By Bernadette H. Carreon, Manila
A newer method of assessing bigeye tuna stocks in the Western and Central Pacific Ocean has resulted into a more positive appraisal of the population.
In 2014, the key scientists responsible for assessing the stock published new studies suggesting bigeye tuna stocks were down to 16 percent of the original population – a critical level.
Now the same scientists have completed much more detailed studies which suggest bigeye tuna are at 32 percent of their potential population.
Dr John Hampton told Pacific journalists here at the meeting of the region’s tuna management body, the Central and Western Pacific Fisheries Commission, that the latest assessment indicated a more productive stock that is more resilient to fishing that had previously been estimated.
Hampton, one of the marine biologists of the WCPFC Scientific Committee, said he and his colleagues have changed the way they measure the population and now have a different estimate on population size.
New research indicates bigeye grow and mature faster than they previously thought and do not grow as big.
The work is based on detailed data collected across the Pacific since 2011.
Analysis of the data was only completed early this year.
The results are a ‘profound’ change according to Dr Hampton and there is still much uncertainty, so in order to determine whether the big eye tuna stocks have decreased or increased, they need to keep studying the population using their new methods for longer period.
“I should say when we do these assessments we don’t just do one analysis using one formulation of the dynamics, we use a whole bunch of stock assessment models that try to capture all the different areas of uncertainty that we have throughout the stock so that we can capture and present what we hope is an honest assessment of the stock so that we can present a picture of what we know and what we don’t know,” Hampton said.
The current fishing rules for bigeye are contained in a resolution of WCPFC called the Tropical Tuna Measure, which expires at the end of the year.
Representatives from over 30 countries here at WCPFC14 in Manila have the job of deciding what will replace the Tropical Tuna Measure.
The Scientific Committee has recommended that there be no increase in bigeye mortality.
Forum Fisheries Agency (FFA) Director General James Movick too, warns that even with the more optimistic stock assessment, there is still no room for complacency when it comes to managing the stocks,
“It would be dangerous to suggest that given the current state of the stocks, maybe we can permit more fishing, particularly for bigeye,” Movick told reporters here over the weekend.
“The FAD closure measures agreed to by Pacific countries, even at an economic cost to them, have contributed to improvement in the stock status, and our general position is that we should — particularly at this early stage–call for caution,” he said.
Wez Norris, FFA Deputy Director General in today’s briefing with reporters said that there are some suggestions from (WCPFC) member nations that because of the tuna stocks positive assessment, fishing measures can be relaxed.
“I think the main concern for us ..is some fairly generous interpretations of the science in terms of how far we can relax existing measures.’ Norris said
The scientists are expected to deliver a more definitive report on their new studies next year.