Analysis shows training wild fish to herd is economically advantageous.
Ranching cod off the coast of Iceland is far more financially sensible than conventional fishing methods or keeping the fish in cages, according to a new analysis.
Fish ranching — where the animals are free to roam but trained to return to a certain point so they can be caught — could one day become a significant part of global fisheries, fitting between traditional catching and aquaculture, says Björn Björnsson, the lead author of the study, published in Marine Policy on 1 April. It could even reduce the catching of fish that are not the target species or are undersized, says Björnsson, a fisheries scientist at the Marine Research Institute in Reykjavik.
‘Ranching’ allows fish to roam free but attempts to condition their behavior so they can be rounded up for feeding and eventual capture. Some researchers are experimenting with sound signals that condition the fish to return to feeding stations. But Björnsson’s economic analysis is based on a simpler method, by which otherwise wild fish are conditioned by regular feeding at specific feed stations.
Based on data from an experiment off Iceland conducted in 2005-06, Björnsson estimates that ranching is the most profitable way of putting cod on dinner plates, followed by traditional fishing and then capturing wild fish for growing in pens.
He estimates that a typical fishing boat could make a profit of €71,000 (US$103,000), through traditional fishing, for 200 tons of cod. But the same boat involved in cod ranching could bring in more than 36 tons of cod with a net profit of €150,000.
“In the future, ranching in ‘herds’ could become a significant part of the fishing/farming industry globally,” says Björnsson. “It will not have to reduce the conventional farming and fishing; it may rather increase the total yield of fish for human consumption.”
And it could be done in an environmentally friendly way, he adds. Rather than indiscriminately netting all fish around the target animals, training a herd to respond to stimuli would mean fishermen could take just the species they were after at a time they were the right size.
- Atlantic Cod Show Signs of Recovery Off Nova Scotia (news.sciencemag.org)
- Exotic fish to replace cod (telegraph.co.uk)