SS1.09 Fisheries Population Linkage Spatial and Temporal Variation in Zooplankton
Date: Wednesday, June 12, 2002
Time: 12:00:00 PM
Location: Carson C
Ringuette, M, , Département de Biologie, Université Laval, Sainte-Foy, QC, Canada, 
Castonguay, M, , Fisheries and Oceans, Institut Maurice Lamontagne, Mont-Joli, QC, Canada, 
Runge, J, , OPAL, University of New Hampshire, Durham, NH, USA,
Grégoire, F, , Fisheries and Oceans, Institut Maurice Lamontagne, Mont-Joli, QC, Canada, 
A previous study identified relationships linking variations in the physical environment to fluctuations in zooplankton biomass and Atlantic mackerel (Scomber scombrus) recruitment in the southern Gulf of St. Lawrence, Canada. Here, diets of mackerel larvae captured in late June/early July in the southern Gulf were compared among four years, one of these years producing an exceptional year-class (1982). Comparisons were standardized for larval length and time of day. Stomach fullness differed significantly among years, with highest values observed in 1982. Wet weight of stomach contents was significantly larger in 1982 than in 1987 and 1996. The mean weight of C. finmarchicus naupliar prey in the diet was also significantly greater in 1982 than in 1985, 1987, or 1996. Female Calanus finmarchicus were more abundant and more extensively distributed in the southern Gulf of St. Lawrence in 1982 compared with 1985, 1987, and 1990. These observations are consistent with the hypothesis of a link between production of C. finmarchicus nauplii, feeding of mackerel larvae and recruitment success. However, despite the evidence for better feeding conditions for larvae in the 1982 exceptional year-class, the size of juvenile mackerel at the end of the first year, as measured by otolith size, varied significantly between years and was smallest in 1982. We propose hypotheses that could account for coupling between low juvenile growth and strong cohorts.