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Bibliography of the Maurice Lamontagne Institute

Fishes / Sebastes fasciatus / Acadian redfish

MCALLISTER, M., D.E. DUPLISEA, 2011. Production model fitting and projection for Atlantic redfish (Sebastes fasciatus and Sebastes mentella) to assess recovery potential and allowable harm ; Ajustement du modèle de production et projection pour le sébaste atlantique (Sebastes fasciatus et Sebastes mentella) afin d’évaluer le potentiel de rétablissement et les dommages admissibles. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2011/057, 81 p.

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A recovery potential analysis was carried out for stocks of Atlantic redfish falling within three designatable units recently assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) as either threatened or endangered. A state-space Schaefer surplus production model was fitted to trawl survey biomass estimates considered as relative indices of abundance for these different stocks. Bayesian methods were applied for parameter estimation, evaluation of stock status and stock projections for three populations of Acadian redfish, Sebastes fasciatus, and two populations of deepwater redfish, Sebastes mentella, on the Atlantic coast of Canada for the purpose of assessing recovery potential. This stock assessment methodology has been previously applied to other Sebastes species on the Pacific coast of Canada. The state-space version of this model allowed for the inclusion of process error which can account for deviations in dynamics from surplus production assumptions. Though apparently an esoteric methodological detail, allowing a process error estimate for each year means that the model can incorporate irregular population processes such as spasmodic recruitment events which seem to characterise Atlantic redfish populations and which can invalidate non-state-space implementations of production models. Results suggest that the Laurentian Channel population of S. mentella is presently in a very low biomass state with a 0 % chance of being above 40 % of the most productive stock biomass level (0.4 Bmsy) while the northern population is doing only slightly better with 1 % chance of being above this level. There would appear to be little prospect for any allowable harm on the Laurentian channel population if the goal is to increase the biomass of the stock even to only 40 % of Bmsy. The situation is only slightly better for the northern population. Results suggest that populations of S. fasciatus, are not nearly in such a poor state as S. Mentella and the southern population in Unit 3 would appear to be healthy. The Laurentian Channel-Grand bank population of S. fasciatus would appear to be able to support a directed fishery when considered as a unit stock. The 2J3K population of S. fasciatus is not very abundant and even small fisheries on this stock would slow down its recovery to 40 % Bmsy. S. Fasciatus, taken as a whole as the Atlantic designatable unit, would appear to have a very low risk of extinction and in most places could support directed fishing.

DUPLISEA, D., D. POWER, 2011. Recovery potential assessment of redfish (Sebastes fasciatus and S. mentella) in the northwest Atlantic. DFO, Canadian Science Advisory Secretariat, Science Advisory Report, 2011/044, 18 p.

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DUPLISEA, D., D. POWER, 2011. Évaluation du potentiel de rétablissement du sébaste (Sebastes fasciatus et S. mentella) dans l'Atlantique Nord-Ouest. MPO, Secrétariat canadien de consultation scientifique, Avis scientifique, 2011/044, 20 P.

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ARCHAMBAULT, D., H. BOURDAGES, B. BERNIER, A. FRÉCHET, J. GAUTHIER, F. GRÉGOIRE, J. LAMBERT, L. SAVARD, 2011. Résultats préliminaires du relevé multidisciplinaire de poissons de fond et de crevette d’août 2011 dans l’estuaire et le nord du golfe du Saint-Laurent ; Preliminary results from the groundfish and shrimp multidisciplinary survey in August 2011 in the Estuary and northern Gulf of St. Lawrence. MPO, Secrétariat canadien de consultation scientifique, Document de recherche ; DFO, Canadian Science Advisory Secretariat, Research Document, 2011/112, 108 p.

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In 2011, the annual summer survey for the assessment of abundance and distribution of groundfish and shrimp in the Estuary and the northern Gulf of St. Lawrence was conducted from August 1st to 29th onboard the CCGS Teleost. One of the primary objectives was to estimate abundance indices for the main groundfish species (cod, Greenland halibut, Atlantic halibut and redfishes – Sebastes fasciatus and S. mentella -), and for the Northern shrimp, and to identify the spatial distribution and biological characteristics of these species. The two other main objectives of the survey included monitoring the biodiversity of the Estuary and the northern Gulf, and describing oceanographic conditions observed in August for the sampling area. This report describes preliminary results on the catch rates and distribution of 25 taxa, as well as their size frequency distribution. These results were compared with results from the historical survey series that began in 1990, taking into account the equivalency factors used to convert data from the tandem CCGS Alfred Needler-URI to the tandem CCGS Teleost-Campelen. In 2011, the abundance and biomass indices of many species were stable or decreased compared to 2010. In fact, the two redfish species, cod, black dogfish and longfin hake showed index values below their respective means calculated for the comparative period of 1990-2010. Even if Atlantic halibut, witch, thorny skate, hagfish, northern shrimp and snow crab indices decreased from 2010 to 2011, they were comparable or higher than the mean estimated for the 1990-2010 period. Five species (Greenland halibut, white hake, American plaice, capelin and herring) showed an increase for their indices in 2011. Except for white hake, the indices for these species were similar or higher than the 1990-2010 period means. The geographic distributions of catches recorded for the different species in 2011 showed the same pattern as in previous years. Finally, the size distributions ranges determined for each species remains relatively stable for the entire time of the historical series. However, for some species (Greenland halibut, thorny skate, white hake, witch, American plaice, hagfish and northern shrimp), some size classes observed in 2011 were clearly dominant, and their abundance well above the calculated average for the comparative period.

