rfmcdonald | [LINK] "Keeping Farm Fish Locked Up Keeps Ecosystem Calamity at Bay" (Reply)

Brendan I. Koerner in Wired looks at how aquaculture specialists are trying to limit the potential environmental danger of aquaculture.

Aquaculture is fast becoming the main way that humans get their seafood fix. But fish aren’t cattle; they don’t turn passive when cooped up. Every year, hundreds of thousands of salmon, cod, and rainbow trout wriggle through damaged or defective cages and flee into the open seas, never to be recaptured. In addition to costing farmers millions in lost revenue, these escapees can wreak havoc on their wild brethren by polluting gene pools and spreading pathogens.

To prevent that sort of environmental calamity, Trine Thorvaldsen is studying how best to keep farmed fish from going on the lam. A labor health and safety expert at a Norwegian research institute, Thorvaldsen recently set out to determine why her country loses around 200,000 captive salmon per year. In addition to analyzing reams of incident reports and industry statistics, she also convinced numerous farmers to speak to her anonymously—no small feat in Norway, where allowing fish to escape is a criminal offense with stiff penalties. Her research has led her to conclude that avoidable human errors play a key role in Norway’s’ salmon escapes.

“There was one instance in which fish were being pumped from one cage to another, but the workers didn’t realize there was no net to keep them,” says Thorvaldsen, who is a cultural anthropologist by training; by the time anyone noticed the silly mistake, 13,000 salmon had swum away. Most of the fateful miscues that lead to mass “fishbreaks,” however, are less spectacular in nature. Workers sometimes have difficulty operating equipment, for example, and brush the vessels’ destructive propellers against the containment nets. Or they inadvertently tear those nets while using cranes to adjust the weighted tubes that maingtain the shape of underwater cages. Farmers are often unaware of these small fissures until hours later, at which point it’s often too late to dispatch recovery teams to the site. They must instead keep their fingers crossed that nearby fishermen will catch the piscine escapees before they start to interbreed with wild fish. (To encourage the recapture of escaped salmon, Norwegian cultivators have been known to offer 60-euro-per-fish bounties.)

For many years, fish farmers have pined for a technological solution to their escape problem: an alarm that can be wired into the nylon nets, to alert workers when tears are beginning to develop. But such a system has proven tough to invent and implement, largely because saltwater doesn’t play well with electrical wires. With no reliable alarm on hand, Thorvaldsen instead urges farmers to curtail errors by adhering to some common-sense workplace policies. These include making sure that laborers don’t work past the point of mental exhaustion, suspending operations when harsh weather or darkness approach, and insisting that all critical maintenance instructions be put down in writing rather than squawked over fuzzy radio channels. Thorvaldsen also wants managers to understand that certain delicate fish-farming procedures, such as using cranes, should never be rushed.

“We’ve had a lot of workers say, ‘We are under a lot of pressure, we have to do things fast, we have to deliver the fish when the boat’s there,’” Thorvaldsen says. The net tears that can result from such haste are what farmed fish dream of when they sleep.