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Bibliography of the Maurice Lamontagne Institute

Philippe ARCHAMBAULT

DROUIN, A., P. ARCHAMBAULT, P. SIROIS, 2011. Distinction of nektonic and benthic communities between fish-present (Salvelinus fontinalis) and natural fishless lakes. Boreal Environ. Res., 16(2): 101-114 .

Boreal Environment Research Publishing Board

WEISE, A.M., C.J. CROMEY, M.D. CALLIER, P. ARCHAMBAULT, J. CHAMBERLAIN, C.W. McKINDSEY, 2009. Shellfish-DEPOMOD : modelling the biodeposition from suspended shellfish aquaculture and assessing benthic effects. Aquaculture, 288(3-4): 239-253 .

By predicting the dispersal of particulate aquaculture wastes around farm sites, numerical modelling can provide an effective tool to assess the spatial extent of environmental effects. The present paper describes how the aquaculture waste model DEPOMOD (Cromey, C.J., Nickell, T.D., Black, K.D. 2002a. DEPOMOD – modelling the deposition and biological effects of waste solids from marine cage farms. Aquaculture 214, 211-239.), originally developed for finfish aquaculture sites, was adapted and validated for suspended shellfish aquaculture. Field data were collected for species-specific model input parameters (mussel biodeposition rates and particle settling velocities) and several finfish model parameters (farm representation and calculation of aquaculture wastes) were adjusted for the shellfish scenario. Shellfish-DEPOMOD was tested at three coastal mussel Mytilus edulis farms with differing hydrodynamic regimes in Quebec, Canada. For each site, model predictions were compared to observed deposition measured in situ with sediment traps. Sedimentation rates under the three mussel culture sites were ca. Two to five times those observed at corresponding reference sites. Mussel biodeposits were predicted to accumulate within 30 m of the farms in the shallow depositional sites while being dispersed more than 90 m in the deeper dispersive site. At the farm site in Great-Entry Lagoon, model predictions agreed well with field data for the 0+ and 1+ mussel cohorts when the maximum biodeposit production parameter was used. At the farm site in House-Harbour Lagoon, model predictions did not agree with observed sedimentation rates, due most likely to the resuspension and advection of non farm-derived material and complex hydrodynamics. The model correctly predicted the pattern of waste dispersal at the third farm site in Cascapedia Bay, although it underestimated biodeposition. Predicted fluxes may have been underestimated at this site because biodeposits from biofouling communities were not included in the calculation of aquaculture wastes. The relationship between modelled long-term biodeposition and benthic descriptors was assessed for the three farms. Alterations to the benthic community were observed at high biodeposition rates (>15 g m-2d-1). At the most disturbed site, predicted fluxes were best correlated with the Infaunal Trophic Index (ITI) (R=-0.79, P<0.001), followed by AZTI's marine disturbance index (AMBI) (R=0.64, Pb0.001). The potential application of Shellfish-DEPOMOD in terms of the management of shellfish aquaculture sites is discussed.©2008 Elsevier B.V.

D'AMOURS, O., P. ARCHAMBAULT, C.W. McKINDSEY, L.E. JOHNSON, 2008. Local enhancement of epibenthic macrofauna by aquaculture activities. Mar. Ecol. Prog. Ser., 371: 73-84 .

