Tentative conclusions from two sea otter studies nearing
completion are that some of the smaller fuzzy-faced charmers can get
into, but cannot get out of, traps designed to capture fish alive.
It all depends on the size of the trap's opening and how big the otter is,; said Brian Hatfield, marine biologist with U.S. Geological Survey's field station at Piedras Blancas. 'We do know sea otters will drown in traps of various designs. We have evidence of that, which adds to the concern. And we have some anecdotal reports from fishermen about the live-fish traps. But some fishermen are using traps with small enough openings that would preclude most, if not all, sea otters.'
In one phase of the test, rehabilitated otters due for release from the Monterey Bay Aquarium repeatedly got into or tried to enter the test traps to get to the bait inside, said Jim Estes, a USGS marine biologist who also teaches at UC Santa Cruz. That otter inclination could put the mammals at risk of drowning when they can't get back out of traps in the open ocean, he said.
'Each time we'd get a wild otter in that has to be rehabilitated and released, just before the release, we'd run a test,' Estes said. 'We baited pots with crabs or other food the otters would be interested in to see if they'll enter or investigate the pots. We have seen, in most instances, they will do so very willingly, some repeatedly. They'd go in and get caught. We'd pull them out, and they'd go right back in again.'
The result was not a big surprise to the scientists. 'I imagine it's a lot like the ocean bottom to them, where they're constantly sticking their heads down into holes to find food,' Estes said. 'The trap is the same to them, but the only problem is they can't get out once they get in.
The second study, with observers in the field, was less definitive, he said, probably because stringent new state restrictions may have driven many fishermen from the live-fish fishery.We may reinstitute the studies later in the spring, when weather improves, if theres something to watch. It may be a moot point if there are not many people participating in the fishery, Estes said.
However, in San Luis Obispo County, Hatfield said, 'use of the fishery had started to decline before the new regulations went into effect. It could be that the fishermen switched to'stick fisheries instead, or that their catches may have been dwindling.'
Overall, the otter studies did not address whether or not the otters in the open ocean will use the same aggressive techniques to get into the traps, Estes said. The research doesn't speak to if they carry that behavior into the field. They may be more leery in the wild, but they may be hungrier.
The $30,000 studies were funded by the U.S. Fish and Wildlife Service and the World Wildlife Fund.
The need for the studies came to light when Hatfield 'brought the issue to my attention several years ago'Estes said. 'He saw the traps regularly being fished in the Morro Bay/San Simeon area, and suspected that juvenile otters could potentially be caught. He is also the steward of the sea otter census and mortality databases.'
A next step, as yet unfunded, Estes said, would be to work with the fishing industry to redesign the traps so that fish can get in but otters cannot.