Past Records of Salmon Abundance by Francis Choi

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Past Records of Salmon Abundanceby Francis Choi
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Outline

• The importance of salmon abundance information
• What are salmons?
• Methods to measure the abundance
• Causes for abundance variation
• Study 1 climate and salmon abundance
• Study 2 biocomplexity and salmon sustainability
• Problems in past salmon abundance data
• Present day population dynamics of the salmon
• Future direction of salmon sustainability

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Why is Salmon abundance important?

• It is all about fish stock sustainability
• With salmon abundance history
• Management and stock prediction can be made
• Maximum stock harvest can be estimated

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Why do we want to sustain the salmon stock?

• Salmon is an important part of the North American
  Pacific Coast.
• Pacific Canada culture
• - part of the heritage of many First Nations of
  BC
• - ceremonial use
• - everyday resource food, tools, medicine
• - commercial trading

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Why do we want to sustain the salmon stock?

• Salmon is a backbone resource for Pacific coastal
  economy
• - commercial or recreational fishing
• - fish dependent businesses
• - Marina operations
• - Fish processing
• industries
• - Transportation/distributor
• - Boat building and repair
• business
• - retail fish sales

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What is a salmon?

• They are anadromous fish
• Two types
• Pacific salmon Atlantic salmon
• - terminal spawners - repeated spawners

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• Types of salmon found on the Pacific coast
• Chinnok
• Chum
• Coho
• Sockeye
• Pink

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Methods to measure salmon abundance

• Past accumulated data of the CPUE of the salmon.
• CPUE Catch per unit effort
• N15 isotope-indicators
• - Algal bio-indicators
• Past DNA check
• Visual juvenile monitoring

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Abundance of salmon can be affected by

• Combination of
• Human disturbance
• - harvesting
• - pollution
• - urbanization
• Biotic factor
• - predation
• - competition
• Abiotic factors
• - climate change

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• Climate change can affect
• - flow rate of streams
• change in spawn location
• migration time
• - Life history time
• spawning time
• hatching time
• - favorable spawning location
• - abundance of food resources
• biomass of salmon

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• Advantages for studying the population dynamics
  of Pacific salmon
• - Have more accurate methods for
  measuring abundance
• - able to use algal bio-indicator and N15
  isotopes
• - Pacific Ocean is less disturbed than
  Atlantic Ocean
• - human disturbance can be eliminated from
  factors affecting salmon abundance

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Study 1 Fisheries productivity in the northern
Pacific Ocean over the past 2,200 yearsFinney
B.P., Gregory-Eaves I., Douglas M.S.V. Smol
J.P. (2002) Nature, 416, 729-733

• The study creates the abundance of Pacific
  sockeye for the past 2,200 years
• Purpose determine that climate variability is
  related to the population dynamics of the
  Pacific salmon
• Methods used N15 isotopes, algal bio-indicators
• collected core samples from spawning sites
• - used N15 (SDN) and the abundances of diatom
  remains as indexes for measuring the abundance
  of salmon at a certain time
• SDN salmon derived nutrients

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Area of observation
Kodiak Island, Alaska 3 lakes Karluk Lake
(main lake), Afognak Lake, Frazer Lake
(controlled)
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Figure 1 N15 isotope () and diatom abundance
() through 2,200 years in Karluk Lake
Oligotrophic diatom domination
Mesotrophic diatom domination
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• Results from Figure 1
• - 100BC Decline in N15 isotopes (abundance of
  salmon)
• Decline in mesotrophic diatom taxa
• Increase in oligotrophic diatom taxa
  (Cyclotella Comensis, Cyclotella
  ocellata)
• (oligotrophic taxa dominant)
• (suggest ? colder climate)
• - 250 AD Increase in N15 isotopes
• Increase in mesotrophic diatom taxa
• Decrease in oligotrophic diatom taxa
• - 1200 -1900 High percentage of N15
• (suggest high abundance in salmon)
• Mesotrophic diatom taxa dominants
• (suggest ? warmer climate)

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Figure 2 Sockeye salmon from Kodiak Island
compare to other fish species along the pacific
coast through 2,200 years.
Data collected from the coast of California
Data from the coast of southern British Columbia
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• Results from Figure 2
• - Karluk Lake Sockeye salmon show a negative
  correlation with the other fish species to the
  south.
• - Salmon shows weak abundance before 1200 AD,
  while the other fish species to the south show
  strong abundance
• - After 1200 AD, their characteristic reversed
• - This study suggest there might be a shift in
  ocean-atmospheric circulation that moved north
  to favor the salmon population of Karluk Lake.

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Study also observed that cultural change can also
affect salmon abundance

• At each transition between archaeological
  phases, there is a dramatic change in salmon
  abundance.
• Early to Late Kachernak
• It is known that there were huge cultural
  change at this period, this study suggests this
  cultural change could have involve the
  population of salmon.
• Kachernak to Koniag
• Evidence of a shift towards greater abundance
  of fishing tools

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Study 2 Biocomplexity and fisheries
sustainabilityHilborn, R., Quinn, T. P.,
Schindler, D. E., Rogers, D. E. (2003)
Proceedings of the National Academy of Sciences
of the United States of America, 100, 6564-6568.