BOURDAGES, H., ARCHAMBAULT, D., BERNIER, B., FRECHET, A. GAUTHIER, J. GREGOIRE, F, LAMBERT, J, L. SAVARD, 2010. Résultats préliminaires du relevé multidisciplinaire de poissons de fond et de crevette d’août 2010 dans l’estuaire et le nord du golfe du Saint-Laurent ; Preliminary results from the groundfish and shrimp multidisciplinary survey in August 2010 in the Estuary and northern Gulf of St. Lawrence. MPO, Secrétariat canadien de consultation scientifique, Série des comptes rendus ; DFO, Canadian Science Advisory Secretariat, Proceedings Series, 2010/107, 98 p.

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In 2010, the annual summer survey for the assessment of abundance and distribution of groundfish and shrimp in the Estuary and the northern Gulf of St. Lawrence was conducted from August 2nd to September 1st onboard the CCGS Teleost. One of the primary objectives was to estimate abundance indices for the main groundfish species (particularly cod, Greenland halibut, Atlantic halibut and redfishes - fasciatus and mentella-), and for the Northern shrimp, and to identify the spatial distribution and biological characteristics of these species. Other objectives included monitoring the biodiversity of Estuary and the northern Gulf and describing oceanographic conditions observed in August. This report describes preliminary results on the catch rates and distribution of 18 taxa, as well as their size frequency distribution. These results were compared with results from the historical survey series that began in 1990, taking into account the equivalency factors used to convert the data from the tandem CCGS Alfred Needler-URI to the tandem CCGS Teleost-Campelen. In 2010, the abundance and biomass indices of many species were stable or decreased compared to 2009. In fact, the two redfish species (Sebastes fasciatus and S. mentella), cod, black dogfish, white hake and longfin hake show index values below the historical series means. Even if the Northern shrimp and snow crab indices presented a small decrease, they were in the range of the historical series means. Six species (Atlantic Halibut, Greenland Halibut, hagfish, American Plaice, witch, thorny skate) showed an increase for their indices in 2010. Except for Greenland Halibut, the indices for these species were among the highest values of their respective historical series. Besides the fact that no fishing activities took place along the southwestern part of Newfoundland due to mechanical problems, the geographic distributions of catches recorded for the different species in 2010 showed the same pattern as in previous years.

GAUTHIER, J., M. CASTONGUAY, D. POWER, K. DWYER, 2010. Assessment of redfish stocks (Sebastes fasciatus and S. mentella) in Units 1 and 2 in 2009. DFO, Canadian Science Advisory Secretariat, Science Advisory Report, 2010/037, 20 p.

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GAUTHIER, J., M. CASTONGUAY, POWER, D., K. DWYER, 2010. Évaluation des stocks de sébastes (Sebastes fasciatus et S. mentella) des unités 1 et 2 en 2009. MPO, Secrétariat canadien de consultation scientifique, Avis scientifique, 2010/037, 22 p.

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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.

SÉVIGNY, J.-M., 2008. Advice on the stock definition of redfish (Sebastes fasciatus and S. mentella) in units 1 and 2. DFO, Canadian Science Advisory Secretariat, Science Advisory Report, 2008/026, 12 p.

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SÉVIGNY, J.-M., 2008. Avis sur la définition des stocks de sébastes (Sebastes fasciatus et S. mentella) des unités 1 et 2. MPO, Secrétariat canadien de consultation scientifique, Avis scientifique, 2008/026, 13 p.