Bivalve aquaculture can influence coastal marine ecosystems by increasing organic material deposition, which, in turn, can have multiple direct and indirect effects on the surrounding benthic community. We assessed the influence of blue mussel Mytilus edulis aquaculture on the epibenthic macrofauna at 4 sites in Prince Edward Island, eastern Canada. The abundance of macroinvertebrates and benthic fishes (>2 cm) was evaluated by visual counts using SCUBA within 4 mussel aquaculture facilities (‘farms’) and at locations at distances of 50, 100, 500 and 2000 m outside of them in June, August and November 2005. Benthic assemblages were dominated by seastars Asterias sp. (79 %), rock crabs Cancer irroratus (8 %), mud crabs Neopanope sayi (6 %), moon snails Lunatia heros (2 %), winter flounders Pleuronectes americanus (2 %), American lobsters Homarus americanus (1 %) and hermit crabs Pagarus sp. (1 %). Although there was great variability among sites and sampling dates, mussel aquaculture had a clear effect on total abundance, which was generally greater within farms than at distances outside of them. These increases in abundance were mainly associated with increased numbers of seastars and rock crabs. Taxonomic richness and evenness differed among some mussel farms and distances outside of mussel farms, but there were no clear trends that suggested a negative influence of mussel aquaculture. Multivariate analyses indicated that communities within mussel farms differed from those at corresponding communities at distances outside of farms, but that the taxa that contributed to these differences varied among farms. Taxonomic assemblages for a specific farm and date were generally similar among distances outside of farms and increases in the abundance of epibenthic macrofauna appeared to be largely restricted to the immediate vicinity of mussel farms, i.e. <50 m. This increase in abundance probably reflected the attraction of mobile fauna due to increased food supply and possibly to the creation of a more heterogeneous habitat. These results suggest that large macroinvertebrates and benthic fishes, including ecologically and commercially important species, seem to respond positively to the presence of suspended mussel culture.©2008 Inter-Research

CLYNICK, B.G., C.W. McKINDSEY, P. ARCHAMBAULT, 2008. Distribution and productivity of fish and macroinvertebrates in mussel aquaculture sites in the Magdalen islands (Que´bec, Canada). Aquaculture, 283: 203-210 .

Aquaculture structures may function in a manner analogous to artificial reefs, in that they provide a complex three-dimensional habitat for marine organisms and/or modify the surrounding environment. Further, aquaculture structures may increase the productivity of fish and macroinvertebrates similarly to natural complex habitats, such as seagrass beds. This research tested the general hypothesis that suspended bivalve culture increases the abundance and productivity of fish and macroinvertebrates. The study was done at two mussel farms in the Magdalen Islands, eastern Canada. Fish and macroinvertebrates were sampled in different areas within farms sites and in adjacent natural vegetated and unvegetated habitats. The instantaneous growth rates of winter flounder (Pseudopleuronectes americanus), sand shrimp (Crangon septemspinosa) and the rock crab (Cancer irroratus) were estimated using physiological indicators (RNA/DNA ratios). The results demonstrated that mussel sites are not equivalent to natural structurally complex seagrass beds with respect to fish and macroinvertebrate assemblages. Several species were abundant in mussel farms, including winter flounder and rock crab. This work, however, provided little evidence to suggest that there was greater productivity of these fish and macroinvertebrates at mussel farms, as growth rates were usually equivalent in different habitats. This study, to our knowledge, is the first attempt to determine changes in productivity brought about by aquaculture. As future development of mussel aquaculture increases in many regions around the world, the methods presented here will provide baseline information on the abundance and productivity of fish and macroinvertebrates associated with aquaculture sites.©2008 Elsevier B.V.

D'AMOURS, O., P. ARCHAMBAULT, C.W. MCKINDSEY, L. ROBICHAUD, 2008. The influence of bivalve aquaculture on ecosystem productivity. World Aquacult., 39(3) : 26-31 .

CUSSON, M., P. ARCHAMBAULT, A. AITKEN, 2007. Biodiversity of benthic assemblages on the Arctic continental shelf : historical data from Canada. Mar. Ecol. Prog. Ser., 331: 291-304 .