• Purpose provide evidence that biocomplexity also
  affects the stability and sustainability of the
  Pacific salmon stock
• Species used Pacific Sockeye in Bristol Bay,
  Alaska

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• Sites of study Three fishing sites at Bristol
  Bay
• Nushagak, Naknek-Kvichak, Egegik

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Table of biocomplexity of sockeye salmon
determined in Bristol Bay
Using two case studies to present how climate
variation affect the biocomplexity of salmon,
thus changing the salmon abundance through time
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Case 1 climate variation and flow rate -
determine how Pacific Decadel Oscillation (PDO)
correlated with salmon abundance

• Method Comparing stream flow (index) to PDO
  through the past decade
• Result high flow is positively correlated with
  PDO anomaly
• High flow high sockeye productivity
• - increase access to nursery for larger fish
• - reduced migration time to the ocean
• - reduced vulnerability for juveniles to
  encounter freshwater predators

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Case 2 Climate variation and Pattern of
productivity - to determine changes in abundance
within different sites
Method Using past catch data from the three
fishing site to reconstruct past salmon abundance
from 1890-2000
Results - Before 1977, the sockeye production
was ranked as followed Naknek- Kviehak,
Nushagak, Egegik - After the regime shift of PDO
in 1977, Egegik increased dramatically

• Nushagak remained small.
• In 1990, Egegik stock diminished, Naknek-kviehak
  crashed but Nushagak increased to the present
  most important fishery in Bristol Bay
• Concludes At different times, different
  biocomplexity variations will favor one site over
  the others

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Recap of Study 1 and 2

• Study 1
• - using N15 in core sample to determine climate
  change is correlated with salmon abundance in
  the past
• - It presented a long term population dynamics
  of salmon at one site
• Study 2
• - Using past flow rate and PDO change to suggest
  that climate change is correlated with salmon
  abundance
• - Using catch to determine that different sites
  will have different opportunities to become
  productive at certain biocomplexity that favors
  the site
• - This study presented a short term population
  dynamics of salmon at multiple sites.
• Both studies stress that climate variation
  influences the past dynamics of salmon, therefore
  understanding the climate and the population
  dynamics link can lead to a better sustainability
  for the salmon stock.

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Problems with the population dynamics for the two
studies

• The indexes are not accurate
• - CPUE
• - CPUE catch / effort (where catch harvest
  ratebiomass)
• - Data collected from fishermen
• - N15 isotopes
• - Climate change, created variations in
  spawning locations along the river
• - Therefore, hard to estimate a consistent
  nursery site

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Present day population dynamics of salmon

• Human interactions has the greatest affect on the
  present age abundance of salmon.
• Abundance of stock is now depended on the
  management of the stock by each country
• - Alaska (Record high abundance of salmon)
• - Scandinavian (Growing abundance)
• - British Columbia (declining population)
• - Ireland (declining population)

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Future directions for sustaining salmon stock

• Well planned and strict management policies
  implemented for ALL salmon nurseries.
• Fixed escapement policy or fixed harvest rate
  policy
• Use more recent and more accurate methods to
  collect the population dynamics of salmon
• Visual juvenile counting
• Mark-Recapture method, most recent DNA tagging

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Reference

• Key reference
• Finney B.P., Gregory-Eaves I., Douglas M.S.V.
  Smol J.P. (2002) Fisheries productivity in the
  northeastern Pacific Ocean over the past 2,200
  years. Nature, 416, 729-733.
• Hilborn, R., Quinn, T. P., Schindler, D. E.,
  Rogers, D. E. (2003) Biocomplexity and fisheries
  sustainability. Proceedings of the National
  Academy of Sciences of the United States of
  America, 100, 6564-6568.
• Other reference
• Gregory-Eaves I., Finney B., Douglas M.S.V., Smol
  J.P. (2004) Inferring sockeye salmon
  (Oncorhynchus nerka) population dynamics and
  water quality changes in a stained nursery lake
  over the past 500 years. Canadian Journal of
  Fisheries Aquatic Sciences, 61(7), 235-1246.
• Schindler D., Leavitt P., Johnson S., Brock C.
  (2006) A 500-year context for the recent surge in
  sockeye salmon (Oncorhynchus nerka) abundance in
  the Alagnak River, Alaska. Canadian Journal of
  Fisheries Aquatic Sciences, 63 (7), 1439-1444.
• Boylan P., Adams C.E. (2006) The influence of
  broad scale climatic phenomena on long term
  trends in Atlantic salmon population size an
  example from the River Foyle, Ireland. Journal of
  Fish Biology, 68 (1), 276-283.
• Gregory-Eaves I., Smol J., Douglas M.S.V., Finney
  B.P. (2003) Diatoms and sockeye salmon
  (Oncorhynchus nerka) population dynamics
  Reconstruction of salmon-derived nutrients over
  the past 2,200 years in two lakes from Kodiak
  Island, Alaska. Journal of Paleolimnolgy, 30,
  35-53
• Camilla F., Yang D.Y., Hayden B. (2005) Ancient
  DNA investigation of prehistoric salmon resource
  utilization at Keatly Creek, British Columbia,
  Canada. Journal of Archaeological Science, 32(9),
  1378-1389