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首页> 美国政府科技报告 >Estimates of Abundance of Northeastern Offshore Spotted, Coastal Spotted, and Eastern Spinner Dolphins in the Eastern Tropical Pacific Ocean
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Estimates of Abundance of Northeastern Offshore Spotted, Coastal Spotted, and Eastern Spinner Dolphins in the Eastern Tropical Pacific Ocean

机译：东热带太平洋东北近海斑点，沿海斑点和东部旋转海豚的丰度估计

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Stratified large-scale line-transect surveys were carried out with oceanographic research vessels in the eastern tropical Pacific Ocean in 12 different years between 1979 and 2000. The surveys were designed to estimate the abundance of northeastern offshore spotted (Stenella attenuata) and eastern spinner (S. longirostris orientalis) dolphins, which are affected by the purse-seine tuna fishery for yellowfin tuna (Thunnus albacares). In the most recent surveys in 1998-2000, estimates of the coastal subspecies of spotted dolphins (S. attenuata graffmani) were also possible. Searching was carried out primarily with pedestal-mounted 25x150 binoculars fitted with azimuth rings and reticles for angle and distance measurements. Aerial photography was used to measure dolphin school sizes when possible, and to improve observers estimates of school size when not. Estimates of dolphin abundance for each stock were based on modified line-transect methods, using covariates to model the detection process and group size. Variances and confidence intervals were estimated by bootstrap. For the 21-year period, the low and high total estimates of abundance (in numbers of animals) were: 494,268 to 953,547 for northeastern offshore spotted dolphins, 271,322 to 741,867 for eastern spinner dolphins, and 96,738 to 228,038 for coastal spotted dolphins. Weighted linear and quadratic regressions of abundance against time were not statistically significant for either northeastern offshore spotted or eastern spinner dolphins.

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