Marine Protected Areas: Boon or Bust for Restoring Depleted Stocks?

The value of marine reserves has been hotly debated recently with last year’s establishment of the Papahanaumokuakea Marine National Monument and the federal determination that overfishing of bottomfish is occurring in the Main Hawaiian Islands. Some have argued that marine reserves don’t really protect fish stocks because fishermen simply shift there efforts elsewhere. Others say closing off areas from exploitation is the best way to enhance fish stocks and protect ecosystem integrity.

The state of Hawai`i has its own system of marine reserves. Some of them have been in place for just a few years, while others were established decades ago. At the Hawai`i Conservation Conference held in Waikiki last July, scientists presented data on both the successes and failures of these reserves, as well as new information on larvae transport and how large fish compete with monk seals for food.

Protected status does not necessarily guarantee protection. And in the case of the Wai`opae tide pools in Kapoho, Hawai`i, the state’s decision to establish a Marine Life Conservation District there may have done more harm than good. That’s according to preliminary research by Chelsie Settlemier of the Cape Kumukahi Foundation, which was hired in 2003 by the community to monitor user impacts on the area.

Several years ago, the remote and rugged swath of tide pools, tucked away in a quiet neighborhood, had begun to see increasing numbers of recreational users. They had become a regular stop for commercial snorkel tour operators working with cruise ships sailing to Hilo and surrounding area residents were concerned that the influx was degrading the coral reef, nearshore fisheries, as well as the water quality in the tide pools.

Residents were torn over what to do, Settlemier said. They wanted to establish an MLCD in the hope that it would offer some protection, but were concerned that calling attention to the area in such a way would bring even more visitors.

Ultimately, based on recommendations from the Division of Aquatic Resources, the state Board of Land and Natural Resources designated the area as an MLCD in June 2003. Under its new status, fishing or taking of any marine life, taking or altering geological features, anchoring, mooring, and commercial activities are prohibited.

In anticipation of the board’s decision, Settlemier and several other students at the University of Hawai`i at Hilo were paid by the community to conduct human use and water quality monitoring before the MLCD was established and for five years afterward. The group of students, now known as the Cape Kumukahi Foundation, started its work in May 2003 and plans to present its results to the state next year as part of a five-year review of the MLCD, Settlemier said.

The results of this effort, called the Kapoho Reef Watch project, indicate that use has intensified since the MLCD was established. Between May 2003 and July 2006, the foundation conducted 331 human use surveys, 42 fish surveys, and collected 108 water samples. It found that the number of visitors increased from 46,000 people in the first year of study to 87,000 in the third. It also found that the MLCD sees most of its visitors on federal holidays – an average of 394 visitors a day – and that 90 percent of them use the tide pools.

“Although visitor rates are increasing, no public restrooms are available; therefore, visitors have no choice but to use the tide pools as their restroom. Seven of the ten tide pools sampled for water quality were in violation of the state’s standard of Enterococcus [a fecal bacteria],” an abstract by Settlmier and UHH’s Josh Ballauer states. It adds, “Our fish surveys indicate an overall decrease in fishes, with the area open to fishing experiencing a greater decline. Although the marine resources in the MLCD are protected from fishers, anthropogenic impacts such as sewage inputs may be a greater impact on the overall health of the tide pools.”

Settlemier says she believes the increase in visitors is a direct result of the establishment of the MLCD. “It’s more publicized. People think, ‘Oh, it’s an MLCD. I’ll go check that out,’” she says. To reduce the negative impacts people are having on the area, she suggests that the state may need to further restrict activities at Wai`opae or employ a full-time, on-site steward to educate visitors. In her presentation, she added that public restrooms should be installed at the MLCD, the surrounding area should upgrade its cesspools to a septic or sewage treatment system, and the state should “get kupuna involved” in managing the area.

Marine Life Conservation Districts are one of several tools the state uses to manage Hawai`i’s nearshore resources, and, over the decades, 11 have been established on O`ahu, Maui and Hawai`i. Managed by the Department of Land and Natural Resources’ Division of Aquatic Resources, MLCDs are designed to conserve and replenish marine resources by prohibiting or strictly limiting fishing and other potentially detrimental activities.