This study describes patterns of abundance, diversity, and assemblages of benthic macrofauna within the Canadian Arctic Archipelago. A review of data reports and the published literature yielded 219 stations and 947 taxa from 7 sources in various regions of the Canadian Arctic Archipelago (i.e. Beaufort Sea and Mackenzie Shelf, Victoria Island, Hudson and James Bays, Frobisher Bay, Ungava Bay, and Southern Davis Strait). In general, we observed that eastern regions of the Canadian Arctic Archipelago showed greater values of species richness (or a diversity) than the western and central regions, whereas no specific patterns were observed for Shannon-Wiener’s diversity (H') and Pielou's evenness (J') indices. The Beaufort Sea and Mackenzie Shelf region exhibited high values of taxonomic distinctness (Δ+), whereas Hudson Bay showed low values. However, the Hudson Bay region showed high values of turnover (βw) diversity. A non-metric multi-dimensional scaling plot of similarity (Bray-Curtis index) and analysis of similarity revealed that species composition differed among regions, even those located in close proximity to one another. These investigations were conducted at different levels of taxonomic resolution (Species, Order, Class and Phyla) and the results demonstrated that most patterns were maintained up to the Order and Class level. A relatively small number of taxa, mainly annelids, were responsible for most of the dissimilarity among regions. Bottom salinity and temperature were the most important environmental variables (among depth of site, bottom temperature, salinity, physical and chemical sediment characteristics) for determining these assemblage patterns. Multiple regression analyses also demonstrated that variance in species richness and diversity (H’) was best explained by variance in salinity (55 and 43 % respectively). The analysis of a time series from Frobisher Bay revealed that the temporal (mo/yrscale) variability of assemblages was of the same order as the spatial (km-scale) variability among sites.©2007 Inter-Research

CHABOT, D., A. RONDEAU, B. SAINTE-MARIE, L. SAVARD, T. SURETTE, P. ARCHAMBAULT, 2007. Distribution des invertébrés benthiques dans l'estuaire et le golfe du Saint-Laurent ; Distribution of benthic invertebrates in the Estuary and Gulf of St. Lawrence. MPO, Secrétariat canadien de consultation scientifique, Document de recherche ; DFO, Canadian Science Advisory Secretariat, Research Document, 2007/018, 108 p .

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This study had two objectives. The first was to gather all the available data from scientific surveys both at the Maurice-Lamontagne Institute (MLI) and the Gulf Fisheries Centre (GFC) in order to establish distribution patterns and relative abundance of benthic invertebrates in the lower estuary and the gulf of St. Lawrence (LEGSL). The second objective was to propose Ecologically and Biologically Significant Areas (EBSAs) for benthic invertebrates of the LEGSL, according to these distribution and relative abundance data. Surveys from the MLI are mainly conducted in the lower estuary and in the northern gulf of St. Lawrence (nGSL) but some cover Gaspesie, including Chaleurs bay, and the Magdalen Islands. The southern gulf of St. Lawrence (sGSL) is covered by the GFC surveys. The bulk of the information presented here comes from annual scientific surveys carried out by the two regions: the multi-species survey and the mobile gear Sentinel survey by the MLI and the fall survey, snow crab survey, and Northumberland survey by the GFC. Several other surveys by MLI provided useful data, some even with a long time series but with limited geographical coverage (surveys for snow crab, scallop and surf clam), while others were conducted less frequently and at a small geographic scale (surveys for clam and whelk). Cod and Greenland halibut stomach contents have also been used as a sampling device for the distribution on some benthic invertebrates. Despite the large number of surveys considered here, the coastal zone (less than 50 m deep in the Estuary and the nGSL and less than 30 m deep in the sGSL) was not adequately sampled, except for the Northumberland Strait. In the main section of this document, distributions of 44 taxa are presented and have guided the identification of EBSAs : 4 general groups (soft corals, anemones, sponges, ascidians), 5 echinoderms, 6 molluscs, 1 mysid, 22 shrimps, and 6 crabs. Zones of maximum relative abundance of each taxa, weighted inversely to their surface area of high abundance, were used to calculate an index of benthic invertebrate concentration for each 10 x 10 km square sampled in the study area. This index was the primary tool in the identification of potential EBSAs. As a result, 17 EBSAs for benthic invertebrates are proposed. However, it is important to keep in mind that only a small proportion (approximately 0.02 %) of the benthic invertebrate species known to be present in the study area was considered in the process. In particular, the lack of data for the coastal zone is a major gap. We present in appendix to this report the data on 6 coastal species that we were able to obtain.

