Showing posts with label Eastern Pacific. Show all posts
Showing posts with label Eastern Pacific. Show all posts

Tuesday, May 10, 2011

Tuna in the Eastern Pacific: can scientists and fishermen at sea improve sustainability?

Tuna. Many of us grew up with our mother's weekly tuna casserole or that fragrant tuna fish sandwich that we could never trade for extra Oreos in the school cafeteria. For decades it truly was, to borrow a brand name, the "Chicken of the Sea."

But the once vast populations of tuna are now a shadow of their former selves, and the fate of this powerful pelagic predator is unclear at best.

However, scientists are trying to improve the methods by which tuna are hunted and caught - not to increase the commercial tuna fishing fleet's take, but to bring it to levels that will allow for long-term sustainability of the tuna.

The International Seafood Sustainability Foundation (ISSF) - a collaboration between scientists, the fishing industry, and the World Wildlife Fund - is working with a leading tuna industry association, the Inter-American Tropical Tuna Commission, to come up with techniques that will both help preserve tuna stocks at acceptable levels and reduce the enormous amount of bycatch that the tuna boats generate through the use of seine nets.

Departing from Ecuador, members of ISSF will spend two months aboard a tuna seine net vessel in the eastern Pacific to observe and study, ultimately with the idea of making recommendations on improved techniques that will enable tuna boats to harvest at levels that will allow for their economic survival while better managing the take of tuna and unintended bycatch.

"The problem and its scope have been identified," said Susan Jackson, President of ISSF. "Now it's time to get on the water and make significant improvements alongside industry that help them to remain viable without jeopardizing the world's tuna resources and the ocean's complex marine ecosystem." "In reality all fisheries have trade-offs and a certain level of environmental impact. Some have advocated for abandoning these fisheries, a move that industry has warned us would cut the world's tuna supply in half, lead to thousands of job losses and additional financial strain on developing economies. Rather than walking away and giving up, we must help a willing industry improve its practices."

If I may interject some personal commentary, based on what I have heard and read from a variety of knowledgeable sources regarding the present condition of the tuna populations, "walking away" may be our best option at this point. A moratorium on tuna would not be giving up, it would be a rational step in allowing the tuna stocks to recover (there are many scientists who fear that the tuna have been so heavily impacted by commercial fishing that a moratorium may be too little, too late).

Would a moratorium produce economic hardship for the tuna fishing fleet? To a noticeable extant, yes. Some fishermen could be re-trained to work in tuna aquafarming; others perhaps could shift to other more sustainable species. And others would have to leave the industry all together. One way or the other, it would not be easy. However, having listened to all the arguments coming from past international meetings, like those of the ICCAT (International Commission on the Conservation of Atlantic Tuna), it is my opinion that the tuna stocks are reaching - or in some areas of the world, have reached - perilous levels of depletion. And at these low levels there is no degree of fishing activity that would not push the tuna further towards extinction.

The ISSF's initial cruise will be followed by additional expeditions in both the Pacific and Atlantic Oceans, and what improvements are ascertained will be incorporated into teaching workshops for other fishermen. According to Dr. Victor Restrepo, Chair of the ISSF Scientific Advisory Committee,
"This cruise will help our team of scientists and collaborators improve the educational workshops already being conducted with fishing crews around the world. As scientists identify new solutions, we will incorporate the findings into workshops so that skippers and vessel captains can provide real-time feedback. If something isn't realistic or fishers have an idea on how to improve it, we'll have the ability to take the idea back onto the water."

I wish the ISSF much success in their undertaking, I truly do. But I have my doubts about sustainable tuna fishing and, indeed, any commercial venture that harvests fish in the wild. Nature never intended for tuna and other sealife to be harvested at the levels we do now to feed an expanding world population. True sustainable seafood will be that which is grown and harvested by man - just like the chicken, the tuna's commercial namesake.

Read about the ISSF's expeditions in the Canadian Business Network.

Monday, July 19, 2010

Jumbo Squid in Oxygen-Poor Zones: new study shows ability to expand territory and evade predation

New research adds further insight into the ability for the Humboldt, or jumbo, squid to expand its territory and become even more of a destabilizing predatory influence along the coast of the Eastern Pacific. In the latest issue of Progress in Oceanography, researchers from the University of Lisbon, Portugal, and the University of Rhode Island, U.S., studied the squid's metabolic rates in water with different oxygen levels - duplicating the oxygen-poor environment found in waters several hundred meters deep and also the oxygen-rich environment of relatively shallower depths.

Dr. Ruis Posa, of Portugal's Center for Oceanography, posed the question,
"Jumbo squid display oxygen consumption rates that are among the highest in the oceans. This high energy demand reflects the low efficiency of jet propulsion. So the question is how can they survive in these deep, cold and oxygen depleted zones?"

According to Dr. Rosa, from Portugal's Center of Oceanography, the squid displayed the ability to shut down its metabolism by as much as 80% in the oxygen minimum layer (OML). This enables the squid to find a safe haven during the day beyond the reach of many of its predators. During the night, the squid rejuvenates itself in shallower waters where its metabolic demands increase dramatically as it hunts for food using its jet propelled speed coupled with tentacles laced with tooth-lined suction disks.

As mankind continues to alter the marine environment, we are finding more and more areas of lower-than-normal or even near-depleted oxygen levels in the oceans, thereby providing the voracious Humboldt squid with the capability of expanding its range. An animal's territorial range can be maintained by a variety of factors, some of which are based on the quality of its environment and on the predators that help keep the population in check. With this newly studied metabolic ability, the Humboldt squid can utilize spreading OMLs to its advantage, avoiding predators during the day and causing havoc amongst commercially fished species at night.

Read the study in Progress in Oceanography. Read more about the study in BBC News. Watch video below from Google Earth/Ocean.