Research Document - 2010/109
Summary of the 2008 Herring Acoustic Surveys in NAFO Divisions 4VWX
By M.J. Power and G.D. Melvin
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 the Bay of Fundy and coastal Nova Scotia. These areas are within the Northwest Atlantic Fisheries Organization (NAFO) divisions 4VWX. In 2008, regularly scheduled surveys, conducted by industry vessels at approximately 2-week intervals were focused on the main spawning components, and the spawning stock biomass for each component was then estimated by summing these results. Four structured surveys were conducted in Scots Bay, two on Trinity Ledge, two in the Spectacle Buoy area and five on German Bank. These surveys provided good coverage of the spawning areas consistent with established protocols in most cases. Additional data from fishing nights in various areas were also examined but were not applied to the overall spawning stock biomass (SSB).
In 2008 biomass estimates decreased for survey areas in Scots Bay, Trinity Ledge and German Bank to 223,100t. This is a 42% decrease from 2007 and is also the lowest recorded since acoustic surveys began in 1997. The overall estimate for 2008 also remains below the long term average, as it has since 2005.
Biomass estimates made from surveys of the coastal Nova Scotia spawning components for the Little Hope/Port Mouton, Eastern Shore and Glace Bay areas showed a large increase in the Port Mouton area and little change in other areas. No acoustic surveys were conducted in the Bras d’Or Lakes or the offshore Scotian Shelf in 2008.
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