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Too many hatchery fish in the Ocean?
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Author Topic: Too many hatchery fish in the Ocean?  (Read 2307 times)
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« on: January 29, 2014, 05:48:50 PM »

I believe I posted this before, but since we are in the heated debate about the future of hatchery production here in Oregon, it deserves another play:

"Abstract.—–Abundance estimates of wild and hatchery Pacific salmon Oncorhynchus spp. are important
for evaluation of stock status and density-dependent interactions at sea. We assembled available salmon catch
and spawning abundance data for both Asia and North America and reconstructed total abundances of pink
salmon O. gorbuscha, chum salmon O. keta, and sockeye salmon O. nerka during 1952–2005. Abundance
trends were evaluated with respect to species, regional stock groups, and climatic regimes. Wild adult pink
salmon were the most numerous salmon species (average¼2683106 fish/year, or 70% of the total abundance
of the three species), followed by sockeye salmon (633106 fish/year, or 17%) and chum salmon (483106
fish/year, or 13%). After the 1976–1977 ocean regime shift, abundances of wild pink salmon and sockeye
salmon increased by more than 65% on average, whereas abundance of wild chum salmon was lower in recent
decades. Although wild salmon abundances in most regions of North America increased in the late 1970s,
abundances in Asia typically did not increase until the 1990s. Annual releases of juvenile salmon from
hatcheries increased rapidly during the 1970s and 1980s and reached approximately 4.53109 juveniles/year
during the 1990s and early 2000s. During 1990–2005, annual production of hatchery-origin adult salmon
averaged 783106 chum salmon, 543106 pink salmon, and 3.23106 sockeye salmon, or approximately 62,
13, and 4%, respectively, of the combined total wild and hatchery salmon abundance. The combined
abundance of adult wild and hatchery salmon during 1990–2005 averaged 6343106 salmon/year (4983106
wild salmon/year), or approximately twice as many as during 1952–1975. The large and increasing
abundances of hatchery salmon have important management implications in terms of density-dependent
processes and conservation of wild salmon populations; management agencies should improve estimates of
hatchery salmon abundance in harvests and on the spawning grounds."



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