Fish can be sorted under the water 

The future prospects are palpable. Every year in the North Sea alone, about 500,000 tons of fish are thrown overboard from the decks of trawlers because they are undersized or of the wrong species.

This can be avoided by filming the fish with underwater cameras and sorting out those which one does not want to catch before they even come into the net, thereby preventing injury to the undersized fish which would normally be returned to the sea.

The concept has been developed by COWI’s subsidiary, Matcon, which got the idea of the underwater camera from its work on a digital picture process that recognises fish. But the model has yet to be put into production.

A financial problem

“We do not know how many of the fish that are returned to the sea survive, but without doubt mortality is high, as the fish are crushed in the net during trawling and are affected by the handling they receive on deck. This is not just an ethical problem, but also a financial one,” says Erik Andersen, development and mechanical engineer at COWI.

He hopes that the model will contribute to solving some of the major problems affecting fishing stocks in the North Sea, the Skagerak, the Kattegat and the Baltic.

“We have witnessed major technological developments within mechanics, process control and sensors, which pave the way for new initiatives. It is about time we took a look at the fishery industry from the point of view of the new technologies, e.g. for improving selectivity. What is important is to switch from passive to active sorting,” Erik Andersen believes.

Published: 16.01.2004