Global Survey Confirms Threat To Sharks – But Proves Conservation Can Work
A detailed survey of shark populations reveals that on nearly 20 per cent of coral reefs they have been wiped out. However, the study also shows that basic conservation steps can successfully protect reef sharks.
The survey published in Nature this week used data from more than 15,000 underwater video stations set up on 371 reefs in 58 different countries.
It confirms that the ruthless global overfishing of sharks has caused widespread collapses in shark populations threatening the survival of coral reefs themselves.
The footage gathered over more than four years found that sharks were 'functionally extinct' on almost one in five of the reefs studied. The worst-hit countries were the Dominican Republic, the French West Indies, Kenya, Vietnam and Qatar. In Qatar only three sharks were seen during 800 hours of filming.
Some 34 out of 58 nations had shark numbers that were half what was expected, 'suggesting that loss of reef sharks is pervasive among reefs globally', the study said.
However, the story was very different in countries such as The Bahamas, Micronesia, the Maldives and French Polynesia were the banning of fishing practises such as long-lines and gillnets has allowed strong local population to thrive.
Dr Mark Meekan, from Global FinPrint which carried out the study, said: 'Stopping destructive fishing practices and getting some good governance into these fisheries could change the situation almost overnight. These are very doable things.'
The report highlighted that shark depletion is strongly related to socio-economic conditions such as the density of local human populations and poverty.
The footage recorded 59 different shark species - the vast majority of which were resident on the reefs. It indicates that there has been widespread damage to populations of migratory, pelagic sharks such as blue sharks and oceanic whitetip sharks.
There are areas of the world which are faring better, such as the Central Pacific where shark populations were 40 per cent higher than other regions. This is partly caused by the distance from key markets for shark fins as well as local protection.
One disturbing trend the study showed is that where shark finning for primarily the Chinese market has become established there is a significant local growth in the consumption of shark meat. The authors argue that this indicates the need for effective local interventions to reduce the consumption in such areas.
It also showed that shark sanctuaries plus a ban on the trade in shark products, on average, means more than a 50 per cent higher abundance of sharks – 68 per cent in one case.
The Bahamas, the Solomon Islands, Micronesia and French Polynesia were shown to be significantly better than regional expectations would suggest.
The report said: 'These nations had many of the key attributes that we found to be associated with increased abundances of reef sharks, including being well-governed and/or remote, and having strong, directed management of shark fisheries or shark sanctuaries. By contrast, the worst-ranked nations for reef sharks included Qatar, the Dominican Republic, continental Colombia, Sri Lanka and Guam, which have suffered from varying levels of poor governanceand extreme overfishing.'
The analysis also suggests which countries would benefit most from introducing some shark protect and management. The nations with the highest conservation potential were listed as Madagascar, Mayotte, Vanuatu, USA-Pacific (Hawaii), the British West Indies and Barbados.
The lead author of the study, Dr Aaron MacNeil of Dalhousie University in Canada, said: 'From restricting certain [fishing] gear types and setting catch limits, to national-scale bans on catches and trade, we now have a clear picture of what can be done to limit catches of reef sharks throughout the tropics.'
The study also looked at the potential importance shark conservation can have for economies. For example in Palau, a country with a strong diving sector, as much as nine per cent of its GDP was generated by shark-related tourism.