The current biomass of the Pacific bluefin "is near historically low levels and experiencing high exploitation rates above all biological reference points commonly used by fisheries managers," they write.
Sharks are one of the most threatened groups of marine animals, as high exploitation rates coupled with low resilience to fishing pressure have resulted in population declines worldwide.
Intensive removals are probably only feasible at relatively small spatial scales where very high exploitation rates (i.e., >50%) can be obtained [14].
High exploitation rates coupled with a slow life history and low resilience to fishing mortality have resulted in population declines, particularly of large sharks, worldwide [e.g. 10] [17] and pose a serious threat for the survival of many species.
Under these conditions, the stock did not go extinct even at the highest exploitation rates (Fig. 5).
Furthermore, although radio-telemetry studies have suggested high exploitation rates for the Teno salmon fisheries in general (up to 60 70%; Erkinaro et al. 1999; Karppinen et al. 2004), practically nothing is known about the relative population-specific harvest rates.
For example, expected lifetime egg production estimated from a growth model for North Sea cod indicated strong selection favouring early maturity at high exploitation rates but little selection for age at maturation in the absence of fishing (Rowell 1993).
In southern Lake Michigan specifically, high exploitation rates significantly truncated age and size structures, skewed the sex ratio toward males, and caused a stock collapse in the mid-1990s (Wilbetg et al. 2005; Lauer et al. 2008).
On a large-scale, the creation of a fishery with a high exploitation rate may produce sustainable and measurable results, but the infrastructure and demand for such a fishery does not currently exist.
