Friday, August 17, 2007

Do marine reserves work?

Do Marine Life Conservation Areas work?

The answer, depending on what you mean by the question, appears to be yes, and no.

But the more appropriate response would appear to be, “Work at what?”

In the journal Ecological Applications in April, Oceanic Institute's Alan Friedlander, along with Eric Brown of the National Park Service at Kalaupapa and Mark Monaco of NOAA's National Centers for Coastal and Ocean Science, wrote of “Coupling ecology and GIS to evaluate efficacy of marine protected areas in Hawaii.”

It's a scary title, but a couple of bits of interesting information hide in there.

They studied the state's 11 Marine Life Conservation Areas.

One finding: There are indeed more and bigger fish generally inside than outside the areas. There are also more predatory fish inside. That's interesting in part because recent research has shown that unfished, intact marine ecosystems, like those in the Northwestern Hawaiian Islands and at Palmyra Atoll in the Line Islands, have dramatically higher percentages of predatory fishes than heavily fished areas like the main Hawaiian Islands.

Another finding: They also found that there's not a lot of spillover into the fished areas next to the conservation areas. They assume that could be because the conservation areas are really too small to have an appreciable impact on fish populations nearby.

“Overall fish biomass was 2.6 times greater in the MLCDs compared to open areas. In addition, apex predators and other species were more abundant and larger in the MLCDs, illustrating the effectiveness of these closures in conserving fish populations within their boundaries,” the authors wrote.

A further finding of interest: The bigger the preservation area, the more and bigger the fish seem to be. Here's how they phrased that:

“Although size of these protected areas was positively correlated with a number of fish assemblage characteristics, all appear too small to have any measurable influence on the adjacent fished areas. These protected areas were not designed for biodiversity conservation or fisheries enhancement yet still provide varying degrees of protection for fish populations within their boundaries.”

The message from this, perhaps, is that a marine preserve, regardless of size, will have benefits in terms of more wildlife. But if it's too small, don't expect it to enhance fishing success in neighboring areas.

There IS some evidence that marine preserves, if properly designed, can improve overall catch.

In Kona, a collection of reserves, designated fish replenishment areas, was established to protect aquarium fish from overcollecting.

Thirty-five percent of the West Hawai'i coastline was closed to marine fish aquarium collecting, in a series of nine closed areas running from North Kohala all the way down to Miloli'i.

After just a few years, the fish populations recovered. But importantly, the catches of aquarium fish in the neighboring areas improved, and it turned out that the overall aquarium fish catch from all of West Hawai'i increased.

© 2007 Jan W. TenBruggencate

1 comment:

Gil said...

Jan:
I haven't seen the report but did it address the waters around the Kahoolawe Island Reserve -- I recall, as a commissioner on KIRC, fishermen on the commission and others remarking that the areas outside the closed waters of the reserve anecdotally were a lot more healthy than in the past. . . .
Gil Keith-Agaran