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Bibliographie de l'Institut Maurice-Lamontagne

Poissons / Boreogadus saida / Morue polaire, Saida, Morue du nord

POMERLEAU, C., S.H. FURGUSON, W. WALKUSZ, 2010. Stomach contents of bowhead whales (Balaena mysticetus>/i>) from four locations in the Canadian Artic. Polar Biol., 34(4): 615-620.

[Résumé disponible seulement en anglais]
Abstract The stomach contents of four bowhead whales (Balaena mysticetus) harvested between 1994 and 2008 from the Canadian Arctic were examined to assess diet composition. Three samples were collected from bowhead whales of the Eastern Canada––West Greenland (EC––WG) population and represent, according to our knowledge, the first diet analysis from this bowhead whale stock. We also examined the stomach content of one bowhead whale from the Bering-Chukchi-Beaufort (BCB) population hunted in 1996. All four whales had food in their stomachs and their diet varied from exclusively pelagic (BCB whale), with Limnocalanus macrurus being the main prey, to epibenthic and benthic (EC––WG) with Mysis oculata playing an important role. These results indicate broad foraging spectrum of the bowhead whales and add to a basic knowledge of their diet.&Copy;2010 Springer-Verlag

BENOIT, D., Y. SIMARD, J. GAGNÉ, M. GEOFFROY, L. FORTIER, 2010. From polar night to midnight sun : photoperiod, seal predation, and the diel vertical migrations of Polar Cod (Boreogadus saida) under landfast ice in the Arctic Ocean. Polar Biol., 33(11): 1505-1520.

[Résumé disponible seulement en anglais]
The winter/spring vertical distributions of polar cod, copepods, and ringed seal were monitored at a 230-m station in ice-covered Franklin Bay. In daytime, polar cod of all sizes (7–95 g) formed a dense aggregation in the deep inverse thermocline (160–230 m, –1.0 to 0 °C). From December (polar night) to April (18-h daylight), small polar cod <25 g migrated into the isothermal cold intermediate layer (90–150 m, –1.4 °C) at night to avoid visual predation by shallow-diving immature seals. By contrast, large polar cod (25–95 g), with large livers, remained below 180 m at all times, presumably to minimize predation by deep-diving mature seals. The diel vertical migration (DVM) of small polar cod was precisely synchronized with the light/dark cycle and its duration tracked the seasonal lengthening of the photoperiod. The DVM stopped in May coincident with the midnight sun and increased schooling and feeding. We propose that foraging interference and a limited prey supply in the deep aggregation drove the upward re-distribution of small polar cod at night. The bioluminescent copepod Metridia longa could have provided the light needed by polar cod to feed on copepods in the deep aphotic layers.©2010 Springer

MORISSETTE, L., M. CASTONGUAY, C. SAVENKOFF, D.P. SWAIN, D. CHABOT, H. BOURDAGES, M.O. HAMMILL, J. MARK HANSON, 2009. Contrasting changes between the northern and southern Gulf of St. Lawrence ecosystems associated with the collapse of groundfish stocks. Deep-Sea Res., Part II, Top. Stud. Oceanogr., 56(21-22): 2117-2131.

[Résumé disponible seulement en anglais]
In order to have a global view of ecosystem changes associated with the collapse of groundfish species in the Gulf of St.Lawrence during the early 1990s, Ecopath mass balance models were constructed in corporating uncertainty in the input data.These models covered two ecosystems (northern and southern Gulf of St.Lawrence; NAFO divisions 4RSand 4T), and two time periods (before the collapse, in the mid-1980s, and after it, in the mid 1990s). Our analyses revealed that the ecosystem structure shifted dramatically from one previously dominated by piscivorous groundfish and small-bodied forage species during the mid-1980s to one now dominated only by small-bodied pelagic species during the mid-1990s in both southern and northern Gulf.The species structure in the northern Gulf versus southern Gulf was different, which may explain why these two ecosystems did not recover the same way from the collapse in the early1990s. Productivity declined in the northern Gulf after the collapse but increased in the southern Gulf. The collapse of groundfish stocks resulted in declines in the mean trophic level of the landings in both the northern and the southern Gulf. Even though fishing mortality was then intentionally reduced, this part of the total mortality was taken up by predation.The temporal changes in the internal structure of both ecosystems are reflected in their overall emergent properties.©2009 Elsevier Ltd.

BENOIT, D., Y. SIMARD, L. FORTIER, 2008. Hydroacoustic detection of large winter aggregations of Arctic cod (Boreogadus saida) at depth in ice-covered Franklin Bay (Beaufort Sea). J. Geophys. Res. (C Oceans), 113(6), art. no C06S90, 9 p.

[Résumé disponible seulement en anglais]
In the Canadian Arctic, the large biomass of Arctic cod that must exist to explain consumption by predators has eluded detection. From December 2003 to May 2004, acoustic estimates of Arctic cod biomass at a 225-m-deep station in central Franklin Bay (southeastern Beaufort Sea) increased progressively by 2 orders of magnitude, reaching maximum values of 2.7 and 55 kg m-2 in April. During accumulation in Franklin Bay, the fish occupied the lower part of the Pacific halocline (140 m to bottom), where the temperature-salinity signature (-1.4 to 0.3 °C; 33 to 34.8 practical salinity units) corresponded to slope waters. Currents at 200 m along the western slope of Amundsen Gulf headed SSE in early winter, suggesting the passive advection of Arctic cod from Amundsen Gulf into Franklin Bay. Retention in Franklin Bay against the general circulation resulted from the fish keeping at depth to reduce predation by diving seals and/or to benefit from relatively warm temperatures in the lower halocline. Extrapolating a standing biomass of 11.23 kg m-2 at the station in April to the whole of Franklin Bay, the availability of polar cod would amply satisfy the requirements of predators. Dense accumulations of Arctic cod in embayments in winter likely play an important role in structuring the ecosystem of the Beaufort Sea. Understanding how climate change and the reduction of the sea ice cover will affect the stability of the oceanographic/behavioral accumulation process requires further research and modeling.© 2008 American Geophysical Union.

STENSON, G.B., M.O. HAMMILL, J.W. LAWSON, 1997. Predation by harp seals in Atlantic Canada : preliminary consumption estimates for Arctic cod, capelin and Atlantic cod. J. Northwest Atl. Fish. Sci., 22: 137-154.

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FORTIER, L., M. GILBERT, D. PONTON, R.G. INGRAM, B. ROBINEAU, L. LEGENDRE, 1996. Impact of freshwater on a subarctic coastal ecosystem under seasonal sea ice (southeastern Hudson Bay, Canada). III. Feeding success of marine fish larvae. J. Mar. Syst., 7: 251-265.

FORTIER, L., PONTON, D., M. GILBERT, 1995. The match/mismatch hypothesis and the feeding success of fish larvae in ice-covered southeastern Hudson Bay. Mar. Ecol. Prog. Ser., 120: 11-27.

PONTON, D., J.A. GAGNÉ, L. FORTIER, 1993. Production and dispersion of freshwater, anadromous and marine fish larvae in and around a river plume in subarctic Hudson Bay, Canada. Polar Biol., 13: 321-331.

GILBERT, M., L. FORTIER, D. PONTON, R. DROLET, 1992. Feeding ecology of marine fish larvae across the Great Whale River plume in seasonally ice-covered southeastern Hudson Bay. Mar. Ecol. Prog. Ser., 84: 19-30.

DROLET, R., L. FORTIER, D. PONTON, M. GILBERT, 1991. Production of fish larvae and their prey in subarctic southeastern Hudson Bay. Mar. Ecol. Prog. Ser., 77: 105-118 .