Research Document - 2005/024
Summary of the 2004 herring acoustic surveys in NAFO divisions 4VWX
By Power, M.J., G.D. Melvin, F.J. Fife, D. Knox, L.M. Annis
Abstract
Automated acoustic recording systems deployed on commercial fishing vessels have been used since 1997 to document the distribution and relative abundance of Atlantic herring in NAFO Division 4VWX from industry vessel surveys and fishing excursions. In 2004 regularly scheduled surveys, at approximately 2-week intervals, were conducted on the main spawning components and the spawning stock biomass for each component was estimated by summing these results. Four structured surveys were conducted in Scots Bay, two on Trinity Ledge and three on German Bank following established protocol. This provided good coverage of these spawning areas consistent with previous years. Additional data from fishing nights in Scots Bay and German Bank were examined. Biomass estimates for Scots Bay, Trinity Ledge and German Bank were approximately 107,600t, 6,500t, and 367,600t for an estimated total SSB of 481,700t in the traditional survey areas.
Biomass estimates from surveys of the coastal Nova Scotia spawning components for the Little Hope/Port Mouton and Eastern Shore areas were down from those observed in recent years. Various equipment problems precluded estimates being made for the Glace Bay area in 2004. There was again no acoustic survey effort in the Bras d’Or lakes. For the offshore Scotian Shelf there were no large aggregations of herring observed and no acoustic surveys were conducted.
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