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On The Floor Of The Sea: Biologists Search For Rare White Abalone

Date:
October 20, 1999
Source:
U.S. Geological Survey
Summary:
White abalone - 1,000 to 5,000 per acre - were easy to find in the early 1970s around the Channel Islands off California's southern coast. But by the late 1970s, intense commercial and recreational harvesting made the abalone as difficult to locate a needle in an ocean-sized haystack.

White abalone - 1,000 to 5,000 per acre - were easy to find in the early 1970s around the Channel Islands off California's southern coast. But by the late 1970s, intense commercial and recreational harvesting made the abalone as difficult to locate a needle in an ocean-sized haystack.

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"People thought it was impossible to take such a fecund animal - a single female can produce 10 million eggs in a season - and drive it to extinction through fishing," said Gary Davis, a senior scientist at the Channel Islands National Park.

Next week, a determined group of university, government and private biologists is setting out in a two-person submersible to cruise the ocean floor in search of the rare marine snail. In all, the team will make more than 50 dives to search for the abalone around Santa Catalina, San Clemente and Anacapa Islands and on Cortez, Tanner and Fansworth Banks, all prime white abalone habitat in the 1970s. "We've gone to some senior abalone divers to help learn specific spots that used to be productive for the fishery," said marine ecologist Kevin Lafferty of the U.S. Geological Survey (USGS).

If successful in their forays, the researchers will attempt to develop a captive-breeding program similar to those used to replenish imperiled terrestrial species. The group, informally known as the Abalone Restoration Consortium, has a proactive plan to help the vanishing marine invertebrate. Biologists from the U.S. Geological Survey, the University of California, and the National Marine Fisheries Service, working with the National Park Service and the California Department of Fish and Game, obtained federal funds to initiate a recovery program.

"In addition to looking for white abalone in previously surveyed and unsurveyed areas, we will be recording data on habitat type, algae, the food of abalone, and the animals associated with this species so that we will have a better understanding of the distribution of suitable white abalone habitat for future restoration efforts," said abalone researcher Pete Haaker of California Department of Fish and Game.

If surveys confirm the mounting evidence that white abalone are indeed rare, the scientists will use two strategies to give the abalone a better chance for survival. The first approach will be to act as match-makers and simply get the abalone together in the first place - one of the biggest problems the abalone face is that they are too distant from each other to mate. Unlike more mobile animals, abalone are slow-moving creatures confined to a small area for their entire life. They reproduce by broadcasting their eggs and sperm into the seawater, and for fertilization to occur, the spawners need to be within three feet of a member of the opposite sex to effectively reproduce. Without neighbors, the remaining animals are effectively sterile, said Lafferty.

"We will move isolated individuals next to each other to give them a chance to begin recovery on their own," Lafferty said. "The most optimistic prediction is for a small-scale version of the baby boom that began when GI's returned to their brides after WWII. It's too bad the weather is so nasty in February or we could schedule this for Valentine's Day."

The second approach will be to bring white abalone back to several laboratories up and down the West coast for safe keeping and breeding. Presently, only one white abalone is in captivity, a five-inch female named Abigail, who lives in a special, cooled tank at the University of California at Santa Barbara. Unfortunately, said Dr. Dan Morse of UCSB and a long-time leader in developing husbandry technology for abalone, the basic husbandry for culturing white abalone is not known. Morse's job on the team is to try to crack the white abalone's fertility cycle and learn how to effectively propagate juveniles. Morse said that although techniques already exist that work well for other abalone species, the challenge is to adapt them to the food and environmental idiosyncracies of white abalone.

To reduce the likelihood that an accident could kill all the captive stock, several husbandry locations will be used. At the primary facility, Tom McCormick, a mariculturist, is putting the finishing touches on two white abalone-holding systems at the Channel Islands Marine Research Institute in Oxnard, Calif. Each system has six individual holding vats for the abalone, a submerged biofilter, particulate filter, chiller, UV sterilizer, an aeration system and a packed column for oxygenation and degassing.

The systems, said McCormick, are also equipped with an alarm should any of the life-support systems fail.

Determining breeding will be just the start, however. To find and collect just 200 white abalone to launch a captive breeding program would cost $1.2 million or more, Davis estimates.

