Jamal H. Moss

Evidence for Size-Selective Mortality after the First Summer of Ocean Growth by Pink Salmon

Abstract Pink salmon Onchorhynchus gorbuscha with identifiable thermal otolith marks from Prince William Sound hatchery release groups during 2001 were used to test the hypothesis that faster-growing fish during their first summer in the ocean had higher survival rates than slower-growing fish. Marked juvenile pink salmon were sampled monthly in Prince William Sound and the Gulf of Alaska, and adults that survived to maturity were recovered at hatchery release sites the following year. Surviving fish exhibited significantly wider circuli spacing on the region of the scale formed during early marine residence than did juveniles collected at sea during their first ocean summer, indicating that marine survival after the first growing season was related to increases in early marine growth. At the same circuli, a significantly larger average scale radius for returning adults than for juveniles from the same hatchery would suggest that larger, faster-growing juveniles had a higher survival rate and that signifi...

Interannual Variability in Early Marine Growth, Size-Selective Mortality, and Marine Survival for Prince William Sound Pink Salmon

Abstract The main objective of this study was to use scale patterns to compare the early marine growth of the average pink salmon Oncorhynchus gorbuscha with that of fish from the same year-class that survived to adulthood to gain insight on critical periods for growth and survival. During 2001–2004, pink salmon that survived to adulthood were larger and grew faster than the average juvenile throughout the first growing season, indicating that larger, faster-growing juveniles experienced higher survival. Growth rate declined from mid–late June to early–mid-July for both juveniles at-large and fish that survived to adulthood. The adult survivors then grew at a faster rate than the average juvenile through September. Both the juvenile pink salmon population at-large and all cohorts that survived to adulthood grew at a faster rate during high-survival years than low-survival years from mid–late June to mid–late August. Greater variability in the growth trajectories of surviving adults was observed during high-survival years, potentially a result of diversified feeding or distribution strategies. This study supports findings that significant size-selective mortality of juvenile pink salmon occurs after the first growing season. Investigating the timing and magnitude of size-selective mortality on juvenile pink salmon during their first growing season is an initial step toward understanding the processes regulating growth and survival.

Interannual and Spatial Feeding Patterns of Hatchery and Wild Juvenile Pink Salmon in the Gulf of Alaska in Years of Low and High Survival

Abstract To improve understanding of the mechanisms affecting growth and survival, we evaluated the summer diets and feeding patterns (prey composition, energy density, and stomach fullness) of hatchery and wild juvenile pink salmon Oncorhynchus gorbuscha in Prince William Sound (PWS) and the northern coastal Gulf of Alaska (CGOA). Our study (1999-2004) included 2 years of low (∼3%), mid (∼5%), and high (∼8-9%) survival of PWS hatchery pink salmon. Because variations in diet should affect growth and ultimately survival, we expected that the variations in diet, growth, and survival would be correlated. During August in the CGOA, pteropod-dominated diets and higher gut fullness corresponded to high survival (5-9%), and copepod-dominated diets and lower gut fullness corresponded to low survival (3%). Within years, no significant differences were found in diet composition or gut fullness between hatchery and wild fish or among the four PWS hatchery stocks. Diets varied by water mass (habitat) as juveniles mov...

Stock‐Specific Migration Pathways of Juvenile Sockeye Salmon in British Columbia Waters and in the Gulf of Alaska

AbstractWe outlined the route and relative timing of juvenile Sockeye Salmon Oncorhynchus nerka migration by analyzing stock composition and relative CPUE in marine sampling conducted in coastal British Columbia and the Gulf of Alaska. Variation at 14 microsatellites was analyzed for 10,500 juvenile Sockeye Salmon obtained from surveys conducted during 1996–2011. Using a 404-population baseline, we identified the sampled individuals to 47 populations or stocks of origin. Stock compositions of the mixtures increased in diversity in more northerly sampling locations, indicating a general northward movement of juveniles. The primary migration route of Columbia River and Washington stocks was northward along the west coast of Vancouver Island, with a majority of the juveniles subsequently migrating through Queen Charlotte Sound and Dixon Entrance. Fraser River stocks migrated principally through the Strait of Georgia and Johnstone Strait. Some Fraser River populations, such as the Cultus Lake population, appe...

Stock-Specific Size of Juvenile Sockeye Salmon in British Columbia Waters and the Gulf of Alaska

AbstractThe variation at 14 microsatellites was analyzed for 10,500 juvenile Sockeye Salmon Oncorhynchus nerka obtained from coastal British Columbia and Gulf of Alaska surveys during 1996–2011. A 404-population baseline was used to determine the individual identifications of the fish sampled, with individuals being identified to 47 populations or stocks of origin. Columbia River and Washington juveniles were consistently larger than those from British Columbia and Alaska. During July, larger individuals from the same Fraser River stock were observed in more northerly locations compared with those in the Strait of Georgia. There was a relationship between the timing of northward migration from the Strait of Georgia and juvenile body size, with individuals from larger populations or stocks migrating earlier than individuals from smaller stocks which remain resident for longer. There was a wide divergence among stocks in juvenile size and dispersion among sampling locations.Received August 1, 2013; accepted...

Eastern Gulf of Alaska Ecosystem Assessment, July through August 2017

The goal of the Gulf of Alaska Ecosystem Assessment is to characterize ecosystem function and status in the eastern Gulf of Alaska. This survey is a coordinated research effort, conducted by the Recruitment Processes Alliance within the Alaska Fisheries Science Center. The scientific objectives of the survey are to assess age-0 groundfish, juvenile salmon, zooplankton, and oceanographic conditions in the coastal, shelf, slope, and offshore waters of the eastern Gulf of Alaska. This information is used to describe species distributions, ecosystem processes, marine productivity, and recruitment processes in response to changes in climate patterns and temperature anomalies (i.e., “The Blob”, and El Niño).