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

Salmon stocking and climate change

Tom ReedBeaufort Marine Research Award in Fish Population GeneticsUniversity College Cork, Ireland

Boosting salmon numbers - is stocking the answer or the problem? AST/IBIS conferenceGlasgowNovember 2013

Talk outline1. 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

Global scale: atmospheric CO2 is increasing…

Tripati et al. Science 2009

1. Physical changes 2. Signatures in salmon pops 3. Marine survival 4. Freshwater impacts 5. Burrishoole case study 6. Resilience

… 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 http://www.stateoftheocean.org


Source: http://www.nature.com/scitable/knowledge/library/ocean-acidification-25822734

http://www.stateoftheocean.org/



http://www.nature.com/scitable/knowledge/library/ocean-acidification-25822734

Global scale: average temperatures rising at unprecedented rate

Source: Moritz and Agudo Science 2013


MOVE… ADAPT… …OR DIE.

Source: http://news.stanford.edu/news/2013/august/climate-change-speed-080113.html


http://news.stanford.edu/news/2013/august/climate-change-speed-080113.html

Source: http://news.stanford.edu/news/2013/august/climate-change-speed-080113.html


http://news.stanford.edu/news/2013/august/climate-change-speed-080113.html

Source: http://en.wikipedia.org/wiki/El_Niño

Tem

pera

ture

diff

eren

ce fr

om b

asel

ine

glob

al m

ean


http://en.wikipedia.org/wiki/El_Ni%C3%B1o



Pacific decadal oscillation


Mantua et al. Bull Am Met Soc 1997


Climate change impacts on salmonMARINE ENVIRONMENT FRESHWATER 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.


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 75.10 (2009): 2381-2447.

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): 252-270.

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. 2013 In Press


2SW Non-maturing 1SW Maturing

Changes in marine productivity are associated with the Atlantic Multi-decadal Oscillation

Source: Friedland et al. 2013 In Press


“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. 2012. Atlantic salmon at sea: Findings from recent research and their implications for management. NASCO document CNL(12)60. Edinburgh, UK. 20pp.


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.”

“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.”


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

Resilience in the face of uncertainty

• Resilience = sustained productivity despite major environmental change.


ECOSYSTEM PRODUCTIVITY

STOCK COMPLEX orMETAPOPULATION

PRODUCTIVITY

POPULATIONPRODUCTIVITY

Rate of generation of biomass.

Recruits per spawnerAbundance


Time

Degree of local adaptation

(match between phenotype + environment)

Population abundance (of naturally

spawning fish)

Environmental change

Perfect adaptation

Increasing maladaptation


Time

Degree of local adaptation

(match between phenotype + environment)

Population abundance (of naturally

spawning fish)

Environmental change

Perfect adaptation

Increasing maladaptation

Stocking

Burrishoole Case study:Introgression with captive bred fish

Longterm experiment (Burrishoole River)

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

Observed changes in climate

Future projections




Resilience of stock complexes


ECOSYSTEM PRODUCTIVITY

STOCK COMPLEX orMETAPOPULATION

PRODUCTIVITY

POPULATIONPRODUCTIVITY

North Pacific Ocean

Bristol Bay

Wood RiverL.A. Rogers

each withmany

populations

9 major rivers

Sockeye Salmon habitat in Bristol Bay

L.A. Rogers

Lake beaches

Small streams

Salmon biological features are adapted to local

habitat conditions and how these ‘filter’ climate

1

2

3

Age diversity

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

Commercial fisheries for sockeye salmon in Bristol Bay have been sustained for over 120 years

0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

35,000,000

40,000,000

45,000,000

50,000,000

1893

1903

1913

1923

1933

1943

1953

1963

1973

1983

1993

2003

Year

Co

mm

erc

ial

ca

tch

Togiak

Ugashik

Egegik

Nushagak

Naknek-Kvichak

data from ADFG

Com

mer

cial

cat

ch

Number of sockeye salmon caught in Bristol Bay (1893-2010)

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

X X X X

XXXXXXXXXXXXXXXXXXXXXXXXXXXX X X

Time (100 years)

Num

ber

of r

etur

ning

sal

mon

(m

illio

ns)

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)

http://www.cbr.washington.edu/crisp/hydro/hydrolwg1.html

“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

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 (2006-2013),

with the support of the Marine Institute, funded under the Marine Research Sub-Programme of the National Development Plan 2007–2013.

Extra slides

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 CO2?

4. Have human activities led to a net emission of CO2?

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 changes 2. Signatures in salmon pops 3. Marine survival 4. Freshwater impacts 5. Burrishoole case study 6. Resilience

?

1

2

3

Age diversity

0.01

0.1

1

10

1

Major rivers

0.01

0.1

1

10

1

Streams

0.01

0.1

1

10

1

All the same age

0.01

0.1

1

10

1

year

Tota

l ret

urn

(rel

ativ

e)

Bristol Bay

1960 2010

Salmon returns to Bristol Bay are two times more reliable than the individual

components of the portfolio

0.01

10

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


Scale and the detection of climatic influences on productivity

Rogers and Schindler 2008 Global Change Biology1. Physical changes 2. Signatures in salmon pops 3. Marine survival 4. Freshwater impacts 5. Burrishoole case study 6. Resilience

Population unit Nursery Lake Most important climate variable Direction of effect

Bear creek Alegnagik Lake T second summer +

Hansen creek Alegnagik Lake T second summer +

Happy creek Alegnagik SST second summer +

Ice creek Alegnagik Lake T second summer +

Fenno creek Nerka SST second summer +

Hidden creek Nerka Lake T first summer

Lynx creek Nerka - +

Pick creek Nerka Lake T first summer +

Climate variables affecting productivity of individual streams


“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

Population unit Number of lakes Most important climate variable Direction of effect

Lake Alegnagik 1 Lake T second summer +

Lake Nerka 1 Lake T first summer +

All streams 2 Lake T second summer +

Wood river system 5 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)


• 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.


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: http://en.wikipedia.org/wiki/El_Niño1. Physical changes 2. Signatures in salmon pops 3. Marine survival 4. Freshwater impacts 5. Burrishoole case study 6. Resilience



Image: www.speakupforblue.com


http://www.speakupforblue.com/in-ocean-news/sockeye-salmon-return-to-rivers-using-magnetic-field-during-migration

Source: http://sealevel.jpl.nasa.gov/elnino/971205.html

Warm water pool; sea level

well above normal


• 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.


Average Stream Temperature oC

Spaw

ning

day

of y

ear

Peter Lisi

Schindler et al. 2010

High intensity stocking might lead to loss of biocomplexity

River A River B

HATCHERY STOCK


River A River B

HATCHERY STOCK

River A River B


River A River B

HATCHERY STOCK

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. 2003 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??

Documents

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