Seafood has long been an integral part of the human diet and many people regard the oceans as an inexhaustible source of food. Mankind, however, has harnessed technology to sweep the oceans clean. Fish-finding sonar, satellite locating systems, 100-mile-plus longlines with thousands of hooks, giant nets, fish aggregating devices (FADs), spotter helicopters and factory ships operating 24 hours a day all mean that for many fish, there is nowhere to hide.
Poor fisheries management, illegal fishing and destructive methods such as bottom-trawling and the use of cyanide and dynamite have not only left many species teetering on the brink of extinction, they have also harmed untargeted species.
Each year, an astounding 27 million tonnes of "bycatch" - juvenile fish and unwanted species - are discarded, often thrown overboard dead to free up freezer space for higher value specimens. Overfishing has caused stocks of various types of tuna, salmon, cod, shark and turtles, among others, to fall dramatically globally.
According to the WWF, the global fishing fleet is 2.5 times bigger than that which the oceans' fish stocks can support. The situation makes commerical fishing one of the worst-performing industries.
According to the WorldFish Center, a non-governmental research organisation, average global fish consumption has almost doubled in less than 50 years, and catches would have to double again in the next 25 years to keep up with demand.
HUNDREDS OF MILES FROM land and at least eight kilometres above the sea floor, I gaze in awe at the scene around me. I know I am nowhere near a coral reef, yet this is the picture that's being painted by the countless oceanic triggerfish, golden trevally and rainbow runners that appear to be answering some undersea call to arms.
Despite their number, they are no match for what has actually drawn them here, against their collective will. By day's end, these unwitting creatures will be in a deep freeze, victims of an FAD.
Made from steel drums, ropes, chains, nets, logs, buoys and an array of other objects, FADs are a familiar sight in international waters. I swim towards a bamboo FAD, struck by what looks to be the oceanic food chain in full working order; ironic, given the very purpose of an FAD is to facilitate the removal of fish from the seas and, thereby, from the food chain.
Sharks accompanied by pilot fish circle the FAD's colourful line, followed by hundreds of smaller fish, as if they are hoping that the big kid on the block will clear a path to the prize. In the distance, small fish congregate around the central line; further away, the fish increase in size, all with a common goal: dinner.
The crew of the Japanese purse seiner fishing vessel on the surface have a similar goal, although the dinner they will be providing will be served hundreds of miles away.
Purse seine tuna fishing started replacing the pole-and-line technique in the 1950s. Named after the purse shape the net creates in the water, the technique vastly increased the catch rate. However, it also had an unforeseen consequence. Schools of tuna were being encircled by the nets along with pods of dolphins, many of which died as a result.
The FAD was born when the fishing industry discovered that some species of tuna collected under floating objects such as tree trunks, branches, kelp and objects discarded by people. According to Martin A. Hall, principal scientist on the Tuna-Dolphin Programme of the Inter-American Tropical Tuna Commission, more than half of all tuna caught by purse seiners today are lured by FADs.
Although much of the tuna now sold is dolphin-safe, up to 10 per cent of each purse seiner catch made with an FAD consists of unwanted species such as sharks, turtles and juvenile tuna as well as other fish, according to Sari Tolvanen, oceans campaigner for Greenpeace International. This has been especially detrimental to the bigeye and yellowfin tuna. Their stocks are in sharp decline across all the oceans, because the juveniles of these species are caught by FAD fishermen in large numbers before they have had a chance to breed.
THE DEMAND FOR shark's fin soup has driven massive overfishing, threatening the survival of many species. The fins from between 26 million and 73 million sharks move through the major shark fin markets each year.
In large parts of the oceans, shark species have declined in number by 90 per cent or more in the past 20 years. Sharks reproduce slowly - after years spent reaching sexual maturity they produce few young. Many species will be unable to out-reproduce the demands of the shark fin trade as it stands.
In Indonesia, shark fishermen use dolphins as bait.
"They use dynamite placed in beer bottles and throw them at dolphins," says a local fisherman. "Once the dolphins get weak, they capture them and tie their tails. They use them as baits for sharks, whose fins could be worth one million rupiah [HK$800] for 1kg."