Abalone have been a favored food of Californians for a long time, with fossilized remains of the tasty-fleshed marine snails having been found in the earliest Indian middens of some 10,000 years ago. The white abalone is a deep-water species found between 80 and 200 ft. on rocky reefs from Point Conception in California to Punta Abreojos in Baja California, Mexico. Highly prized for their tender white meat, they often brought a 20 percent higher price than red abalone, the primary mainstay of the abalone fishery. During the 1970s, however, an intense commercial and recreational fishery for white abalone developed, quickly peaked and then crashed.

The fishery for white abalone was closed in 1996, and on July 8, 1997, the National Marine Fisheries Service (NMFS) made the abalone a candidate species for federal listing under the Endangered Species Act. Based on information indicating major declines in the abundance of white abalone, NMFS contracted with Scripps Institution of Oceanography in August 1998 to review the status of white abalone. NMFS will use the results of this review to determine whether white abalone should be listed under the Endangered Species Act.

During the 1980s and 1990s, scuba surveys found less than one white abalone per acre. In November 1996 and October 1997, marine biologists set out on an experimental expedition to explore 24 deep reefs (to 200 feet) for remnant pockets of white abalone, and to describe white abalone habitat below 130 feet. Using a two-person research submarine called the R/S Delta - a veteran of nearly 4,000 dives on shipwrecks, geological surveys and fishery assessments - researchers searched known white abalone habitat and adjacent reefs from 100 to 200 feet around Anacapa, Santa Cruz and Santa Barbara islands. They recorded all live white abalone and dead shells, mapped their distribution with global satellite positioning systems and recorded white abalone habitat on video tape and 35-mm film.

What they discovered was both alarming and heartening said the researchers. No large aggregations of white abalone survived on those deep reefs, even beyond reach of the 1970s scuba and hookah divers. Even surveys of more than 25 acres of white abalone habitat at depths of 100 to 200 feet at the California Channel Islands revealed no new populations of white abalone, and only 12 large individuals. Researchers did find hundreds of empty shells, a few from recently dead individuals, but most shells were old and disintegrating, bearing mute testimony to once abundant populations.

The researchers also discovered that white abalone habitat on deep reefs was similar to that on shallower reefs: small reefs with low relief and boulders scattered on sand, with sparse brown and red algal growth. Extensive white abalone habitat was rare and did not extend below depths of 180 feet.

On those deep reefs, they found considerable amounts of man-made debris, including fish nets, rope, and abandoned lobster and fish traps.

Before these cruises, research submersibles had never been used to search for such animals as difficult to see as abalone. The submersibles, though, provide a clear, close view of abalone habitat, access to large areas, and longer hours for observation. In addition, the submersible's continuous video and tracking systems provided excellent records of surveyed areas and environmental conditions.

In May 1999, environmentalists petitioned the National Marine Fisheries Service to list white abalone as endangered. If listed, the white abalone would become the first recognized endangered marine invertebrate. Lafferty warned, however, that since the fishery is already closed, legal protection, by itself, might be insufficient to slow the road to extinction, which is why the Abalone Restoration Consortium is acting now.

As the nation's largest water, earth and biological science and civilian mapping agency, the USGS works in cooperation with more than 2000 organizations across the country to provide reliable, impartial, scientific information to resource managers, planners, and other customers. This information is gathered in every state by USGS scientists to minimize the loss of life and property from natural disasters, contribute to the sound conservation, economic and physical development of the nation's natural resources, and enhance the quality of life by monitoring water, biological, energy and mineral resources.


Story Source:

The above story is based on materials provided by U.S. Geological Survey. Note: Materials may be edited for content and length.


Cite This Page:

U.S. Geological Survey. "On The Floor Of The Sea: Biologists Search For Rare White Abalone." ScienceDaily. ScienceDaily, 20 October 1999. <www.sciencedaily.com/releases/1999/10/991020080616.htm>.
U.S. Geological Survey. (1999, October 20). On The Floor Of The Sea: Biologists Search For Rare White Abalone. ScienceDaily. Retrieved November 24, 2014 from www.sciencedaily.com/releases/1999/10/991020080616.htm
U.S. Geological Survey. "On The Floor Of The Sea: Biologists Search For Rare White Abalone." ScienceDaily. www.sciencedaily.com/releases/1999/10/991020080616.htm (accessed November 24, 2014).

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