NOAA Technical Memorandum
NMFS-AFSC-105
Survey of juvenile Pacific salmon
in the northern region of southeastern Alaska, May-October 1997
Abstract
This report summarizes the initial findings of a 1997 juvenile Pacific salmon (Oncorhynchus spp.) rope trawl survey in the northern region of southeastern Alaska. We include surface ocean conditions, distribution and abundance of juvenile salmon and associated species, coded-wire tag (CWT) recoveries, juvenile salmon fork lengths, and onboard diet analysis. Fish and oceanographic data were collected during daylight hours in May, June, July, August, and October at 20 stations in inside (inshore and strait) and outside (coastal) waters. Mean sea surface (less than or equal to 2 m) temperature and salinity data ranged from 6.7° to 15.1°C and 15.1 to 31.6 ppt respectively and differed between inside and outside waters. Mean settled zooplankton volumes ranged from 1.0 to 28.3 ml and were highest in inside waters from May through July. A total of 31 taxa of fish and squid (Gonatidae) were captured. Pacific salmon, sablefish (Anoplopoma fimbria), Pacific herring (Clupea pallasi), and capelin (Mallotus villosus) made up 95% of the catch. All species of Pacific salmon native to North America were caught. Over 99% of the total salmon catch were juveniles. Chum (0. keta) and pink salmon (0. gorbuscha) made up 89% of the juvenile salmon catch. At the strait stations, catch rates of juvenile pink and chum salmon were highest in July, and declined from July-October with a corresponding decrease in zooplankton abundance. Along the outer coast, catch rates of juvenile salmon were also highest in July, and most juvenile salmon were captured within 25 km from shore. The most notable CWT recovery was from a juvenile Umatilla River chinook salmon (0. tshawytscha) captured along the outer coast in June. This recovery documents the arrival of Columbia River chinook salmon off the coast of southeastern Alaska three months earlier than previously reported information. Pacific herring, capelin, and Pacific sand lance (Ammodytes hexapterus) were the predominant fish prey in predator stomachs examined, and minimal predation on juvenile salmon was observed.
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