保护海洋食物链中的小鱼儿

Perhaps you've had salmon, tuna, or swordfish for dinner recently. Or maybe it's on the menu tonight. Every big fish that lands on your plate got that big by eating lots of little fish. If you don't have abundant small fish in the ocean, you won't have the big fish.

That's why scientists, fishery managers and advocacy groups are paying more attention to the small prey in the world’s oceans. Some environmental groups also want tighter regulation on ocean catches of these smaller fish, and that's making fishermen nervous.

Fisheries biologist Jen Zamon learned lots of things in graduate school, but how to get a newly-captured seabird to barf in a bucket was not one of them. She finds squirts of warm water down the gullet and squeezing the tummy does the trick.

VOA - T. Banse

Zamon and her team from the NOAA research station in Warrenton, Oregon, want to know what fish the diving birds at the mouth of the Columbia River are eating.

"Yeah, it's definitely anchovies," she says after examining the vomit.

The day before, Zamon says, the vomit samples mostly contained half-digested surf smelt.  Other examples of prey fish include sardines, herring and mackerel.

"Things like sardines and anchovy, which are extremely abundant, are very important not just for fishery, but for feeding other creatures in the food web - mammals, birds, larger fish," she says. "It's very nice, we know these bird species are indicators of where these fish species of interest are."

This seabird dining survey is just one example of scientists paying greater attention to the fortunes of smaller fish. A significant transformation is even more noticeable among policy makers, managers and some environmental groups. Earlier this year, the Pew Environment Group started a campaign to protect small, schooling fish.

"We knew it was the next logical step," says Paul Shively, who manages the campaign out of Portland, Oregon. "This issue is picking up more and more steam all across the nation.  There's more and more attention, more and more science pointing to the fact that we need to make sure there's enough food in the oceans."

Another environmental advocacy group, called Oceana, is running a similar healthy ocean campaign. Conservationists report progress in moving fishery managers to base decisions not just on the "big money" fish, but on the entire ocean food web. Insiders call this "ecosystem-based management."

But when talks turns to limits on fishing for small, schooling fish, then resistance crops up.  On America's West Coast, ocean advocates want fishery managers to cap quotas for bait fish at current levels and put a moratorium on any new fisheries.

Commercial fisherman Ryan Kapp of Bellingham, Washington, argues that the West Coast sardine, anchovy and herring fisheries are already managed quite conservatively.  

"Seeing that none of these stocks are overfished or even approaching overfished, I’d just as soon leave it alone," says Kapp. "We have enough regulations to keep track of as it is."

Environmentalists worry that rising global demand for seafood and fish meal will put pressure on small fish. At the Pew Environment Group, Paul Shively urges what he calls a precautionary approach.

"We don't need to wait until there is a crisis in our oceans to address an issue. For so many years, we've looked at our oceans and we wait until there is a collapse of a fishery before we take action. We're saying it doesn't hurt to have a new paradigm where perhaps we take some precautionary measures."

Shively has made that case to federal fishery advisors including Bob Emmett, a marine biologist with the federal oceans and atmosphere agency, NOAA. Emmett says it's premature to come down with a hard, regulatory hand.

"There are still a lot of data needs," Emmett says. "If you are actively managing these fishes, that means you have a lot of information. We don't believe at the time that we really have it."

The fortunes of small fish are also surfacing at the state level. The California legislature is considering a law to promote ecosystem-based management in nearshore state waters.