UNAM researcher Walter Ritter Ortiz. (Photo: dgcs.unam.mx)
Effects of 'El Niño' and 'La Niña' analysed in tuna stocks
Monday, January 02, 2012, 23:50 (GMT + 9)
A team of experts from the Centre for Atmospheric Science (CCA) of the National Autonomous University of Mexico (UNAM) showed that the dynamics of the tuna stocks is linked to the oceanic events El Niño and La Niña, which are atypical heating and cooling phenomena in tropical waters.
Under the research project entitled 'Climatic effects on the pelagic tuna abundance,' scientists found out that the effect of El Niño causes a decrease of up to 14 per cent in the tuna population.
However, they noted that after this oceanographic condition the rejuvenation of the population takes place, which leads to the formation of recovery loops.
This has been remarked by Walter Ritter Ortiz, head of the Department of Bioclimatology of CCA, who along with Sergio Guzman Ruiz is working on mathematical models of natural resources such as fisheries, among others.
Ritter Ortiz noted that the Eastern Pacific Ocean (EPO) is the world's most productive area of yellowfin tuna. Besides, it is the place where are all atmospheric phenomena are climatically formed in the Northern Hemisphere.
UNAM scientists explain that if the event is too large, the fish schools rejuvenate and remain above their proportions. In 1982, for example, it was noted that the advent of El Niño caused an increase of 40 per cent of fish stocks, including the pelagic ones.
According to Ritter Ortiz, the temperature and the presence of tuna can be used to predict the presence of El Niño phenomenon: "We've studied it but from the viewpoint of a new physics and mathematics called Analysis of Complex Dynamic Systems.”
"We have proposed a new vision in the mathematical modelling of these resources, through Complex Dynamic Systems, which produce a better representation of the natural phenomena than the traditional formula," he points out.
The researchers argue that "the classical methods are necessary but not sufficient", so a "new transdisciplinary and interdisciplinary vision that allows for better management should be used."
According to these experts, if these methods are followed and are complemented with the existing ones, the benefits will be very important, since the populations could increase up to 40 per cent.
According to the data from the Inter American Tropical Tuna Commission (IATTC), between 1 January and 30 October, 2011 a total of 474,552 tonnes of tuna was caught, 17.7 per cent more than in the same period last year, when 402,868 tonnes were captured.
Until 30 October, the Mexican vessels captured 118,613 tonnes of tuna, the Ecuadorian fleet caught 171,140 tonnes, the vessels from Panama captured 48,558 tonnes and those from Venezuela caught 40,659 tonnes, among others.
By Analia Murias