I think with all the the issues being discussed concerning bluefin tuna, one that needs to be brought to light is the incidental catch of spawning bluefin tuna in the Gulf of Mexico by the U.S. pelagic longline fleet targeting yellowfin tuna. I’m no expert on the matter but this is what I’ve learned so far.
For those who are not up to date on the matter, our Western Atlantic stock of bluefin tuna spawns from April through June in a localized region in the Gulf of Mexico. Currently there is no protection in place for our prime breeding stock in the Gulf of Mexico from the pelagic longline fleet . The pelagic longline fleet actively targets Yellowfin Tuna in this region during the bluefin’s spawning season. The obvious result is the bycatch and dead discard of spawning bluefin tuna. Keep in mind that the Bluefin Spawning Stock Biomass has declined by 80% since 1970.
While there are currently two time/area closures in place in the Gulf of Mexico, these areas are outside of the bluefin’s known “breeding hotspot’s”. These time/area closures are in place to protect endangered sea turtles and juvenile swordfish and do little (to nothing at all) to protect the bluefin spawning stock biomass.
Certain groups have been actively seeking a time/area closure in the Gulf of Mexico in order to protect the bluefin spawning stock. In June 2005 a petition was filed with the U.S. Secretary Of Commerce calling for NMFS to establish a time/area closure to protect the spawning bluefin from the pelagic longline fleet in the Gulf of Mexico.
Here’s a link to the petition. The petition is full of information on the matter and worth reading.
http://www.oceana.org/fileadmin/ocea...n_Petition.pdf
Link to the proposed time/area closure
http://www.oceana.org/fileadmin/ocea...unaGRAPHIC.pdf
The petition was essentially ignored by NMFS.
This article gives an excellent overview of the situation and discusses the findings of Dr Barbara Block’s electronic tagging research conducted in the Gulf of Mexico and the Western Atlantic.
http://news-service.stanford.edu/new...na-042705.html
Dr. Block’s research discovered that incidentally hooked bluefin face an increased risk of mortality when hooked in the warmer waters of the Gulf of Mexico (inability to cope with high levels of body heat and the warm water of the Gulf of Mexico) compared to bluefin hooked in the cooler waters of the Atlantic which had a better chance of survival.
This is an excerpt from the article discussing Dr Block's research
Quote:
The problem, she notes, is that the longliners sometimes unintentionally snag bluefin tunas during the breeding season, and it's likely that many bluefins die before they can be released back into the sea. The researchers observed this first hand when they tried to catch bluefins from commercial longliners. "We found it difficult to tag and release live bluefin tuna off longlines, which created frustration for all involved," Block recalls.
The TRCC lab has conducted cardiac physiology studies that highlight the physical limitations of these fish. "Warm water holds less oxygen than cooler water," Block says. "We hypothesize that large endothermic bluefin are physiologically stressed during the hot breeding season when their need for oxygen is greatest. Being caught on a longline may be too much for breeding bluefin tuna to tolerate, male or female. We found the bluefin were easily killed on our scientific longlines in warm Gulf waters when the hooks were soaked for more than two hours. Lab studies suggest that the limitations to the tuna may be that its cardiac system cannot be pushed any further at the warm end of the performance curve." Capture on a hook must be stressful, she adds, so the fish simply die from lack of ventilation.
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The bluefin caught as bycatch in the Gulf of Mexico had survived to reach sexual maturity, made it to their spawning grounds and are/were actively spawning. However they are in direct threat of being caught as bycatch with an increased risk of mortality in the warmer waters of the Gulf of Mexico due to their inability to regulate their body heat once hooked.
How can this problem be allowed to exist with the current state of the fishery? How can Bill Hogarth go to ICCAT and call for a moratorium in the Med when he can’t even clean up the mess in his own back yard? The “Breeding Hotspots” in the Gulf of Mexico exist within the US EEZ (exclusive economic zone), our federal waters. We have the ability to resolve this issue without having to deal with foreign countries and economic sanctions (the problem of over fishing in the med).
It’s obvious that a time/area closure is warranted to protect our western bluefin spawning stock. It's common sense and it's supported by research.
As I said, I'm no expert on the matter. This post is mainly to get the information out there for people to read and be aware of. If anyone has some additional information on the matter please contribute
The bycatch of spawning bluefin tuna in the Gulf of Mexico 