For the past several years, Eric Brown of the National Park Service, Alan Friedlander and Mark Monaco of the National Oceanic and Atmospheric Administration, and the DAR’s Athline Clark have studied these MLCDs to determine their effectiveness, determine essential fish habitat, and identify biologically relevant district boundaries.

Their results, presented by Brown at the conference, suggest that while fish seem to benefit from MLCDs, there is room for improvement.

Using aerial images of the study areas, the researchers delineated and color-coded various types of habitats onto a map. The team then set 950 transects in and around marine protected areas throughout the state and counted the fish.

They found that no matter what type of habitat was being protected – whether it was sand, dominated by macroalgae, rocky, or colonized by coral – the fish biomass was greater and the fish were larger within protected areas than they were outside. Generally, MLCDs contained the highest biomass. Fishery management areas, which are not as strictly regulated, came in second. Open areas, where fishing is minimally regulated, had the lowest biomass.

Also, Brown reported that fish biomass in marine protected areas is two to three times higher for fish at the bottom of the food chain, 1.5 times greater for secondary consumers, and nine times greater for apex predators. At the Hanauma Bay MLCD, biomass was 8.5 times greater than in adjacent waters, at Molokini, it was 6.5 times greater, at Honolua 4.5 times greater, 3.7 times greater at Pupukea, and 2.5 times greater at Waikiki.

While the study found that fish biomass is, overall, 2.6 times greater inside an MPA than outside, Brown said that habitat complexity, or its rugosity (roughness) had a far greater influence on biomass variation than did the mere fact of an area’s protected status. He also found that species richness and biomass increased with depth.

Based on their findings, the team recommended that future MPAs include a range of habitat types, including sand corridors; extend from the shoreline to deep water; offer full protection from fishing; and have low macroalgae cover; among other things.

It’s hard to tell how or whether limits on fishing have benefited the fish in a given area when that area has been invaded by alien algae. But Ivor Williams of the Hawai`i Coral Reef Initiative has attempted to do just that. Using data from the state’s long-term reef monitoring program, Williams has found that the rotational fishing management regime at the state’s Waikiki-Diamond Head Fishery Management Area fails to protect fish stocks from declining.

The Waikiki-Diamond Head FMA was established in 1978. In its first ten years, the state would close the area to fishing for two years, then open it for two. In 1988, when the state closed a small portion of the FMA to fishing altogether, those intervals were reduced to one year.

In his presentation at the conference, Williams stated that total fish biomass within the Waikiki-Diamond Head FMA has dropped 75 percent since it was established. The number of big fish, including parrotfish and goatfish, declined as well. In pre-1985 surveys, these larger fish accounted for 31 percent of the fish biomass in the FMA; after 1990, they accounted for only four percent, he said.

Hurricane Iniki in 1992 and the invasion of Gracilaria salicornia algae in the early 1990s bore much of the blame for the decline, Williams said, but he added that the rotational management made things worse. Fishing effort would spike as soon the FMA reopened, he said. In 2000, the mean number of spear fishers in the FMA was less than .5 per day and that the “normal” peak number of fishermen was 11. However, at 8 a.m. on the day that the FMA reopened, 82 fishermen were counted.

While fish biomass tended to increase during the closed seasons, he explained, it never fully rebounded from the losses sustained during the open seasons. As a result, the biomass was driven lower and lower over the decades.

He acknowledged that “Waikiki is a terrible area and it’s tough to do anything.” Still, he concluded that the FMA “didn’t do a whole lot of good… There was a total failure to achieve objectives.” He added that many reef fish are long-lived and require time to mature, “so it’s difficult to see the benefits in short closures.”

An abstract for Williams’ work, published in Marine Ecology Progress Series, says that the Gracilaria invasion made it more difficult to assess the effect of the adjoining Waikiki Marine Life Conservation District in protecting fish stocks.

