Climate Change and Alaskan Fisheries Mike Litzow UAF Fisheries Department Kodiak Seafood and Marine Science Center Source ScrippsUniversity of California Atmospheric carbon dioxide 1958present Source ScrippsUniversity of California ID: 765241
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Climate Change and Alaskan Fisheries Mike Litzow UAF Fisheries DepartmentKodiak Seafood and Marine Science Center
Source: Scripps/University of California Atmospheric carbon dioxide: 1958-present
Source: Scripps/University of California Atmospheric carbon dioxide: last 800,000 years
Source: NASA Change from 1951-1980 average (°C) Global land and sea temperature 1880-2017
Source: NOAA Change from 1951-1980 average (°F) Gulf of Alaska surface temperature 1950-2018
Source: NOAA Change from 1951-1980 average (°F) Gulf of Alaska surface temperature 1950-2018 Shrimp/crab collapse Salmon/cod/halibut boom
Source: NOAA Change from 1951-1980 average (°F) Gulf of Alaska surface temperature 1950-2018 2014-2016 marine heatwave
Source: NOAA Change from 1951-1980 average (°F) Gulf of Alaska surface temperature 1950-2018 Impossible with pre-industrial atmosphere
Source: NOAA Change from 1951-1980 average (°F) Gulf of Alaska surface temperature 1950-2018 Cod collapse
Change can be fast
NMFS bottom trawl survey Halibut longline survey Sablefish longline survey ADF&G bottom trawl survey Bottom temperature estimates Commercial catch data Data Sources Assessment model Stock estimate (Female spawning biomass) 10,000s tons 2016 estimate 2017 estimate How do we know the stock collapsed? Source: Barbeaux et al., 2017 GOA P. cod assessment
Estimated natural mortality over time Why did the stock collapse? Source: Barbeaux et al., 2017 GOA P. cod assessment
2018 UAF Beach Seine Survey Age-0 Pacific cod abundance – Catch per unit effort
Source: NOAA Change from 1951-1980 average (°F) Gulf of Alaska surface temperature 1950-2018 Pink salmon survival ↓ Sockeye survival ↓ Unusual run timing
Source: NOAA Change from 1951-1980 average (°F) Gulf of Alaska surface temperature 1950-2018 Pollock size ↓ Arrowtooth abundance ↓
Source: NOAA Change from 1951-1980 average (°F) Gulf of Alaska surface temperature 1950-2018 Big questions: Compensatory booms? Short climate perturbation, or new steady state? Switch to a new ecosystem state?
+6,000% +900% -90% Northern Bering Sea climate changes and range extensions
Carbon emissions drive fisheries outcomes “Representative concentration pathways” – scenarios of different future emissions “Business as usual”
Carbon emissions drive fisheries outcomes Source: IPCC
Source: Nick Bond (U. Washington, State of WA Climatologist) Gulf of Alaska sea surface temperature: changing extremes Temperature variability is expected to continue increasing (strong scientific certainty)
Conclusions Present-day effects of global warmingPacific cod crashPoor/volatile salmon returns Short-term future (< 5 years) Elevated chance of a switch to a new ecosystem state Little ability to predict year-to-year temperature Longer term (now and future decades) Increasing frequency and severity of temperature shocks (high scientific certainty) Increasing ocean acidification (high scientific certainty) Increasing volatility in fisheries (high scientific certainty)