Tuesday, April 3, 2012

Eating Wicked Tuna - Great Stuff

Bluefin programming debate? What debate?
Over at Deep Sea News more in depth discussion on Nat Geo's new show Wicked Tuna.

One of the reasons we feature this outstanding blog is the constant stream of independent and critical thought that emanates from it like the raw unrestricted energy from a Pulsar.

Read this post today, it's as good as it gets.

"When I wrote about Wicked Tuna, the National Geographic channel’s Atlantic bluefin tuna fishing reality show (first aired Sunday night), I thought it would be pretty straightforward. Every rating system  – Seafood Watch, Sea Choice, Blue Ocean Institute – lists Atlantic bluefin as an “Avoid.” A look through the scientific literature – though I am not a tuna or fisheries expert – showed a vast gap between the fisheries literature, which focuses on bluefin population structure , and the conservation literature, which is trying to sound the alarm about bluefin’s decline. Frankly, I didn’t think it would be terribly controversial to argue that a purportedly conservation-focused organization like National Geographic shouldn’t encourage consumption of Atlantic bluefin tuna."

Complete post here.

Shark catches in the Marshall Islands Tuna Fishery

Identification of factors influencing shark catch and mortality in the Marshall Islands tuna longline fishery and management implications


Bromhead, D., Clarke, S., Hoyle, S., Muller, B., Sharples, P. and Harley, S.


Recent average annual catches of sharks by tuna longline vessels fishing in the Republic of the Marshall Islands (RMI) are estimated to be between 1583 and 2274 t. Although 22 shark species have been recorded by the observer programme for this fishery, 80% of the annual catch comprises only five species: blue shark Prionace glauca, silky shark Carcharhinus falciformis, bigeye thresher shark Alopias superciliosus, pelagic thresher shark Alopias pelagicus and oceanic whitetip shark Carcharhinus longimanus. Wire leaders (i.e. branch lines or traces) were also used by nearly all observed vessels. Generalized additive model (GAM)-based analyses of catch rates indicated that P. glauca and A. superciliosus are caught in higher numbers when vessels fish in relatively cooler waters, at night, close to the full moon, when the 27° C thermocline is close to the surface and during El NiƱo conditions. In contrast, C. falciformis, A. pelagicus and C. longimanus are caught in higher numbers when shark lines are used (all three species) or hooks are set at a shallow depth (A. pelagicus and C. longimanus and, also, P. glauca). These findings are generally consistent with current knowledge of these species’ habitat preferences, movement and distribution. The results of these analyses were combined with information pertaining to shark condition and fate upon capture to compare the likely effectiveness of a range of potential measures for reducing shark mortality in the longline fishery. Of the options considered, the most effective would be to combine measures that reduce the catch rate (e.g. restrictions on the use of wire leaders, shark baits and shark lines) with measures that increase survival rates after post-capture release (e.g. finning bans).

Journal of Fish Biology. Early View Version. doi: 10.1111/j.1095-8649.2012.03238.x