Midwater Assessment & Conservation Engineering (MACE) Program
Tests of Halibut Excluders for Cod Trawls
From 18 to 23 June, the Conservation Engineer-ing team tested a range of configurations for devices to reduce bycatch of halibut in cod trawls in the Gulf of Alaska. The principal excluders consisted of an array of slot-shaped holes approximately 67 x 600 mm ahead of the codend of the trawls. These slots are too narrow to allow most cod to escape, while being large enough to release the smaller halibut that have been a significant part of halibut bycatch during the last several fall cod fisheries.
The principal challenge was to make sure that halibut spent enough time near the holes to escape, while not clogging up the net during periods of rapid cod capture. Observations ahead of the trawl showed many larger halibut escaping over the lower bridles, just ahead of the trawl net. Reducing structures that inhibit such escapes seemed to improve this movement.
Cooperating partners from the fishery have arranged a test fishery, under an exempted fishing permit, to determine the effectiveness to the resulting devices. That work will occur in August 2006.
