| LONG TIME NO SEE: THE ONSET OF A NATURAL DYNAMIC FOR THE RE-INTRODUCED STRIPED BASS IN THE ST. LAWRENCE ESTUARY (CANADA) |
| MORISSETTE, O.; LECOMTE, F.; SIROIS, P., Research Chair on Exploited Aquatic Species, Universite du Quebec a Chicoutimi, Chicoutimi, QC, G7H 2B1 Canada, olivier.morissette@uqac.ca, frederic.lecomte@mrnf.gouv.qc.ca, pascal_sirois@uqac.ca; LEGAULT, M. and VERREAULT, G., Ministere des ressources naturelles et de la faune, Qubec, QC, G1S 4X4 Canada, michel.legault@mrnf.gouv.qc.ca; guy.verreault@mrnf.gouv.qc.ca |
| As many striped bass populations along the North American East Coast, the St. Lawrence Estuary stock had undergoes wide abundance variations leading to periodical decline of commercial landings. This population was driven toward a complete extirpation by the mid-1960's following a strengthening of several deleterious factors (habitat alteration, overfishing, etc.) while the population was in a period of low abundance and recruitment. In 2002, a re-introduction program has begun by the stocking of a few adults and juveniles from Miramichi River (New Brunswick, Canada). In 2008, six years after initiating the stocking program, natural reproduction was deduced from the occurrence of juvenile in eel fishery surveys. The reproductive dynamic remains mostly unknown since the beginning of the re-introduction program and doubts persist on the presumed dynamic of the historical population. To circumvent this limitation, a research project dealing with the striped bass larval distribution and abundance was set to better understand the dynamics of this newly established population. Sampling was carried out in the St. Lawrence estuarine turbidity maximum (ETM) in 2010. To discriminate the morphologically similar co-occuring congeneric species, molecular techniques were developed to complement (and validate) the morphological identification. Further analyses were performed on the otolith microstructure to estimate the spawning date and growth rate. Results showed that striped bass larvae are originating from a natural spawning event that took place along the south shore in late May 2010. The distribution and abundance of early life stage suggest that the introduced population already exhibit a spawning dynamics typical of other estuarine populations. The newly discovered spawning site is closer to ETM than what was thought for the extinct population. The reestablishment of a natural spawning dynamic for the actual striped bass population suggest it has taken the right steps toward its ultimate return as the top predator in the St. Lawrence Estuary. |
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