This special issue journal is titled Understanding Ecosystem Processes in the Gulf of Alaska: Volume 3, Deep-Sea Research II. It contains 13 papers ranging on topics such as oceanography, nearshore environments, fish communities, and fisheries management applications. More than 70 authors from 15 different agencies and organizations contributed to these publications, including many NOAA scientists from the Alaska Fisheries Science Center.
“It’s an especially exciting time for researchers investigating the Gulf of Alaska ecosystem,” according to Mandy Lindeberg, a NOAA Fisheries scientist and guest editor for the special issue. “The Gulf has recently experienced periods of unusually cool conditions contrasted with an extreme marine heatwave. These extreme conditions are sending ripple effects through the food web and make research and monitoring in the Gulf of Alaska anything but boring.”
Findings published in this issue provide considerable new insights into the processes at work in the Gulf of Alaska. They range, from oceanography and localized processes that provide food for commercially and ecologically important species, to animal responses to stressors like a marine heatwave. Highlighted below are just a few of these findings.
Oceanography and the Pacific Marine Heatwave
Oceanographic processes in the Gulf of Alaska are driven by winds, tides, and freshwater runoff, which in turn create eddies and mix water to enhance growth of phytoplankton. These processes fuel the Gulf’s food web, including ecologically important forage fish such as herring and commercially important groundfish such as Pacific cod.
The 2014–2019 Pacific marine heatwave caused major changes across the Gulf of Alaska ecosystem. Several papers in this volume address the Pacific marine heatwave and place its impacts in a broader context.
Physical oceanographers Seth Danielson (University of Alaska Fairbanks) and coauthors examined the long-term trends in temperature. They wanted to understand how different regions of the Gulf of Alaska responded to the Pacific marine heatwave. They found coastal surface water warmed in concert with offshore waters through 2013, but deep inner shelf waters had a delayed response. In contrast, offshore waters cooled from 2014 to 2016 despite ongoing warming on the shelf. Overall, the rate of warming has intensified when examining the past 50 years compared to the past 120 years.
Biological oceanographers Sonia Batten (North Pacific Marine Science Organization) and coauthors analyzed continuous plankton recorder data from across the Gulf of Alaska. They concluded that the benefits of warmer water on zooplankton growth and abundance for some species were offset by the overall reduction in zooplankton quality. For example, there were fewer species with high lipid content normally associated with colder water. These results highlight the dynamic nature of the Gulf, complicating the prediction of ecosystem response to warming.
Fisheries and Management Applications
The Gulf of Alaska ecosystem produces some of the highest value commercial fisheries in the world. They are managed by NOAA Fisheries and the North Pacific Fishery Management Council under the Magnuson-Stevens Act. The Council has been supporting efforts toward ecosystem-based fisheries management for sustaining marine resources under changing environmental conditions. Several papers within this issue highlight ways to develop and use information for ecosystem-based fisheries management.
Some of the avenues for providing ecosystem science to the Council are through integrated ecosystem assessments and annual Ecosystem Status Reports compiled by the Science Center. This includes ecosystem and socioeconomic profiles and ecosystem indicators to understand connections between ecosystem research and fishery management. To quantitatively include ecosystem indicators into fisheries stock assessments, Kalei Shotwell (Alaska Fisheries Science Center) and co-authors synthesized data of five commercially and ecologically valuable groundfish species. They proposed a direct avenue for a new ecosystem and socioeconomic profile framework. This framework permits identification of mechanistic relationships and tests ecosystem linkages within the stock assessment process. This type of integration ensures that identified ecosystem linkages are evaluated concurrently with the stock assessment. Ultimately, they are transferred to fishery managers in an efficient and effective format for informed decision-making.
Coastal community outreach and engagement is also critically important to ecosystem-based fisheries management. Judith Rosellon-Druker (University of Alaska Fairbanks) and coauthors created a small-scale integrated ecosystem assessment and a socio-ecological conceptual model for sablefish in the fishing community of Sitka, Alaska. They developed models from participatory focus groups, including stakeholders, and literature reviews to identify ecosystem attributes driving sablefish abundance. Model results suggest a need for management strategies that differentiate between small and large adult sablefish. This is especially important if there is a lack of older ﬁsh contributing to spawning biomass and uncertainties in estimates of year-class strength.
A Nod to Integrated Ecosystem Programs
Much of the research presented in this volume originates from a suite of multi-disciplinary, integrated ecosystem programs:
- Gulf of Alaska Integrated Ecosystem Research Program (North Pacific Research Board)
- Gulf Watch Alaska and Herring Research and Monitoring (Exxon Valdez Oil Spill Trustee Council)
- Northern Gulf of Alaska Long Term Ecological Research program (National Science Foundation)
These uniquely designed programs have amassed, and continue to curate, unparalleled data repositories, including long-term time series spanning many decades. These programs synthesize information and have produced hundreds of publications, advancing our knowledge of complex ecosystem processes in a rapidly changing environment.
“A small army of tireless scientists with wide-ranging expertise have coalesced around these integrated ecosystem programs,” says Lindeberg. “Only through long term collaborations and partnerships by agencies and organizations have we been able to push our knowledge of the Gulf of Alaska ecosystem forward.”