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DUBÉ, S., D. BERNIER, C. CYR, 2007. Compte rendu de l'atelier zonal : examen de l'information dont dispose le secteur des Sciences du MPO sur le sébaste (Sebastes sp.) pour l'évaluation du COSEPAC : discrimination des stocks de sébaste des unités 1 et 2 : examen de la pêche indicatrice, 19 et 20 septembre 2007, Institut Maurice-Lamontagne, Mont-Joli, QC ; Proceedings of the zonal workshop : review of the information on redfish (Sebastes sp.) available from DFO Science sector for the COSEWIC assessment : discrimination of redfish stocks of units 1 and 2 : index fishery review, September 19th and 20th, 2007, Maurice Lamontagne Institute, Mont-Joli, QC. MPO, Secrétariat canadien de consultation scientifique, Série des comptes rendus ; DFO, Canadian Science Advisory Secretariat, Proceedings Series, 2007/040, 26 p.

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A two-day workshop on redfish was held at the Maurice Lamontagne Institute on September 19th and 20th, 2007. This meeting gathered nearly 40 participants from research to management to industry. There were three objectives on the agenda. First, review the information on redfish (Sebastes sp.) available from the Department of Fisheries and Oceans (DFO) Science sector for the assessment by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). In fact, in its call for bids of the fall of 2006, COSEWIC was requesting that a report be produced on the status of redfish (Sebastes fasciatus and S. mentella), which triggered the assessment process for these species. The second objective was to present the recent data on the stock structure of redfish in the Northwest Atlantic in order to determine the biological relevance of management units 1 and 2. This objective followed a zonal workshop (DFO 2006) where the discussions did not lead to any consensus. The last objective of the workshop was to re-examine the relevance of maintaining the redfish index fishery in Unit 1, which has been under moratorium since 1995. Examining the information on redfish led to the discovery of complex structure patterns, but also to some reflection on the value of the data obtained and the methods used. The second objective led to a series of recommendations, including consolidating Units 1 and 2 into one unit for each of the two species: S. mentella and S. fasciatus. It was also recommended to consider the complexity of the structure patterns in the assessment process and in developing management and conservation measures. Finally, the meeting did not lead to any conclusion in terms of the relevance of maintaining the index fishery in Unit 1. It was suggested to conduct a redfish stock assessment by considering the overall data, including the index fishery data, prior to agreeing on this issue.

CAMPANA, S. E., A. VALENTIN, J.-M. SÉVIGNY, D. POWER, 2007. Tracking seasonal migrations of redfish (Sebastes spp.) in and around the Gulf of St. Lawrence using otolith elemental fingerprints. Can. J. Fish. Aquat. Sci., 64: 6-18.

Large concentrations of beaked redfish (Sebastes mentella and Sebastes fasciatus) overwinter in the Cabot Strait and the approaches of the Gulf of St. Lawrence each year. Synoptic research vessel surveys indicate that redfish are distributed more widely in the summer than in the winter, particularly within the Gulf. Significant differences in the trace element composition of the otolith ("otolith elemental fingerprint") were observed among summer aggregations, indicating that the aggregations maintained some degree of separation while in the Gulf. Sebastes mentella and S. fasciatus were readily distinguished based on otolith elemental fingerprints. Using the elemental fingerprints of the summer samples as a natural tag, we found that S. mentella tended to move out of the Gulf in the winter. Aggregations of S. mentella found in the east during the summer were not found in our winter collections. The elemental fingerprints of S. mentella from the Saguenay Fjord were clearly distinct from redfish further east in the Gulf of St. Lawrence, indicating that this group had been separated from other redfish for much of their life. The implications of our findings extend not only to the fisheries management of redfish, but also to the extent of movement expected of deepwater fish species.

SÉVIGNY, J.-M., R. MÉTHOT, H. BOURDAGES, D. POWER, P. COMEAU, 2007. Review of the structure, the abundance and distribution of Sebastes mentella and S. fasciatus in Atlantic Canada in a species-at-risk context: an update ; Revue de la structure, de l’abondance et de la distribution de Sebastes mentella et S. fasciatus dans le Canada atlantique dans le contexte des espèces en péril : mise à jour. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2007/085, 109 p.

