Hawaii MPAs Work

In the wake of recent news from Southern California's Channel Islands that marine protected areas there have resulted in bigger and more abundant fish, I've just received similar (and not altogether surprising) news from Hawaii of MPA successes there.

You may recall that I've written extensively here and there on the complex free-for-all situation that exists in Hawaii with regard to commercial harvesting of reef fish for the aquarium trade. As I've previously described, the State of Hawaii Division of Aquatic Resources have attempted to better manage heavily targeted ornamental reef species through the use of no-take protected areas called Fish Replenishment Areas (or FRAs). The idea being that fish stocks protected within FRA's are able to recover and both adults and juveniles spillover and replenish stocks in non-protected areas.

When I wrote about this issue last year, there was what appeared (to me at least) to be a rush to judgement by some locals in concluding that FRAs were not working. Fewer fish (notably Yellow tangs, Zebrasoma flavescens) were observed on reefs and aquarium fish collectors were said to be holding the smoking gun. The State of Hawaii was called upon to ban fish collection or heavily regulate it.

I won't deny there is a need for the State of Hawaii to add restrictions to the lack of regulations around aquarium fish collecting. But according to Impacts of West Hawaii Marine Protected Areas on Yellow Tang Stocks and Fishery Sustainability, a report issued last week by the Kona DAR offices, FRAs are working remarkably well along the Big Island's Kailua-Kona coast. (The report I describe here is a redacted version of the more expansive study, Impacts of a Hawaiian marine protected area network on the abundance and fishery sustainability of the yellow tang, Zebrasoma flavescens, published in the journal Biological Conservation [Vol. 142:1066 -1073, 2009]. I haven't found an online link to the redacted report, but send me an email and I'd be happy to forward a pdf version to you.)

In 1999, before the FRAs were implemented, there was no difference in yellow tang density between ‘open’ sites (green squares in the graph on the left) and sites which were slated to become FRAs (red circles). Both had about half the abundance of the established ‘older reserves’ (blue triangles). By 2003, and in all subsequent years, densities in FRAs had increased to levels similar to those in the older reserves. Monitoring data therefore provides unequivocal evidence of population recovery within FRAs.

But wait, there's more.

FRAs don't just increase fish stocks within their protected waters, but outside their boundaries as well (see graph at top of post). High densities of fish in boundary areas are evidence of ‘spillover’ (outward movement of fish from reserves into surrounding open areas) and indicate that reserves supplement adult stocks not only within their own boundaries, but also in open areas up to a kilometer or more away. This is not to say that tighter regulations on aquarium collecting are not needed. FRAs alone are likely insufficient to meet a growing aquarium collection industry. But the data paints a promising picture of how to successfully manage reef fish recovery.

I can't put it any better than the conclusion presented in the report, so I'll close with this assessment by the State of Hawaii on the value of FRAs as a resource management tool,

The West Hawaii reserve system has been shown to have a number of benefits above and beyond impacts on yellow tang. Those include greater numbers of other targeted species, reduced conflict between collectors, commercial ocean recreation operations, and community members, and greater numbers of attractive and conspicuous fishes in reef areas which are readily accessible to commercial and recreational divers and snorkelers.

In addition, survey data provides clear evidence that the West Hawaii protected areas network, by sustaining adult stocks over large areas of the coastline, helps to ensure the long-term sustainability of yellow tang stocks in West Hawaii and of the fishery which depends heavily on this species. Increased fishing effort and catches in recent years demonstrate scope for severe over-exploitation in the absence of reserves, and suggest that additional management, including perhaps limits on participation as well as specific additional protection of breeding stocks may be necessary to optimize future fishery benefits.