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海洋资源—动植物微生物矿产加工养殖与生物经济

Defining and estimating global marine fisheries bycatch Unselective fishing catches non-target organisms as ‘bycatch’—an issue of critical ocean conservation and resource management concern. However, the situation is confused because perceptions of target and non-target catch vary widely, impeding efforts to estimate bycatch globally. To remedy this, the term needs to be redefined as a consistent definition that establishes what should be considered bycatch. A new definition is put forward as: ‘bycatch is catch that is either unused or unmanaged’. Applying this definition to global marine fisheries data conservatively indicates that bycatch represents 40.4 percent of global marine catches, exposing systemic gaps in fisheries policy and management. surplus production model with latent truncation and species targeting, with an application to Papua New Guinean fisheries 海洋鱼类品种跟踪与深加工 This paper first reviews traditional bio-economic models of catch–effort equilibrium and later contributions based on augmented and revised specifications. To overcome some of the pitfalls in fisheries analysis, an approach is formulated which accounts for latent truncation in the fishing fleet, species targeting and non-linear long-term relationships among catch, effort and biomass. The procedure is applied to purse seine and longline offshore marine fisheries in Papua New Guinea, where tuna and other fish resources are believed to be under-exploited on the whole, but selective overfishing is reported to take place. Statistical evidence of incidental truncation is weak, with results being sensitive to the selection of variables. Based on regression diagnostics and expected signs/statistical significance of parameter estimates, non-linear surplus production specifications prove to be more suited than original and unrestricted versions of the conventional approach for modelling the dominant (purse seine) fishery in PNG over the period 1979–2007, with both main and secondary target fishing being found not to exceed the maximum sustainable yield. In either case, policy implications of these results should be pondered against underreporting of official fish catches. The importance of oceanographic fronts to marine birds and mammals of the southern oceans 海鸟的作用与意义 During the last 30 years, at-sea studies of seabirds and marine mammals in the oceans south of the Subtropical Front have described an association with major frontal areas. More recently, the advancement in microtechnology



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