Pro­tected reefs bring lit­tle re­lief for sharks

BBC Wildlife Magazine - - Wild News - FIND OUT MORE PNAS:­tent/ early/2018/06/12/1708001115

For­mal pro­tec­tion of the world’s co­ral reefs is not enough to sus­tain pop­u­la­tions of their largest in­hab­i­tants.

A new sur­vey re­veals that top preda­tors are miss­ing from all but the most pris­tine habi­tats. Bi­ol­o­gists have as­sessed al­most 1,800 co­ral reefs around the world. In­evitably, sharks and other large preda­tors such as snap­pers were al­most en­tirely ab­sent from reefs ex­posed to high lev­els of fish­ing and pol­lu­tion. More sur­pris­ing was that pro­tected reefs close to high lev­els of hu­man ac­tiv­ity were also largely preda­tor-free, even when fish­ing reg­u­la­tions are prop­erly en­forced.

Sci­en­tists sus­pect that such re­serves are too small to safe­guard large mo­bile an­i­mals, vul­ner­a­ble when they stray out of the pro­tected ar­eas. The mar­ket-value of sharks’ fins make them an at­trac­tive tar­get. More re­mote pro­tected reefs con­tained four times as many sharks.

“It is in pro­tected ar­eas lo­cated where hu­man pres­sures are gen­er­ally low that sharks are most com­monly found,” says Lan­caster Univer­sity’s Nick Gra­ham. “Clearly these re­mote pro­tected ar­eas are im­por­tant for shark con­ser­va­tion.” SB

For grey reef sharks, even pro­tected reefs can be chal­leng­ing.

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