RICHARD, M., P. ARCHAMBAULT, G. THOUZEAU, C.W. McKINDSEY, G. DESROSIERS, 2007. Influence of suspended scallop cages and mussel lines on pelagic and benthic biogeochemical fluxes in Havre-aux-Maisons Lagoon, I^les-de-la- Madeleine (Quebec, Canada). Can. J. Fish. Aquat. Sci., 64: 1491-1505 .

An in situ experiment was done in July 2004 to test and compare the influence of suspended bivalve cultures (1- and 2-year-old blue mussels (Mytilus edulis) and sea scallops (Placopecten magellanicus)) on biogeochemical fluxes in the water column and at the benthic interface in Havre-aux-Maisons Lagoon (Quebec, Canada). Aquaculture structures increased the pelagic macrofaunal biomass (PMB) and acted as an oxygen sink and nutrient source in the water column under dark conditions. Although PMB was lower in scallop culture, the influence of scallop cages on pelagic fluxes was similar to or greater (nitrate and nitrite) than that of mussel lines. Sediments were organically enriched, and benthic macrofaunal abundances were decreased in mussel culture zones relative to the control zone, but such an effect was not observed in the scallop zone. Nevertheless, benthic oxygen demand did not vary among culture types and control zones. Benthic nutrient fluxes were greatest beneath aquaculture structures. Both pelagic and benthic interfaces may modify oxygen and nutrient pools in culture zones in Havre-aux-Maisons Lagoon. The contribution of aquaculture structures to oxygen, ammonium, and phosphate pools may be a function of PMB and type. While aquaculture structures had an important role on nitrate and nitrite cycling, silicate turnover was mainly driven by benthic mineralization of biodeposits.©2007 NRC Canada

GILBERT, D., D. CHABOT, P. ARCHAMBAULT, B. RONDEAU, S. HÉBERT, 2007. Appauvrissement en oxygène dans les eaux profondes du Saint-Laurent marin : causes possibles et impacts écologiques. Naturaliste can., 131(1): 67-75 .

[Abstract only available in French]
Depuis les années 1930, les concentrations d'oxygène ont baissé de moitié dans l'estuaire maritime du Saint-Laurent, à 300 m de profondeur. Un accroissement de la proportion d'eau chaude et pauvre en oxygène du GulfStream, au détriment de la proportion d'eau froide et bien oxygénée du courant du Labrador, expliquerait entre la moitié et les deux tiers de la baisse. Parmi les autres facteurs naturels et anthropiques susceptibles d'expliquer le reste de la baisse d'oxygène, les plus probables impliquent un flux accru de matières organiques des eaux de surface vers les fonds marins, où leur décomposition augmente la consommation d'oxygène. Nous montrons notamment une faible tendance à la hausse des nitrates à Lauzon, depuis 1990. Certaines espèces d'animaux marins comme le turbot, la crevette nordique et les polychètes Myriochele et Ampharete sont très abondantes dans les zones les plus pauvres en oxygène de l'estuaire et du golfe du Saint-Laurent, tandis que d'autres espèces comme la morue en sont absentes. Le seuil de tolérance aux faibles teneurs d'oxygène varie donc d'une espèce à l'autre. Nous devrons améliorer nos connaissances à cet égard afin de mieux comprendre les conséquences de l'appauvrissement en oxygène sur la biodiversité et le fonctionnement de l'écosystème.©2007 La Société Provancher d'histoire naturelle du Canada

RICHARD, M., P. ARCHAMBAULT, G. THOUZEAU, G. DESROSIERS, 2007. Summer influence of 1 and 2 yr old mussel cultures on benthic fluxes in Grande-Entre´e lagoon, Îles-de-la-Madeleine (Que´bec, Canada). Mar. Ecol. Prog. Ser., 338: 131-143 .

