition are representative of wild cod in the Gulf of St. Lawrence during the spring and during the fall-early winter, respectively. The improved condition did not change mass-specific SMR. However, mass-specific AMR, aerobic scope, and EMR decreased with the improvement in condition. The various measures of swimming performance were affected differently. Ucrit increased and cost of transport at 1.3 and 1.5 body lengths s-1 decreased with improved condition, but the cost of transport at 0.3, 0.9, 1.1, 1.7, and 1.9 body lengths s-1, sprint performance, and time to exhaustion did not change. Hierarchies for the speed at first burst-coast, the proportion of U crit supported by burst-coasts, and time to exhaustion were maintained with the improvement in condition. The relationships between metabolic rates and swimming performance differed with condition level, with stronger correlations apparent in the cod at their initial condition. Given the low condition of wild cod stocks, these responses indicate that reduced performance, due to both maintenance of metabolic expenditures and modified swimming capacities, may impair survival under conditions of reduced food availability.© 2006 The University of Chigago

DUTIL, J.-D., G. GODBOUT, P.U. BLIER, D. GROMAN, 2006. The effect of energetic condition on growth dynamics and health of Atlantic cod (Gadus morhua). J. Appl. Ichthyol., 22(2): 138-144 .

Prolonged starvation resulting in sublethal condition factor values was hypothesized to have a detrimental effect on shortterm growth capacity upon refeeding. Cod (Gadus morhua) were food-deprived and their length and mass measured before refeeding and after 3, 6, 9 and 12 weeks of ad libitum feeding. Total mass increase during the first 3 weeks of feeding was greatest in fish with a higher initial condition factor. The reverse situation was observed during the last 3 weeks of feeding. Specific growth rate peaked in the period from week 4 to week 6, except in cod with the highest condition factor for which a steady decline in specific growth rate was observed, and was not influenced by the condition factor at the start of the feeding period. Total mass increase over 12 weeks was also not influenced by initial condition factor. Thus by the end of the experiment, condition factors were lowest in fish with initially low condition factors. The hepatosomatic index and gonadosomatic index did not differ at the end of the experiment, but the proportion of mature cod increased with increasing initial condition factor. A disease outbreak caused significant mortalities among fish shortly after the start of the feeding period. Forty-one percent of the fish had died after 84 days. No mortality was observed among fish that had started the experiment with the highest condition factor. Mortality was inversely related to initial condition factor. Growth was examined for survivors exclusively. Poor condition in wild fish may increase vulnerability to diseases and compensatory growth may not allow cod with low condition factors to fully recover unless food availability remains high over a long period of time. © 2006 The Authors. Journal compilation © 2006 Blackwell Verlag, Berlin.

DUTIL, J.-D., R. MILLER, C. NOZÈRES, B. BERNIER, D. BERNIER, D. GASCON, 2006. Révision des identifications de poissons faites lors des relevés scientifiques annuels de l'abondance des poissons de fond et de la crevette nordique dans l'estuaire et le nord du golfe du Saint-Laurent. Rapp. manus. can. sci. halieut. aquat., 2760, 87 p .

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Long time series of data are a source of invaluable information to put a current situation in a historical perspective. The data obtained from the scientific research surveys for the assessment of demersal fish and northern shrimp abundance conducted annually in the estuary and northern Gulf of St. Lawrence are regularly used for this purpose. The validity of these data is not questioned with regard to the identification of commercial species managed by our region, but this overall statement may not apply as well to the identification of non commercial fish species. Following a workshop held at IML in 2005, a working group has determined whether the data on the identification of non commercial species and commercial species not being managed by our region and collected between 1978 and 2003 are valid. For these species, the sampling protocol varied markedly over time. Not all fish were identified to the species level and in many instances very broad taxonomic levels were used. The identification of some species was inadequate, particularly in the Cottidae, Liparidae and Zoarcidae families. Overall, this data set must be used with caution if one is interested in the rare species, in measuring biodiversity, or in studying the temporal trends in the case of the species which are not managed by our region. In this report, we identify the weaknesses and suggest solutions to improve quality in the historical data as well as in the process of acquisition of new data.

FRIEDLAND, K.D., L.M. CLARKE, J.-D. DUTIL, M. SALMINEN, 2006. The relationship between smolt and postsmolt growth for Atlantic salmon (Salmo salar) in the Gulf of St. Lawrence. Fish. Bull., 104(1): 149-155 .

DUTIL, J.-D., J. GAUTHIER, A. FRÉCHET, M. CASTONGUAY, Y. LAMBERT, P. OUELLET, 2005. Northern Gulf of St. Lawrence (NAFO 3Pn and 4RS). Pages 105-113 in K. Brander (ed.). Spawning and life history information for North Atlantic cod stocks. International Council for the Exploration of the Sea (ICES Coop. Res. Rep., 274) .

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LEMIEUX, H., J.-D. DUTIL, H. GUDERLEY, R. LAROCQUE, 2004. Growth, starvation and enzyme activity in white muscle of Atlantic cod: at what point do muscle metabolic capacities change?. Mar. Fresh. Behav. Physiol., 37(4): 287-294 .

Muscle protein decreases only during prolonged starvation of Atlantic cod (Gadus morhua, Gadidae), but in the absence of protein renewal, muscle metabolic capacities may decrease before marked loss of muscle protein. This study aimed at elucidating the threshold at which decreases in growth and condition reduce muscle metabolic capacities, as well as identifying the indicators that best explain changes in metabolic capacities. To generate a wide spectrum of individual growth rates, condition factors and proximate compositions, cod showing different initial condition were fed or starved for different periods of time. The relationships between muscle proteins and metabolic enzyme activities (LDH and CCO) on one hand, and growth rate, condition factor, hepato- and gonadosomatic index and muscle and liver water and energy contents, on the other hand, were examined through linear regression models. Multiple linear regressions explained a large proportion of the observed variability in proteins and enzyme activities. Changes in LDH and CCO activities were not driven by changes in growth rate. Muscle water was the only significant correlate for both enzymes. Enzyme activities decreased as soon as muscle water began to rise. Increases in water content from 79 to 92 % resulted in a 10-fold decrease in LDH and CCO activities.©2004 Taylor & Francis Ltd

MARTINEZ, M., M. BÉDARD, J.D. DUTIL, H. GUDERLEY, 2004. Does condition of Atlantic cod (Gadus morhua) have a greater impact upon swimming performance at Ucrit or sprint speeds?. J. Exp. Biol., 207: 2979-2990 .

