If we can maintain adequate stocks, there is no apparent reason why there should not still be a stable and viable trap fishery, especially when trap crews can combine it with other fishing methods such as handlining, gill-netting and longlining. But as time and fish have been lost, it is obvious that something needs to be done to preserve the fishery. What Technology Tells Us H igh-resolution sonars, a refinement of the same sounders fishermen use, also help scientists understand fish behaviour. A computer then processes the sonar data to generate a vivid snapshot of a school of fish and how the school is organized. E very year scientists comb the ocean surveying the abundance of groundfish, including the all-important northern cod.
Technicians sort, measure, weigh each fish and determine the sex.
The data is carefully recorded and compared to surveys done in other years. S ometimes some of the livelier fish are set aside for tagging - an old, reliable method of tracking where fish move. The tag is attached to a wire passed through the muscle under dorsal fin. Numbers on the tag record where and when the fish was first caught. When people who catch tagged fish return the tags together with details of the time and place, the tags can supply a lot of valuable information on fish growth and movement.