Marine Reserves Net Sustainable Fish Catch

Setting aside areas of coastal waters where fishing is prohibited--creating "no-take" marine reserves--can help preserve biodiversity and at the same time produce a sustainable harvest for fishers, say Alan Hastings and Louis Botsford, faculty members in the Center for Population Biology.

In a paper published in the May 28, 1999, issue of the journal Science, authors Hastings and Botsford use simple mathematical models to show that the yield from coastal waters incorporating "no-take" zones would equal the harvest fishers get under current practice, which allows the industry to take a fixed percentage of the available fishery stock.

Fearing reduced harvests, fishing industry groups have been wary of proposed marine reserves as a remedy for overfishing and as a way to preserve marine biodiversity, according to Botsford and Hastings.

But the scientists say that reserves can work as well as traditional fisheries management, particularly for populations composed of sedentary adults and widely dispersed larvae--for example, sea urchins, Dungeness crab, and lobsters--that might not have a chance to reproduce otherwise.

If an equal harvest can be collected under the reserve system, this plan could counter industry pressure to increase the allowable catch and thus avert more rapid depletion of the fish population. No-take zones would also be easier to monitor and enforce than quota and size limits. In addition, fisheries management through reserves would eliminate the need to assess stock constantly.

Citing examples in Chile and South Africa, Hastings and Botsford say that at present few no-take marine reserves exist.

In California, nine no-take marine reserves exist, comprising 7,000 acres, just 0.2 percent of the state's waters.

"There's been an inertia to this idea. People thought there would be less efficient management with reserves. But this way, you just divide up the coast, with fishing allowed here, but not there," Botsford says.

"With the reserves, there's less uncertainty in predictions of what you can catch," Hastings adds.

The research was supported by a National Science Foundation grant, and conducted at the National Center for Ecological Analysis and Synthesis at UC Santa Barbara.

Reference: Hastings A and LW Botsford. 1999. Science 284: 1537-1538.