To compare the sensitivity of sprint and critical (Ucrit) swimming speeds to the condition of Atlantic cod (Gadus morhua) and to identify the best anatomic, behavioural and biochemical correlates of these types of swimming, we established two groups of cod that were fed or starved for 12 weeks. We evaluated sprint swimming and Ucrit performance as well as the speed at which repeated burst-coast movements began in the Ucrit test before measuring the metabolic capacities of red and white muscle sampled caudally, centrally and rostrally and the anatomic characteristics of the cod. White muscle lactate was measured directly after the Ucrit test. As expected, the twofold difference in Fulton's condition factor (0.5±0.04 for starved and 1.0±0.1 for fed cod) was accompanied by large differences in the anatomic and biochemical parameters measured. Despite the relative sparing of muscle aerobic capacity during starvation and despite the greater use of oxidative fibres during Ucrit compared with sprint swimming, these types of swimming differed by much the same extent between starved and fed cod. In the Ucrit tests, white muscle lactate levels and lactate accumulation per burst-coast movement were considerably higher in fed than starved cod, suggesting more intensive use of fast muscle fibres in cod in good condition. Multiple regression analysis indicated strong correlations between Ucrit, the speed at which regular burst-coasting began and the activity of pyruvate dehydrogenase (PDH) in red muscle (both caudal and central positions). PDH activity may limit the rate of oxidative ATP production by red muscle. The activity of cytochrome c oxidase in rostral white muscle was the strongest correlate of sprint swimming, suggesting that aerobic preparation of white muscle facilitates rapid contraction. The correlation between Ucrit and sprint swimming was weak, perhaps due to inter-individual differences in sensitivity during sprint tests.©2004 The Company of Biologists

DUTIL, J.-D., Y. LAMBERT, D. CHABOT, 2003. Winter and spring changes in condition factor and energy reserves of wild cod compared with changes observed during food-deprivation in the laboratory. ICES J. Mar. Sci., 60: 780-786 .

MARTINEZ, M., H. GUDERLEY, J.D. DUTIL, P.D. WINGER, P. HE, S.J. WALSH, 2003. Condition, prolonged swimming performance and muscle metabolic capacities of cod (Gadus morhua). J. Exp. Biol., 206(3): 503-511 .

DUTIL, J.-D., K. BRANDER, 2003. Comparing productivity of North Atlantic cod (Gadus morhua) stocks and limits to growth production. Fish. Oceanogr., 12: 502-512 .

GUDERLEY, H., D. LAPOINTE, M. BÉDARD, J.-D. DUTIL, 2003. Metabolic priorities during starvation :enzyme sparing in liver and white muscle of Atlantic cod, Gadus morhua. Comp. Biochem. Physiol., Part A, 135: 347-356 .

McGRATH, K.J., J. BERNIER, S. AULT, J.-D. DUTIL, K. REID, 2003. Differentiating Downstream Migrating American Eels Anguilla rostrata from Resident Eels in the St. Lawrence River. Am. Fish. Soc. Symp., 33: 315-327 .

DUTIL, J.-D., J. GAUTHIER, A. FRÉCHET, D. CHABOT, 2003. Cod stocks rebuilding and fish bioenergetics: low productivity hypothesis ; Le rétablissement des stocks de morue et la bio-énergique des poissons: l'hypothèse d'une faible productivité. DFO, Canadian Science Advisory Secretariat, Research Document ; DFO, Canadian Science Advisory Secretariat, Research Document, 2003/060, 39 p .

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The lack of response of several cod stocks and other species to management regulations expected to promote stock rebuilding is hypothesized to stem from a combined (multiplicative) effect of 3 factors : 1. natural intrinsic productivity is low; 2. natural intrinsic productivity has declined; 3. pressures on production associated with natural and fishing mortality have remained high or have increased relative to these stocks/species rates of production. Annual production per capita and per unit biomass varies among stocks, with northerly distributed stocks or stocks inhabiting cold and sometimes hypoxic environments being notably less productive than other stocks. Cod in less productive stocks grow slowly, recruit at an older age, become sexually mature at a later age and a smaller size and produce fewer eggs. Fish condition is on average lower and varies much more in these stocks compared to other stocks. Environmental conditions have changed progressively after the mid ‘80s with conditions during the moratorium not favorable to cod production in northern areas of the western North Atlantic. Fish stocks in these areas have thus become less productive and hence less resilient, i.e., less able to resist and respond to perturbations, whether man-made or environmental. There are several recent indications that individual performance has improved, but fishing pressure has not been relaxed sufficiently to offset increased predation pressures and low productivity associated with limiting environmental conditions. These stocks are unable to produce new biomass fast and as a result stock rebuilding is expected to take much longer than would be predicted for other stocks living in more favorable environments, particularly if exploited under enduring adverse environmental conditions. Strengths and weaknesses of this hypothesis are discussed.

BÉLANGER, F., P.U. BLIER, J.-D. DUTIL, 2002. Digestive capacity and compensatory growth in Atlantic cod (Gadus morhua). Fish. Physiol. Biochem., 26: 121-128 .

The objective of this study was to examine whether digestive capacity correlates with growth rate in Atlantic cod (Gadus morhua). Ninety fish (1035±240 g; 478±36 mm) were assigned to one of three treatments: deprived of food for 5 weeks and then re-fed for 24 days, deprived for 10 weeks and then re-fed for 24 days, or fed for 24 days without deprivation (controls). Three times a week during feeding, the fish were provided with meals of capelin (Mallotus villosus) in excess. Within each treatment, ten fish were sacrificed before and twenty after the feeding period. The relative masses of the pyloric caeca, intestine, and white muscle were determined. Cytochrome c oxidase (CCO), citrate synthase (CS), and nucleoside diphosphate kinase (NDPK) activities were assayed in the pyloric caeca, intestine, and muscle as was trypsin activity in the pyloric caeca. During the re-feeding period, fish that had been deprived of food for 10 weeks showed compensatory growth, growing 1.9 times faster than the controls (0.94±0.26 versus 0.50±0.31 % body mass ·day-1). Fish that displayed compensatory growth had a lower relative white muscle mass than controls (66.5±4.1 % vs.69.6± 7.4 %) while the relative masses of the pyloric caeca (2.21±0.49 % vs. 1.78±0.31 %) and intestine (0.95±0.20 % vs. 0.77±0.15 %) were greater than the controls, suggesting that the sizes of these digestive tissues might correlate with compensatory growth capacity. Citrate synthase in the pyloric caeca was the only enzyme that showed higher activity during compensatory growth (8.57±0.94 U·g tissue-1 compared to 7.13±1.03 U·g tissue-1 in the control group). This suggests that aerobic catabolic capacity of pyloric caeca could be related to growth capacity during recovery, possibly via the energetic cost of digestive enzyme synthesis.©2003 Kluwer Academic Publishers

DUTIL, J.-D., D. CHABOT, 2002. Impact of hypoxia on Atlantic cod in the northern Gulf of St. Lawrence. Pages 51-60 in R.V. Thurston (ed.). Fish Physiology, Toxicology and Water Quality : proceedings of the Sixth International Symposium, La Paz, B.C.S. Mexico, January 22-26, 2001 .

Oxygen levels range from 70 to 30 % saturation or less in waters deeper than 175 m in the Gulf of St. Lawrence. The potential impact of hypoxia on two stocks of Atlantic Cod (Gadus morhua) that live in the Gulf of St. Lawrence was investigated. In a first experiment (84 days, three meals per week), cod were raised under six oxygen treatments between 45 and 93 % saturation. Growth and food ingestion were limited by oxygen below 70 % saturation. In a second experiment (56 days), we varied meal frequency (one, three, and seven meals per week) for cod held at two regimes of dissolved oxygen (40 and 90 % saturation). In normoxia, growth was significantly reduced at one meal per week compared to three and seven meals per week. In hypoxia, however, there was no difference in growth between the three feeding frequencies. At one meal per week, growth was equally poor at both oxygen levels. At three and seven meals per week, growth was faster in normoxia than in hypoxia, although this was significant only at the highest feeding frequency. In both experiments, food consumption explained practically all of the variability in growth rate.Crown©2002

GODBOUT, G., J.-D. DUTIL, D. HARDY, J. MUNRO, 2002. Growth and condition of post-moult male snow crab (Chionoecetes opilio) in the laboratory. Aquaculture, 206: 323-340 .