The summer influence of 1 and 2 yr old suspended mussel lines on benthic fluxes (oxygen, silicates, ammonium, phosphates, nitrates and nitrites) was studied in Grande-Entrée lagoon (GEL), Îles-de-la-Madeleine, Québec, Canada. This influence and its temporal variation were examined in relation to bottom water, sediment and macrofauna characteristics. In situ mensurative experiments using benthic chambers and sediment cores were carried out at 2 mussel sites (M1 and M2) and 2 control sites (C1 and C2) in July, August and September 2003. In contrast to 1 yr old mussel lines (M1), 2 yr old lines (M2) enriched the sediment in organic matter and increased silicate, ammonium, phosphate and nitrite fluxes at the water-sediment interface. Silicate, ammonium and phosphate fluxes were highest in August, when temperature was highest. The main nutrient releases observed at the water-sediment interface in M2 could reduce nitrogen and silica limitation in the water column. Mussel lines did not influence benthic macrofauna biomass, but favoured the recruitment of many small-sized organisms. No influence of mussel lines was observed on oxygen consumption at the water-sediment interface. Macrofauna biomass and oxygen consumption increased in parallel during the summer, but the respiration of the low biomass alone cannot explain the greater overall benthic oxygen demand. The latter was probably also driven by the oxidation of reduced compounds such as sulfides. The reduced nature of the sediment could be natural in GEL, but the continuous accumulation of mussel biodeposits since 1985 has probably contributed to the degradation of the benthic environment in the mussel farm. ©2007 Inter-Research

LANDRY T., M. SKINNER, A. LEBLANC, D. BOURQUE, C.W. McKINDSEY, R. TREMBLAY, P. ARCHAMBAULT, L. COMEAU, S. COURTENAY, F. HARTOG, M. OUELLETTE, J.-M. SÉVIGNY, 2006. A scientific review of bivalve aquaculture : interaction between wild and cultured species. Pages 80-138 in A scientific review of the potential environmental effects of aquaculture in aquatic ecosystems. Dept. of Fisheries and Oceans (Can. Tech. Rep. Fish. Aquat. Sci., 2450(5)) .

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This paper reviews the present state of knowledge on interactions between wild and cultured species within the context of bivalve mariculture in Canada. It also identifies critical knowledge gaps and recommends research to address these gaps. The literature reviewed includes national and international information covering bivalve aquaculture, bivalve restoration, coastal community and ecology. This review is focused on changes affecting the pelagic community, benthic communities, predator species, genetic structures, and the risk of introducing invasive species.

DROUIN, A., P. SIROIS, P. ARCHAMBAULT, 2006. Structure des communautés d’invertébrés et des espèces d’amphibiens dans des lacs avec et sans omble de fontaine (Salvelinus fontinalis) en forêt boréale. Rapp. tech. can. sci. halieut. aquat., 2628, 40 p .

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The influence of stocking fishless lakes on the biological integrity and diversity is unknow. The objective was to compare the structure of invertebrate communities and amphibian species between lakes with and without fish. Zooplanktonic, nektonic, benthic communities and amphibians were sampled in five fishless lakes as well as in five lakes containing allopatric populations of brook trout (Salvelinus fontinalis). The structure of invertebrate communities and amphibian species were analysed according to univariate (abundance, richness, Shannon’s diversity index, equitability) and multivariate (PERMANOVA, MDS) approaches. Fishless lakes had a greater abundance of zooplanktonic organisms and a greater diversity of amphibians than lakes with fish. The multivariate approach seemed to be more sensitive than the diversity indexes commonly used to illustrate the differences in invertebrate communities between both types of lakes.