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This document presents the information reviewed and analyzed by Fisheries and Oceans (DFO) that can be used by the Committee on Status of Endangered Wildlife in Canada (COSEWIC) in assessing status and extinction risk of the two main redfish species (Sebastes fasciatus and S. mentella) in the Northwest Atlantic. Redfish population structure was evaluated in the context of Evolutionarily Significant Units (ESU). The review did not provide evidence of the existence of ESUs within current management units. Therefore, all the analyses were carried out on the actual unit stocks. Methods developed to separate redfish by genotype (for Unit 1-3) or meristics (for NAFO Divisions 2GHJ3KLMNO) were applied to the research vessel survey data to obtain abundance indices. Three distribution indices were calculated: the area of occupancy, the minimum area occupied by 95 % of the stock, and the Gini index of aggregation. No general pattern or trend in geographic distribution was evident. The Unit 1 stock experienced a substantial decline at the beginning of the 1990 and has not recovered yet. However, a new year-class (2003), which seems to be quite important, was observed since the 2005 survey. The stock in NAFO Divisions 2GHJ 3K experienced declines but has shown some signs of recovery. The redfish stocks in remaining management units have not shown signs of decline or the information available for these stocks may not reflect the abundance. Fishery and/or the lack of recruitment were considered the main causes of abundance decline for the stocks in Unit 1 and in NAFO Div. 2GHJ 3K. However, environmental changes and elevated natural mortality were also identified as possible causes of decline. Mature population abundance indices of all redfish stocks in Atlantic Canada are at from one to three orders of magnitude greater than the COSEWIC threshold of 10 000 mature individuals.

VALENTIN, A., J.-M. SÉVIGNY, B. MORIN, D. POWER, R.M. BRANTON, 2006. Extensive sampling and concomitant use of meristic characteristics and variation at the MDH-A* locus reveal new information on redfish species distribution and spatial pattern of introgressive hybridization in the Northwest Atlantic. J. Northwest Atl. Fish. Sci., 36: 65-80.

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Variability at theMDH-A* locus, of anal fin ray number and extrinsic gasbladder muscle pattern is used to describe the distribution of Sebastes fasciatus and S. mentella in the Northwest Atlantic and to define the geographical boundaries of the area of introgressive hybridization between the two species. Sebastes mentella distribution extends from the Gulf of St. Lawrence northward while S. fasciatus is distributed from the southern Grand Banks southward as described in earlier studies. Sebastes fasciatus is also found in the southern Labrador Sea where the species appears to reach its northernmost limit. The distribution of the two species overlaps mainly in the Gulf of St. Lawrence and the Laurentian Channel, around the Grand Banks and on Flemish Cap. This area of sympatry comprises a smaller area where heterozygous individuals at the MDH-A* locus are observed and where introgressive hybridization occurs. This area is mostly restricted to the Gulf of St. Lawrence and the Laurentian Channel. The west-east gradient in the abundance of introgressed individuals suggests that the Gulf of St. Lawrence is the centre of introgressive hybridization and that larval dispersion or migration of juveniles and adults takes place from the Gulf of St. Lawrence towards south Newfoundland and the Grand Banks. In contrast, the absence of heterozygous individuals at the MDH-A* locus outside the Gulf of St. Lawrence and the Laurentian Channel indicates that the dispersion of these individuals is limited for all stages of the life cycle.

MÉTHOT, R., B. MORIN, D. POWER, 2004. Description of the methods used for estimating the abundance of Sebastes fasciatus and S. mentella in Units 1 and 2 ; Description des méthodes utilisées pour estimer l’abondance de Sebastes fasciatus et de S. mentella dans les unités 1 et 2. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2004/092, 53 p.

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Efforts have been made to assess the situation of Sebastes fasciatus and S. mentella in Units 1 and 2. Because no visual distinction is possible between those two redfish species, methods have been developed to estimate indices of abundance of each species from the historic databases. The discrimination criteria used, coming mainly from the Redfish Multidisciplinary Research program 1995-99, were anal fin ray counts (AFC) and the analysis of the malate dehydrogenase (MDH). These characters have been used to split the redfish sp. into species or genotypes. The main method use AFC to evaluate the number of each species caught by tow. A correction was calculated at different depth intervals to reflect the difference in depth distribution for the two species. Proportions of species abundance by depth zone have been calculated from MDH analysis and applied for sets when no discrimination criterion had been recorded. Another method using AFC-length keys subsequently converted into species using MDH was also elaborated. Those methods have been used to analyze different surveys in Units 1 and 2. The estimates of S. fasciatus abundance can be different depending of the method used. These gaps are more important for years when no discrimination character were recorded. In Unit 1, S. fasciatus was dominant at lower depth zone and S. mentella in deep water, the mixing zone being mainly between 183-274 m. Each species showed different length frequencies, S. fasciatus is generally smaller then S. mentella. Because of this, the AFC-length key method was found appropriate to separate species. In Unit 1, the Cod Sentinel summer survey, the GEAC survey and the survey in 4T showed decreasing trends in the last years or low historic abundance for both species. Only the Cod Sentinel fall survey showed stable but low level indices of abundance from 1995 to 2002. In Unit 2, little information was available. Like in Unit 1, S. fasciatus dominates in shallow areas (less than 366 m). Moreover, a survey covering only division 4V showed indices of abundance at a low level in the last years. The discrimination by AFC recorded at each tow and corrected to genotype is simple to perform and could give good estimates of species composition. In years with no criteria of separation recorded, genotype proportions by depth or AFC-length keys could give acceptable estimates of the two species, but should be interpreted with caution because fluctuations of abundance due to mortality, recruitment and/or switch in depth preference could have affected the results of these methods. However, abundance of S. fasciatus evaluated by whatever methods show the same trend, so both methods were found useful to get general trends of the redfish species.

