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Population diversity and the portfolio effect in fisheries Daniel Schindler

Population diversity and the portfolio effect in fisheries Daniel Schindler Keeler Professor of Aquatic and Fishery Sciences University of Washington Seattle, WA 98195 deschind@u.washington.edu. Thanks to:

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Population diversity and the portfolio effect in fisheries Daniel Schindler

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  1. Population diversity and the portfolio effect in fisheries Daniel Schindler Keeler Professor of Aquatic and Fishery Sciences University of Washington Seattle, WA 98195 deschind@u.washington.edu Thanks to: National Science Foundation, Gordon and Betty Moore Foundation, Alaska Salmon processors

  2. Biological diversity is important for ecosystem stability… …but does this apply to individual species?

  3. 9 major rivers Bristol Bay each with many populations L.A. Rogers Salmon habitat in Bristol Bay North Pacific Ocean Wood River

  4. data from ADFG Commercial fisheries for sockeye salmon in Bristol Bay have been sustained for over 120 years - record catches have occurred within the last 20 years - Number of sockeye salmon caught in Bristol Bay (1893-2010) Commercial catch

  5. Different dynamics in stocks of Bristol Bay sockeye produce portfolio effects in fisheries Sockeye salmon returns to Bristol Bay rivers 10 1 Relative run size Relative run size 0.1 0.01 1956 1961 1966 1971 1976 1981 1986 1991 1996 2001 2006 Year

  6. Bristol Bay Major rivers Streams All the same age Total return (relative) Age diversity 1 2 1960 2010 year 3 Salmon returns to Bristol Bay are two times more reliable than the individual components of the portfolio Eroded portfolio 2.2 times more variable than the Bristol Bay salmon portfolio

  7. http://www.absc.usgs.gov/research/Fisheries/Lake_Clark/subsistence.htmhttp://www.absc.usgs.gov/research/Fisheries/Lake_Clark/subsistence.htm The front line at Egegik How does reliability affect people dependent on fisheries?

  8. 100 90 80 70 60 50 40 30 20 10 X X X X 0 100 90 80 70 60 50 40 30 20 10 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 0 Variability in salmon increases the rate of fisheries closures Fisheries are closed 4 years every century Bristol Bay (intact portfolio) average minimum spawners Number of returning salmon Bristol Bay (eroded portfolio) Fisheries are closed 40 times every century Time (100 years)

  9. L.A. Rogers Sockeye salmon have different biological features, depending on the habitat they occupy Lake beaches Small streams

  10. Habitat conditions vary among locations in watersheds

  11. Locations where juvenile salmon enter the ocean Salmon habitat is also different among locations in the ocean August 2000, NASA

  12. Portfolio effects derive from intact and viable habitat Pacific Northwest Bristol Bay, Alaska NOAA

  13. Bristol Bay * Conservation and management should recognize the value of diversity within individual species, and the habitat conditions that produce this diversity* Maintaining genetic diversity and viable habitat is one way to build insurance for climate change. The weak stock today may be the strong one tomorrow!* Climate change, ocean acidification, etc. make the future far more uncertain than usual, the portfolio concept is one way to build insurance for the future (How are you spreading your risk? Among species? Among stocks?)* Specific strategies will be ecosystem-specific, but do not necessarily require finer scale management.

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