Bycatch and bycatch mitigation

Abstract

In the 20 years since the IUCN Species Survival Commission (SSC) Shark Specialist Group’s (SSG) first status report (Sharks, rays and chimaeras: the status of the chondrichthyan fishes), much has changed for sharks, rays and chimaeras. This report updates our understanding, and the scope of information in its 2,000-odd pages reflects the scale of these two decades of change. The breadth of research topics has expanded, mirroring the inclusion of a greater diversity of species, and attention is being trained on the emerging threats and the accelerating global changes to aquatic ecosystems. The diversity of researchers who contribute to science and conservation within the SSG network and beyond, and of the regions they investigate and endeavour to conserve, has grown exponentially: 353 contributors have compiled information for 10 (arbitrary) geopolitical regions, delving into information from 158 countries or jurisdictions with a coastline. The 2005 report heralded a sea change for sharks, rays and chimaeras, whose historical obscurity in policy, conservation and fisheries management was a serious concern as the pace of their declines threatened to outstrip our information for and attention to them. In this report, the increased focus that was called for is now apparent in the scale of work happening across the planet.Our understanding of the diversity of sharks, rays and chimaeras has revolutionised over the course of the past two decades. Of the 1,266 species that have been described to date, about a quarter (>340) have been described since 2001. Accessibility to remote areas of the world, especially across Africa, has unlocked new information about the scale of exploitation and the dependence on shark, ray and chimaera fisheries for food security. These insights provide a new outlook on what conservation should look like and what management solutions might be acceptable to local communities that depend on these species for their livelihoods.Innovative research methods are providing us with opportunities to explore the species’ ecology and behaviour like never before. For example, genetic tools are unlocking new possibilities in fisheries and trade management by tracing evolutionary pathways and sequencing whole genomes (11 annotated genomes of sharks, rays and chimaeras have been published to date). This report also reflects our shift in understanding of the ecological role that these species play in aquatic ecosystems and highlights the research imperative as climate change begins to move animals out of their known distributional ranges. Access to the oceans and the diversity of habitats and oceanographic conditions in which sharks, rays and chimaeras live has improved as the concurrent diversification in technological tools grants us the ability to investigate them more critically in their diverse forms and ecological roles.