MORIN, B., R. METHOT, J.-M. SEVIGNY, D. POWER, B. BRANTON, T. McINTYRE, 2004. Review of the structure, the abundance and distribution of Sebastes mentella and S. fasciatus in Atlantic Canada in a species-at-risk context ; Revue de la structure, de l’abondance et de la répartition de Sebastes mentella et S. fasciatus dans le Canada atlantique dans le contexte des espèces en péril. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2004/058, 96 p.

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This document presents the information reviewed and analyzed by Fisheries and Oceans (DFO) that could be used by the Committee on Status of Endangered Wildlife in Canada (COSEWIC) in assessing status and extinction risk of the two main species of redfish (Sebastes fasciatus and S. mentella) in the Northwest Atlantic. Redfish population structure was evaluated in the context of “evolutionarily significant units”. The review did not provide evidence to indicate the existence of ESUs within current management units, therefore all the analyses were realized on the current unit stocks. Methods have been developed to separate redfish by genotype and applied to the research vessel (RV) survey data to obtain abundance indices. Three distribution indices were calculated: the area of occupancy, the minimum area occupied by 95 % of the stock, and the Gini index of aggregation. No general pattern or trend in geographic distribution was evident. One stock experienced a substantial decline and had not recovered (Unit 1). One stock experienced declines but has shown some recovery (NAFO divisions 2GHJ 3K). The remaining management units have not shown a decline or the information available may not reflect the abundance. Fishery exploitation and the lack of recruitment were considered the main causes of abundance decline for two stocks (Unit 1 and 2GHJ 3K), although environmental changes and elevated natural mortality were identified as possible factors. Mature population abundance indices of all redfish stocks in Atlantic Canada are at least two orders of magnitude greater than the COSEWIC threshold of 10 000 mature individuals.

VALENTIN, A., J.-P. CHANUT, X. PENIN, J.-M. SEVIGNY, 2003. Morphométrie du sébaste. Modélisation et correction d'une déformation indésirable. Pages 863-866 in Actes des XXXVèmes Journées de statistique.

GASCON, D. (éd.), 2003. Redfish Multidisciplinary Research Zonal Program (1995-1998) : Final Report. Can. Tech. Rep. Fish. Aquat. Sci., 2462, 152 p.

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This report provides under the form of extended abstracts the main results of the Redfish Multidisciplinary Research Program (1995-1999) which sought to examine aspects of the biology and fisheries of redfish to develop a better understanding of these species in order to insure long term economic viability and sustainability of the fishery. The program was divided into four main components: 1) Species identification and stock structure; 2) Improved stock assessment and management approaches; 3) Distribution in relation to enbroad consultation with the redfish fishing industry and the results presented to them at a final workshop held in Novembre 1999.

GASCON, D. (éd.), 2003. Programme de recherche multidisciplinaire sur le sébaste (1995-1998) : rapport final. Rapp. tech. can. sci. halieut. aquat., 2462, 152 p.

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This report provides under the form of extended abstracts the main results of the Redfish Multidisciplinary Research Program (1995-1999)_which sought to examine aspects of the biology and fisheries of redfish to develop a better understanding of these species in order to insure long term economic viability and sustainability of the fishery. The program was divided into four main components: 1) Species identification and stock structure; 2) improved stock assessment and management approaches; 3) distirbution in relation to environmental conditions; and 4) recruitment studies. These objectives were established in a broad consultation with the redfish fishing industry and the results presented to them at a final workshop held in November 1999.

MORIN, B., S. HURTUBISE, 2003. Shrimp fishery bycatches of redfish and review of the possible causes of the disappearance of the 1988 year-class. Pages 95-98 in Gascon, D. (ed.). Redfish Multidisciplinary Research Zonal Program (1995-1998): Final Report. Can. Tech. Rep. Fish. Aquat. Sci., 2462, 139 p.

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VALENTIN, A., J.-M. SÉVIGNY, J.-P. CHANUT, 2002. Geometric morphometrics reveals body shape differences between sympatric redfish Sebastes mentella, Sebastes fasciatus and their hybrids in the Gulf of St. Lawrence. J. Fish Biol., 60: 857-875.

