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Salmon stocking and climate change Tom Reed Beaufort Marine Research Award in Fish Population Genetics University College Cork, Ireland Boosting salmon.

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Presentation on theme: "Salmon stocking and climate change Tom Reed Beaufort Marine Research Award in Fish Population Genetics University College Cork, Ireland Boosting salmon."— Presentation transcript:

1 Salmon stocking and climate change Tom Reed Beaufort Marine Research Award in Fish Population Genetics University College Cork, Ireland Boosting salmon numbers - is stocking the answer or the problem? AST/IBIS conference Glasgow November 2013

2 Talk outline 1.Physical changes 2.Signatures of climate change in salmon pop. dynamics 3.Reduced marine survival of Atlantic salmon 4.Freshwater impacts on Atlantic salmon 5.Case study of Burrishoole salmon (wild + ranched) 6.Resilience of populations and stock complexes in the face of uncertainty

3 Global scale: atmospheric CO 2 is increasing… Tripati et al. Science Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

4 … and the oceans are getting more acidic. "This [acidification] is unprecedented in the Earth's known history. We are entering an unknown territory of marine ecosystem change, and exposing organisms to intolerable evolutionary pressure. The next mass extinction may have already begun.“ From: IPSO State of the Ocean Report 2013: see 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience Source:

5 Global scale: average temperatures rising at unprecedented rate Source: Moritz and Agudo Science Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

6 MOVE…ADAPT……OR DIE. Source: 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

7 Source: 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

8 Source: Temperature difference from baseline global mean 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

9 Pacific decadal oscillation 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

10 Mantua et al. Bull Am Met Soc Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

11 Climate change impacts on salmon MARINE ENVIRONMENTFRESHWATER ENVIRONMENT ABIOTIC/DIRECT EFFECTS BIOTIC/INDIRECT EFFECTS Death or stress due to high temperatures. Increased energetic costs of migration Altered growth and maturation patterns Changes in food supply. Changes in predation. Increased disease risk and parasites. 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience Death or stress due to high temperatures. Increased energetic costs of migration Altered growth and maturation patterns Changes in food supply. Changes in predation. Increased disease risk and parasites. Jonsson, B., and N. Jonsson. "A review of the likely effects of climate change on anadromous Atlantic salmon Salmo salar and brown trout Salmo trutta, with particular reference to water temperature and flow." Journal of Fish Biology (2009): Crozier, L. G., et al. "Potential responses to climate change in organisms with complex life histories: evolution and plasticity in Pacific salmon." Evolutionary Applications 1.2 (2008):

12 Problems due to changes in ocean climate Marine survival has decreased substantially in recent decades; especially affecting MSW fish but 1SW also affected, particularly from Southern European stock complex Source: Friedland et al In Press 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience 2SW Non-maturing1SW Maturing

13 Changes in marine productivity are associated with the Atlantic Multi-decadal Oscillation Source: Friedland et al In Press 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

14 “The clear message from the ‘Salmon Summit’ in this challenging global environment is to maximise the number of healthy wild salmon that go to sea from their home rivers, since management options in the ocean are limited.” Malcolm L. Windsor, Peter Hutchinson, Lars Petter Hansen and David G. Reddin Atlantic salmon at sea: Findings from recent research and their implications for management. NASCO document CNL(12)60. Edinburgh, UK. 20pp. 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience What about freshwater impacts on regional/local scales? “… there may be only limited opportunities to respond to further declines through management of the fisheries, as these have already been closed or greatly reduced.”

15 “Managing salmon in the face of the uncertainty about future environmental changes will be challenging. The goal should be to protect the genetic diversity of the wild Atlantic salmon in order to maximise their potential to adapt to the changing environment. Consistent with a Precautionary Approach, where there are uncertainties there is a need for caution. The absolute priority should be to conserve the productive capacity of the resource.” 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience So managing salmon in the face of CC will realistically be all about minimising impacts in freshwater, estuarine and coastal environments, where we have more direct control. Should stocking be a part of the repertoire of management options, or do the risks outweigh the potential benefits? Source: NASCO Salmon Summit report

16 Resilience in the face of uncertainty Resilience = sustained productivity despite major environmental change. 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience ECOSYSTEM PRODUCTIVITY STOCK COMPLEX or METAPOPULATION PRODUCTIVITY POPULATION PRODUCTIVITY Rate of generation of biomass. Recruits per spawner Abundance

17 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience Time Degree of local adaptation (match between phenotype + environment) Population abundance (of naturally spawning fish) Environmental change Perfect adaptation Increasing maladaptation

