Some curious studies on the long-term impact of commercial fishing by David O. Conover (University of New York, Stonybrook) were covered in a recent Science News.
"Fish are becoming smaller and growing more slowly in response to pressures introduced by fishing, scientists say. That shift, which new data suggest is hard to undo, creates populations of fish that are poor at reproducing and inefficient at bulking up.National Public Radio covered this story couple of years ago, but at that point the science was based on record keeping, not laboratory observation. This link to a transcript of a 2003 "All Things Considered" report, is distressing.
Conover suggests one tactic to counteract such trends: Require that fleets throw back the largest fish as well as the smallest ones, thereby preserving fast-growing fish in any population."
As someone who has spent many hours offshore fishing for bluefin and yellowfin tuna, I am myself witness to the dwindling numbers. It isn't just migratory fish species that are declining in numbers, though. If these were animals of the sky or land, we would be able to observe the slaughter more easily, and perhaps then a sound conservation policy would be implemented. As is, we seem to feel that what we can't see doesn't matter.
Photo credit: Ed Pritchard, AntiqueFishingReels.com