April 29, 2014

Newsletter: 
April 2014

One quarter of the world's sharks and rays face extinction in the next few decades, according to the first global study to systematically assess their status and conservation.

The study was conducted by the International Union for Conservation of Nature (IUCN) Shark Specialist Group (SSG) which envisages a world in which sharks, rays, skates and chimaeras are valued and managed for sustainability. Australian members of the IUCN group include NERP Marine Biodiversity Hub scientists William White, Richard Pillans and Ross Daley of CSIRO, and Peter Kyne of Charles Darwin University. William is the co-chair of taxonomy, and Peter is the regional vice-chair for Australia and Oceania.

Group members conduct IUCN Red List assessments, develop science-based advice for conservation strategies and policies, identify research needs, and communicate to a range of audiences. In keeping with this approach, the study seeks to guide effective responses to the issue of shark declines.

 ‘As a group we have been working on the extinction risk paper for 12 years,’ Peter says. ‘It was an ambitious task to assess all known shark and ray species (although more have since been described).’

The task was achieved by means of 13 workshops held worldwide, the first of which Peter organised in Queensland in 2003. He subsequently organised the batoid (ray) workshop in Cape Town and the North and Central American workshop in Florida.

‘Between us we have authored or co-authored more than 100 Red List assessments for sharks and rays, equating to about 10 percent of all assessments, Peter says. ‘That’s a significant contribution, considering there were 300 assessors in total, from 64 countries.’

The study estimated extinction risk across 1,041 species of sharks and rays. Information about better-understood species was used to derive general patterns associated with higher extinction risk, and predict the likely status of lesser-known species. Larger species, and those that swim in shallower waters, had the largest risk.

Improving local knowledge

A key challenge for the future of sharks and rays lies in developing species assessments with better population estimates that can then be linked with effective management practices. This is an important area of Marine Hub research.

Novel genetic and electronic tagging techniques and protocols are being developed to assess and monitor shark populations in Australia, and to help assess the effectiveness of management measures. Are populations stable, declining or increasing? 

The key species being studied are largetooth sawfish, speartooth sharks and northern river sharks in the Top End, and white sharks in eastern and western Australian waters.

Seascape approaches to conservation

Another Marine Hub project is looking at a landscape (or seascape) approach to managing sharks and rays by identifying areas where specific management actions would benefit many species.

Maps of important areas shared by such species will be overlaid with pressures (such as fishing effort) and spatial protection measures (such as fisheries closures and marine reserves), to identify areas important to key life history stages for multiple species that are vulnerable to human impacts.

Mapping tools are being developed that will help identify the costs and benefits of alternative uses of the seascape at scales of about 100 km.

Together, these approaches will assist Australia in protecting this part of its unique biodiversity; one-third of all shark and ray species call Australia home, and many do not occur elsewhere. In particular, these approaches are designed to reduce the risk that additional shark and ray species are listed as threatened; they will improve the effectiveness of threatened species recovery planning for listed species through better monitoring; and will increase the value of scientific results to decision makers by looking at this vulnerable group in a co-ordinated approach.

 

Further reading

 

Image

Scalloped Hammerhead Shark, Dubai market.  Image: William White, CSIRO

 

Contact

Peter Kyne, Charles Darwin University
William White, CSIRO