Summary of conversation with Rich Brenner

  1. Five current salmon hatcheries in operation in Prince William Sound (PWS)
  2. Approximately 650 million pink salmon released each year. Combined with chum salmon and sockeye salmon nearly 3/4 billion total releases
  3. What is a stray? A fish that is found dead (of natural causes) on the spawning grounds of a wild population
  4. Straying concerns: 1) introgression (sharing of genes among populations), competition (limited spawning area, egg retention), management (confounds escapement estimates)
  5. SEC.01, Chapter 111, SLA, 1974 “the hatchery program shall be operated without adversely affecting natural stocks of fish”
  6. Pink salmon straying studies initiate in 1991 in response to oil-spill responses, pike up in 1997-1999, 2008-2010, 2013-on-going
  7. Strays assessed by thermal marking of otoliths. 100% of PWS released fish are marked
  8. Initial straying studies suggested wide spread high straying rates (high proportions of hatchery fish on the spawning grounds)
  9. Stray rates decline quickly with increasing distance from release hatchery, and declines with increasing population size (small populations have high proportions of strays)
  10. For chum salmon, the proportion of strays declined throughout the spawning season while pink salmon strays increased (likely reflects brood stock life history. Chum are early returning stocks, and pinks are late returning stocks)
  11. Limited data for sockeye salmon, but straying proportions could be high for some sample locations
  12. Remaining conundrum…to reduce amount of straying, managers might aim to catch as many hatchery-produced fish as possible (given that they can sustain a high exploitation rate), however, by doing so wild fish that co-mingle with hatchery fish can be caught incidentally and over exploited.

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