MARTINEZ, M., H. GUDERLEY, J.A. NELSON, D. WEBBER, J.-D. DUTIL, 2002. Once a fast cod, always a fast cod : maintenance of performance hierarchies despite changing food availability in cod (Gadus morhua). Physiological and biochemical zoology, 75(1): 90-100 .

DUTIL, J.-D., M. CASTONGUAY, D. GILBERT, D. GASCON, 2002. Production analyses for cold-water and warm-water stocks and their use to predict surplus production. Pages 50-54 in N. Anderson, G. Ottersen & D. Swain (ed.). Report of the ICES/GLOBEC Workshop on the Dynamics of Growth in Cod. International Council for the Exploration of the Sea (ICES Coop. Res. Rep., 252 .

Surplus and net production per capita became nil or negative in the mid-1980s in the northern Gulf of St. Lawrence (Dutil et al., 1999). This situation was partly explained by a marked decline in growth production and is consistent with smaller sizes-at-age (Chouinard and Fréchet 1994) but also lower condition factor values during the same period (Lambert and Dutil 1997). The nutritional condition of cod in the Gulf of St. Lawrence varies markedly both seasonnally and annually (Lambert and Dutil 1997, Schwalme and Chouinard 1999) and this has been found to be associated with changes in swimming capacity (unpublished data), reproductive investment (Lambertet al., 2000, Lambert and Dutil 2000) and risks of natural mortality (Dutil and Lambert 2000; and unpublished data). Positive slopes between size-at-age and temperature suggested faster growth rates at higher temperatures for northern Gulf cod, but correlations between size-at-age and temperature were not significant (Dutil et al., 1999). Production analyses conducted for the northern Gulf of St. Lawrence were extended to other stocks. Growth production was assessed in order to determine its variability among and within stocks as a first step to measure its impact on the stock biomass.©2008 ICES

LAMBERT, Y., J.D. DUTIL, 2001. Food intake and growth of adult Atlantic cod (Gadus morhua L.) reared under different conditions of stocking density, feeding frequency and size-grading. Aquaculture, 192: 233-247 .

CHABOT, D., J.-D. DUTIL, C. COUTURIER, 2001. Impact of chronic hypoxia on food ingestion, growth and condition of Atlantic cod, Gadus morhua. ICES C.M., 2001/V:05, 17 p .

DUTIL, J.-D., G. GODBOUT, F. BÉLANGER, P. BLIER, 2001. The effect of energetic condition on growth in cod (Gadus morhua). ICES C.M., 2001/V:11, 19 p .

Following periods of weight losses due to food shortages, refed fish experience a period of fast growth which may compensate for negative growth periods. Prolonged starvation was hypothesized to have a detrimental effect on the growth capacity of fish with sub-lethal condition factor values. Two experiments were conducted. The increased relative mass of the pyloric caeca and intestine relative to body mass following food deprivation in one of the experiments suggests that growth compensation is associated with an increased capacity of cod to produce digestive enzymes and to absorb nutrients across the gut wall. Cod were food deprived in the other experiment, so as to achieve a range of condition factors. Size was measured before refeeding and after 3, 6, 9 and 12 weeks of ad libitum feeding. Maximum growth occurred in the first 3 weeks in controls and declined after 6 weeks with very slow growth being observed in the last 3 weeks of the experiment. In contrast, cod with low condition factors experienced very slow growth in the first 3 weeks and maximum growth after 6 and 9 weeks of feeding. Weight gains over a period of 12 weeks were nearly identical in all groups. By the end of the experiment, condition factors were lower in fish with lower initial condition factors. These results suggest that compensatory growth would not allow cod with low condition factors to fully recover over a 3 month period of high food availability. The potential impact of partial recovery on survival is discussed.©2001 ICES

LE FRANÇOIS, N.R., J.-D. DUTIL, P. BLIER, K. LORD, D. CHABOT, 2001. Tolerance and growth of juvenile common wolffish (Anarhichas lupus) under low salinity and hypoxic conditions: preliminary results. AAC Spec. Publ., 4: 57-59 .

Juvenile wolffish salinity and hypoxia tolerance were investigated at constant water temperature (10 °C). Twenty fish (mean weight 0.11g) were transferred directly to 0 (FW), 7, 14, 21, 28 and 35 ppt water in a closed-circulation system to assess salinity tolerance. No fish survived more than 6h in FW, however, mortality was negligible at 0-0.05 % for the other groups. A second challenge test using O.408-g fish, was conducted for 72 h at 0 to 7 and 28 ppt. Cumulative mortality was 100 % in FW and was down to 33 % at 6 ppt after 72 h. No mortalities occurred between 7 and 28 ppt. A 2O-day growth trial was performed using the survivors from the first challenge test (7, 14, 21, 28, and 35 ppt). This indicated no detrimental growth effect at salinities as low as 7 ppt. Protein content and total length were significantly higher at lower salinities. The impact of low oxygen tension on the survival of 1 +juveniles (average weight - 40 g) was also examined (LC50 96 hours; 16, 22, 28, 34, 40 and 100 % oxygen saturation). No fish survived at 16 % saturation; however, no mortality occurred beyond 22 %. The impact of low oxygen tension on growth performance is underfurther investigation.©2001 Aquaculture Association of Canada

COTTRILL, R.A., R.S. McKINLEY, G. VAN DER KRAAK, J.-D. DUTIL, K.B. REID, K.J. McGRATH, 2001. Plasma non-esterified fatty acid profiles and 17β-oestradiol levels of juvenile immature and maturing adult American eels in the St. Lawrence River. J. Fish Biol., 59: 364-379 .

DUTIL, J.-D., Y. LAMBERT, 2000. Natural mortality from poor condition in Atlantic cod (Gadus morhua). Can. J. Fish. Aquat. Sci., 57: 826-836 .

The extent of energy depletion was assessed in Atlantic cod (Gadus morhua) in spring and early summer (1993-1995) to assess relationships between poor condition and natural mortality. Several indices of condition were compared in wild fish in the northern Gulf of St. Lawrence and in fish exposed to a prolonged period of starvation in laboratory experiments. Discriminant analyses classified only a small fraction of the wild fish as similar to cod that did not survive and a much larger fraction as similar to cod that survived starvation. This percentage increased from April to May and peaked in June 1993 and 1994. Condition factor and muscle somatic index allowed a clear distinction between live and dead fish. Muscle lactate dehydrogenase activity suggested that cod had experienced a period of negative growth early in 1993, 1994, and 1995. Fish classified as similar to starved individuals were characterized by a higher gonad to liver mass ratio than others. Reproduction may have a negative impact on survival not only in spring but also later into summer, as some individuals were found not to have recovered by late summer. This study shows that natural mortality from poor condition contributed to lower production in the early 1990s.

MAYRAND, E., J.-D. DUTIL, H. GUDERLY, 2000. Changes in muscle of postmoult snow crabs Chionoecetes opilio (O. Fabricius) fed different rations. J. Exp. Mar. Biol. Ecol., 243: 95-113 .

