An analysis of by-catch in the Icelandic blue whiting fishery

By-catch arising in the period May-November 2003 in the Icelandic blue whiting fishery was analyzed by random collection of 450 catch samples selected from 42 trips (9.4% of the total). By-catch species in the samples were quantified and their length measured. In general, by-catch was a relatively rare occurrence, but associated with rather wide confidence limits. Saithe and silver smelt were recorded in 21.1% and 19.1% of samples, respectively. Their total by-catch was 1605 and 1188 t, respectively. Lumpfish, cod, golden redfish and deepwater redfish were recorded in 2.2-5.6% of samples, and their total by-catch was 30-156 t by species. The remaining five fish species were recorded in <1% of samples, and their total by-catch was 6 t or less by species. In addition, unidentified cephalopods were recorded in 1.8% of samples with a total by-catch of 31 t. Spatial distributions of the main species indicate that saithe and silver smelt are primarily caught in Faroese, but cod and lumpfish in Icelandic waters. Length distributions indicate that the by-catch mainly constitutes the catchable component of the stocks in question. In terms of the effect of the by-catch on fish stocks, the main concerns are with saithe and lumpfish. There are indications that by-catch of cod and saithe in 2003 may have been at a relatively low level in a longer-term perspective.