VALENTIN, A., J.-P. CHANUT, J.-M. SÉVIGNY, 2001. Point de concordance et de différenciation dans la morphologie du sébaste. Pages 692-696 in Actes des XXXIIIèmes Journées de statistique.

MORIN, B., B. BERNIER, H. BOURDAGES, D. BERNIER, R. CAMIRAND, 2001. L'état du stock de sébaste de l'unité 1 (golfe du Saint-Laurent) en 2000 ; The status of the redfish stock in unit 1 (Gulf of St. Lawrence) in 2000. MPO, Secrétariat canadien de consultation scientifique, Document de recherche ; DFO, Canadian Science Advisory Secretariat, Research Document, 2001/001, 73 p.

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The fishery in management unit 1 [divisions 4RST +  3Pn and 4Vn (Jan.-May)] has been closed since 1995. Before the fishery was closed, the catch was dominated by fish born in the early 1970s and around 1980. Both groups consisted of the species Sebastes mentella. The abundance of the 1988 year-class, composed mainly of S. fasciatus, has decreased rapidly since 1991. The reasons for the small size of the current stock are heavy past exploitation and lack of recruitment. Following the 1995 closure of the fishery, the stock’s abundance seems to have stabilized; the abundance index derived from DFO’s research surveys has been stable, if low. Two cohorts of juveniles were observed in DFO’s 2000 research survey: the 1996 and 1998 year-classes. Most of these redfish are S. fasciatus, and both of these yearclasses seem relatively weak compared with that of 1988. The catch rate index obtained from the Groundfish Enterprise Allocation Council (GEAC) grid surveys trended downward from 1998 to 2000. The catch per unit effort (CPUE) figures from the index fishery were similar in 1999 and 2000, but lower than those obtained before the fishery was closed in 1995. The indices from the sentinel fishery surveys have also been stable for the period 1995-1999, but the value from the summer 2000 survey amounts to only about half of the 1999 estimate. Overall, the outlook for this stock remains poor for the foreseeable future.

ROQUES, S., J.-M. SEVIGNY, L. BERNATCHEZ, 2001. Evidence for broadscale introgressive hybridization between two redfish (genus Sebastes) in the North-west Atlantic : a rare marine example. Mol. Ecol., 10:149-165.

SÉVIGNY, J.-M., P. GAGNÉ, Y. de LAFONTAINE, J. DOBSON, 2000. Identification and distribution of larvae of redfish (Sebastes fasciatus and S. mentella : Scorpaenidae) in the Gulf of St. Lawrence. Fish. Bull., 98: 375-388.

ROQUES, S., J.-M. SÉVIGNY, L. BERNATCHEZ, D. POWER, 2000. Redfish species distribution and population genetic structure in the Northwest Atlantic: preliminary results. NAFO SCR Doc., 00/48, 17 p.

MORIN, B., B. BERNIER, N. ST-HILAIRE, 1999. The status of redfish in Unit 1 (Gulf of St. Lawrence) in 1998 ; L'état du stock de sébaste de l'unité 1 (Gulf of St. Lawrence) en 1998. DFO, Canadian Stock Assessment Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 99/132, 38 p.

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The fishery in management Unit 1 [Divisions 4RST + 3Pn and 4Vn (Jan. to May)] has been closed since 1995. Before it was closed, it was dominated by fish of species Sebastes mentella born around 1980 and in the early 1970s. Abundance of the 1988 year-class, chiefly species S. fasciatus, declined sharply starting in 1991. The small size of the stock at present is due to heavy fishing and lack of recruitment. Stock abundance seems to have stabilized since the fishery was closed in 1995. DFO research surveys and the sentinel fisheries seem to indicate decreased availability of redfish to trawls from August on. The DFO research surveys have found a new year-class (1996), but it will take several years of survey data before its true size can be determined. Catches of approximately set, the level established last year for redfish industry surveys, are not likely to result in a high exploitation rate if the abundance index remains at its current level.

DESROSIERS, B., J.-M. SÉVIGNY, J.-P. CHANUT, 1999. Restriction fragment length polymorphism of rDNA in the redfishes Sebastes fasciatus and S. mentella (Scorpaenidae) from the Gulf of St. Lawrence. Can. J. Zool., 77: 267-277.