ARCHAMBAULT, P., P. GOUDREAU, 2006. Effet de la pêche commerciale sur le gisement de pétoncles d'Islande (Chlamys islandica) de l'Ile Rouge dans l'estuaire du Saint-Laurent : impact sur les pétoncles et la communauté benthique ; Effect of the commercial fishery on the Ile Rouge Iceland scallop (Chlamys islandica) bed in the St. Lawrence estuary : assessment of the impacts on scallops and the benthic community. MPO, Secrétariat canadien de consultation scientifique, Document de recherche ; DFO, Canadian Science Advisory Secretariat, Research Document , 2006/079, 22 p .

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Many studies have shown that scallop dredging seriously disturb marine substratum. This study was done to evaluate the dredging impact on scallop and benthic communities on the Ile Rouge Icelandic scallop bed, in Saguenay-St-Lawrence Marine Park. The results of photographic sampling and experimental dredging did not showed effects of dredging on benthic communities on this highly dynamic ecosystem (high velocity currents, upwelling zone, etc.). Furthermore, there is no evident sign of a decline in the size of scallops, contrary to many studies around the world and this could be the result of a relatively low fishing effort. The study site, a sandy-gravel substrate with high velocity currents recover in a few months from the impacts of dredging gear.

CRANFORD, P.J., R. ANDERSON, P. ARCHAMBAULT, T. BALCH, S.S. BATES, G. BUGDEN, M.D. CALLIER, C. CARVER, L.A. COMEAU, B. HARGRAVE, W.G. HARRISON, E. HORNE, P.E. KEPKAY, W.K.W. LI, A. MALLET, M. OUELLETTE, P. STRAIN, 2006. Indicators and thresholds for use in assessing shellfish aquaculture impacts on fish habitat ; Indicateurs et seuils pour l'évaluation des effets de la conchyliculture sur l'habitat du poisson. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2006/034, 116 p .

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The purpose of this research document is to provide science advice needed to allow DFO Habitat Management to make and justify management decisions related to the potential harmful alteration, disruption and destruction (HADD) of fish habitat by shellfish aquaculture. The overall goal of this exercise and of our recommendations is to promote the avoidance and mitigation of a HADD. Our specific objectives were the following: 1. identify, evaluate and make recommendations regarding a range of quantitative indicators (measures of habitat and ecosystem status) that could be used to monitor for potential shellfish aquaculture effects; and 2. provide science-based decision support for the development of an environmental monitoring framework, based on identification of predetermined impact limits (operational thresholds) intended to trigger management actions. A wide range of ecosystem and habitat status indicators and methodological approaches were identified to support industry management and each was initially screened based on habitat impact predictions and observations. Selected indicators were classified based on associated strengths and weaknesses using predefined criteria, including: availability of operational thresholds; regulatory needs; cultured species; scales of impact addressed; cost/benefit; and the needs of responsive management. A habitat assessment framework is recommended for shellfish aquaculture that addresses the need for a consistent and transparent decision-making approach that is science-based, and reflects both fish habitat and ecosystem concerns. The highly diverse Canadian shellfish aquaculture industry (e.g. species cultured, husbandry method, and stocking density) and regional differences in environmental impact risks (related primarily to geographic and hydrodynamic factors) were identified as important considerations for our evaluation of shellfish aquaculture impact assessment options. Recommendations are made towards establishment of an environmental monitoring framework that incorporates sufficient flexibility to be of use in a wide range of environmental settings and that is both effective and practical for current aquaculture operations that range from less than 0.5 to 500 hectares. A primary recommendation of this report is that habitat assessments could be based on a tiered approach that recognizes that an increased risk to fish habitat requires an increase in monitoring effort. Various levels of monitoring could be triggered based on assessments of environmental sensitivity and risk (e.g. dispersive vs. depositional environment and presence of sensitive habitat), the nature of the operation (e.g. size, species and husbandry), and previous measurement and verification of environmental impacts. Inherent within the recommended framework is that ongoing monitoring programs could be continually adaptive to changes in our state-of-knowledge on potential environmental impacts, indicators and related methodologies. It is important to maintain an ability to add or remove indicators to monitoring programs based on sound science. The recommended multi-tiered impact assessment approach addresses the potential for benthic marine habitat impacts in the immediate vicinity of each shellfish aquaculture lease and it therefore parallels science recommendations for finfish aquaculture monitoring in Canada. Scientifically defensible thresholds are available for benthic biogeochemical indicators (sulfides and redox potential) and these could be used to define the hypotheses that need to be addressed in an operational monitoring program. Effective measures are also available for mitigating benthic organic enrichment impacts, and these can be linked to the operational thresholds incorporated in a responsive management framework. Ecosystem-level interactions with dense shellfish aquaculture populations are more complex than for finfish culture and many potential and observed effects on fish habitat cannot be assessed using only site-specific benthic habitat indicators. Measurements with selected far-field impact indicators are needed under certain conditions to compliment benthic operational monitoring. The inability to fully define quantitative operational thresholds for many valid and highly relevant indicators of habitat and ecosystem status (particularly those describing the structure and dynamics of pelagic habitat), owing to present gaps in our knowledge of ecosystem dynamics, should not preclude their potential use. Surveillance sampling programs based on water column parameters are needed under conditions where environmental impact assessments and ongoing monitoring data indicate a relatively high risk that bay-scale impacts will occur. Of particular importance is the need to assess the impacts of longline mussel culture operations on suspended particle concentrations and distribution and the pelagic food web (micro-flora and fauna) in extensively leased coastal embayments. Industry shellfish stocking information for all farms within a management area is considered fundamental to assessments of shellfish aquaculture impacts on fish habitat. The use of sound science practices is required for the design of monitoring programs (statistically valid sampling approaches) and for the analysis of habitat status indicators and data (e.g. quality assurance/quality control).