18 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience Time Degree of local adaptation (match between phenotype + environment) Population abundance (of naturally spawning fish) Environmental change Perfect adaptation Increasing maladaptation Stocking

19 Burrishoole Case study: Introgression with captive bred fish

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21 Longterm experiment (Burrishoole River)

22 The Model Main factors determining egg to smolt survival in Burrishoole  % hatchery eggs in spawning cohort (- survival)  Winter temperature for eggs & fry (- survival)  Winter temperature for parr (- survival)  Winter temperature for smolts (+ survival)  Interaction between % hatchery eggs and winter temperature (- survival) McGinnity et al. (2009). PRSB, 276:3601–3610

23 Observed changes in climate

24 Future projections McGinnity et al. (2009). PRSB, 276:3601–3610

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26

27 Resilience of stock complexes 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience ECOSYSTEM PRODUCTIVITY STOCK COMPLEX or METAPOPULATION PRODUCTIVITY POPULATION PRODUCTIVITY

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

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30 L.A. Rogers Lake beaches Small streams Salmon biological features are adapted to local habitat conditions and how these ‘filter’ climate Age diversity

31 Salmon landscapes are shifting mosaics of suitable habitat (sensu Stanford et al. 2005)

32 Commercial fisheries for sockeye salmon in Bristol Bay have been sustained for over 120 years data from ADFG Commercial catch Number of sockeye salmon caught in Bristol Bay ( )

33 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 (millions)

34 NOAA Stability and productivity derive from diverse and changing habitat Bristol Bay, Alaska Pacific Northwest “To keep every cog and wheel is the first precaution of intelligent tinkering” Aldo Leopold (Round River, 1953)

35 “Disease is the bullet that's killing the frogs, but climate change is pulling the trigger. Global warming is wreaking havoc on amphibians, and soon will cause staggering losses of biodiversity” J. Alan Pounds 2006

36 Acknowledgments IBIS/AST and the organisers Daniel Schindler (University of Washington, Seattle) for slides Phil Mc Ginnity for slides and great discussions always! Beaufort Marine Research Award in Fish Population Genetics This Beaufort Marine Research Award is carried out under the Sea Change Strategy and the Strategy for Science Technology and Innovation ( ), with the support of the Marine Institute, funded under the Marine Research Sub-Programme of the National Development Plan 2007–2013.

37 Extra slides

38 Are humans causing current climate change? Quote from George Monbiot’s recent book: “If you reject this explanation [man-made climate change] for planetary warming, you should ask yourself the following questions: 1.Does the atmosphere contain carbon dioxide? 2.Does atmospheric carbon dioxide raise the average global temperature? 3. Will this influence be enhanced by the addition of more CO 2 ? 4. Have human activities led to a net emission of CO 2 ? If you are able to answer ‘no’ to any one of them, you should put yourself forward for a Nobel Prize. You will have turned science on its head”. 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience ?

39 1 2 3 Age diversity Major riversStreamsAll the same age year Total return (relative) Bristol Bay Salmon returns to Bristol Bay are two times more reliable than the individual components of the portfolio

40 Zooming in to more regional scales… The previous analysis was focussed at a very broad organizational scale (i.e. all salmon in the Atlantic, or N American, S European stock complexes, etc…) Showed that there is this broad coherence in the responses of populations to large-scale climate drivers, but also showed differential responses of the S and N European stock complexes However, the synchronizing effects of climate can be reduced by heterogeneity in (a) the local expression of regional climate variation, (b) other extrinsic determinants of population dynamics, such as the density of predators or competitors, and (c) population traits and local adaptations which determine the sensitivity of populations to changes in their environment. While much focus has been placed on the synchronizing effects of climate, less attention has been paid to the possibility that populations may show sensitivity to different climatic drivers, even within the same geographic region or WATERSHED, due to genetic and phenotypic heterogeneity among populations and differences in the physical and biotic features of habitats that they occupy 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

41 Scale and the detection of climatic influences on productivity Rogers and Schindler 2008 Global Change Biology 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

42 Population unitNursery Lake Most important climate variable Direction of effect Bear creekAlegnagikLake T second summer + Hansen creekAlegnagikLake T second summer + Happy creekAlegnagikSST second summer + Ice creekAlegnagikLake T second summer + Fenno creekNerkaSST second summer + Hidden creekNerkaLake T first summer Lynx creekNerka- + Pick creekNerka Lake T first summer + Climate variables affecting productivity of individual streams 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