Somatic growth, muscle cell condition and metabolism, and gonadal production have been studied in male snow crabs Chionoecetes opilio fed 0, 0.4 and 2 g•animal-1•day-1 and sampled 5, 25, and 60 days after the terminal moult. Twenty-five days after moulting, muscle growth rate was low in crabs fed a high ration and negative in the other groups, and no gonadal production took place. This suggests that the energy was utilised in priority to sustain a high maintenance metabolism. Between 25 and 60 days post-moult, maintenance costs were apparently lower and more energy was directed, in decreasing order of priority, towards gonadal production, which was independent of food ration, muscle growth and reserve build-up in the digestive gland, the two latter being directly related to food ration. Starvation caused the death of merus muscle cells, as indicated by the significant decrease in DNA content, but after 60 days the size of the remaining cells (protein:DNA ratio) had increased as much as that of crabs fed a high ration. It may be a better strategy to maintain fewer cells, by using material and energy obtained from the sacrificed ones, than to keep all cells in a deficient state. Crabs fed a high ration filled the new larger exoskeleton through hypertrophy and hyperplasia. After 25 days of undernutrition, the reduced number of muscle cells relatively to the merus volume was counterbalanced by an enhanced activity of phosphofructokinase (PFK), citrate synthase (CS) and cytochrome C oxidase (CCO) per g of muscle dry weight. An inverse relationship between food ration and enzyme activity per g dry weight further attenuated the effect of food ration on the enzyme total activity in the whole merus muscle. After 60 days of starvation, the still high enzyme activity per g dry weight could no longer compensate for the continuing loss of cells and, at that time, the enzyme total activity was directly related to food ration. Our results suggest that the feeding status of wild crabs may affect their locomotor ability through effects on muscle capabilities.©2000 Elsevier Science B.V.

LAMBERT, Y., J.-D. DUTIL, P. OUELLET, 2000. Nutritional condition and reproductive success in wild fish populations. Pages 77-84 in Norberg (ed.). Proceeding of the 6th international symposium on the reproductive physiology of fish, 4-9 July 1999 .

LAMBERT, Y., J.-D. DUTIL, 2000. Energetics consequences of reproduction in Atlantic cod (Gadus morhua) in relation to spawning level of somatic energy reserves. Can. J. Fish. Aquat. Sci., 57: 815-825 .

The influence of a lower condition on reproductive investment, somatic energy losses, and postspawning condition of Atlantic cod (Gadus morhua) was examined under the hypothesis that females, in response to lower available energy reserves, would reduce reproductive investment in order to limit somatic energy losses. Laboratory experiments revealed that female cod with high prespawning condition factors ended reproduction in better condition than females with low prespawning condition factors. Fecundity and total egg dry weight were significantly lower in poor-condition females. The loss in somatic mass and energy in these poor-condition females was nevertheless higher, in relative terms, than the losses experienced by females in good condition. Consequently, energy reserves invested in reproduction by poor-condition females increase their risk of mortality. In the northern Gulf of St. Lawrence during the early 1990s, reproductive females had lower fecundities and were in worse prespawning and postspawning condition. The condition of spent females suggested a greater impact of changes in environmental conditions on adult than on immature cod. Reproductive potential and possibly recruitment may have suffered from that situation and could have contributed to the failure of that stock to recover despite the moratorium on commercial fishing.

MARTINEZ, M., J.-D. DUTIL, H. GUDERLEY, 2000. Longitudinal and allometric variation in indicators of muscle metabolic capacities in Atlantic cod (Gadus morhua). J. Exp. Zool., 287: 38-45 .

HARDY, D., J.D. DUTIL, G. GODBOUT, J. MUNRO, 2000. Survival and condition of hard shell male adult snow crabs (Chionoecetes opilio) during fasting at different temperatures. Aquaculture, 189: 259-275 .

DUTIL, J.-D., M. CASTONGUAY, D. GILBERT, D. GASCON, 2000. Production analyses for cold-water and warm-water stocks and their use to predict surplus production. Pages 61-65 in N.G. Andersen, G. Ottersen & D.P. Swain (ed.). Report of the ICES/GLOBEC workshop on the dynamics of growth in cod, Dartmouth, Canada, 8-10 May 2000 (ICES C.M., 2000/C:12) .

DUTIL, J.-D., Y. LAMBERT, D. CHABOT, 2000. Estimating natural mortality of wild cod from controlled feeding and starvation experiments conducted in the laboratory. ICES C.M., 2000/R:01, 16 p .

The contribution of individual factors to the rate of natural mortality is usually unknown because it can hardly be measured in the wild, particularly in large ecosystems. Atlantic cod experienced a decline of their nutritional condition in the early 1990s in the Gulf of St. Lawrence. Whether or not natural mortality increased as a result of that decline was determined from controlled experiments conducted in the laboratory. The maximum range of several variables reflecting the nutritional condition of fed and unfed cod >30 cm was determined. By comparing values observed in the wild and in the laboratory, we concluded that wild cod may die of inanition during the spring period. The decline in the nutritional condition of wild cod from January to April was slower however than in cod deprived of food during a similar period of time in laboratory experiments. This indicates that cod fed but did not meet their energy requirements in winter prior to spawning. In contrast, the decline in condition from April to May matched the rate observed in the laboratory experiments, indicating that wild cod probably fast at this time. Estimates of survival probability based on the frequency distribution of condition factor during the spawning period appear to be unbiased as the rate of energy mobilization observed in the field never exceeded the rate observed in the laboratory.©2000 ICES

DUTIL, J.D., C. ROLLET, R. BOUCHARD, W.T. CLAXTON, 2000. Shell Strength and carapace size in non-adult and adult male snow crab (Chionoecetes opilio). J. Crust. Biol., 20(2): 399-406 .

Cannibalism occurs in snow crab and has been observed both in the wild and in the laboratory, but crabs larger than 60 mm CW are not killed by large male adult snow crabs either in the wild or in laboratory experiments. We tested the hypothesis that cannibalism failed to occur as smaller snow crabs became large enough to resist the force of larger male snow crabs. Chela force and resistance of the cuticle to loading were compared. Chela, merus, and carapace cuticles differed markedly in mechanical properties. The Chela was hard compared to the merus which was the most flexible cuticle. Strength of the cuticle generally increased with size of crab, but decreased markedly at molting and remained low for several months past molting. The mechanical advantage (MA) of the chela was larger in adult than in non-adult snow crabs of similar size. The force of the Chela was calculated from MA and previously documented size and contractile force of the closer muscle. Closing force at the first denticle on the dactyl of large male adult snow crabs was large enough to break the cuticle of non-adult and adult snow crab of any size. Only crabs less than 60 mm CW, however, were vulnerable to forces delivered at the tip of the dactyl of large adult, but not of large non-adult, snow crab. Factors other than strength of the cuticle may explain size-selective cannibalism.©2000 The Crustacean Society

MAYRAND, E., H. GUDERLEY, J.-D. DUTIL, 2000. Biochemical indicators of muscle growth in the snow crab Chionoecetes opilio (O. Fabricius). J. Exp. Mar. Biol. Ecol., 255: 37-49 .

