An appetite for parrotfish is putting the future of the world’s coral reefs in jeopardy, according to a paper published this week in Nature. Lead author Peter Mumby from the University of Exeter warns in this paper that mass die off of the seaweed munching sea urchin urchin Diadema antillarum in 1983 has left parrotfish doing the majority of grazing on reefs. But the parrotfish are under threat. This means reefs that are taken over by seaweed are unlikely to be able to recover, according to his computer modelling of reef ecosystems (coverage in Reuters, BBC, and Conservation Magazine – with the headline Parrots of the Caribbean) .

“The good news is that we can take practical steps to protect parrotfish and help reef regeneration,” he says (press release 1). “We recommend a change in policy to establish controls over the use of fish traps, which parrotfish are particularly vulnerable to. We also call on anyone who visits the Caribbean and sees parrotfish on a restaurant menu to voice their concern to the management.”

Parrotfish are something of a delicacy in the region, which complicates conservation. I can heartily agree with Mumby’s stance and add another reason not to eat them – they really don’t taste very good at all.

Fellow researcher Alan Hastings, a UC Davis theoretical ecologist, explains that the paper examines the process of hysteresis, where an effect lags behind its cause (press release 2). “In this case, the loss of sea urchins sent the reef off the road, and now the only guardrail is the parrotfish. Our model showed that if we overfish parrotfish, and the reef goes off the cliff, we would need four times the fish we have now to bring the reef back.”

There’s a mass of parrot fish video on the BBC.

Image: Florida Keys National Marine Sanctuary