CAMPAGNA, S., J. LAMBERT, P. ARCHAMBAULT, 2005. Abondance et distribution du concombre de mer (Cucumaria frondosa) et prises accidentelles obtenues par dragage entre Matane et Cap-Gaspé (Québec) en 2004. Rapp. tech. can. sci. halieut. aquat., 2620, 70 p .

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The results of an abundance survey aimed to determine the potential of a sea cucumber (Cucumaria frondosa) fishery on the north shore of the Gaspésie peninsula are presented. Abundance of C. frondosa was high between 10 and 40 m, with more than 50 % of the estimated biomass located at a 10 m depth. The drag used, LGS type (Light Green Sweep Urchin Drag), was not very selective and bycatch was abundant. Based only on abundance estimates, a commercial exploitation could be possible. Such a fishery would have to be developped cautiously

HUTIN, E., Y. SIMARD, P. ARCHAMBAULT, 2005. Acoustic detection of a scallop bed from a single-beam echosounder in the St. Lawrence. ICES J. Mar. Sci., 62(5): 966-983 .

Single-beam seabed echoes combined with epi-macrobenthos photographs were used to remotely detect a scallop bed and characterize the specific acoustic signal of Iceland scallop (Chlamys islandica). A dense scallop bed was surveyed in 2002, with a QTC VIEW Series IV acoustic ground-discrimination system (AGDS) connected to a 38 kHz, 7° split-beam SIMRAD EK60 scientific echosounder. In 2003, a 50 kHz, 42° single-beam SUZUKI ES-2025 echosounder was connected to a QTC VIEW Series V AGDS. The QTC VIEW data were analysed with QTC IMPACT following the standard procedures and classified into acoustic classes. Several approaches were tested: unsupervised and supervised survey strategies directed to specific benthic communities. The SIMRAD EK60 seabed volume-backscattering strength (Sv) was submitted to a principal component analysis (PCA), before and after removal of a depth trend, and the scores on the first 10 principal components were classed by a K-means cluster analysis. The same seabed Sv data were submitted to stepwise discriminant analysis whose training data sets were defined with the ground-truth photographs using different groupings: biotope types, community types, and finally scallop-density classes. All the QTC AGDS approaches failed to reveal the scallop bed, community structures, or biotopes. The QTC classifications mimicked the bathymetry with a strong correlation of the acoustic classes with depth. The seabed Sv PCA + K-means approach presented similar depth-dependence, but, the PCA + K-means on the Sv residuals revealed the scallop bed. The discriminant analysis was the best solution for the scallop density with a general classification success rate of 75 % and up to 91 % for the highest density class. The Sv signature of the scallop bed is presented, and the most discriminant part of the acoustic signal is identified.©2005 Elsevier Ltd on behalf of International Council for the Exploration of the Sea

