Sharks and rays are among the most endangered group of marine animals and include many species for which there is little information on abundance and distribution. There are no global abundance trends for elasmobranchs as a group, and very few robust regional trend indicators. Population-level stock assessments, which provide the most reliable index of abundance, are available for only about 10 per cent of 1,088 chondrichthyan species (FAO 2012; Worm et al., 2013; Dulvy et al., 2014; Cortes et al. 2012). Almost all of these assessments report a depleted and/or over-exploited population. In light of the scarcity of time series of absolute abundance indicators, the conservation status of elasmobranchs as a group is most commonly based on trends in reported landings, trajectories of standardized catch rates or indices of current status.

Global catches and trends

Global landings of sharks, rays and chimaeras (chondrichthyans) as reported to the Food and Agriculture Organization of the United Nations (FAO) have increased steadily since the 1950s, peaking at about 888,000 mt in 2000 before declining (Figure 40.1). In 2012, landings were 14 per cent lower than in 2000. The increasing trend in global catches reflected a combination of fisheries expansions into previously-unexploited regions, changes in the species composition of catches, and changes in the way countries reported landed catch for sharks and rays (e.g. changes in the taxonomic resolution of the reported landings; Ferretti et al. 2010). Historically, many species of sharks and rays had low commercial value, and were not regularly recorded in fisheries statistics. Since the 1980s, sharks became an alternative resource for some fisheries as many fish stocks collapsed and demand for shark fins in Asian markets strongly increased. The resulting increased fishing pressure on elasmobranchs and reports of severely depleted populations attracted the attention of management agencies, which increasingly reported shark statistics.

Although it has been assumed that the recent decline in reported landings may reflect better management for the species (FAO 2010), a recent analysis of the FAO chondrichthyan landings disaggregated by countries (Davidson et al. 2015) evaluated the importance of direct and indirect indices of fishing exploitation and measures of fisheries management performance, revealing that the decline is more closely related to fishing pressure and population declines (Eriksson and Clarke 2015, Davidson et al. 2015).