This study examined the relationship between muscle growth rate, the activity of metabolic enzymes and the RNA:DNA ratio, in adult snow crabs Chionoecetes opilio. After moulting, crabs were assigned to three feeding rations to attain a range of tissue growth rates. Muscle growth rate, estimated by the variation in dry tissue content per ml of merus of the first walking leg, was positively correlated with changes in muscle cell number, as evaluated by the DNA content per ml of merus. However, no significant correlation was detected between growth rate and the variation in muscle cell size, the later being estimated by the change in the protein:DNA ratio. This is due to the fact that, in starved crabs, a reduction in the number of cells is partially compensated by a size increment of the remaining ones. This phenomenon also weakened the overall relationship between muscle growth rate and the phosphofructokinase (PFK) capacity per ml of merus. The simple correlation between those two variables was significantly positive for animals wich increased their mass of muscle but insignificant for those wich were loosing muscle mass. The lactate dehydrogenase (LDH), citrate synthase (CS) and cytochrome c oxydase (CCO) capacity per ml of merus did not match the growth rate. The significant simple correlations that were detected between growth rate and the various enzyme activity expressed per g of protein, peraeg of DNA and per g of dry mass did not hold when partial correlations were computed. Variations in muscle cell size were related to adjustments in the quantity of RNA per cell, as depicted by the RNA:DNA ratio. Since muscle growth was not correlated with variation in muscle cell size, it was not correlated with the RNA:DNA ratio either.©2000 Elsevier Science B.V.

CHABOT, D., J.-D. DUTIL, 2000. Reduced growth of Atlantic Cod (Gadus morhua) in chronic hypoxia : the effect of varying meal frequency. Pages 75-79 in D. Val & D. MacKinlay. Fish surviving in extreme conditions : symposium proceedings : International Congress on the Biology of Fish, University of Aberdeen, Scotland, July 23-27, 2000 .

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FRIEDLAND, K.D., J.-D. DUTIL, T. SADUSKY, 1999. Growth patterns in postsmolts and the nature of the marine juvenile nursery for Atlantic salmon, Salmo salar. Fish. Bull., 97: 472-481 .

LEMIEUX, H., P. BLIER, J.-D. DUTIL, 1999. Do digestive enzymes set a physiological limit on growth rate and food conversion efficiency in the Atlantic cod (Gadus morhua)?. Fish. Physiol. Biochem., 20: 293-303 .

CHABOT, D., J.-D. DUTIL, 1999. Reduced growth of Atlantic cod in non-lethal hypoxic conditions. J. Fish Biol., 55: 472-491 .

DUTIL, J.-D., M. CASTONGUAY, D. GILBERT, D. GASCON, 1999. Growth, condition, and environmental relationships in Atlantic cod (Gadus morhua) in the northern Gulf of St. Lawrence and implications for management strategies in the Northwest Atlantic. Can. J. Fish. Aquat. Sci., 56(10): 1818-1831 .

Northern Gulf of St. Lawrence Atlantic cod (Gadus morhua) is one of several stocks that collapsed in eastern Canada following a long period of intensive exploitation. Surplus and net production per capita became nil or negative in the mid-1980s so that any level of exploitation would have caused a decline of the stock. This was partly explained by a marked decline in growth production and is consistent with smaller sizes-at-age but also lower condition factor values during the same period. Correlations between size-at-age and temperature were not significant when corrected for autocorrelation, but slopes were always positive, suggesting higher growth rates at higher temperatures. Smaller sizes-at-age in the 1980s were not associated with changes in the fishery or increased fishing mortality, nor were they consistent with the density-dependence hypothesis. Lengths at age 8 decreased by more than 10 cm as the stock decreased 10-fold in abundance. While size-at-age and temperature covary in cod when all stocks are examined, size-temperature relationships are not as clear if the analysis is restricted to cold-water stocks, possibly because of differences in food availability. Biological production varies from year to year and among stocks and should be taken into consideration when managing fisheries in variable or extreme environments.

PLANTE, S., D. CHABOT, J.-D. DUTIL, 1998. Hypoxia tolerance in Atlantic cod. J. Fish Biol., 53: 1342-1356 .

COUTURE, P., DUTIL, J.-D., H. GUDERLEY, 1998. Biochemical correlates of growth and condition in juvenile Atlantic cod (Gadus morhua) from Newfoundland. Can. J. Fish. Aquat. Sci., 55: 1591-1598 .

This study examines how the biochemical composition of tissues varied with growth rate and condition in juvenile Atlantic cod (Gadus morhua) caught in the wild and kept in captivity. The hepatosomatic index, brain water content, and muscle sarcoplasmic protein content as well as the activities of phosphofructokinase, lactate dehydrogenase, nucleoside diphosphate kinase, and citrate synthase in the muscle, nucleoside diphosphate kinase and citrate synthase in the intestine, and cytochrome C oxidase and citrate synthase in the brain increased with growth rate or condition factor. Conversely, liver and muscle water contents were lower in fish with a higher growth rate. A multiple regression model that included the hepatosomatic index, water content of muscle and brain, and citrate synthase activity in the intestine explained 79.7 % of the variability of growth in mass under control conditions. A similar model, using liver water content instead of muscle water content, explained 82.5 % of the variability of growth in length. These easy to measure variables may be used in fisheries management to estimate the growth rate of fish in the wild.

DUTIL, J.-D., Y. LAMBERT, H. GUDERLEY, P.U. BLIER, D. PELLETIER, M. DESROCHES, 1998. Nucleic acids and enzymes in Atlantic cod (Gadus morhua) differing in condition and growth rate trajectories. Can. J. Fish. Aquat. Sci., 55: 788-795 .

Atlantic cod (Gadus morhua) were exposed to one of four feeding regimes, 16 weeks of food deprivation (U) or satiation feeding (F) or two 8-week periods of food deprivation followed by satiation feeding (UF) or vice versa (FU), to determine whether relationships between nucleic acids or enzymes and growth rates result from a general enhancement of individual condition or are a direct result of enhanced growth rates. Final condition factor (K) differed between treatments, but did not differ between the mixed treatments after either 8 weeks of negative growth (FU) or 8 weeks of positive growth (UF). Intestinal cytochrome C oxidase activity matched the expected short-term growth rates, not only in fed and unfed fish but also in cod exposed to the mixed treatment (FU and UF). White muscle lactate dehydrogenase activity reflected growth rates, but initial levels were not reached within 8 weeks in FU cod. The liver glutamate pyruvate transaminase:DNA ratio reflected differences in K, but not differences in recent growth rates. Myofibrillar proteins decreased in unfed cod, while sarcoplasmic proteins followed changes in K more closely. The RNA:DNA ratio in white muscle did not reflect changes in K or changes in growth rates.

CHABOT, D., J.-D. DUTIL, S. PLANTE, 1998. Survival and growth of Atlantic cod in hypoxia. Pages 39-44 in C. Kennedy & D. MacKinlay (ed.). Fish response to toxic environments : symposium proceedings. Physiology Section, American Fisheries Society .

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MAYRAND, E., H. GUDERLEY, J.-D. DUTIL, 1998. Effect of morphometric maturity and size on enzyme activities and nucleic acid ratios in the snow crab Chionoecetes opilio. J. Crust. Biol., 18(2): 232-242 .

