Biological Indicators of Climate Change

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Biological Indicators of Climate Change
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Keying Historical Fish Landing Data (S-15, for
continuation)

• Alec D. MacCall and Don Pearson
• NMFS/Southwest Fisheries Science Center
• Meisha Key
• California Department of Fish and Game

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Albacore and Climate 1

• Calif. albacore landings are related to the PDO

• CDMP data (light green) double the length of
  the time series, confirming regime-like behavior
  and earlier consistency
• CDMP data also provide more detail, including
  locations

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Albacore and Climate 2

• During 1930-1970, mean latitude of albacore catch
  locations off California varied inversely with
  PDO

• After 1970, the fishery moved progressively
  offshore (coastal latitude means less) and
  location data were also discontinued in landings
  data

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Some Surprises

• Example Octopus have an episodic pattern of
  landings
• Unrelated to any currently known oceanic
  condition or pattern
• Presumably a biological indicator of an unusual
  condition

• Recent peaks confirmed by observations of
  juveniles in trawl surveys
• Nobody seems to have noticed this before
• The longer time series allows these insights

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Catch Reconstructions 1

• There are over 60 species of rockfishes off
  California
• New species are still being discovered
• Published landings combined all of these into
  rockfish (not very useful)
• Original landings receipts (being captured by
  CDMP) showed various subgroups as well as fishing
  gear
• Species mixes in subgroups by fishing gear have
  been sampled since 1970s
• Knowledge of receipt subgroups has allowed
  reconstruction of approximate landings by
  individual species

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Catch Reconstruction 2

• Example Bocaccio was severely depleted by the
  1990s
• Rebuilding began in 2000, and is proceeding well
• What should the rebuilding target be?
• Assumed early catches (red) were too large before
  CDMP
• In 2007 relative abundance was 32 of target
• In 2009 (using new reconstruction) relative
  abundance was 70 of target
• Abundance is similar, but the difference is due
  to changing the target according to the effect of
  early catches
• CDMP-based reconstructions were used in seven
  stock assessments done in 2009
• CDMP data are being used!