Some of the longest and most comprehensive marine ecosystem monitoring programs were established in the Gulf of Alaska following the environmental disaster of the Exxon Valdez oil spill over 30 years ago. These monitoring programs have been successful in assessing recovery from oil spill impacts, and their continuation decades later has now provided an unparalleled assessment of ecosystem responses to another newly emerging global threat, marine heatwaves. The 2014–2016 northeast Pacific marine heatwave (PMH) in the Gulf of Alaska was the longest lasting heatwave globally over the past decade, with some cooling, but also continued warm conditions through 2019. Our analysis of 187 time series from primary production to commercial fisheries and nearshore intertidal to offshore oceanic domains demonstrate abrupt changes across trophic levels, with many responses persisting up to at least 5 years after the onset of the heatwave. Furthermore, our suite of metrics showed novel community-level groupings relative to at least a decade prior to the heatwave. Given anticipated increases in marine heatwaves under current climate projections, it remains uncertain when or if the Gulf of Alaska ecosystem will return to a pre-PMH state.

Northern pike (Esox lucius) were introduced to the northern Susitna Basin of south-central

The location and timing of spawning play a critical role in pelagic fish survival during early life stages and can affect subsequent recruitment. Spawning patterns of Pacific herring (Clupea pallasii) were examined in Prince William Sound (1973–2019) where the population has failed to recover since its collapse in 1993. Abrupt shifts in spawn distribution preceded the rapid increase in population size in the 1980s and later its collapse by one and two years, respectively. Following the population collapse, spawning contracted away from historical regions towards southeastern areas of the Sound, and the proportion of occupied spawning areas declined from 65% to <9%. Spatial differences in spawn timing variation were also apparent, as the median spawn date shifted earlier by 26 days in eastern and 15 days in western areas of Prince William Sound between 1980 and 2006, and then shifted later by 25 (eastern) and 19 (western) days over a 7-year period. Effects of contracted spawning areas and timing shifts on first-year survival and recruitment are uncertain and require future investigation.

Pacific salmon (Oncorhynchus spp.) are exposed to increased environmental change and multiple human stressors. To anticipate future impacts of global change and to improve sustainable resource management, it is critical to understand how wild salmon populations respond to stressors associated with human-caused changes such as climate warming and ocean acidification, as well as competition in the ocean, which is intensified by the large-scale production and release of hatchery reared salmon. Pink salmon (O. gorbuscha) are a keystone species in the North Pacific Ocean and support highly valuable commercial fisheries. We investigated the joint effects of changes in ocean conditions and salmon abundances on the productivity of wild pink salmon. Our analysis focused on Prince William Sound in Alaska, because the region accounts for ~50% of the global production of hatchery pink salmon with local hatcheries releasing 600-700 million pink salmon fry annually. Using 60 years of data on wild pink salmon abundances, hatchery releases, and ecological conditions in the ocean, we find evidence that hatchery pink salmon releases negatively affect wild pink salmon productivity, likely through competition between wild and hatchery juveniles in nearshore marine habitats. We find no evidence for effects of ocean acidification on pink salmon productivity. However, a change in the leading mode of North Pacific climate in 1988-1989 weakened the temperature-productivity relationship and altered the strength of intraspecific density dependence. Therefore, our results suggest non-stationary (i.e., time varying) and interactive effects of ocean climate and competition on pink salmon productivity. Our findings further highlight the need for salmon management to consider potential adverse effects of large-scale hatchery production within the context of ocean change.

Forested landscapes support a diversity of ecological processes and organisms having direct value to society. Assessments placing monetary value on forest processes and organisms can help inform management actions affecting these ecosystem services. The temperate rain forest ecoregion along the west coast of North America is home to five species of Pacific salmon Oncorhynchus spp. that support subsistence, personal‐use, sport, and commercial fisheries. This study aimed to quantify the number and monetary value of commercially caught Pacific salmon originating from Alaska's Tongass and Chugach national forests, two adjacent national forests containing some of the world's largest remaining tracts of intact temperate rain forest. The proportion of commercially harvested wild Pacific salmon originating from streams and lakes within national forest boundaries was estimated by subtracting hatchery salmon and salmon originating outside national forest areas from the total commercial catch. The Tongass and Chugach national forests were major contributors to the overall number and value of commercially caught Pacific salmon in southeastern and southcentral Alaska. From 2007 to 2016 these national forests contributed an average of 48 million Pacific salmon annually to commercial fisheries, with a dockside value averaging US$88 million (inflation adjusted to the base year 2017). These “forest fish” represented 25% of Alaska's commercial Pacific salmon catch for this time period and 16% of the total commercial value. These findings emphasize the importance of Alaska's forest rivers and lakes for sustaining Pacific salmon and can contribute to discussions about alternative land management strategies that might impact Pacific salmon populations and associated commercial salmon fisheries.