Increasing production of hatchery salmon over the past four decades has led to concerns about possible density-dependent effects on wild Pacific salmon populations in the North Pacific Ocean. The concern arises because salmon from distant regions overlap in the ocean, and wild salmon populations having low productivity may compete for food with abundant hatchery populations. We tested the hypothesis that adult length-at-age, age-at-maturation, productivity, and abundance of a Norton Sound, Alaska, chum salmon population were influenced by Asian hatchery chum salmon, which have become exceptionally abundant and surpassed the abundance of wild chum salmon in the North Pacific beginning in the early 1980s. We found that smaller adult lengthat-age, delayed age-at-maturation, and reduced productivity and abundance of the Norton Sound salmon population were associated with greater production of Asian hatchery chum salmon since 1965. Modeling of the density-dependent relationship, while controlling for other influential variables, indicated that an increase in adult hatchery chum salmon abundance from 10 million to 80 million adult fish led to a 72% reduction in the abundance of the wild chum salmon population. These findings indicate that competition with hatchery chum salmon contributed to the low productivity and abundance of Norton Sound chum salmon, which includes several stocks that are classified as Stocks of Concern by the State of Alaska. This study provides new evidence indicating that large-scale hatchery production may influence body size, age-atmaturation, productivity and abundance of a distant wild salmon population.

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The hypothesis that growth in Pacific salmon Oncorhynchus spp. is dependent on previous growth was tested using annual scale growth measurements of wild Chinook salmon Oncorhynchus tshawytscha returning to the Yukon and Kuskokwim Rivers, Alaska, from 1964 to 2004. First-year marine growth in individual O. tshawytscha was significantly correlated with growth in fresh water. Furthermore, growth during each of 3 or 4 years at sea was related to growth during the previous year. The magnitude of the growth response to the previous year's growth was greater when mean year-class growth during the previous year was relatively low. Length (eye to tail fork, L(ETF)) of adult O. tshawytscha was correlated with cumulative scale growth after the first year at sea. Adult L(ETF) was also weakly correlated with scale growth that occurred during freshwater residence 4 to 5 years earlier, indicating the importance of growth in fresh water. Positive growth response to previous growth in O. tshawytscha was probably related to piscivorous diet and foraging benefits of large body size. Faster growth among O. tshawytscha year classes that initially grew slowly may reflect high mortality in slow growing fish and subsequent compensatory growth in survivors. Oncorhynchus tshawytscha in this study exhibited complex growth patterns showing a positive relationship with previous growth and a possible compensatory response to environmental factors affecting growth of the age class.

We photographically identified 534 individual fin whales (Balaenaptera physalus) in the Gulf of Maine from 1980 to 1988, including 64 females and 40 young, Arrival patterns of mother-young pairs were similar to other whales within years. Individual females showed strong site fidelity to either the northern or southern Gulf of Maine, suggesting substock separation on the feeding range. Gross annual rates of reproduction (proportion of individuals that were young-of-the-year) for the Gulf of Maine ranged from 0.03 to 0.12 (X ~ 0.08) among years. Greater proportions of young were observed in samples from the southern Gulf of Maine (X ~ 0,12) than in the northern Gulf of Maine (X ~ 0,05), Greater proportions of females also were observed in the southern Gulf of Maine (X = 0.22) than in the northern Gulf of Maine (X = 0.10). The average time between consecutive births was 2.71 years, which represented a crude birth rate of 0.37 young per mature female per year. We estimated a potential mean interval of birthing of 2.24 years by making some assumptions for three females with incomplete sighting histories. The overall gross annual rates of reproduction that we observed were similar to rates predicted by harvest data, but rates from the northern Gulf of Maine were less than predicted. Spatial segregation of sexes or age classes may be occurring within the Gulf of Maine.