Methods
At each station, a Nordic 264 rope trawl built by Nor'Eastern Trawl Systems, Inc. was towed in surface waters by a chartered fishing vessel (F/V Sea Eagle in 2000 and F/V Frosti in 2002). It was towed with about 300 m of warp for 30 min at 1.5 m/sec with a pair of 3.0-m foam-filled trawl doors and 90.7-kg weight chains to spread the mouth open. Except for two mid-water trawling events, six A-4 Polyform floats were clipped to wingtips and the headrope to fish the trawl at the surface. The trawl has a maximum mouth opening of approximately 30-m wide x 18-m high. Mesh sizes ranged from 162.6 cm in the throat of the trawl near the jib lines to 8.9 cm in the codend. To maintain catches of small fish and squid, a 6.1-m long, 0.8-cm knotless liner was sewn into the codend. All but several tows were 30 min in duration. The majority of trawls were done during daytime, although a few were done at dawn and dusk and two diel series were completed in 2002.

All juvenile salmon caught were immediately frozen for laboratory analysis. All fish, squid, and large jellyfish caught were counted and up to 50 of them measured at sea. However, when very large catches of a species occurred, a subsample was measured, counted, and weighed; remaining individuals were mass weighed and total count estimated from known number/kg. When the trawl was full, weight of the total catch was estimated and species counts derived from a subsample as just described. Catches were standardized to number per 10⁶ m³.

In the laboratory, all frozen juvenile salmonids were weighed prior to dissections for subsamples of growth, condition, pathology, genetic analysis, and food habits. As large subadult/adult salmonids were released shortly after being captured, their weights were estimated from length-weight regressions. Also, common species of non-salmonid fish and squids not weighed at sea had their weights computed from length-weight regressions where their lengths were available. For those individuals without length data, station or cruise-wide average of number/kg was used to estimate weights.

trawl.csv