Science Advisory Report  2011/014

Allowable harm assessment of Striped Bass (Morone saxatilis) in the southern Gulf of St. Lawrence

Summary

• Abundance of Striped Bass returning to the Northwest Miramichi River to spawn increased during 2007 to 2010, the result of three good recruiting year classes which followed more than 10 years of weak year classes.
• The constricted length and age distributions of Striped Bass in the southern Gulf of St. Lawrence (sGSL) is consistent with the high levels of annual mortality (28% to 47%) estimated for this population.
• Results from a questionnaire circulated to all DFO Conservation and Protection detachments and sub-detachments in Gulf Region indicated that nearly 70% of all adult Striped Bass fishery-related losses are the result of illegal (55%) and recreational (14%) fisheries. Losses from striped bass bycatch in commercial fisheries for gaspereau, rainbow smelt, Atlantic herring, American shad, American eel and Atlantic silverside were less important.
• Responses from First Nations in Gulf Region with Food, Social, and Ceremonial (FSC) gillnet and trapnet fisheries for Atlantic salmon indicated that the losses of striped bass were less than 5% of the total fisheries related losses.
• The uncertainty around the estimates of striped bass mortality for each fishery is not quantifiable with the available information but is considered to be large.
• In the absence of any fishery related losses, there is a high probability (>75%) that striped bass in the southern Gulf of St. Lawrence will meet the recovery limit of 21,600 spawners by 2015 and remain above it into 2020.
• Striped bass losses associated with illegal fishing by themselves result in a low probability (<25%) of meeting the recovery limit.
• An allocation of 2,000 adult Striped Bass to First Nations in the sGSL was not considered additional mortality on the population as this level of bycatch mortality is currently being experienced in FSC fisheries for Atlantic salmon. By itself, this fishery allocation would result in a medium chance (25% to 75%) of meeting the recovery limit for the population.
• Under any commercial fisheries bycatch scenario, and assuming no illegal or recreational fishery losses, there is a medium probability (25% to 75%) of meeting the recovery limit by 2015 and being compliant into 2020.
• With the cumulative mortality from all sources remaining at current levels, there is no measurable chance that Striped Bass from the sGSL will meet and remain above the recovery objectives into 2020.

This Science Advisory Report has resulted from a Fisheries and Oceans Canada, Canadian Science Advisory Secretariat Gulf Regional Advisory Process of February 4, 2011 on Allowable Harm assessment for the striped bass population from the southern Gulf of St. Lawrence.  Additional publications resulting from this process will be posted as they become available on the DFO Science Advisory Schedule.

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