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March 2002 Vol. 17, No. 3   RSS Feed for Undercurrent Issues
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REEF’s Science Saves the Goliath Grouper

from the March, 2002 issue of Undercurrent   Subscribe Now

REEF ’s mission is “to educate, enlist and enable divers and non-divers alike to become active stewards in the conservation of coral reefs and other marine habitats.” It has enlisted more than 20,000 volunteer divers to conduct regular fish biodiversity and abundance surveys, individually or in groups. This year, its 15 scheduled field surveys range from the Grenada to Midway in the far NW Hawaiian Islands. REEF regularly updates it Web site with member marine census input. Its 40,000 plus survey data base is used as an aid in marine management by several federal and state agencies, including the National Oceanic and Atmospheric Administration, the Biscayne Bay Foundation and the Florida Fish and Wildlife Conservation Commission, among others.

Since 1997 REEF has annually monitored 16 no-take sites within the Florida Keys National Marine Sanctuary to evaluate the effects of restrictions on fish populations. Similar monitoring is also being conducted at six sites in the Dry Tortugas. And, the REEF database helps the state access data on fish population at artificial reefs. Paul Humann told Undercurrent that REEF data is keeping the Goliath Grouper safe from fishermen. While the Goliath has been protected since 1990, fishermen are clamoring to fish for this 500-pound denizen, claiming it has returned to harvestable numbers. Humann says, however, that the low Goliath counts by REEF divers persuaded Florida officials to keep it on the no-fishing list.

REEF even sees action in scientific journals. An article in the Atoll Research Bulletin states that “The status of reef fishes in the Cayman Islands, REEF databases and findings by REEF Atlantic and Gulf Rapid Reef Assessments team helped provide an updated species list for the Islands, a comparison between Grand Cayman and Little Cayman, 33 sites, and an analysis of the relationships between herbivorous fishes and algal cover.” The REEF data resulted in 44 species being added to the list of fishes known to occur on these Islands.

Given the obvious impact of this data, its reliability, validity and applicability are important. Most people knowledgeable in fish surveying agree that the REEF “Roving Diver Technique” (RDT) provides useful data on the abundance of species in the marine environments selected for a census. This technique instructs the surveying diver to look in all places and directions. Across samples, it certainly tells how often a species is seen by REEF divers. Humann says that noted biologist Peter Sale has observed REEF divers first hand and now uses the REEF protocol wherever he can.

However, the usefulness of such findings for more fine-grained applications, such as fishery management decisions, is questioned by some. A prominent marine biologist told Undercurrent that REEF’s methodology makes certain types of quantification problematic. He explained, “If one guy likes to look in crevices and crannies for gobies or blennies, and searches that way, he can’t possibly be scanning above for chubs or barracuda or needlefish higher in the water column. Conversely, if another guy swims along looking out at the UW horizon searching for parrotfish and grouper, he will not see the small cryptic fishes hiding under ledges or coral rubble.”

Laddie Akins, Executive Director of REEF, counters that the RDT produces valid species counts. He told Underurrent that REEF is the “marine equivalent of the Audubon Society” and provides surveys that are of equivalent value to those conducted by scientists and wildlife management decision-makers. Before such survey approaches, it was standard practice to poison or dynamite an area and then count the dead fish. This is hardly acceptable anymore, thank heavens. Subsequent alternate approaches included ROVs, video transects, acoustic technology (e.g.,sonar) and catch counts by commercial fishermen. However, Akins notes that just as with the surveying diver, a lot depends upon where such devices are aimed. Humann says that REEF divers, who are trained at different levels of competency, are told to keep an eye at all levels; if they are concentrating on the cryptic and have to check out the water column too. One dive doesn’t produce valid data, but after hundreds of observations in a set area, validity increases and becomes exceptionally useful.

No census procedure is without its particular bias. Because multiple divers survey a site, and at major sites multiple surveys are performed over a relatively short period, this suggests at least adequate coverage of the crevices and crannies, water column above and blue water off to the sides.

In addition, there is no denying the excitement and education inherent in REEF survey activities. Becoming an expert in critter identification can help you turn a ho-hum dive into a great thrill. You may visit the REEF Web site at www.reef.org.

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