MARINE SCIENCE: by Peter WestmoreNews Weekly
Bluefin tuna: an endangered species?
, May 14, 2011
One of the most important fish species is tuna, and, of these, bluefin tuna are regarded as being of iconic significance because of their beauty and their economic importance to the fishing industry.
Like many fish species, not very much is known about their life cycle, and therefore reports of a collapse in fish numbers need to be taken seriously. This is especially so because there are many parts of the world, particularly in the northern hemisphere, where controls on commercial fishing have been poor.
A recent report by the International Union for the Conservation of Nature (IUCN) claimed that more than 40 species of marine fish currently found in the Mediterranean could disappear in the next few years. According to the report, commercial species, including the bluefin tuna, are considered threatened or near threatened with extinction in the Mediterranean, mainly due to over-fishing.
“The Mediterranean and Eastern Atlantic population of the Atlantic Bluefin Tuna is of particular concern,” said Kent Carpenter, IUCN global marine species assessment coordinator.
“There has been an estimated 50% decline in this species’ reproduction potential over the past 40 years due to intensive over-fishing. The lack of compliance with current quotas, combined with widespread under-reporting of the catch, may have undermined conservation efforts for this species in the Mediterranean.”
These alarmist claims, which were widely reported in the media, are flatly contradicted by the most recent detailed reports from the International Commission for the Conservation of Atlantic Tunas (ICCAT), a body set up in 1969 to ensure the sustainable harvesting of tuna species.
Because it has refused to impose a full ban on tuna-fishing, the ICCAT has been vilified by various conservation organisations — among which the World Wildlife Fund (WWF), Greenpeace, the International Union for the Conservation of Nature (IUCN) and the Pew Environment Group have been most prominent.
The ICCAT, which has 48 member-states among its affiliates, was established to protect the fishing industries in these countries, by ensuring sustainable fishing of tuna and related species. It exists to regulate, not ban, fishing of these species.
Because tuna are a migratory species, there is no point in any single country attempting to limit fishing in isolation from other fishing nations. Equally, it is important that all tuna-fishing nations adhere to the agreement, as partial efforts to ensure the sustainability of the tuna-fishing industry would clearly be totally ineffective.
Additionally, the life cycle of tuna and other ocean species is still poorly understood, and there is considerable disagreement among fishing nations as to the effect of fishing, as opposed to other factors, including availability of food and impact of predators on the number of tuna.
One of the functions of the ICCAT has been to collect scientific data on the impact of tuna-fishing.
In fact, the ICCAT is the only fisheries organisation that can undertake the range of work required for the study and management of tuna and tuna-like fish in the Atlantic.
Its work includes research on biometry, ecology and oceanography, with a principal focus on the effects of fishing on stock abundance. It collects and analyses statistical information relative to current conditions and trends of the fishery resources in the ICCAT Convention area. The commission also undertakes work in the compilation of data for other fish species that are caught during tuna-fishing.
One result of this research is that the ICCAT has been able to identify areas of the Atlantic Ocean and the Mediterranean where there had been over-fishing of particular tuna species, and it has established quotas for each country, to ensure the continuation of tuna fisheries.
ICCAT’s standing committee on research and statistics in October 2010 calculated the Mediterranean stock of bluefin tuna at approximately 175,000 metric tons, a significant improvement over a 2007 estimate of 78,000 metric tons, 57 per cent of the historical highpoint of the stock in 1955-1957. Management measures put in place by ICCAT have outlawed illegal unreported catches and set the stock on a track to regain its former prominence.
This, however, is not enough for the extreme environmentalists, who want a total ban on tuna-fishing, and have used media organisations such as the BBC to campaign for it.
One effect of the work done by the ICCAT has been to encourage fish-farming of tuna, where one of the largest companies, Umani Sustainable Seafoods, has established farm fisheries in the Adriatic Sea near Croatia, and off Mexico.
Umani strongly supports smaller quotas and stricter controls on the industry. It believes that all fishing should be subject to quota, based on a scientific assessment of maximum annual yield.
The tuna that are caught by Umami are being farmed year round in cages at its facilities in Croatia and Mexico, a step that is helping to increase biomass and decrease the need to over-fish wild stocks. Its ultimate aim is to remove the need for wild catch.