Science & Data

Juvenile Pacific salmon (Oncorhynchus spp.), ecologically-related species, and associated biophysical data were collected along a primary marine migration corridor in the northern region of southeastern Alaska. Thirteen stations were sampled over six time periods (31 sampling days) from May to August 2004. This survey marks the eighth consecutive year of systematic monitoring on how juvenile salmon interact in marine ecosystems, and was implemented to identify the relationships among biophysical parameters that influence the habitat use, marine growth, predation, stock interactions, and year-class strength of salmon. Habitats sampled included stations in inshore (Auke Bay and Taku Inlet), strait (four stations each in Chatham Strait and Icy Strait), and coastal (four stations off Icy Point) localities. At each station, fish, zooplankton, surface water samples, and physical profile data were collected using a surface rope trawl, conical and bongo nets, water sampler, and a conductivity-temperature-depth profiler, usually during daylight. Surface (3-m) temperatures and salinities ranged from 6.9 to 17.4 ºC and 9.5 to 31.6 PSU from May to August. A total of 13,460 fish and squid, representing 29 taxa, were captured in 75 rope trawl hauls from June to August. Juvenile salmon comprised 48% of the total catch and occurred frequently in the trawl hauls, with pink (O. gorbuscha) occurring in 75% of the trawls, sockeye (O. nerka) in 73%, chum (O. keta) in 72%, coho (O. kisutch) in 51%, and chinook salmon (O. tshawytscha) in 19%. Of the 6,552 salmonids caught, over 99% were juveniles. Walleye pollock (Theragra chalcogramma) and Pacific herring (Clupea pallasi) were the only non-salmonid species that comprised more than 1% of the total catch. Temporal and spatial differences were observed in the catch rates, size, condition, and stock of origin of juvenile salmon species. Catch rates of juvenile salmon were generally highest in June for all species except coho that had catch rates highest in August. Between habitat types, juvenile salmon catch rates were almost always highest in the strait habitat for each species and in each time period. Size of juvenile salmon increased steadily throughout the season; mean fork lengths in June, July, and August were, respectively: 98, 129, and 163 mm for pink; 104, 139, and 166 mm for chum; 111, 137, and 165 mm for sockeye; 170, 203, and 246 mm for coho; and 199, 228, and 279 for chinook salmon. Coded-wire tags were recovered from 14 juvenile coho, three juvenile and six immature chinook salmon; all but one were from hatchery and wild stocks of southeastern Alaska origin. The non-Alaska stock was a juvenile chinook originating from Oregon. Alaska hatchery stocks were also identified by thermal otolith marks from 74% of the chum, 18% of the sockeye, 9% of the coho, and 45% of the chinook salmon. Onboard stomach analysis of 199 potential predators, representing 10 species, revealed four predation instances on juvenile salmon: three by adult coho salmon and one by an immature chinook salmon. This research suggests 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, on both intra- and interannual bases, will enable researchers to understand how growth, abundance, and ecological interactions affect year-class strength and to better understand the role salmon play in North Pacific marine ecosystems.

