Overfishing of the Bluefin Tuna
There are many ways to serve up tuna—raw, boiled, cooked, smoked, grilled, on a roll, in a sandwich, in a wrap, with mayonnaise, with wasabi, with soy sauce, just to name a few. Tuna can even be in your cat’s feed with all kinds of combinations the animal-feed companies can conjure. The global demand for tuna has driven tuna fisheries along the Northern Atlantic, Pacific and Southern Ocean to thrive, and caused the tuna population to dwindle to precarious numbers.
The tuna-farming technology was introduced in 1975 to relieve pressure on natural tuna stocks. Wild tuna populations were allowed to regenerate while tuna farmers hold a certain amount of tuna and sell them instead. Tuna-farming is the practice of harvesting wild tuna and rearing them in open pens to be fattened for the markets. The tuna are kept in open sea feedlots and fed with fresh or frozen fish pieces. This essay will discuss the benefits of tuna-farming, and the Precautionary Principle (PP) (United Nations Environment Programme, 1992) will be used to analyse why tuna-farming is not sustainable and to argue that immediate attention is required to prevent irreversible serious damage to the tuna population. The tuna-farming industry reaps high profits and improves many economies, but it has inadvertently worsened the over-exploitation of fishes, and caused water pollution. However, the farming industry does seem hopeful as long as we look into solutions and improve the farming practices.
YearTotal Export Value (Millions)
Table 1: Total Export Value of Tuna-farming industry in Australia.
Australian Department of Agriculture, Fisheries and Forestry; Economic Impact Report
The tuna-farming industry generates numerous direct and indirect benefits to the local economies. Table 1 shows that the direct revenue from the tuna-farming industry in Australia grew exponentially over a decade. The Economic Impact Report 2002/03 revealed that in 2002/03, the industry also generated another $242 million from processing, transport, and downstream activities in other sectors. Such revenue has driven economic growth and infrastructure developments in the countries practicing tuna ranching.
In this multi-million dollar industry where one farmed fish may sell for more than US$100,000 in Tokyo, it is not hard to imagine that many people would hunt down schools of wild tuna to farm. However, while harvesting half-grown tuna and fattening them for the expanding Japanese market may be a golden goose for the tuna-farmers, it is a tragedy for the tuna as this may cause irreversible harm.
The initial goal of tuna-farming is similar to that of aquaculture—to relieve pressure off wild tuna populations by encouraging the trade of farmed tuna, leaving the wild stocks untouched. However, tuna-farming is the practice of rearing fish caught from wild populations to be fattened, as opposed to aquaculture where fish is raised from eggs. Essentially, tuna-farming is not very different from tuna fisheries that harvest wild tuna for trade, and therefore it certainly does not help to reduce pressure on the natural populations.
To make things worse, tuna-farming has switched from farming post-spawning tuna to juvenile ones, and the harvest of tuna before they are old enough to breed is a guaranteed path toward population collapse (Ellis, 2009). This is causing a substantial reduction in the spawning population, which means smaller future populations. The economic benefits of tuna-farming attracted many countries to invest in this industry. Records show that in 2000, every country around the Mediterranean was farming tuna for sale to Japan. With dozens of countries catching hundreds of thousands of half-grown tuna that have yet to reach maturity, it is evident that the wild stocks is leaning towards an accelerated depletion due to anthropogenic causes.
(ii)Feed for farmed tunas
Tuna-farming takes a toll on not only the tuna populations, but also on the fishes caught to be fed to the caged tuna. Capturing fish to feed fish is an ecologically unsound concept, but tuna are carnivorous like salmon, hence tuna-farming requires vast amounts of live or frozen baitfish, adding pressure on declining populations of these small fish. Tuna-farming is grossly inefficient, with roughly 25kg of baitfish required to produce just one kilogram of tuna (Lovatelli, 2005). It was reported that the annual consumption of a single farm in Croatia was 4,500 tons of anchovy, which were hauled from already-dwindling populations in the Adriatic Sea (Santojanni et al, 2003). Catches bound for the ranches go unreported as they do not go through the local markets, further hindering efforts to manage these dwindling populations.
In some cases, farmers turn to alternative species never fished for trade as an alternative feed for the tuna. Cetacean specialists pointed out that fishing for these fish not only pose risks to their population; it can also affect some very delicate ecosystems and disrupt food chains. An example would be the Round sardinella (Sardinella aurita) in the Alboran Sea, which is the food source for the common dolphin (Delphinus dephis) (Sociedad, 2005) and never fished for until recently.
In addition, as most tuna feed are imported and unprocessed, it could introduce diseases to the farmed tuna and local fish populations (Tudela, 2005). In some ranches, tuna are fed almost entirely on imported fish, which originates from African, North and South American, and North European regions (Oray and Karakulak, 2003). Disease outbreaks through infected feed can cause high mortality rates and result in economic loss for tuna-farms and other local fisheries. Despite previous disease outbreaks in Australia, no preventive measures have been implemented to mitigate such risks. Tuna-farming as such is a practice that could cause irreversible harm to the environment as envisaged by the PP, hence it is unacceptable for it to be allowed to continue without measures to eliminate the risks.
