Research Document 2022/030

Multi-species Considerations for Defining Fisheries Reference Points for Striped Bass (Morone saxatilis) from the Southern Gulf of St. Lawrence

By Chaput, G.

Abstract

The reference points and management strategies based on single species management approaches for the purpose of optimizing utility functions specific to Striped Bass do not take into account the interactions among multiple species of equally important conservation and fisheries values. Modifying the single species Striped Bass reference points to account for interactions with other species requires evidence of interactions between Striped Bass and the other species. The most direct interaction considered is the predation by Striped Bass on other species with a focus on Atlantic Salmon. Several data sources are presented and examined to inform on these associations, including recorded commercial landings of important diadromous species, indices based on catches at estuarine index trapnets operated by DFO Science, and studies directly related to predation and survival rates of Atlantic Salmon smolts during the seaward migration phase. A cohort model relating population specific indices of juvenile salmon abundance to adult returns is also presented. There is conflicting evidence of reductions in a few anadromous fish species abundance indicators associated with increased abundance of Striped Bass in the southern Gulf. There is direct evidence of predation by Striped Bass on gaspereau, Rainbow Smelt and Atlantic Salmon smolts. Several studies using acoustic tag technologies have inferred predation events and changes in estimated survival rates in the early phase of migration of Atlantic Salmon smolts through Miramichi Bay that point to Striped Bass predation as a likely driver of these variations. It is not clear from the available studies that reducing Striped Bass spawner abundances to a level of the mid 2000s, i.e., 100 thousand spawners or less, would improve the acoustic tagged smolt survival estimates or the population level relative survival rates derived from the cohort model, nor landings of gaspereau and Rainbow Smelt in the commercial fisheries.

Research Document 2022/030 (PDF, 3884 KB)

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