Can shark resources be harvested sustainably? A question revisited with a review of shark fisheries

Abstract

Sharks and other chondrichthyans are often described as long lived, slow growing and producing few offspring. These biological characteristics, together with the common assumption that recruitment is directly related to stock, and pessimistic stock prognoses obtained from application of demographic analysis, have led to doubts that sharks can be harvested sustainably. Developed over the past 40 or so years from studies of only a few shark species, these doubts have been reinforced by declining catch rates in industrial, artisanal and recreational fisheries and in fishing programmes designed to reduce the risk of sharks attacking humans at bathing beaches. However, more recent studies and application of modelling techniques allowing for density-dependent responses to the effects of stock reduction indicate that shark stocks can be harvested sustainably and, if carefully managed, can provide very stable fisheries. It is now understood that some species (such as Galeorhinus galeus, Carcharhinus plumbeus, Carcharodon carcharias and several species of dogfish) have low productivity, whereas other species (such as Mustelus antarcticus, Rhizoprionodon terraenovae, Sphyrna tiburo and Prionace glauca) have higher productivity. This paper reviews the use of shark products, the effects of fishing on shark populations of the world, and recent developments in assessment of shark fishery stocks.