The vast amounts of waste from the caged tuna is another problem, as tunas’ excreta and decomposition of uneaten feed can result in concentrated levels of pollution, posing a threat to surrounding ecosystems, for example the seagrass meadows that is highly sensitive to degrading water quality. Due to their proximity to the shore and urban areas, the resulting pollution also adversely affects fisheries as the poor water quality affects the health of the nearby fish stocks. Tourism is also affected, due to bad smells and dirty beaches. To worsen the problem, there are no international regulations on tuna-farming, which falls between the definition of a fishery and aquaculture (both of which have global regulations on pollution).
Uncertainty in Tuna Stock Numbers
The difficulty in keeping proper accounting of the population of BFT could present an inaccurate picture of the extent of tuna population depletion. A report in Science by Barbara Block and her colleagues (2001) suggested that the North Atlantic BFT (NABFT) is actually a single, ocean-wide metapopulation as opposed to the long-held belief that there were two populations, the eastern and western NABFT, that are discreet and localized. As the International Commission for the Conservation of Atlantic Tunas (ICCAT) set quotas based on the assumption that the eastern and western populations are separate and unmixed, there is a possibility of double-counting the tuna that migrated from one side of the ocean to another, which could mean the actual population is much less than estimated.
Since there is now uncertainty in gauging the actual population size of the NABFT, it is wiser to apply the PP to this situation to ensure the wild BFT population is sustainable. Under the 1992 Rio Declaration, the PP states that scientific uncertainty shall not be used to justify the delay of preventive measures against environmental degradation when faced with threats of serious or irreversible damage (UNEP, 1992). Hence, despite any uncertainty, there is a need for the quotas set by ICCAT to be reviewed immediately, and for NABFT to be listed as a critically endangered species in order to enforce the maximum protection possible for the NABFT.
As the main driver for tuna-farming is the demand for it, decreasing demand would be the most effective solution to the tuna-farming problem. However, it is an uphill task to change consumption patterns, since sashimi is an integral part of Japanese cuisines, and the top lunchtime seafood in America (Ellis, 2009).
Despite the challenges to reduce demand, there is still a need to campaign and raise awareness among the consumers about the plight of tuna. Influencing demand could start by promoting reduced consumption of tuna, and encouraging consumers to demand their restaurateurs serve only tuna caught or farmed in a sustainable manner, though that would require high transparency and accessibility of information for consumers. Apart from individual action, there are several other protection measures that can be implemented at a national and international level.
It is evident that the continued harvest of juvenile tuna would be unsustainable and should be abolished. Local governments can provide subsidies to aid the costly transition from tuna-harvesting to tuna aquaculture. The methods pioneered by Kinki University of Japan can be replicated to breed tuna in captivity and rear them from hatched eggs to marketable sizes (Ellis, 2009). Tuna-aquaculture is more sustainable in the long run as it can allow natural fisheries to replenish and truly lessen pressure from the wild stock. Furthermore, once tuna-farms transit to aquaculture, the international regulations on aquaculture would apply to these aquaculture-farms, and hence they would be legally bounded to abide by the pollution limits.
Governments can also help to subsidize research and development of better farming technologies. Developing improved and less-polluting aquaculture technology could prevent the spill-over effects of pollution. Development of pellets that could fatten tuna up with minimal use of fish could reduce the reliance on fish pieces for feed. Pellets combining grain, fish and vitamins have been developed but were unpopular as the fat content from grains was insufficient to fatten the tuna. Nonetheless, there is potential in the pellet technology as lower volumes of small fish are needed, and it requires only about six to seven days to change the diet of tuna from baitfish into pellets. Moreover, the cooking process in pellet-production can eradicate diseases and reduce chances of infection.
Tuna-farms and known spawning areas can be turned into marine reserves where fishing is strictly illegal. Satellite imaging can be used to provide live-feed monitoring on tuna schools and marine reserves and to facilitate low man-power deployment and more effective monitoring at a bigger scale. While that might mean losing a lucrative industry, it might also mean that future generations can still get to enjoy the world’s best-loved fish.
Japan’s high demand for tuna sets the astronomical prices in the tuna market. The high prices are due to and also the reason for the scant numbers of tuna left in the oceans (Seabrook, 1994). An international price ceiling for both tuna fisheries and farms could be implemented. By intervening directly with the market price, supply can be effectively slowed as the profit margins would be drastically reduced. Laws and severe punishment have to be enforced to deter illegal catches, while closer monitoring has to be put in place to ensure catches do not end up in black markets that might have emerged due to the setting of a price ceiling. Rising demand from lowered prices can defeat the purpose of a price ceiling. Hence, efforts to reduce demand have to be taken alongside.
If we continue harvesting BFT in this unsustainable manner, ignoring the ill-effects because of scientific uncertainty, we would be heading towards a destructive path where irreparable damage would have been done to the wild BFT populations, perhaps with no possibility of rebuilding stocks (Tudela et al., 2005). Tuna-farming has brought with it many problems that further threaten the very survival of the BFT, but it can be properly managed.
However, this might require enough political will in individual countries, and unprecedented multinational cooperation. If we succeed in changing the economic and political landscape of the tuna-farming industry, there is hope of saving the BFT. While fishery and farming management is a fine and noble goal, there must be something left to manage. We should not wait until it is too late as extinction would be beyond recall.
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