finding 22.4 : ocean-temp-chem-affect-fisheries

Current and projected increases in Alaska’s ocean temperatures and changes in ocean chemistry are expected to alter the distribution and productivity of Alaska’s marine fisheries, which lead the U.S. in commercial value.



This finding is from chapter 22 of Climate Change Impacts in the United States: The Third National Climate Assessment.

Process for developing key messages: A central component of the assessment process was the Alaska Regional Climate assessment workshop that was held September 12-15, 2012, in Anchorage with approximately 20 attendees; it began the process leading to a foundational Technical Input Report (TIR).6e174e7d-28f7-4ce4-9141-c378d82b4f53 The report consists of 148 pages of text, 45 figures, 8 tables, and 27 pages of references. Public and private citizens or institutions were consulted and engaged in its preparation and expert review by the various agencies and non-governmental organizations (NGOs) represented by the 11-member TIR writing team. The key findings of the report were presented at the Alaska Forum on the Environment and in a regularly scheduled, monthly webinar by the Alaska Center for Climate Assessment and Policy, with feedback then incorporated into the report. The chapter author team engaged in multiple technical discussions via regular teleconferences. These included careful expert review of the foundational TIR6e174e7d-28f7-4ce4-9141-c378d82b4f53 and of approximately 85 additional technical inputs provided by the public, as well as the other published literature and professional judgment. These discussions were followed by expert deliberation of draft key messages by the writing team in a face-to-face meeting before each key message was selected for inclusion in the Report. These discussions were supported by targeted consultation with additional experts by the lead author of each message, and they were based on criteria that help define “key vulnerabilities” (Ch. 26: Decision Support).

Description of evidence base: The key message and supporting chapter text summarize extensive evidence documented in the Alaska Technical Input Report.6e174e7d-28f7-4ce4-9141-c378d82b4f53 Technical input reports (85) on a wide range of topics were also received and reviewed as part of the Federal Register Notice solicitation for public input. Numerous peer-reviewed publications describe evidence that ocean temperatures are rising and ocean chemistry, especially pH, is changing.6e174e7d-28f7-4ce4-9141-c378d82b4f53 New observational data from buoys and ships document increasing acidity and aragonite under-saturation (that is, the tendency of calcite and aragonite in shells to dissolve) in Alaskan coastal waters. Accumulating strong evidence suggests that these changes in ocean temperature and chemistry, including pH, will likely affect major Alaska marine fisheries, although the relative importance of these changes and the exact nature of response of each fishery are uncertain.34d601bb-7781-4785-bde8-3b10be88994c b33c6aba-d652-4f20-9809-e0948a06bcfd 7ab1d9e1-75a1-48c5-8d85-02258496f919 79042600-c08d-4569-8741-7f00d598cd02 d8db2d8d-d1d1-4d24-b662-67b26b8ac92b 215b842d-1f34-40c2-8e0e-04965ad303d6 8d612e8b-b96e-48db-a8b4-17bcc3550f7d Alaska’s commercial fisheries account for roughly 50 percent of the United States’ total wild landings. Alaska led all states in both volume and ex-vessel value of commercial fisheries landings in 2009, with a total of 1.84 million metric tons worth $1.3 billion.4e7a9c25-dc8f-4b57-b72b-adafed7627df

New information and remaining uncertainties: Important new evidence confirmed many of the findings from a prior Alaska assessment (http://nca2009.globalchange.gov/alaska), which informed the 2009 NCA.e251f590-177e-4ba6-8ed1-6f68b5e54c8a The new evidence included results from improved models and updated observational data. The assessment included insights from stakeholders collected in a series of distributed engagement meetings that confirm the relevance and significance of the key message for local decision-makers. A key uncertainty is what the actual impacts of rising temperatures and changing ocean chemistry, including an increase in ocean acidification, will be on a broad range of marine biota and ecosystems. More monitoring is needed to document the extent and location of changes. Additional research is needed to assess how those changes will affect the productivity of key fishery resources and their food and prey base.

Assessment of confidence based on evidence: Given the evidence base and remaining uncertainties: High confidence of increased ocean temperatures and changes in chemistry. Medium confidence that fisheries will be affected.

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