Research Document 2022/029

Fisheries Reference Points for Striped Bass (Morone saxatilis) from the Southern Gulf of St. Lawrence

By Chaput, G. and Douglas, S.

Abstract

The Striped Bass (Morone saxatilis) population of the southern Gulf of St. Lawrence, the most northern spawning population of the species distribution in eastern North America, is widely distributed in estuaries and coastal waters of the southern Gulf of St. Lawrence from the north shore of the Gaspe Peninsula in Quebec to the northern tip of Cape Breton Island, Nova Scotia. For purposes of assessment and development of fisheries reference points, the southern Gulf Striped Bass population distribution comprises the Gulf of St. Lawrence region. Following on the sustained rebuilding of the spawner abundances from the lows of the late 1990s to the current high abundances that exceed 300 thousand spawners, DFO Gulf Ecosystems and Fisheries Management requested the development of fisheries based reference points that conform to the Precautionary Approach (PA) to guide further management decisions on the development of the Striped Bass fisheries. The extensive information on the abundance and biological characteristics of the Striped Bass population of the southern Gulf of St. Lawrence is presented. An age structured population model is used to estimate stock and recruitment parameters and associated mortality rates at age based on assessed abundances of spawners for the years 1996 to 2019. Equilibrium modelling is used to define candidate Limit Reference Point (LRP), Upper Stock Reference (USR), and removal rate references that would conform to the Precautionary Approach. Despite model uncertainties, a LRP value of just over 330 thousand spawners is consistent with one of the population model results as well as with the history of the management decisions for re-opening of fisheries access since 2013. The USR value of 720 thousand spawners would represent a healthy condition for this population, based on the assessed spawner abundances to 2019 and on the potential productive capacity of this population. A number of knowledge gaps and uncertainties remain. The most important assessment and management gap is the incomplete to non-existent catch statistics for any of the Striped Bass fisheries in the southern Gulf of St. Lawrence, including Indigenous Food Social and Ceremonial fisheries and the larger recreational fisheries. In the absence of these catch and harvest data, it is not possible to provide fisheries management advice in terms of total allowable catches nor can the status of the population relative to removal rates be assessed. Striped Bass is a predator of other valued anadromous fisheries species in the southern Gulf of St. Lawrence. The reference points presented are derived based on optimizing value functions specific to Striped Bass. No multi-species reference points or management options are discussed.

Research Document 2022/029 (PDF, 9667 KB)

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