MIRON, G., T. LANDRY, P. ARCHAMBAULT, B. FRENETTE, 2005. Effects of mussel culture husbandry practices on various benthic characteristics. Aquaculture, 250(1-2): 138-154 .

SIMARD, N., C.W. McKINDSEY, P. ARCHAMBAULT, C. CYR, 2005. Découverte d'espèces marines envahissantes aux îles de la Madeleine. Naturaliste can., 129(2): 62-64 .

CHEVARIE, L. B. MYRAND, F. BOURQUE, M. GIGUÈRE, L. PROVENCHER, P. ARCHAMBAULT, R. TREMBLAY, J. PARIZEAU, G. DESROSIERS, 2003. "Programme MIM":A new program to develop soft-shell clam (Mya arenaria) culture in Îles-de-la-Madeleine (Gulf of St. Lawrence). AAC Spec. Publ., 6: 49-52 .

ARSENEAU, M.J., P. ARCHAMBAULT, P. GOUDREAU, 2003. Effets de la pêche commerciale sur le gisement de pétoncles d’Islande (Chlamys islandica) de l’île Rouge dans l’estuaire du Saint-Laurent: évaluation des impacts sur le pétoncle et la communauté benthique associée. Rapp. tech. can. sci. halieut. aquat., 2512, 38 p .

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Many studies have shown that scallop dredging seriously disturb marine substratum. This study is conducted to evaluate the dredging impact on scallop and benthic communities on the Ile Rouge scallop bed, in Saguenay-St-Lawrence Marine Park. Photographic sampling and experimental dredging do not document effects of dredging on benthic communities. However, a decrease in scallop size at landing suggests that dredging could have an impact on the scallop population. The study site, a sandy-gravel substrat with high velocity currents recover in a few mounths from the impacts of dredging gear.

BISHOP, M.J., A.J. UNDERWOOD, P. ARCHAMBAULT, 2002. Sewage and environmental impacts on rocky shores: necessity of identifying relative spatial scales. Mar. Ecol. Prog. Ser., 236: 121-128 .

SUNDBY, B., A. MUCCI, C. GOBEIL, D. GILBERT, Y. GRATTON, P. ARCHAMBAULT, 2002. Hypoxia in the Deep Waters of the Laurentian Trough, Lower St. Lawrence Estuary. Pages 29-31 in J.J. Martin (ed.). Developments for a Canadian GEOHAB (Global Ecology and Oceanography of Harmful Algal Blooms) program: 2001 Workshop report. Rapp. tech. can. sci. halieut. aquat., 2400 .

HARTOG, F., ARCHAMBAULT P., 2002. Revue de littérature sur les impacts de la pêche du pétoncle. Rapp. manus. can. sci. halieut. aquat., 2627, 38 p .

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Mobile fishing gear such as trawls and dredges are used extensively woldwide to catch numerous marine fishes and invertebrates despite the fact that criticism about their impact on the environment. This report presents a review of published studies on the effects of mobile gear fishing with an emphasis on scallop dredging. Dredging for scallop and other molluscs is known to have the greatest environmental impacts on benthic biota. Results from studies on the effects of dredging on the physical sea floor, on bycatches, on benthic habitat biological components and on marine communities are discussed.

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