Science & Data

This document summarizes data on salmon collected by SECM scientists on biophysical parameters from May-September 2001 in southeastern Alaska.

Biophysical data were collected along a primary marine migration corridor of juvenile Pacific salmon (Oncorhynchus spp.) in the northern region of southeastern Alaska at 20 stations in five, six-day sampling intervals from May to September 2000. This survey marks the fourth consecutive year of systematic monitoring, and was implemented to identify the relationships among biophysical parameters that influence the habitat use, marine growth, predation, stock interactions, year-class strength, and ocean carrying capacity of salmon. Habitats were classified as inshore (Taku Inlet and Auke Bay), strait (Chatham Strait and Icy Strait), and coastal (Cross Sound and Icy Point), and were sampled from the National Oceanic and Atmospheric Administration ship John N. Cobb. At each station, fish, zooplankton, surface water samples, and physical profile data were collected during daylight using a surface rope trawl, conical and bongo nets, and a conductivity-temperature-depth profiler. Surface (2-m) temperatures and salinities during the survey ranged from 6.6 to 14.1°C and 11.5 to 32.0 PSU. A total of 7,920 fish and squid, representing 30 taxa, were captured in 89 rope trawl hauls from June to September. Juvenile Pacific salmon comprised 86% of the total catch and were the most frequently occurring species: pink (O. gorbuscha; 60%), chum (O. keta; 55%), coho (O. kisutch; 49%), sockeye (O. nerka; 47%), and chinook salmon. Of the 6,846 salmonids caught, > 99% were juveniles. Non-salmonid species making up > 2% of total catch included walleye pollock (Theragra chalcogramma), Pacific herring (Clupea pallasi), and soft sculpin (Psychrolutes sigalutes). Temporal and spatial differences were observed in the catch rates, size, condition, stock of origin, and predation rates of juvenile salmon species. Catches of juvenile chum, pink, and coho salmon were highest in July, whereas catches of juvenile sockeye and chinook salmon were highest in June and September, respectively. By habitat type, juvenile salmon except chinook were most abundant in straits; juvenile chinook salmon were most abundant in inshore habitat. In the coastal habitat, catches along the Icy Point transect were highest within 40 km of shore. Size of juvenile salmon increased steadily throughout the season; mean fork lengths (mm) in June and September were: pink (95 and 198), chum (106 and 218), sockeye (114 and 196), coho (166 and 285), and chinook salmon (157 and 264). Coded-wire tags (CWTs) were recovered from seven juvenile and one immature chinook; only one was of non-Alaska origin, a juvenile chinook from the Columbia River Basin recovered in September. CWTs were recovered from seven juvenile and two adult coho; all were of Alaska origin. In addition, otoliths of 1,260 juvenile chum and 401 juvenile sockeye salmon revealed that 59% and 27% of these fish were Alaska hatchery stocks represented by thermal marks. Onboard stomach analysis of 214 potential predators, representing eleven species, indicated that 11% of adult coho salmon, 4.5% of spiny dogfish (Squalus acanthias), and 1% of adult walleye pollock preyed on juvenile salmon. Our results suggest that, in southeastern Alaska, juvenile salmon exhibit seasonal patterns of habitat use synchronous with environmental change, and display species- and stock-dependent migration patterns. Long term monitoring of key stocks of juvenile salmon, both on intra- and interannual bases, will enable researchers to understand how growth, abundance, and ecological interactions affect year-class strength and ocean carrying capacity for salmon.

In 1999, biophysical data were collected along a primary marine migration corridor of juvenile (age-.0) Pacific salmon (Oncorhynchus spp.) in the northern region of southeastern Alaska at 24 stations during five sampling intervals. This survey marks the third consecutive year of systematic sampling and monitoring within the region, and was implemented to identify the relationships among the habitat use, marine growth, predation, stock interactions, year-class strength, and ocean carrying capacity of salmon. Stations were stratified into three different habitats—inshore (Taku Inlet and three stations near Auke Bay), strait (four stations each at Chatham Strait and Icy Strait), and coastal (four stations each at Cross Sound, Icy Point, and Cape Edward)—and were sampled from the National Oceanic and Atmospheric Administration ship John N. Cobb, May to October. At each station, fish, zooplankton and surface water samples, and temperature and salinity profile data were collected during daylight using a surface rope trawl, conical and bongo nets, and a conductivity, temperature, and depth profiler.

