Increases in the relative abundance of mid-trophic level fishes concurrent with declines in apex predators in the subtropical North Pacific, 1996–2006
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Date
2009
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Show full item recordAbstract
Catch rates for the 13 most abundant species caught in thedeep-set Hawaii-based longline fishery over the past decade (1996–2006) provide evidence of a change among the top North Pacific subtropical predators. Catch rates for apex predators such as blue shark (Prionace glauca), bigeye (Thunnus obesus) and albacore (Thunnus alalunga) tunas,shortbill spearfish (Tetrapturus angustirostris), and striped marlin (Tetrapturus audax) declined by 3% to 9% per year and catch rates for four midtrophic species, mahimahi(Coryphaena hippurus), sickle pomfret (Taractichthys steindachneri), escolar (Lepidocybium flavobrunneum), andsnake mackerel (Gempylus serpens), increased by 6% to 18% per year. The mean trophic level of the catch for these 13 species declined 5%, from 3.85 to 3.66. A shift in the ecosystem to an increase in midtrophic-level, fast-growing and short-lived species is indicated by the decline in apexpredators in the catch (from 70% to 40%) and the increase in species with production to biomass values of 1.0 orlarger in the catch (from 20% to 40%). This altered ecosystem may exhibit more temporal variation in responseto climate variability.Journal
Fishery BulletinVolume
107Issue/Article Nr
4Page Range
523-531Resource/Dataset Location
http://fishbull.noaa.gov/1074/polovina.pdfCollections