DUTIL, J.-D., M. CASTONGUAY, M.O. HAMMILL, P. OUELLET, Y. LAMBERT, D. CHABOT, H. BROWMAN, D. GILBERT, A. FRÉCHET, J.-A. GAGNÉ, D. GASCON, L. SAVARD, 1998. Environmental influences on the productivity of cod stocks : some evidence for the northern Gulf of St. Lawrence, and required changes in management practices. DFO, Canadian Stock Assessment Secretariat, Research Document, 98/18, 42 p .

FRIEDLAND, K.D., J.-D. DUTIL, T. SADUSKY, 1998. Post-smolt growth in Atlantic salmon form North America and the nature of marine juvenile nurseries. ICES C.M., 1998/N:08, 12 p .

LAMBERT, Y., J.-D. DUTIL, 1997. Condition and energy reserves of Atlantic cod (Gadus morhua) during the collapse of the northern Gulf of St. Lawrence stock. Can. J. Fish. Aquat. Sci., 54: 2388-2400 .

Interannual variations and seasonal cycles in condition and energy reserves were investigated for the northern Gulf of St. Lawrence cod (Gadus morhua) before and during the collapse of this stock. Significant decreases in cod condition between the late 1980s and the early 1990s coincided with the reduction in biomass. Cod exhibited clear seasonal variations in condition factor (Fulton's K), energy reserves and tissue composition. Maximum K(0.87-0.91) and highest hepatosomatic index(HSI; 4.3-5.7 %) occurred during the autumn while minimum levels occurred in spring. In May, the levels of condition (K,0.69-0.74; HSI,2.2-3.0) were below those reported for other stocks. In spring during spawning, a proportion of the wild cod had condition and energy reserves that were within the range that resulted in mortality among unfed fish held in the laboratory. Feeding experiments also indicate that the condition of wild cod in fall was lower than that observed for well-fed fish held in the laboratory. The decline in the condition and energy reserves of cod during several consecutive years may have lowered the productivity of the northern Gulf of St. Lawrence stock. This, along with overfishing, could have contributed to the collapse of this stock.

LEMIEUX, H., P. BLIER, J.-D. DUTIL, 1997. Do digestive enzymes set a physiological limit on upon growth rate and conversion efficiency in Atlantic cod (Gadus morhua)?. Bull. Aquac. Assoc. Can., 97(2): 54-56 .

The objective of this study was to determine potential sites of maximal growth limitation in Atlantic cod (Gadus morhua). The experimental set-up consisted of groups of 5 groups of 8 fish that received different concentrations of bovine growth hormone (0,1,2,4,10 g/g fish/2 weeks) administered by intra-abdominal injections. Fish were fed ad libitum during the 4-week experimental period. Individual ingestion rates, conversion efficiencies and growth rates were measured. The following enzyme activities were determined: intestinal glutamyl transferase and alkaline phosphatase, trypsin and chymotrypsin in the pyloric caecum. We found no correlation between treatment with bovine growth hormone and growth rate, conversion efficiency, ingestion rate nor enzyme activities. The relationship between growth rate and trypsin or chymotrypsin activity was stronger than the relationship between ingestion rate and the same enzymes. We suggest that the relationship between growth rate and enzyme activity (trypsin) may partly be explained by the effect of this enzyme on food conversion efficiency.

LAMBERT, Y., J.-D. DUTIL, 1997. Can simple condition indices be used to monitor and quantify seasonal changes in the energy reserves of Atlantic cod (Gadus morhua)?. Can. J. Fish. Aquat. Sci., 54 (Suppl. 1): 104-112 .

This study examined whether simple indicators of condition in individual Atlantic cod (Gadus morhua) are related to biochemical composition and energy content for the whole range of conditions potentially observed in natural populations. The energy content of muscle was largely associated with its protein content, while liver energy content mainly consisted of lipids. Accurate predictions of muscle and liver energy content can also be made from the measurement of their water content. Relationships between energy content, water content, and simple measures such as condition factor and hepatosomatic index provide a fast and accurate assessment of seasonal changes in total available energy reserves in cod. These indices could provide a fast and accurate assessment of seasonal changes in total available energy reserves in cod. These indices could advantageously be used to monitor the status and recovery of cod stocks and to ensure improved management of that resource.

DUTIL, J.-D., J. MUNRO, M. PÉLOQUIN, 1997. Laboratory study of the influence of prey size on vulnerability to cannibalism in snow crab (Chionoecetes opilio O. Fabricius, 1780). J. Exp. Mar. Biol. Ecol., 212: 81-94 .

BLIER, P.U., D. PELLETIER, J.-D. DUTIL, 1997. Does aerobic capacity set a limit on fish growth rate?. Rev. Fish. Sci., 5(4): 323-340 .

DUTIL, J.-D., Y. LAMBERT, E. BOUCHER, 1997. Does higher growth rate in Atlantic cod (Gadus morhua) at low salinity result from lower standard metabolic rate or increased protein digestibility?. Can. J. Fish. Aquat. Sci., 54 (Suppl. 1): 99-103 .

This study examines whether increased growth rate in Atlantic cod (Gadus morhua) at low salinity (14 %) can be accounted for by a reduction in standard metabolic rate (SMR) or by an increase in food assimilation (protein digestibility). Cod tolerate low salinity and exhibit higher growth rates at low salinity than in seawater. Differences between salinities are not associated with differences in food ingestion rates. SMR measured in cod exposed to low salinity and seawater (28 %) did not decrease or increase with changes in salinity. Similar results were obtained for cod with and without salinity acclimations. Weight loss in cod acclimated to salinity was similar at low salinity as in seawater. No difference in apparent protein digestibility was observed between cod acclimated to low salinity (14 %) and seawater. Estimates of protein digestibility were similar to those reported for cod in earlier studies. Higher growth rates and higher food conversion ratios at low salinity in cod must be attributable to uncontrolled or unmeasured factors such as spontaneous activity and swimming performance rather than to changes in SMR or in protein digestibility.

GUDERLEY, H., J.-D. DUTIL, D. PELLETIER, 1996. The physiological status of Atlantic cod, Gadus morhua, in the wild and the laboratory : estimates of growth rates under field conditions. Can. J. Fish. Aquat. Sci., 53: 550-557 .

The physiological status of Atlantic cod, Gadus morhua, starved or fed at high rations were compared with those of cod sampled in late spring and early fall in the Gulf of St. Lawrence. The white muscle of starved cod had lower lactate dehydrogenase activity, buffering capacity, and sarcoplasmic, myofibrillar, and total protein levels than did that of fed cod. Intestinal cytochrome C oxidase activity was also lower in starved than fed cod. Wild October cod had higher condition factors, hepatosomatic indices, white muscle lactate dehydrogenase activities, sarcoplasmic protein concentrations, and buffering capacities than June cod. The gonadosomatic index and myofibrillar protein concentrations were higher in June than October cod. The intestinal cytochrome C oxidase activity did not differ between cod captured in June and those captured in October. The growth rates predicted for the experimental cod from the established relationship between growth rate and white muscle lactate dehydrogenase activity agreed well with their actual rates. Estimations of growth rates of the wild cod suggests that in June the cod were losing mass, whereas in early October they were growing as quickly as the fed cod.

DUTIL, J.-D., Y. LAMBERT, 1995. Potential bias in growth rate measurements associated with differential mortality of cod in poor condition : the case of cod in the northern Gulf of St. Lawrence. ICES C.M., 1995/P:07, 9 p .

