What Does Climate Change Mean for Alaska's Fisheries? Gordon H. Kruse, Ph.D. University of Alaska Fairbanks School of Fisheries and Ocean Sciences, Juneau Center Juneau, Alaska
Global Warming in the News The Independent (2004) NY Times (1956) NY Times (1932)
Average temperature of Earth's surface increased 0.7 1.4 F (0.4 0.8 C) since the 1880s. Source: NOAA
NASA Surface Temperature Analysis Source: NASA Global mean land-ocean temperature index, 1880 to 2006.
Some Effects of Warming Climate: Land Melting of permafrost in Fairbanks Source: Soils Alaska, PC Source: USFS Increased spruce bark beetle in south-central AK Increased coastal erosion in Shishmaref Photo: Tony Weyiouanna, Sr.
Climate Change & Variability of Marine Ecosystems Climate change change in the average state (or its variability) of the atmosphere of the earth or a region over time scales ranging from decades to millions of years. Time scales relevant to marine ecosystems: Events (days) Seasons Interannual Decadal and longer
Seasonal Battle: Sun vs. Winds Sun tries to warm upper layers of ocean. Wind tries to mix upper and lower waters. Source: NASA Source: Rice Univ.
Simplified Marine Food Chain Chum salmon fry Copepods Fish Zooplankton Herring Euphausiids Diatoms Phytoplankton Nutrients Dinoflagellates
Distribution of Nutrients Mixed Stratified Nybakken (2001)
Seasonal Cycle Kaiser et al. (2006)
Seeing Plankton from Space SeaStar Satellite: Launched August 1, 1997. Carries SeaWiFS instrument used to monitor color of the world s oceans. Chlorophyll-a molecule absorbs more blue and red light than green. H 2 O CO 2 Carbohydrates
Blue to red colors indicate higher Chlorophyll-a (phytoplankton) concentrations from 0 to 6 mg/m 3 Mordy et al. (2003)
El Niño Sea Surface Temperature (SST) Anomalies January-March 1998
10 Strongest El Niños of 20 th Century Source: NOAA, NCDC
Unusual Sightings in Alaska 1997-1998 1998 Pacific white-sided dolphin seen off Southeast Alaska Albacore tuna caught off Kodiak Island Ocean sunfish observed in northern Gulf of Alaska
Coccolithophore Blooms in Bering Sea Observed by SeaWiFS Coccoliths (calcium plates) cause light reflection, making the sea look brighter Emiliania huxleyi Source: NASA
Seabirds and Coccolithophores Short-tailed tailed shearwaters: Emaciated, mass die-offs, reduced availability of euphausiids Photo: USGS Kittiwakes: surface feeders, improved ability to find prey, more offspring Photo: USFWS Murres: diving feeders, obscured visibility, fewer offspring Photo: enature.com
Pacific Decadal Oscillation (PDO) Warm Cool Phase Phase Source: N. Mantua, Univ. Washington
Comparison of PDO and El Niño
Trends include overlay of El Nino, PDO, and global warming signals Source: NASA Cool PDO Phase El Niños
Climate Regime Shift in Late 1970s: Shrimp and Groundfish Walleye Pollock Pacific Cod Yellowfin Sole Northern Shrimp Northern Shrimp Photos: NMFS and marinbi.com
Climate Regime Shift in Late 1970s: Shrimp and Groundfish Relative Species Abundance in Surveys, 1953-1998 Anderson and Piatt (1999)
Typical Survey Catches in Pavlov Bay 1960s & 1970s (mostly shrimp) 1977-1980 1980 (mixed) After 1981 (mostly groundfish) Photos: Paul Anderson, NMFS
Climate Regime Shift in Late 1970s: Pacific Salmon Pink salmon Coho salmon Sockeye salmon Chinook salmon Chum salmon
Climate Regime Shift in Late 1970s: Pacific Salmon Francis and Hare (1994)
Warm Phase Cool Phase Positive PDO Negative PDO
Large low pressure system in the Gulf of Alaska Spies et al. (2007)
Ocean Currents and Precipitation Spies et al. (2007)
Circulation in the Gulf of Alaska Spies et al. (2007)
Increase in Zooplankton after Climate Regime Shift Spies et al. (2007)
Role of Sea Ice in the Bering Sea
Illustration of Timing of Ice Retreat and Spring Bloom Stays in Water Column to Bottom (Hunt et al. 2002)
Some Commercially Important Crabs Red King Crab Blue King Crab Photo: T. Shirley, UAF Tanner Crab Photo: L. Watson, ADF&G Snow Crab Photo: C. Botelho, ADF&G Photo: L. Jadamec, NPOTC
Crab Fisheries Photo: P. Murphy, ADF&G Photo: G. Kruse Photo: ADF&G, Kodiak
Trends in Crab Brood Size Bristol Bay red king crabs Norton Sound red king crabs Pribilof Islands blue king crabs Log (recruits) St. Matthew Island blue king crabs Bristol Bay Tanner crabs Eastern Bering Sea snow crabs 67 70 73 76 79 82 85 88 91 94 97 Hatching year 67 70 73 76 79 82 85 88 91 94 97 Zheng and Kruse (2006)