Despite legislation outlawing the hunting of cetaceans, the practice is rife off the tourist island of Lombok.
But there are alternative ways to make a living from the sea. Elsewhere in Indonesia, switched-on locals are taking tourists on dolphin-watching trips. Lucrative shark-diving tourism, meanwhile, can mean the animals are more valuable alive than dead.
MANTA AND MOBULA are among the most captivating and charismatic of marine species. However, their survival is severely threatened by the demand for gill rakers, which the animals use to filter their food. In traditional Chinese medicine (TCM), gill rakers are used to treat an array of ailments, from chickenpox to cancer.
The size of global manta and mobula (a slightly smaller genus) ray populations are unknown. Even leading scientists are not prepared to offer estimates. Likewise, questions remain regarding their biology and behaviour. What is known, however, is that these species are slow to mature (eight to 10 years), are long-lived (more than 40 years) and reproduce very slowly. A manta ray may produce just a single pup every two to five years. Further underscoring the vulnerability of manta rays, scientists believe specific regional populations may genetically differ from one another.
These characteristics make rays extremely vulnerable to overfishing, regional depletion and extirpation. While they are also taken as bycatch, these rays are subject to significant direct fishing pressure throughout their range. Indonesia, Sri Lanka and India have the largest documented fisheries, with targeted fisheries also reported in Peru, Mexico, Thailand, China, Mozambique, Ghana and other locations. Total annual documented global landings are 3,400 mantas ( Manta birostris only) and 94,000 mobulas (all species). Unreported and subsistence fisheries mean true landings are likely to be much higher.
A mature Manta birostris (oceanic manta ray) can yield up to 7kg of dried gills, which could sell for hundreds of US dollars per kilo in a market in the mainland. Established shark-fin trade networks have exploited the opportunity to profit from gill rakers, especially as shark populations have declined. Gill rakers are sold primarily in Chinese markets and directly marketed by importers from the hub of the trade: Guangzhou, which accounts for as much as 99 per cent of the global market. Market analysis suggests total annual gill-raker trade volume is in excess of 61,000kg (and perhaps as high as 80,000kg), with an estimated value of US$11.3 million a year.
Despite the marketing, a number of practitioners say gill rakers are not a legitimate, acknowledged component of mainstream TCM and that there is no proof they are effective.
The past decade has seen significant declines in both the number and size of manta rays landed in primary fishery sites in Indonesia, Mozambique, India and Thailand. Manta birostris has all but disappeared from the Sea of Cortez, Mexico. Fishermen in the Philippines reported a 50 per cent decline in manta ray landings from the 60s to the 90s and Sri Lankan fishermen have also reported declines in catches.
Though the outlook may appear grim, manta and mobula ray tourism offers sustainable and profitable alternatives. The value of manta ray tourism based on data gathered from only seven sites - of many - is estimated to be US$27 million in direct tour operator revenue, and US$50 million per year when associated tourism expenditures are included.
Populations are currently stable, at best, around tourism sites or within marine reserves. The United Nations' Convention on Migratory Species recently listed Manta birostris as a species of international concern, but, although national laws have been enacted, there is no binding international protection for any manta or mobula species, nor are they regulated by the Convention on International Trade in Endangered Species of Wild Fauna and Flora.
IT IS THE INSATIABLE demand for fish that is killing our oceans. Seafood is seen as a healthy choice and the popularity of Japanese-style fine dining is only whetting appetites. It is of the utmost importance that consumers, restaurants, supermarkets and fish wholesalers accept their share of the responsibility to ensure future fish supplies.
By removing from menus the most threatened species, such as bluefin and bigeye tuna, tuna caught with FADs and sharks, and replacing them with legally, sustainable products such as pole and line-caught skipjack tuna, markets can take the reins in ocean conservation. As consumers, we can do our part by asking about the sustainability of the seafood we consume and demanding products that have been caught with respect to the oceans.
Paul Hilton is a team member of Manta Ray of Hope, a project established to help conserve manta and mobula rays.