“However,” it goes on to say, “the initial effect of full closure was a reversal of the previous downward trend in fish biomass, and even in the post habitat-decline period, biomass of target species within the MLCD has been nearly twice as high as in the FMA. Additionally, there have been no declines or even downward trends in maximum size of target families in the MLCD.”

“I’m not trying to stir up a pot,” says Bishop Museum zoologist Ken Longenecker, who, with Ross Langston of Windward Community College, presented some addmittedly unpopular data regarding the efficacy of marine reserves.

At the conservation conference, Longenecker told the audience that he believed marine protected areas are good for species conservation, preserving cultural resources, supporting the economy and scientific investigation. But when it comes to fisheries management, “We argue that to enhance a fishery, some biological parameter inside a reserve must more than double that in fished areas,” Longenecker stated in his conference abstract. In a talk given earlier this year and posted on YouTube by the Hawai`i Coral Reef Initiative Research Program, Longenecker explained their position:

“Let’s say you have a fishing ground and you`re going to establish a no-take zone smack dab in the middle of it. All of a sudden, you cut the number of catchable fish in half. For this no-take zone to make up for that loss in fishery habitat, the population inside the no-take area has to double its production in terms of biomass or reproductive output and that excess production has to – and this is a very big if – move into a fishable habitat. Unfortunately, there is very little empirical or theoretical evidence that this actually takes place. And if you’re with me so far, it also follows that this production must more than double to enhance the fishery,” he said.

To test their hypothesis, Langston and Longenecker studied the popular aquarium fish Centropyge potteri (Potter’s angelfish), Dascyllus albisella (domino damselfish), and Parupeneus multifasciatus (minibarred goatfish) in Hanauma Bay, which has been closed to fishing for 40 years, and in Moanalua Bay, an area heavily fished by ornamental collectors.

While some have argued that it’s unlikely that reef fish or their larvae from Hanauma Bay would traverse miles of open ocean to replenish Moanalua Bay, Longenecker said that Moanalua Bay was chosen as a comparison site because of its proximity to Hanauma Bay (both are located in southeast O`ahu) and because DAR records show that it’s a popular site for collecting Potter’s angelfish. (Financial constraints played a role as well in site selection, he added.)

In any case, the data collected so far suggest that for all three species, biomass production was greater in Moanalua Bay than in Hanauma Bay. For the angelfish, production was 26.1 kilograms per year in Hanauma Bay compared to 29.7 kg/yr in Moanalua Bay; for the damselfish, it was 13.2 kg/yr in Hanauma versus 102.7 kg/yr in Maunalua Bay; and for the goatfish, it was 186 kg/yr in Hanauma compared to 553.6 kg/yr in Maunalua Bay.

“To be fair, we found out after our presentation that commercial catch for Dascyllus (from DAR records) is very low. So, unless there is a large recreational catch for this species, these differences in biomass could reflect something other than presence or absence of fishing pressure FOR THIS SPECIES. In contrast, reported take for the other two species is quite high in Maunalua Bay,” Langston wrote in an email to Environment Hawai`i.

They also estimate that, per spawning event, the angelfish would produce 0.78 million eggs in Hanauma compared to 0.95 million in Maunalua; the damselfish produced 2.39 million eggs in Hanauma compared to 21.01 million in Maunalua; and the goatfish produced 17.87 million in Hanauma compared to 40.37 million in Maunalua.

Longenecker says that he initially thought it was a tall order for reserves to double fish production, but expected biomass estimates in Hanauma Bay to be higher nonetheless. He says he was dumbfounded when Maunalua Bay appeared to be a far more productive area for the fish than Hanauma Bay.

Some have suggested that the disparity has something to do with the fact that, as Eric Brown reported, marine reserves seem to benefit apex predators the most. While Longenecker hasn’t tested this hypothesis, he says his “knee-jerk” reaction is that “maybe biomass is being locked up in the big guys.”

Longenecker stressed that the results that he and Lansgton were reporting are “very preliminary” and says they still need to get more coverage of Maunalua Bay. He also hopes, funding permitting, to expand his studies to other species and other areas.

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Swept Away: Larvae at Sea