| SELECTION FOR FAST GROWTH DURING EARLY LIFE OF YELLOW PERCH IN SMALL OLIGOTROPHIC LAKES SUBJECTED TO FOREST HARVESTING IN DRAINAGE BASIN |
| LECLERC, V., Sirois, P., Laboratoire d’écologie aquatique, Département des sciences fondamentales, Université du Québec à Chicoutimi, Chicoutimi (QC) Canada, G7H 2B1, veronique_leclerc@uqac.ca, pascal_sirois@uqac.ca and Bérubé, P., Direction de la recherche sur la faune, Ministère des Ressources naturelles et de la Faune, Québec (QC) Canada, G1S 4X4, pierre.berube@mrnf.gouv.qc.ca |
| According to Anderson’s growth-mortality hypothesis, a fish larva growing and developing faster has a higher probability of survival. Thus, small changes in growth rate of fish larvae could lead to important variations in survival and recruitment for both freshwater and marine fishes. Larval fish growth is mainly influenced by abiotic (e.g. temperature) and biotic (e.g. prey field) conditions and any factors that can modify these conditions may have an effect on fish survival. For example, forest harvesting is known to have an impact on abiotic and biotic conditions in Boreal Shield lakes. Our objective was (1) to examine selection for fast growth and (2) to assess the influence of forest harvesting on selection patterns from larval to juvenile stage of yellow perch in small oligotrophic Boreal Shield lakes. Yellow perch were sampled three times in six headwater lakes in summer 2005. There were three control lakes without anthropogenic perturbation on drainage basin and three lakes with harvested drainage basin in a proportion ranging from 35 to 57 %. Growth rate was estimated using otolith microstructure. Back-calculated standard length (growth trajectory) and absolute growth rates were compared among treatments (control vs harvested) and among the three surveys in each lake: population of origin (early July), survivors to 14 days (mid-July), and survivors to 28 days (early August). Survival ratios by growth rate based on hatchdate frequency distribution were calculated to bring out the selective processes. Results of this study will improve our comprehension of survival mechanisms for fish in small freshwater systems under the influence of forest harvesting, an important anthropogenic perturbation of drainage basin of lakes in Canada. |
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