Research Document - 2006/048
Summary of the 2005 Herring Acoustic Surveys in NAFO Divisions 4VWX
By Power, M.J., G.D. Melvin, F.J. Fife, D. Knox and 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 2005 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. Three structured surveys were conducted in Scots Bay, one on Trinity Ledge and three on German Bank following the 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 16,800t, 5,100t, and 211,000t for an estimated total SSB of 233,200t in the traditional survey areas, which is a substantial decrease from previous years.
Biomass estimates from surveys of the coastal Nova Scotia spawning components for the Little Hope/Port Mouton and Eastern Shore areas were also examined and showed increases from the previous year. A survey with an acoustic recorder was completed for the first time in the Glace Bay area (previous estimates were based on mapping surveys). There was again no acoustic survey effort in the Bras d’Or lakes. There were no large aggregations of herring observed and no acoustic surveys were conducted for the offshore Scotian Shelf.
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