SS1.06 The Ecological Impacts of Pelagic Longline Fisheries
Date: Monday, June 10, 2002
Time: 10:45:00 AM
Location: Carson A
 
Ward, PeterPJ, Dept. of Biology, Dalhousie University, Halifax, Canada, ward@mathstat.dal.ca
 
WHERE HAVE ALL THE BROADBILL SWORDFISH GONE?
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Before longline fishing commenced, swordfish were much more abundant in many parts of the world than they are today. Swordfish are inclined to local depletion as longline fisheries develop. Without controls, the fisheries expand geographically and fishing effort increases, often overshooting optimum levels. Nevertheless, it is difficult to distinguish clear evidence of fishery or stock collapse. Modern longliners harvest widely distributed species. They are able to relocate to distant areas or switch between target species in response to fluctuations in species abundance and price. Over half the world's swordfish are taken as an incidental catch of longliners fishing for tuna. Catch quotas have caused tuna longliners to discard swordfish in several areas. Minimum size limits have also resulted in discarding of swordfish in tuna fisheries and in dedicated swordfish fisheries. This presentation reviews historical trends in swordfish fisheries, highlighting how bycatch and discarding add to the complexities of fishery management and uncertainties in assessing the stocks.