The high mortality rate poses a threat to the cod population and the $40 million-a-year New England industry it supports.

When wild cod populations crashed, interest in farming cod increased.

By 1993 six cod populations had collapsed, forcing a belated moratorium on fishing.

The cod population along the Grand Banks of Newfoundland was almost completely wiped out, largely due to bycatch.

The researchers added that the technique could easily be expanded to other cod populations (like those in the northwestern Atlantic, which are also under pressure) and to other fish as well.

Because copepods are the main food of young cod, the cod population cannot recover, Dr. Pauly said.

These methods were not stressful on the cod population.

The use of draggers was found to be extremely detrimental to the cod population in several ways.

The sand-eel represents food to cod and it is the declining stocks of sand-eels that are causing the imbalance in the cod population.

Blue cod populations are managed sustainably under New Zealand's fisheries quota management system, although are becoming scarce in some small areas due to fishing pressure.