Twenty four stations were sampled monthly along a primary marine migration corridor in the northern region of southeastern Alaska to assess the distribution, growth, mortality, and diet of wild and hatchery stocks of juvenile (age -.0) Pacific salmon ( 0ncorhynchus spp.). Stations were stratified into three different habitats-inshore (Taku Inlet and near Auke Bay), strait (Chatham Strait and Icy Strait), and coastal (Cross Sound, Icy Point, and Cape Edward)-and sampled aboard the NOAA ship John N. Cobb from May to August 1998. At each station, fish, zooplankton, temperature, and salinity data were collected during daylight with a surface rope trawl, conical nets, bongo nets, and a conductivity, temperature, and depth profiler. Surface (2-m) temperatures and salinities during the survey ranged from 7.6 to 14.2°C and 16.4 to 32.0%0. A total of 12,814 fish and squid were captured with the rope trawl, representing 30 taxa. All five species of juvenile Pacific salmon and steelhead (0. mykiss) were captured and comprised 85% of the total catch. Of the 10,895 salmonids caught, over 99% were juveniles, and less than 1 % were immatures or adults. Non-salmonid species making up>1 % of the catch included Pacific herring (Clupea harengus), capelin (Mallotus villosus), squid (Gonatidae), and sablefish (Anoplopomafimbria). The highest frequency of occurrence (>25%) in the trawl catches was observed for chum (0. keta), coho (0. kisutch), sockeye (0. nerka), pink (0. gorbuscha), and chinook (0. tshawytscha) salmon, and wolf-eels (Anarrhichthys ocellatus). Overall catch rates of juvenile salmon were highest in June and July, intermediate in August, and zero in May. Catch rates of pink and chum salmon were highest in June, whereas catch rates of sockeye, coho, and chinook salmon were highest in July. Catch rates of juvenile salmon except chinook salmon were highest in strait habitat and lowest in inshore habitat; chinook salmon catch rates were highest in inshore habitat. Overall catch rates for juvenile salmon along the offshore transect declined with distance offshore: most juveniles were captured within 25 km of shore, and only one juvenile salmon was found beyond 40 km. Mean fork lengths ofjuvenile salmon in JuneJuly-August were: pink (94-127-162 mm), chum (102-134-164 mm), sockeye (112-139-153 mm), coho (166-213-253 mrri), and chinook salmon (160-166-190 mm). Twenty-four juvenile and immature salmon ( 13 chinook and 11 coho) containing internally planted coded-wire tags were recovered; 20 originated from Alaska, 3 from the Columbia River Basin, and l from Washington. Recoveries of juvenile chinook salmon from the Columbia River Basin are some of the earliest documented recoveries of these stream-type stocks in Alaska during their first summer at sea. Onboard stomach analysis of potential predators of juvenile salmon indicated a low level of salmon predation by sablefish, spiny dogfish (Squalus acanthias), and adult coho salmon. Results from this study and further laboratory analysis of otolith-marked fish will be used to assess potential competitive interactions between wild and hatchery stocks and stockspecific life history characteristics.

Twenty stations were sampled monthly along a primary marine migration corridor in the northern region of southeastern Alaska to assess the distribution, growth, mortality, and diet of wild and hatchery stocks ofjuvenile (age -.0) Pacific salmon (0ncorhynchus spp.). Stations were stratified into three different habitats-inshore (Taku Inlet and near Auke Bay), strait (Chatham Strait and Icy Strait), and coastal (Cross Sound and Icy Point)-and sampled aboard the NOAA ship John N. Cobb from May to August 1997. At each station, fish, zooplankton, temperature, and salinity data were collected during daylight with a surface rope trawl, conical nets, bongo nets, and a CTD (conductivity, temperature, and depth profiler). A total of 6,252 fish and squid were captured with· the rope trawl, representing 31 taxa. All five species ofjuvenile Pacific salmon and steelhead (0. mykiss) were captured and made up 80% of the total catch. Of the 5,000 salmonids caught, over 99% were juveniles, and less than 1 % were immatures or adults. Non-salmonid species making up > 1 % of the catch included Pacific herring (Clupea harengus), squid (Gonatidae), capelin (Ma/lotus villosus), walleye pollock ( Theragra cha/cogramma ), and sablefish (Anop/opoma .fimbria). Chum ( 0. keta), coho (0. kisutch), pink (0. gorbuscha), sockeye (0. nerka), and chinook (0. tshawytscha) salmon and crested sculpin (Blepsias bilobus) occurred most frequently (~30%) in the trawl catches. Overall catches of juvenile salmon were highest in July and zero in May. Catch rates of coho and sockeye salmon were highest in June, whereas catch rates of chum, pink, and chinook salmon were highest in July. Catch rates of juvenile salmon except chinook salmon were highest in strait habitat and lowest in inshore habitat; chinook salmon catch rates were highest in inshore habitat. Overall catch rates for juvenile salmon along the offshore transect declined with distance offshore: most juveniles were within 25 km of shore, and no juvenile salmon was found beyond 40 km. Mean fork lengths of juvenile salmon in JuneJuly-August were: chum (97-137-162 mm), pink (96-136-156 mm), sockeye (110-146-154 mm), coho (148-207-247 mm), and chinook salmon (143-172-222 mm). Twenty-three juvenile and immature salmon containing internally planted coded-wire tags (CWTs) were recovered; 21 originated in Alaska and two in Oregon (one chinook and one coho salmon). The Oregon chinook salmon is the earliest recorded recovery of a stream-type chinook salmon of the Columbia River stock in Alaska during its first summer at sea. Onboard stomach analysis of potential predators ofjuvenile salmon did not indicate a high level of salmon predation; however, few predators were present during high levels of juvenile salmon abundance, and fish remains in stomachs were often too far digested to identify. Results from this study and further laboratory analysis of otolith-marked fish will be used to assess competitive interactions between wild and hatchery stocks and stock-specific life history characteristics.

Videotapes of beluga whale groups were collected during aerial survey work in Cook Inlet, Alaska, from June 1-5, 1994.