PELLETIER, D., P.U. BLIER, Y. LAMBERT, J.-D. DUTIL, 1995. Deviation from the general relationship between RNA concentration and growth rate in fish. J. Fish. Biol, 47: 920-922 .

DUTIL, J.-D., Y. LAMBERT, G.A. CHOUINARD, A. FRÉCHET, 1995. Fish condition : what should we measure in cod (Gadus morhua)?. DFO, Atlantic Fisheries, Research Document, 95/11, 26 p .

PELLETIER, D., P.U. BLIER, J.-D. DUTIL, H. GUDERLEY, 1995. How should enzyme activities be used in fish growth studies?. J. Exp. Biol., 198: 1493-1497 .

PELLETIER, D., J.-D. DUTIL, P. BLIER, H. GUDERLEY, 1994. Relation between growth rate and metabolic organization of white muscle, liver and digestive tract in cod, Gadus morhua. J. Comp. Physiol. B, 164: 179-190 .

FRÉCHET, A., Y. GAGNON, P. SCHWAB, D. D'AMOURS, J.-D. DUTIL, Y. LAMBERT, L. BOURASSA, C. ROLLET, 1994. Revue de l'état du stock de morue du nord du golfe du Saint-Laurent (3Pn, 4RS) en 1993 ; Review of the status of the northern Gulf of St. Lawrence cod stock (3Pn, 4RS) in 1993. MPO, Pêches de l'Atlantique, Document de recherche ; DFO, Atlantic Fisheries, Research document, 94/29, 50 p .

The 1993 fishing season was conducted with many problems. The fishing season started late because of problems linked with enforcement, the fisheries were stopped many times because of small fish. The initial TAC for 1993 of 31,000 t was reduced at the end of August to 18,000 t on the recommendation of the FRCC. This TAC was based on results of last year's assessment and corresponds to a fishery at the F0.1 reference level. Landings for 1993 were of 18,171 t. There are no directed nor sport fisheries on the 3Pn, 4Rs cod stock in 1994. All available indices indicate a large decline in the last year. The mobile gear catch rates drop by 37 % between 1992 and 1993. The population estimates derived from the 1994 January groundfish research vessel survey represent only 51 % of those estimated in 1993. The population estimates from the summer groundfish survey dropped by 65 %. Catch rates from the Index Fishermen declined in certain cases and maintained themselves in others. For the first time, a calibration of SPA was attempted incorporating results from both the summer and winter surveys. The summer survey series is now long enough to be of interest (4 years) and the winter series will be discontinued in 1995. The 3+ population numbers would have gone from 546 million individuals in 1980 to as low as 95 million individuals in 1993 and the biomass of mature fish (7+) in 1993 could be as low as 10,000 t. Because of problems linked with the quality of the research vessel survey information, the calibration with ADAPT produces anomalously high fishing mortalities. The analysis is thus presented for illustrative purposes only and no projections were done. Biomass is expected to be very low.

HARDY, D., J. MUNRO, J.-D. DUTIL, 1994. Temperature and salinity tolerance of the soft-shell and hard-shell male snow crab, Chionoecetes opilio. Aquaculture, 122: 249-265 .

HARDY, D., J.-D. DUTIL, J. MUNRO, L. PROVENCHER, R.F.J. BAILEY, J.-C.F. BRÊTHES, 1994. La stabulation du crabe des neiges (Chionoecetes opilio). Rapp. can. ind. sci. halieut. aquat., 224, 39 p .

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Fishing season for snow crab (Chionoecetes opilio) is short. This results in an overabundance of fresh crab in spring. Snow crab is rarely available off season and in major cities markets. Holding live unfed snow crab would extend the period of availability beyond the fishing season. This report reviews our knowledge of the biological requirements of snow crabs and suggests handling and transport procedures as well as live-holding techniques. Snow crab survival in holding facilities depends on careful handling on boats and during transportation. Crabs should never be exposed to water temperatures over 10 °C or to salinities below 22 ppt. Live-holding can be carried out at sea using modified fishing gears, higher survival rates being obtained in deep cold water with high salinity. In land-based facilities, excellent results have been obtained for a 3,5 month period at 0 °C. Under these conditions, quality of flesh is high and mortality rates are low. There is a need for information on optimal holding densities and on tolerance to metabolic wastes and low dissolved oxygen concentrations. To make for this lack of knowledge, we review current practices in lobster holding facilities.

CASTONGUAY, M., P.V. HODSON, C.M. COUILLARD, M.J. ECKERSLEY, J.-D. DUTIL, G. VERREAULT, 1994. Why is recruitment of the American eel, Anguilla rostrata, declining in the St. Lawrence River and Gulf. Can. J. Fish. Aquat. Sci., 51: 479-488 .

LAMBERT, Y., J.-D. DUTIL, J. MUNRO, 1994. Effects of intermediate and low salinity conditions on growth rate and food conversion of Atlantic cod (Gadus morhua). Can. J. Fish. Aquat. Sci., 51: 1569-1576 .

MUNRO, J., C. AUDET, M. BESNER, J.-D. DUTIL, 1994. Physiological response of American plaice (Hippoglossoides platessoides) exposed to low salinity. Can. J. Fish. Aquat. Sci., 51: 2448-2456 .

BERTHIAUME, L., J. HEPPELL, M. DÉSY, L. LEBLANC, R. LALLIER, R. BAILEY, J.-D. DUTIL, 1993. Manifestation of lymphocystis disease in American plaice (Hippoglossoides platessoides) exposed to low salinities. Can. J. Fish. Aquat. Sci., 50: 430-434 .

AUDET, C., M. BESNER, J. MUNRO, J.-D. DUTIL, 1993. Seasonal and diel variations of various blood parameters in Atlantic cod (Gadus morhua) and American plaice (Hippoglossoides platessoides). Can. J. Zool., 71: 611-618 .

PELLETIER, D., H. GUDERLEY, J.-D. DUTIL, 1993. Does the aerobic capacity of fish muscle change with growth rates?. Fish. Physiol. Biochem., 12: 83-93 .

PELLETIER, D., H. GUDERLEY, J.-D. DUTIL, 1993. Effects of growth rate, temperature, season, and body size on glycolytic enzyme activities in the white muscle of Atlantic cod (Gadus morhua). J. Exp. Zool., 265: 477-487 .

PROVENCHER, L., J. MUNRO, J.-D. DUTIL, 1993. Osmotic performance and survival of Atlantic cod (Gadus morhua) at low salinities. Aquaculture, 116(2-3): 219-231 .

DUTIL, J.-D., J. MUNRO, R. DUFOUR, Y. GAUTHIER, F. HAZEL, B. SAINTE-MARIE, L. PROVENCHER, J. BOYER, D. HARDY, 1993. L'élevage du crabe des neiges : bilan des travaux de recherche. Ministère des pêches et des océans, Programme fédéral de développement des pêches du Québec, 12 p .

DUTIL, J.-D., J. MUNRO, C. AUDET, M. BESNER, 1992. Seasonal variation in the physiological response of Atlantic cod (Gadus morhua) to low salinity. Can. J. Fish. Aquat. Sci., 49: 1149-1156 .