A restriction fragment length polymorphism (RFLP) analysis was carried out on nuclear ribosomal DNA (rDNA) of the redfishes Sebastes fasciatus and Sebastes mentella from the Gulf of St. Lawrence in an attemps to describe new molecular markers that would discriminate these two sibling species. The RFLP analysis revealed heterogeneity in the size of the repeat unit within and among individuals that is most likely the result of variation in the length of the intergenic spacer. Double digestion of rDNA with the restriction enzymes EcoRI and ScaI and subsequent hybridization with a 28S probe revealed the presence of three patterns of fragments. Two fragment gourps seem to characterize S. mentella and S. fasciatus. Both fragment groups were present in several specimens, suggesting either a restriction-site polymorphism in S. mentella or a hybrid origin for these redfish. Discriminant analysis clearly differentiated all three rDNA patterns. Comparisons of genetic variations at the MDH locus and of the number of soft rays in the anal fin among the three rDNA-defined groups suggest that if the individuals showing the two groups of fragments are hybrids between S. fasciatus and S. mentella, introgression has also occurred in the Gulf of St. Lawrence©1999 National Research Council Canada

MORIN, B., B. BERNIER, 1997. L'état du stock de sébaste de l'unité 1 (golfe du Saint-Laurent) ; The status of redfish in Unit 1 (Gulf of St. Lawrence). MPO, Secrétariat canadien pour l'évaluation des stocks, Document de recherche ; DFO, Canadian Stock Assessment Secretariat, Research Document, 97/112, 23 p.

The fishery in management Unit 1 [Divisions 4RST + 3Pn and 4Vn (Jan. to May)] has been closed since 1995. Commercial catches before the closing were dominated by fish born around 1980 and at the beginning of the 1970s and were mainly of the species Sebastes mentella. The abundance of the 1988 year-class has decreased rapidly since 1991 and these fish were identified as being S. fasciatus. Research survey indicated that the redfish stock abundance has remained stabel since 1996. The high rate of exploitation and the lack of recruitment have resulted in the current low stock size. With the closure of this fishery in 1995, the abundance of the stock seems to have stabilized. At this time, there is no sign of any significant incoming recruitment.

MORIN, B., B. BERNIER, A. FRÉCHET, G.A. CHOUINARD, 1996. L'état du stock de sébaste de l'unité 1 (golfe du Saint-Laurent) ; The status of redfish in Unit 1 (Gulf of St. Lawrence). MPO, Pêches de l'Atlantique, Document de recherche ; DFO, Atlantic Fisheries, Research document, 96/112, 31 p.

The fishery in management Unit 1 [Divisions 4RST + 3Pn and 4Vn (Jan. to May)] was closed in 1995 and remained closed in 1996. Commercial catches before the closing were dominated by fish born around 1980 and at the beginning of the 1970's and were mainly of the species Sebastes mentella. The abundance of the 1988 year-class has decreaded rapidly since 1991 and those fish were identified as being S. fasciatus. Research surveys indicated that the redfish stock abundance has declined slightly in 1996 in comparison to 1995. The high rate of exploitation and the lack of recruitment have resulted in the current low stock size. With the closure of this fishery in 1995, the rate of decline of the abundance of the stock should be much slower. At this time, there is no sign of any significant incoming recruitment.

MORAN, J.D.W., J.R. ARTHUR, M.D.B. BURT, 1996. Parasites of sharp-beaked redfishes (Sebastes fasciatus and Sebastes mentella) collected from the Gulf of St. Lawrence, Canada. Can. J. Fish. Aquat. Sci., 53: 1821-1826.

Twenty-three parasite taxa were identified from 100 sharp-beaked redfishes (50 Sebastes fasciatus and 50 Sebastes mentella) collected in the Gulf of St. Lawrence (August 1992), including 2 Coccidia, 2 Myxosporea, 9 Digenea, 2 Cestoda, 4 Nematoda, 1 Acanthocephala, and 3 Crustacea. New host records are reported for Sebastes fasciatus (Eimeriida gen.sp., Myxidium incurvatum, Brachyphallus crenatus, Gonocerca sp., and Lafystius morhuanus) and for Sebastes mentella (Crepidostomum sp. and Neoechinorhynchus rutili). The parasite faunas of the two redfishes were comparable in species diversity, 20 taxa being identified from Sebastes fasciatus and 18 from Sebastes mentella. Prevalence of M. incurvatum and abundances of Derogenes varicus, Podocotyle reflexa, Anisakinae gen.sp. larva, Contracaecinea gen.sp. larva, Hysterothylacium aduncum larva, and Chondracanthus nodosus were greater in Sebastes fasciatus, while only Sphyrion lumpi was more abundant in Sebastes mentella. The parasitic copepods Chondracanthus nodosus and Sphyrion lumpi show potential as biological tags for the identification of redfish species.

ST-PIERRE, J.-F., J. RUNGE, P. JOLY, Y. DE LAFONTAINE, 1996. Données physiques, chimiques et biologiques sur le plancton du nord du golfe du Saint-Laurent. Partie 1 : juin 1989. Rapp. stat. can. sci. halieut. aquat., 986, 99 p.

