From 2000 to 2010 the FAO click here landings of sharks declined only slightly (by 2.3%) to 383,236 t. Assuming that both discards and IUU fishing declined by a similar fraction between 2000 and 2010, one would estimate total mortality in 2010 at 1,412,000 t,

or between 97 and 267 million sharks, depending on the chosen scenario of species composition and average weights. Using the above estimates, combined with independent figures, a total exploitation rate U (catches over biomass, in percent per year) for global shark populations was calculated ( Table 4). The global biomass of elasmobranchs before the era of modern fishing was estimated by Jennings et al. [18] as 86,260,000 t. Assuming that half of these elasmobranchs

are sharks, a biomass before fishing of 43,130,000 t of sharks was estimated. Conservatively assuming 50% depletion of sharks over the history of modern fishing, a contemporary biomass estimate of 21,565,000 t of sharks was derived. Total mortality was estimated to be 1,445,000 t in 2000 ( Fig. 2), Caspase activity which when divided by total biomass, yields an estimated exploitation rate of 6.7% per year ( Table 4). Using an alternative mortality estimate of 1,700,000 t, a figure that was independently derived from the fin trade [9], an annual exploitation rate of 7.9% was computed. Averaging across actual exploitation rates from published stock assessments and other sources given in Table 5, an independent estimate of 6.4% exploitation rate was derived. These three estimates are remarkably similar, considering that they were derived by entirely independent sources using different assumptions. Comparing actual exploitation rates (Table 5; Fig. 3A) to calculated rebound rates of shark populations in general (Fig. 3B), cAMP and individual shark populations for which exploitation rates were estimated in particular (Fig. 3C), it was found that exploitation rates (Fig. 3A, Median U=0.064) on average exceed the median rebound rates ( Fig. 3B, Median r=0.049) by about 30%, which is

unsustainable over the long term. Notably, the rebound rates for most species were significantly below the three independent estimates of exploitation rates derived in this paper ( Table 4). This suggests that the majority of shark populations will continue to decline under current fishing pressure ( Fig. 3C). The primary goal of this paper was to estimate total catch and fishing-related mortality for sharks worldwide, and to derive an average exploitation rate from these estimates (Table 4). Due to the limited availability of data, particularly for shark discards, this work required a number of assumptions, as detailed above. Yet it allows placement of lower and upper limits on global shark mortality, here estimated to range from 63 to 273 million sharks, with a conservative estimate of ∼100 million sharks in the year 2000, or ∼97 million in 2010.