DUTIL, J.-D., 1992. Les poissons marins, ces grands négligés de l'aquiculture. Pages 39-42 in Colloque Mariculture Québec, le 1er mai 1992, Institut Maurice-Lamontagne. Conseil de l'aquiculture et des pêches du Québec et Ministère des pêches et des océans .

CLAIREAUX, G., J.-D. DUTIL, 1992. Physiological response of the Atlantic cod (Gadus morhua) to hypoxia at various environmental salinities. J. Exp. Biol., 163: 97-118 .

NANCE, J.M., M. BORNANCIN, F. SOLA, G. BOEUF, J.-D. DUTIL, 1990. Study of transbranchial Na+ exchange in Salmo salar smolts and post-smolts directly transferred to sea water. Comp. Biochem. Physiol., 96A: 303-308 .

CASTONGUAY, M., J.-D. DUTIL, C. DESJARDINS, 1990. Distinction entre des anguilles d'Amérique (Anguilla rostrata) d'origines géographiques différentes basée sur leur teneur en contaminants organochlorés. Pages 603-614 in D. Messier, P. Legendre & C.E. Delisle (éd.). Symposium sur le Saint-Laurent : un fleuve à reconquérir. Association des biologistes du Québec et Centre Saint-Laurent (Collection environnement et géologie, 11) .

DUTIL, J.-D., M. BESNER, J. MUNRO, 1990. Response of plasma sodium, chloride and osmotic concentrations in Atlantic cod (Gadus morhua) following direct transfer to diluted seawater. Pages 169-174 in R.L. Saunders (ed.). Proceedings of Canada-Norway Finfish Aquaculture Workshop, September 11-14, 1989. Dept. of Fisheries and Oceans (Can. Tech. Rep. Fish. Aquat. Sci., 1761) .

CASTONGUAY, M., J.-D. DUTIL, C. AUDET, R. MILLER, 1990. Locomotor activity and concentration of thyroid hormones in migratory and sedentary juvenile American eels. Trans. Am. Fish. Soc., 119: 946-956 .

DUTIL, J.-D., M. MICHAUD, A. GIROUX, 1989. Seasonal and diel patterns of stream invasion by American eels (Anguilla rostrata) in the northern Gulf of St. Lawrence. Can. J. Zool., 67: 182-188 .

Seasonal and diel patterns of stream invasion by American eels (Anguilla rostrata) were monitored in a small stream located on the north shore of the Gulf of St. Lawrence from 1981 to 1985. Glass eels and elvers migrated from the sea in late June and July. Glass eels made up only a small percentage of the migrants. Pigmentation progressed quickly in the estuary, but elvers grew very slowly. Migration from the estuary and through the lower reaches of the stream was slow; no glass eels or elvers occurred at a station located only 4 km from saltwater. Juvenile eels reached that station in their second summer of stream residence. Juvenile eels migrated in July and August. They ranged from 70 to 250 mm in length and included more than one age-class. Those less than 100 mm in length were most numerous. Relative abundance of glass eels and elvers decreased in the estuary from 1981 to 1985. This coincided with a decrease in the proportion of smaller sized eels in the stream migration over the same period. Juvenile eels migrated progressively later in summer as the proportion of smaller sized eels decreased. Stream migration was nocturnal. Movements mainly occurred between 21:00 and 23:00. The relationship between glass eel and elver abundance in the estuary and juvenile eel abundance in the stream 1 and 2 years later was not clear©1989 National Research Council Canada

DUTIL, J.-D., C. CANTIN, P. LAUZIER, M. NAUD, J. MUNRO, R. BAILEY, 1989. L'élevage de la morue franche, Gadus morhua : réalités biologiques et économiques. Rapp. can. ind. sci. halieut. aquat., 200, 41 p .

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From a biological perspective, Atlantic cod rearing would appear promising. Atlantic cod can tolerate a wide range of environmental conditions and the production of larvae and juvenile cod from brood stocks does not present major problems. Nevertheless, the production of juvenile cod could be enhanced should we have a better knowledge of the nutritional requirements of the larvae. Little information is available on the mortality rate of cod in on-growing facilities. In Québec, the scarcity of large-size cod and decreased catches of wild cod would suggest that cod farming should be considered as a complement to harvest fisheries. However, prices are also influenced by international markets.

CASTONGUAY, M., J.-D. DUTIL, C. DESJARDINS, 1989. Distinction between American eels (Anguilla rostrata) of different geographic origins on the basis of their organochlorine contaminant levels. Can. J. Fish. Aquat. Sci., 46: 836-843 .

BESNER, M., J.-D. DUTIL, J. MUNRO, 1989. Direct transfer of Atlantic cod (Gadus morhua) to low salinities during winter : survival, ionic and osmotic regulation. Bull. Aquac. Assoc. Can., 89(3): 62-64 .

MICHAUD, M., J.-D. DUTIL, J.J. DODSON, 1988. Determination of the age of young American eels, Anguilla rostrata, in fresh water, based on otolith surface area and microstructure. J. Fish. Biol., 32: 179-189 .

DUTIL, J.-D., A. GIROUX, A. KEMP, G. LAVOIE, J.-P. DALLAIRE, 1988. Tidal influence on movements and on daily cycle of activity of American eels. Trans. Am. Fish. Soc., 117: 488-494 .

DUTIL, J.-D., J.-M. COUTU, 1988. Early marine life of Atlantic salmon, Salmo salar, postsmolts in the northern Gulf of St. Lawrence. Fish. Bull., 86: 197-212 .

DUTIL, J.-D., M. BESNER, S.D. McCORMICK, 1987. Osmoregulatory and ionoregulatory changes and associated mortalities during the transition of maturing American eels to a marine environment. Am. Fish. Soc. Symp., 1: 175-190 .

ES-SOUNNI, A., M.-A. KLYNE, J.-D. DUTIL, M.A. ALI, 1987. Retinal cone movements in the yellow eel. Zool. Anz., 219, 5/6, S: 377-381 .

DUTIL, J.-D., 1987. Towards the development of a recruitment index based on riverine migration of glass eels and juvenile eels (Anguilla rostrata). European Inland Fishery Advisory Commission (FAO). Report on the Meeting of the Working Party on Eel, Bristol, England, 12 p .

ALI, M.A., J.-D. DUTIL, L. FORTIER, 1987. Retinal response in the post metamorphic American eel (Anguilla rostrata) (Pisces, Teleostei). Helgol. Meeresunters., 41: 437-441 .

DUTIL, J.-D., 1986. Energetic constraints and spawning interval in the anadromous Arctic charr (Salvelinus alpinus). Copeia, 1986: 945-955 .

Non-reproductive anadromous Arctic charr of Nauyuk Lake lost 30 % of their fall reserves of energy by the following spring. They restored their reserves of energy through a two month summer in the sea. Spawners became much more depleted. Production of gonads and starvation in the lake prior to spawning were such that postspawners migrating to sea in spring contained as much as 46 % less energy than non-reproductive charrs. Postspawners required more than one summer to replenish their depleted reserves. These results provide an example of the phenotypic plasticity of the life history characteristics of arctic charr and show that production of gonads and related changes in the migratory cycle prevent individual charrs from spawning 2 yr in succession. Length-related energy constraints possibly contribute to shaping the structure of the population and lead to senescence in charrs >90cm . The role of a threshold body condition as a release mechanism in the processes of maturation is discussed.