Is a Global Quantitative Assessment of Shark Populations Warranted?

A recent global quantitative assessment suggested that the majority of shark populations will continue to decline under current fishing pressure (Worm et al. 2013:198) and concluded that global shark mortality needs to be drastically reduced to rebuild populations and restore marine ecosystems with functional top predators. The high exploitation rates inferred by the authors are alarming and, if accurate, justify the increased concern of the global conservation community. To assess the generality and accuracy of this work, I critically evaluate the assumptions and validity of the extrapolations made by the authors. This global study provided a valuable overall perspective on the highly relevant topic of shark conservation; however, the generalizations made carry substantial uncertainty that was not accounted for. My review aims to place the conclusions drawn by the authors into perspective, highlighting numerous factors that, having been considered, would have significantly affected their claims.