Today, sharks, along with sturgeon and sciaenids (known as croakers or drums for the sounds they make undersea), are among the most imperiled of the species that spend most of their lives in the ocean.
Populations of sharks, skates and rays -- creatures known as elasmobranchs that evolved 400 million years ago and have skeletons of cartilage, not bone -- have difficulty rebounding because they mature slowly and produce few offspring. Shark-fin soup, an Asian delicacy that sells for more than $100 a bowl, has spurred intensified shark hunting in recent years.
Despite the sturgeon's fecundity, overfishing and habitat destruction have caused that population to dive as well. Beluga sturgeon, the source of black caviar, release 360,000 to 7 million eggs in a year, Pikitch noted, but they have declined 90 percent in the past 20 years. Just this month, scientists in Kazakhstan reported that they failed to find a single wild, reproducing beluga female, leaving them with no eggs for hatcheries.
Croakers' large swim bladders -- air-holding sacs that help them maintain buoyancy -- account for their imminent demise. Traditional Chinese medicine prizes the bladders, and the sound they make when pressed against vibrating muscles can reveal croakers' location to fishermen through sonar.
"They've been survivors on an evolutionary scale, but they've met their match, and it is us," said Pikitch, who writes about sharks and sturgeon in an upcoming book, "State of the Wild 2006."
Despite scientists' warnings, American and international authorities have been slow to protect marine species. The only U.S. saltwater fish to make the protected list is a ray, the smalltooth sawfish, which was added in 2003.
The National Oceanic and Atmospheric Administration's Fisheries Service is charged with protecting 61 threatened or endangered marine species. Director Bill Hogarth said his agency focuses on protecting vulnerable populations so they will not have to be listed.
"That's our job -- to make sure species don't wind up on the endangered species list," he said.
But conservationists said NOAA officials are reluctant to classify fish as endangered because doing so conflicts with the agency's mission of promoting commercial fishing.
Michael Hirshfield, chief scientist at the advocacy group Oceana, said he has repeatedly seen government officials provide shifting estimates of how many threatened or endangered sea turtles can acceptably die each year in eastern scallop fisheries.
"You never get an answer to the question how many turtles would have to be killed before you would say, 'That's not okay,' " he said.
On Bimini, 50 miles from the Florida coast, Gruber is trying unsuccessfully to stave off the golf resort that could bring 5,000 tourists a day. The island has just 1,600 residents but supports more than a dozen shark species.
Based on an 11-year survey starting in the mid-1990s, Gruber documented that between 2000 and 2001, during the heaviest dredging of the ocean floor for the resort's construction, the survival rate for lemon sharks fell 30 percent, and sharks in the dredging area had higher toxin levels. He has yet to assess the impact of the mangrove destruction, which began on a large scale this year.
The president of the Bimini Bay Resort and Casino, Rafael Reyes, said he understands the concern but questions Gruber's statistics and the idea that "sharks and development don't mix."
"We have a vested interest in making sure things remain as they are," Reyes said, adding that he is demolishing mangroves in a place that is "basically not a sensitive area. . . . I have to make sure the environment's pristine because my clients are fishermen."
But Gruber remains unconvinced.
"I believed when I started the ocean was so vast there was no way you could ever kill off the sharks or anything," he said. When it comes to being a fish, he said, "Now you can run, but you can't hide."