Juvenile Pacific salmon (Oncorhynchus spp.) and associated biophysical data were collected along a primary marine migration corridor in the northern region of southeastern Alaska. Thirteen stations were sampled over six time periods (32 sampling days) from May to August 2003. This survey marks the seventh 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 juvenile salmon. Habitats sampled included stations in inshore (Auke Bay), strait (four stations each in Chatham Strait and Icy Strait), and coastal (four stations off Icy Point) localities. At each station, fish, zooplankton, surface water samples, and physical profile data were collected using a surface rope trawl (fish), conical and bongo nets (zooplankton), and a conductivity-temperature-depth profiler (physical data), usually during daylight. Surface (2-m) temperatures and salinities ranged from 7.6 to 15.8ΕC and 15.5 to 32.0 PSU from May to August. A total of 10,724 fish and squid, representing 23 taxa, were captured in 64 rope trawl hauls from June to August. Juvenile salmon comprised 29% of the total catch and occurred frequently in the trawl hauls, with chum (O. keta) occurring in 66% of the trawls, pink (O. gorbuscha) in 56%, coho (O. kisutch) in 55%, sockeye (O. nerka) in 50%, and chinook salmon (O. tshawytscha) in 2%. Of the 3,254 salmonids caught, 98% were juveniles. Walleye pollock (Theragra chalcogramma) and Pacific herring (Clupea pallasi) were the only non-salmonid species that comprised more than 1% of the total catch. Temporal and spatial differences were observed in the catch rates, size, condition, and stock of origin of juvenile salmon species. Catch rates of juvenile salmon were highest for chinook and sockeye salmon in June, highest for chum and pink salmon in July, and highest for coho salmon in August. By habitat type, juvenile salmon catch rates for pink, chum and sockeye were highest in the coastal habitat, whereas catch rates of coho and chinook were highest in the strait habitat. Size of juvenile salmon increased steadily throughout the season; mean fork lengths in June and early August were, respectively: 105 and 133 mm for pink, 116 and 138 mm for chum, 120 and 145 mm for sockeye, 173 and 215 mm for coho, and 169 mm (June only) for chinook salmon. Coded-wire tags were recovered from two juvenile coho and one immature chinook salmon; all were from hatchery and wild stocks of southeastern Alaska origin. Alaska hatchery stocks were also identified by thermal otolith marks from 32% of the chum, 45% of the sockeye, 11% of the coho, and 100% of the chinook salmon. Onboard stomach analysis of 248 potential predators, representing 10 species, indicated one predation instance on juvenile salmon by a spiny dogfish (Squalus acanthias) in the coastal habitat in July. This research suggests 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, on both 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.

Biophysical data were collected along a primary marine migration corridor of juvenile Pacific salmon (Oncorhynchus spp.) in the northern region of southeastern Alaska. Data were collected at 13 stations in four sampling intervals (25 d total) from May to August 2002. This survey marks the sixth 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 juvenile salmon. Habitats were classified as inshore (Auke Bay), strait (four stations each in Chatham Strait and Icy Strait), and coastal (four stations off 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 using a surface rope trawl (fish), conical and bongo nets (zooplankton), and a conductivity-temperature-depth profiler (physical profile), usually during daylight. Surface (2-m) temperatures and salinities ranged from 6.1 to 13.9EC and 17.4 to 32.2 PSU from May to August. A total of 8,665 fish and squid, representing 21 taxa, were captured in 75 rope trawl hauls from June to August. Juvenile salmon comprised 61% of the total catch and occurred frequently in the trawl hauls, with coho (O. kisutch) occurring in 65% of the trawls, pink (O. gorbuscha) in 57%, chum (O. keta) in 55%, sockeye (O. nerka) in 47%, and chinook salmon (O. tshawytscha) in 21%. Of the 5,336 salmonids caught, more that 98% were juveniles. Walleye pollock (Theragra chalcogramma) and crested sculpin (Blepsias bilobus) were the only non-salmonid species that comprised more than 1% of the total catch. Temporal and spatial differences were observed in the catch rates, size, condition, and stock of origin of juvenile salmon species, and in predation rates on them. Catches of juvenile chum, pink, sockeye, and coho salmon were generally highest in July, whereas catches of juvenile chinook salmon were highest in June. By habitat type, juvenile salmon catches were highest in straits. In the coastal habitat, catches were highest within 40 km of shore. Size of juvenile salmon increased steadily throughout the season; mean fork lengths in June and August were respectively: 86 and 143 mm for pink, 96 and 145 mm for chum, 121 and 139 mm for sockeye, 153 and 235 mm for coho, and 201 and 235 mm for chinook salmon. Coded-wire tags were recovered from 20 juvenile and immature salmon; most were from hatchery and wild stocks of southeastern Alaska origin; however, juvenile chinook and coho salmon from the Columbia River Basin were also recovered. In addition, otoliths were examined from four species of juvenile salmon: 1,525 from chum, 248 from sockeye, 363 from coho, and 18 from chinook salmon. Alaska hatchery stocks were identified by thermal marks from 44% of the chum, 17% of the sockeye, 5% of the coho, and 61% of the chinook salmon. Onboard stomach analysis of 135 potential predators, representing nine species, indicated five predation instances on juvenile salmon in August, including both of the age 1+ sablefish (Anoplopoma fimbria) and 3 of 12 (25%) adult coho 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 an intra- and interannual basis, will enable researchers to understand how growth, abundance, and ecological interactions affect year-class strength and ocean carrying capacity for salmon.

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.

Survey of juvenile salmon in the marine waters of Southeastern Alaska from May to August 1998.

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 of juvenile Pacific salmon.