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

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

5. Relative run size Different dynamics in stocks of Bristol Bay sockeye produce portfolio effects in fisheries Sockeye salmon returns to Bristol Bay rivers 0.01 0.1 1 10 19561961196619711976198119861991199620012006 Year Relative run size

6. 1 2 3 Age diversity Major riversStreamsAll the same age year Total return (relative) Bristol Bay 1960 2010 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. The front line at Egegik http://www.absc.usgs.gov/research/Fisheries/Lake_Clark/subsistence.htm How does reliability affect people dependent on fisheries?

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

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

10. Habitat conditions vary among locations in watersheds

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

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

13. * 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. Bristol Bay