Oceanic sharks make up a part of the by-catch of Hawai’i’s longline fleet, although how large a part is difficult to determine. Frequently, shark catches are not recorded in logbooks.
According to NMFS records, in 1992, “almost 95,000 sharks were caught by Hawai’i-based longline fishermen, but only about 3,600 were retained.” For that same year, NMFS estimates 574,000 pounds of shark were landed commercially, sold at auction for 62 cents a pound, and accounted for $354,000 in income to longline fishermen.
People familiar with the longliners’ practices say that crew members are generally encouraged to remove the fins of sharks caught, dry them, and sell them when they return to port as a means of augmenting their pay. (Dried shark fins, the key ingredient in shark-fin soup, can sell on the wholesale market for $50 a pound and higher, while the costs associated with bringing them to market are, for the longline operator, negligible.)
On occasion, fins may be transferred to foreign vessels while the vessels are still at sea. According to minutes of the December 1992 meeting, when NMFS resource specialist Al Katekaru was asked about shark fin trans-shipment, he responded that such transactions were “making place as they were speaking.”
Members of three families of sharks are among the so-called Pacific Pelagic Management Unit Species (PPMUS), whose catch is supposed to be regulated by the Western Pacific Regional Fishery Management Council. The Carcharhinidae, or requiem, sharks include whitetip, silkey, tiger, blacktip, silvertip, and Galapagos sharks. The Alopiidae, or thresher shark, is also on the PPMUS list, as are hammerhead (Sphyrnidae) and mackerel (Lamnidae) sharks.
In 1990, to comply with federal guidelines from the National Oceanic and Atmospheric Administration, the Council was required (over its strenuous objections) to amend its Pelagic Fishery Management Plan to include a definition of overfishing. In that amendment (Amendment 1), overfishing for bony fish was defined to occur when the spawning potential ratio of the fish species declined to 0.20 or below. That ratio measures the current reproductive ability of a given fish species against what that ability would be in unfished waters.
For sharks, which are not as prolific as bony fish, the threshold for overfishing was set at 0.35. “Typical bony fish produce thousands, and in some cases millions, of eggs annually,” writes Leigh Dayton in New Scientist. “In contrast, most sharks produce between 2 and 50 young per year, take a long time to reach reproductive age and live long lives between 12 and 70 years depending on the species.” When indiscriminate killing of sharks occurs, he adds, “the inevitable result is that there are not enough young ‘recruits’ to replace adults lost to human predation.”1
The Council’s Plan Team for pelagic fish acknowledges that it lacks the information needed to assess the health of shark stocks. In its 1992 annual report on pelagic fisheries (published in October 1993), the Plan Team lists five “issues that may require Council action in the near future.” Issue 4 is a concern over the lack of data on shark harvest and/or by-catch in the region. Although shark data are required to be reported on longline logbooks, it is not certain if sharks that are caught, finned, and disposed of at sea are adequately reported. Species identifications are also commonly inadequate. “Since most sharks have low reproductive rates and long gestation periods, they are highly sensitive to fishing pressure. Data on volume of catch, CPUE [catch per unit effort], species, size, and disposition of sharks are needed.”
The Plan Team made five recommendations to the Council, one of which was that the Council improve “the coverage of shark fishing by state, territory, and federal data collection programs, including catch, effort, identification to species, reporting of finning activity and harvest of fins, and disposition of sharks taken.”
If what is occurring here is anything like what has happened elsewhere, shark stocks may be experiencing what has been described as a “dizzying ecological plunge.”2 An article in U.S. News & World Report in 1992 quoted Sam Gruber, a shark expert at the University of Miami, as saying, “In America and around the world, sharks are being fished to oblivion. Without drastic conservation measures, some species will be lost.”
Without sharks, marine ecosystems could be thrown out of balance in ways still not well understood but certainly damaging. According to Gruber, “We don’t know enough about the true mechanics of the biosphere to predict with certainty what would happen, but we do know a diverse, balanced ecosystem is good. And for that, we need sharks.”
1. “Save the Sharks,” New Scientist (15 June 1991), pp. 34-38.
2. “Can Sharks Survive?” in U.S. News & World Report, June 22, 1992, p. 70.
— Patricia Tummons
Volume 4, Number 10 April 1994