Dr Alex Rogers: How we can save the tigers of the sea

The great predators – bluefin tuna, sharks and billfish – have vanished from our oceans with significant impacts on ecosystems. We are hardly aware that these lions and tigers of the seas are rapidly ending up on the lists of species threatened with extinction.

Yet this has all happened despite international laws, under the UN Convention on the Law of the Sea, aimed at making the world's fisheries sustainable and friendly to marine ecosystems with the intention of providing food for generations to come. What has gone wrong? The institutions set up to manage fisheries have, in many cases, failed. Despite every sign that bluefin in the Med were in serious trouble, the International Commission for the Conservation of Atlantic Tunas set catch levels way above the scientific recommendations.

Even under its current "recovery plan", scientists estimate that next year, bluefin may be fished to a point where reproduction is seriously compromised and they will become critically endangered. It is ironic that the only answer to this is to use the Convention on International Trade in Endangered Species.

What needs to be done? We must reduce the global fishing fleet and remove harmful subsidies that encourage overfishing, strengthen the international legal framework governing fisheries, and consider a network of protected areas.

Coming from a line of fisherfolk, I am deeply saddened by the unrestrained exploitation of the oceans. But with this latest news, I am still hopeful my young daughters will be able to see the great predators of the oceans in their natural environment when they get to my age, and marvel at the tremendous diversity and vitality of a healthy ocean. It belongs to all of us and it is in our interest to look after it.

Dr Alex Rogers is a Reader at the Institute of Zoology, Zoological Society of London, and Scientific Director of the International Programme on the State of the Ocean