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This report forms part of a study of the trophic interactions in the pelagic ecosystem of the north-central Gulf of St. Lawrence. The data presented here were collected during two simultaneous research cruises in the northern Gulf of St. Lawrence in June 1989. Measured variables include salinity; temperature; light extinction; nutrient concentrations; particulate carbon and nitrogen concentrations; size-fractionated chlorophyll a concentrations; abundance, composition and vertical distribution of phytoplankton, microzooplankton and mesozooplankton; copepod egg production rates; and the composition, abundance, vertical distribution, size, and diet of redfish larvae (Sebastes fasciatus-mentella). The methods used to obtain this information are described. The study focuses in particular on the interaction between microplankton, the dominant planktonic copepod, Calanus finmarchicus, and larval redfish, which dominate the ichthyoplankton

ST-PIERRE, J.-F., Y. De LAFONTAINE, 1995. Fecundity and reproduction characteristics of beaked redfish (Sebastes fasciatus and S. mentella) in the Gulf of St. Lawrence. Can. Tech. Rep. Fish. Aquat. Sci., 2059, 32 p.

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This study is designed to quantify environmental perturbations arising from forest harvesting operations and investigate the ability to ameliorate these perturbations through the provision of an unharvested leave strip of varying widths along riparian zones. This initial report from this research project is intended to document background information on the study. The report includes a general description of the study site, identifies the roles and objectives of the various study participants, outlines the general study design, and provides some detail on the various study components and methods to be employed.

MORIN, B., B. BERNIER, A. FRÉCHET, 1995. L'état du stock de sébaste de l'unité 1 (golfe du Saint-Laurent) ; The status of redfish in Unit 1 (Gulf of St. Lawrence). MPO, Pêches de l'Atlantique, Document de recherche ; DFO, Atlantic Fisheries, Research Document, 95/109, 49 p.

The preliminary estimate of total landings of redfish from the Gulf of St. Lawrence in 1994 was 19,500 t. The TAC in 1994 was 30,000 t for management Unit 1 [Divisions 4RST + 3Pn and 4Vn (Jan. to May)] and the fishery was closed in 1995. Commercial catches in 1994 were dominated by fishes born around 1980 and 1970 and were mainly of the species Sebastes mentella. The abundance of the 1985 and 1988 cohorts have decreased rapidly since 1991 and these fish were identified as being S. fasciatus. Research surveys indicated that the stock abundance is declining and that the exploitation rate was between 20 and 30 % for the 1970 and 1980 year-classes during the 1990-1994 period. This is well above the generally accepted F0.1 reference level of 12 % for redfish. This high exploitation combined with the lack of recruitment to the fishery has resulted in the low current stock size. With the closure of this fishery in 1995, the decline in the abundance of the stock should be at a much lower rate. At this time there is no sign of any significant incoming recruitment.

RUBEC, P.J., J.M. McGLADE, B.L. TROTTIER, A. FERRON, 1991. Evaluation of methods for separation of Gulf of St. Lawrence beaked redfishes Sebastes fasciatus and S. mentella : malate dehydrogenase mobility patterns compared with extrinsic gasbladder muscle passages and anal fin counts. Can. J. Fish. Aquat. Sci., 48: 640-660.

De LAFONTAINE, Y., 1990. Distribution and abundance of ichthyoplankton in the Manicouagan River estuary, a tributary of the Lower St. Lawrence Estuary. Estuaries, 13: 43-50.

TROTTIER, B.L., P.J. RUBEC, A.C. RICARD, 1988. Biochemical separation of Atlantic Canadian redfish : Sebastes mentella and S. norvegicus. Can. J. Zool., 67: 1332-1335 .

One of the problems for management of the redfish fishery in the Gulf of St. Lawrence is the difficulty in distinguishing between the different species : deepwater redfish (Sebastes mentella), golden redfish (S. norvegicus), and Acadian redfish (S. fasciatus). Controversy exists concerning whether S. mentella and S. norvegicus are separate species because of similarity of meristic characters and other attributes. We describe a procedure that distinguishes these two forms by isoelectric focusing using polyacrylamide gels of water-soluble muscle proteins. In our samples, the lower part of the gel of S. mentella consistently shows three major protein bands, while that of S. norvegicus shows only one major band. The isoelectric focusing banding patterns from our study agree with those found by other workers for redfish from Greenland and Norway. The unequivocal isoelectric focusing separation and its concordance with morphometric characters indicate that S. mentella and S. norvegicus are genetically distinct, reproductively isolated species. (DBO)©1988 National Research Council Canada