Research Document - 2008/048
An acoustic-trawl survey of offshore over-wintering northern cod, February-March 2007
By L.G.S. Mello and G.A. Rose
Abstract
A dedicated hydroacoustic/bottom trawl survey was conducted during the winter 2007 off southern Labrador and Eastern Newfoundland (NAFO Div. 2J3KL). The survey objectives included determining the distribution, abundance and biological traits of Atlantic cod (Gadus morhua) and the results indicated that most fish were found in two main regions adjacent to the Bonavista Corridor (NAFO 3KL) and Hawke Channel (NAFO 2J). The fish were highly aggregated at these locations and found in the demersal zone at depths ranging between 400-550 m. These fish were predominantly of younger (3-5 years old) - smaller size-classes (24-55 cm), although several larger fish (70-87 cm) were caught in the Bonavista Corridor. The remaining areas were characterized by low abundance levels, including most of NAFO 3L. Biomass estimates (using acoustic data) over the surveyed areas were approximately 2,600 t (3L), 4,000 t (2J) and 17,000 t (3K). The survey design and sampling strategies were effective in detecting fish and area coverage, and particularly suitable to assess cod abundance when most fish are found aggregated over small regions of the offshore.
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