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31.
Julie B Kellner Irene Tetreault Steven D Gaines Roger M Nisbet 《Ecological applications》2007,17(4):1039-1054
Throughout the world "fishing the line" is a frequent harvesting tactic in communities where no-take marine reserves are designated. This practice of concentrating fishing effort at the boundary of a marine reserve is predicated upon the principle of spillover, the net export of stock from the marine reserve to the surrounding unprotected waters. We explore the consequences and optimality of fishing the line using a spatially explicit theoretical model. We show that fishing the line: (1) is part of the optimal effort distribution near no-take marine reserves with mobile species regardless of the cooperation level among harvesters; (2) has a significant impact on the spatial patterns of catch per unit effort (CPUE) and fish density both within and outside of the reserve; and (3) can enhance total population size and catch simultaneously under a limited set of conditions for overexploited populations. Additionally, we explore the consequences of basing the spatial distribution of fishing effort for a multispecies fishery upon the optimality of the most mobile species that exhibits the greatest spillover. Our results show that the intensity of effort allocated to fishing the line should instead be based upon more intermediate rates of mobility within the targeted community. We conclude with a comparison between model predictions and empirical findings from a density gradient study of two important game fish in the vicinity of a no-take marine-life refuge on Santa Catalina Island, California (USA). These results reveal the need for empirical studies to account for harvester behavior and suggest that the implications of spatial discontinuities such as fishing the line should be incorporated into marine-reserve design. 相似文献
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Burger J Murray S Gaines KF Novak JM Punshon T Dixon C Gochfeld M 《Environmental monitoring and assessment》2006,112(1-3):35-52
Levels of 18 elements, including lead, mercury, selenium, and uranium, were examined in three species of snakes from an exposed
and reference site on the Department of Energy's Savannah River Site in South Carolina. We tested the hypotheses that there
were no differences as a function of species, and there were no difference between the exposed and control site for blood
and muscle (tail) samples for banded water snake (Nerodia fasciata), brown water snake (N. taxispilota) and cottonmouth (Akistrodon piscivorous). The banded water snakes collected were significantly smaller than the other two species. For blood, there were significant
species differences only for barium, copper, selenium, uranium and zinc, while for muscle tissue there were significant interspecific
differences in aluminum, arsenic, barium, cobalt, cesium, copper, iron, lead, mercury, manganese, strontium, vanadium and
zinc, suggesting that muscle tissue in the tail is a better indicator of potential interspecific differences. It is also easier
logistically to collect tail tissue than blood. Where one species had significantly higher levels than the other species in
muscle tissue levels, cottonmouth had higherlevels of five elements (aluminum, cobalt, lead, mercury, vanadium), brown water
snake had two (lead, strontium), and banded water snake had only barium. There were few significant differences between the
control and reference site for levels of blood, but several for muscle tissue. All three species had significantly higher
levels of arsenic and manganese at Tim's Branch than the reference site, and nickel and uranium were significantly higher
for banded watersnake and cottonmouth, the larger species. Individuals with high exposure of one element were exposed to high
levels of other elements. 相似文献
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