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Published byDuane Hunt Modified over 9 years ago
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Climate insurance for NW steelhead fisheries: thoughts on incorporating the influence of variable ocean conditions in steelhead management Nate Mantua Climate Impacts Group University of Washington
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Sept 1997 El Niño Sept 1998 La Niña Environmental variability is large
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OPI (hatchery) coho marine survival Why? Leading hypothesis: changes in ocean conditions impact the entire marine food-web
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upwelling food webs in our coastal ocean: the California Current Cool water, weak stratification high nutrients, a productive “subarctic” food-chain with abundant forage fish and few warm water predators Warm stratified ocean, few nutrients, low productivity “subtropical” food web, a lack of forage fish and abundant predators
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Upwelling impacts: August 2000 temperatureChlorophyll For the NW coastal ocean, spring/summer upwelling is a key and highly variable process that structures the coastal ocean food web Columbia River Rivermouth
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1000 smolts 10’s to 100’s post-smolts early summer A few to ~100 adults in 2nd summer key factors? Stratification spring transition date spring winds, upwelling and transport ? 1st spring at sea 1st winter at sea key factors? Stratification winter winds, downwelling and transport ? coastal ocean impacts on coho marine survival (Logerwell et al. 2003, Fish. Oceanogr.)
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4 index Ocean Conditions Model “hindcasts” for OPI coho marine survival, 1969-1998 Logerwell et al. 2003, Fish. Oc. R 2 =.75
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Observed coherence scales in stock specific salmon productivity Stock by stock R/S residuals have 50% decorrelation scales ~500 to 1000km Similar scales of coherence come from stock by stock marine survival estimates based on CWTs (figure taken from Mueter et al., 2002, Fish. Oceanogr.) n=37 n=40 n=43
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Scales of coherence in the coastal ocean Coastal SST and upwelling wind decorrelation scales are largest in winter, smallest in summer Decorrelation scales for salmon productivity are similar to those for summertime SST and upwelling winds (Mueter et al., 2002, Fish. Oceanogr.) J F M A M J J A S O N D 2500 km 1000 km 500 km
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Commercial Sockeye Salmon Catches Since 1883 Bristol Bay, Alaska Composition Commercial catch (millions) Hilborn et al. 2003, PNAS
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Recruits-per-spawner for Bristol Bay sockeye (by major river system) Year Hilborn et al. 2003, PNAS
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Life in uncertain environments Risk spreading characteristics, at the metapopulation level, one evolutionary response: diversity of time-space habitat use provides a buffer for stocks, metapopulations, and species –a variety of sensitivities for different streams (e.g. Hymer WDFW, Hilborn et al. ) –different ocean sensitivities (e.g. Waples, NMFS, Hilborn et al.) for different stocks
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So what? (what I’ve learned) –Sustaining “fish” and sustaining a “fishery” are not the same things expectations and actions for these two goals are often at odds with each other right now, fishery managers generally failing to deal with “climate” –true for year-to-year and decade-to-decade variations
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What are we managing, and why? (McEvoy 1996) What is a fishery? –(1) an ecosystem; (2) a group of people working, and (3) a system of social control
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Sustainability? Saving the fish eliminate harvests Restore diversity, abundance, and distribution restore and protect habitat –remove barriers to fish passage (breach dams) accept variability –acknowledge a lack of predictability Saving the fishery Maximize harvests –focus on productivity, biomass/numbers tweak the status quo –fish passage, hatcheries eliminate variability –use hatcheries, divorce fish production from habitat –emphasize prediction ECOLOGY POLITICS-ECONOMICS- ECOLOGY
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Where predictability matters (Holling 1993 Ecological Applications) 1st stream science system is predictable, science of parts –ex: the population, maximum sustained yield Experimental, seeks explanation and prediction implies we need certainty before taking action Command and Control Management Problem is perceived, a solution for its control is developed (e.g. low salmon production, build a hatchery) Reduce variability to make the system more predictable
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Where Predictability doesn’t matter 2nd stream science Unpredictable, science of integration –ex: the ecosystem Comparative, seeks understanding, accepts inherent unknowability and unpredictability The Golden Rule “Resource management should strive to retain critical types and ranges of variations in ecosystems” (Holling and Meffe 1996)
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The problem? We can’t solve 2 nd stream problems with 1 st stream approaches
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Summary and Conclusions A large and growing body of evidence for climate impacts on salmonids –climate information may aid in improving management short term help through monitoring+biophys models At time frames > 1 year into the future, predictability is severely limited environmental prediction issues now a source of conflict between managing fish and fisheries –scientists must own up to the fact that we cannot predict the future
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What to do? Acknowledge and embrace uncertaintyAcknowledge and embrace uncertainty –wild salmonids have evolved characteristics that cope with environmental uncertainty choose Monitoring over Predictionchoose Monitoring over Prediction restore natural climate insurance for salmonrestore natural climate insurance for salmon –Diversity, abundance, and distribution –restoring lost diversity of life history behaviors; this diversity is directly linked to availability of healthy, complex freshwater habitat Save the FisherySave the Fishery
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Saving the Fishery Save the FishSave the Fish Rethink/revise goals of fishery managementRethink/revise goals of fishery management –Industrial fishery model (MSY) fails to account for environmental uncertainty and highly limited predictability of populations and their food webs, and it fails to value the role of variability in the ecology of populations
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Managing for sustainability nature Legal system Fish economy/ interests
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Note that this talk borrows heavily from: Mantua, NJ, and RC Francis (in press): Natural climate insurance for Pacific northwest salmon and salmon fisheries: finding our way through the entangled bank. To appear in E.E. Knudsen and D. MacDonald (editors). Fish in our Future? Perspectives on Fisheries Sustainability. A special publication of the American Fisheries Society.
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A climate scientist in the field
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Coastal Oregon regional indices and large- scale Oct-Mar Aleutian Low variability DJF SST0 Spring Trans Spring Uwp DJF SST1 AL Index
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“Ocean Conditions Model” predictions Washington-Oregon-California coho landings Catch in millions of coho 2 4 6 OPI survival rate (%) 2 4 6 8 10 Predictions: RY 2000 4-6% RY 2001 3-5% RY 2002 4-8% RY 2003
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WDFW coho marine survival records courtesy Dave Seiler WDFW 5 wild stocks 7 hatchery stocks
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