Bristol Bay Red King Crab Brood Strength May Relate to Climate Regime Shift Total recruits (millions of crabs) 140 120 100 80 60 40 20 0 Cool Phase Recruits ALPI Warm Phase 66 69 72 75 78 81 84 87 90 93 96 Hatching year 6 5 4 3 2 1 0-1 -2-3 Aleutian Low index Strongest broods occurred before 1977 during cool phase Largest brood (1990) in last 20 yr coincided with brief PDO reversal in 1989-1991 King crab larvae eat Thallassiosira diatoms Zheng and Kruse (2003)
Crab Predators Biomass (1000 t) 3000 2500 2000 1500 1000 500 (a) Pacific cod Yellowfin sole Male red king crab 70 60 50 40 30 20 10 Recruits (millions) 0 0 66 69 72 75 78 81 84 87 90 93 96 Year Zheng and Kruse (2006)
What are Future Consequences of Global Warming on Alaska s Fisheries?
Warming is 2X as fast in Arctic as globe since 1960s Working Group, Intergovernmental Panel on Climate Change, 2007
Projected Increases in Temperature Increase of 0.2 C per decade is projected over next two decades. Working Group, Intergovernmental Panel on Climate Change, 2007
Projected Changes in Precipitation Precipitation increases very likely in high latitudes Working Group, Intergovernmental Panel on Climate Change, 2007
Projected Continued Loss of Sea Ice
Potential Invasive Species Native to North and Baltic Seas. Consumed up to 50% of Manila clams in California. Blamed for collapse of the soft-shell shell clam industry in Maine. Potential competitor with native fish and birds. Potential to significantly alter an ecosystem. Arrival at U.S. west coast causes concern for Alaskan Dungeness crab, oyster and clam fisheries. European Green Crab Photo: USGS
Unusual Species Seen in 2004-2005 2005 // Jumbo Squid Northern SE AK Opah Sitka, AK Photos: Bruce Wing, NMFS Thresher Shark, Yakobi Island
Effects on Harmful Algal Blooms? HABs more frequent, but causes are uncertain HABs include: PSP Domoic acid // Source: Red Tide Newsletter (1999)
How Will Mixing/Stratification Change? Nybakken (2001)
How Will Mixing/Stratification Change? Warmer temperatures Increased water column stratification Lower salinity Increased water column stratification Wind? Increased cyclonic activity in tropics predicted Changes for subarctic less certain Increased stratification may: Lengthen summer conditions Shift Shift timing and/or intensity of spring bloom
Groundfish/Salmon Response? Generally benefit from current conditions Projected conditions go beyond range of historical observations Some groundfish stocks are now declining (e.g., cod, some flatfishes)??
Salmon in British Columbia // Temperatures >15ºC C cause stress in sockeye salmon, increasing susceptibility to disease and impairing reproduction. Mortality related to temperature and river flow in Fraser River sockeye salmon. 2 Source: BC Government
Goodbye Salmon, Hello Tuna? //
Increased Predation on BC Salmon // Pacific mackerel productivity off CA highest during warm years Pacific and jack mackerel extend distributions north to BC in warm years Mackerel compete with and predate juvenile salmon Reduced survival of WCVI sockeye salmon correlated with abundance and early arrival of Pacific mackerel Jack Mackerel Pacific Mackerel
Projected Loss of Sea Ice // Northward shift of groundfish predators into northern Bering Sea Potential reduction in bottom-dwelling invertebrates Flock of 80,000 Birds near St. Lawrence Island Photo: USFWS Photo: USFWS Source: NASA Spectacled eiders dive to 70 m to feed on crustaceans and molluscs Listed as threatened under the ESA
Limits to Predicting Fisheries Impacts Uncertainty in climate predictions, especially effects on storms, winds, and ocean currents Limited knowledge of physiological and ecological responses of species to changing conditions No historical observations of ecosystem response within predicted range of environmental changes under global warming
Research Needs Laboratory studies examine biological responses of species to warmer conditions Field studies monitor changes already underway Retrospective analysis examine history of changes from warming to date Modeling need to couple climate/oceanographic models to ecosystem models
Crabs in Hot Water? Questions?