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The Private, Exclusive Guide for Serious Divers Since 1975
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October 2005 Vol. 31, No. 10   RSS Feed for Undercurrent Issues
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Big Fish, Big Egos, Big Bucks

as the biggest fish die, so do the species

from the October, 2005 issue of Undercurrent   Subscribe Now

When the larger fish of a species get killed off, the gene pool changes, the average size of the fish shrinks, and the species become threatened.

So it was alarming news when we learned that the mighty whale shark, is suffering from a severe decline in size. Australian scientist Dr. Mark Meekan says that observation logs of whale sharks in Ningaloo Reef, Western Australia, suggest that the average size of the fish had shrunk from 23 feet in 1995 to 18 feet today, only 10 years later. In search of the ingredients for shark fin soup for Asian banquets, fishermen shoot, harpoon, or do whatever is necessary to slow the fish, then remove the fins, leaving the carcass for other sharks.

"Any fish population that is undergoing unsustainable mortality usually shows a drop in average size of individual fish, and a drop in abundance," said Meekan. "What we're seeing at Ningaloo is particularly worrying, because these waters are protected. If we're losing the adults in the population, leaving only juvenile whale sharks, then we'll have no population there to reproduce."

Yet some divers who spear fish aren't helping. In two cases that made the U.S. press, divers went after huge trophy fish, with no concern for the endangered nature of the species they were pursuing.

The St. Petersburg (FL) Times reported in July that diver Dan MacMahon, had speared a 400- pound Warsaw grouper in 425 feet of water. The Warsaw grouper is listed as "critically endangered" by the World Conservation Union.

In a lurid account posted on, then criticized on other bulletin boards, MacMahon described his kill as a "mission" he'd spent the last year "plotting and planning" to "finally get the big Warsaw I've wanted all my life." When he reached a wreck on the bottom, MacMahon says, "There were a half dozen Warsaws in the 40-100 lb. range close to us when I spotted the monster facing me about 100 feet away."

When the fish approached him, MacMahon boasts, "I pointed my 52- inch SS Hornet and slammed a free shaft into the sweet spot." When the fish "started shaking back and forth," says MacMahon, "I slammed shaft number two into his head." Then, as a coup de grace, he says, "I put a PH [power head] on my kill spike and slammed into his head." After wrestling the huge fish to the surface, it took four men and a block and tackle to get it on the boat.

"What an awesome dive," says MacMahon. "There's (sic) just too few moments like this in ones (sic) life." To which we can only add, "good thing."

In Southern California, according to the San Diego Union-Tribune, lifeguards witnessed Navid Adibi, 22, driving a boat into the San Diego-La Jolla Ecological Reserve on April 24, past a bright yellow buoy marking its boundaries. Two men put on scuba gear and loaded spear guns. About 20 minutes after they entered the water, the men surfaced and the boat operator helped them lift a 171-pound protected giant sea bass aboard; the group celebrated with high-fives before motoring out of the reserve. Authorities intercepted the boat.

Adibi, the boat driver, an undocumented Iranian emigrant with a police record, was fined $500. The man who speared the fish, Omid Adhami, 34, was placed on probation.

" Atlantic swordfish used to grow to more
than 1,000 pounds, but the average one
caught in 1995 weighed just 90 pounds."

Despite these wrist slap punishments, trophy hunting for endangered species or in marine reserves is unconscionable in an era with so much pressure on fish populations. Terry Maas, legendary spear fisherman, author and video maker, points out that a 430-pound, slow-growing California giant black sea bass would be 75 years old. He compares that venerable specimen with a 400- pound bluefin tuna, only 11 years old, that he took while free diving. "Obviously," Maas concludes, "tuna, with their rapid growth, can replace large adults in their population in one-seventh the time it takes black sea bass populations to replace a similarly sized fish."

John Hyde, of the National Marine Fisheries, adds, "It's never good to take exceptionally large fish." Females are usually much bigger than males. And larger females tend to produce more and higher quality eggs, "so catching the biggest fish depletes the female population," Hyde points out. With many groupers and other sex changing species, all the small fish may be one sex. "By catching all the big fish you take away all of one sex, reducing reproductive potential until some of the remaining small fish can change sex ... you can see how easy it would be to alter the average size at which these species change sex."

News reports of an 1,100-pound tiger shark being reeled in during a recent "monster shark derby" at Martha's Vineyard, MA, point out that taking trophy fish is hardly exclusive to spear fishermen. In fact, the fishing industry tactic of targeting the biggest members of a species is now being challenged by new research, according to an article in Science News. Fleets target big fish because they yield more marketable meat. And yet, the biggest species--such as tuna, sharks, and cod--in heavily fished areas tend to be the first to plummet, notes Ransom A. Myers of Dalhousie University in Halifax, Nova Scotia. Ensuing populations get smaller with the disappearance of the "big mammas" (which often produce the largest numbers of eggs and the heartiest offspring). For instance, Atlantic swordfish used to grow to more than 1,000 pounds, but the average one landed in 1995 weighed just 90 pounds--a couple of years short of its first chance to reproduce.

We divers have a special relationship to the fish in the sea and with that comes a special responsibility to protect them. That can mean giving your time or money to organizations that work hard to protect the oceans. There's not a lot of time.

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