43 “One major question then becomes whether it is better to improve production in the SJ Basin by improving the environment, which may take a long time, or through hatchery production, which may foster homogeneity among rivers. Here we argue that restoring environmental heterogeneity, which is the template that gives rise to local adaptations and diverse life history portfolios, will pay larger dividends in the long run.” Weakened portfolio effect in a collapsed Chinook salmon population complex Sacramento R San Joaquin R Carlson & Satterthwaite 2011 CJAFS

44 Population unitNumber of lakes Most important climate variable Direction of effect Lake Alegnagik1Lake T second summer + Lake Nerka1Lake T first summer + All streams2Lake T second summer + Wood river system5 Date of ice breakup in year of smolting - Climate variables affecting productivity at higher spatial scales Inclusion of fall and winter climate variables was never strongly supported, at any scale Inclusion of the PDO (Pacific Decadal Oscillation) never well supported, even at level of entire Wood River system But evidence still for unexplained oscillations in productivity across years (over and above the identified climate effects) 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

45 Inherent trade-off: Modelling effects of climate change: most appropriate level of spatial complexity to consider depends on specific management, scientific, or conservation goals Coarse spatial scale (e.g. entire watershed or region) Fine spatial scale (e.g. individual streams/populations) Improved generality and more confidence in detected climate effects. Ignores ecological complexity and differential responses of populations. Reveals ecological complexity and differential responses of populations. Reduced generality and little predictive power. 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

46 Climate cycles on top of long-term warming Below normal pressure over Tahiti; Above normal pressure over Australia Above normal pressure over Tahiti; Below normal pressure over Australia La Niña El Niño Source: 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

47 Image: 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

48 Source: Warm water pool; sea level well above normal 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

49 It’s worth reflecting for a moment on what is meant by the phrase adapt to a changing environment. Intuitively, the word adapt here would seem to imply the ability of salmon to persist in a changing world, but in fact the word adaptation means something rather subtly different to an evolutionary biologist. Strictly speaking, it refers to the process whereby natural selection drives genetic changes within a population, such that genetic variants that are better ‘fitted’ to the prevailing conditions increase in frequency at the expense of other, poorer adapted types. We can also broaden the definition and define adaptation at the phenotypic level, to encompass any changes in the outward characteristics of individuals such as their morphology or their behaviour, or in their internal physiological workings or patterns of development, that enhance their survival and reproductive success, or in evolutionary terms, their fitness. Such changes could be caused by underlying genetic changes or by phenotypic plasticity. But adaptation is not the same thing as persistence. A population may evolve (i.e. adapt) in response to changing environmental conditions, but go extinct in the process. At a higher level, salmon as a species or stock complexes may not go extinct, despite the loss of certain component populations. Resilience, biocomplexity etc. Genetic diversity of salmon can be considered at different levels, e.g. between stock complexes, among populations within stock complexes, and within populations. There are benefits to conserving diversity at each of these levels, but the benefits derive from quite different biological mechanisms. Within population genetic variation: grist for natural selection to do its thing. Between population/river genetic variation: increases biocomplexity, and biocomplexity increases resilience. 1. Physical changes2. Signatures in salmon pops3. Marine survival4. Freshwater impacts5. Burrishoole case study6. Resilience

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51 Average Stream Temperature o C Spawning day of year Peter Lisi Schindler et al. 2010

52 High intensity stocking might lead to loss of biocomplexity River ARiver B HATCHERY STOCK

53 High intensity stocking might lead to loss of biocomplexity River ARiver B HATCHERY STOCK River ARiver B

54 High intensity stocking might lead to loss of biocomplexity River ARiver B HATCHERY STOCK

55 Some studies have shown genetic homogenization effects of stocking: Allyon et al. (2005) showed that intensive stocking of southern European rivers with Atlantic salmon of Northern European origin led to a loss of regional population structure:  Prior to stocking, there were significant genetic differences (neutral loci) among neighbouring Spanish and French rivers, but these differences disappeared after stocking. Jonsson et al found that hatchery-reared Atlantic salmon leaving the River Imsa (Norway) as smolts were more than twice as likely to stray compared with wild conspecifics Vasemägi et al. (2005) showed that extensive immigration of hatchery fish from one Baltic river into a neighbouring river with a wild population has homogenised the genetic structure (wild fish have become more like the hatchery fish) … will stocking also lead to loss of ‘bio-complexity’ i.e. life history diversity and population-specific local adaptations??


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