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Over-fishing and collapse of fish stocks in the Gulf of St. Lawrence

Mike Hammill, Maurice-Lamontagne Institute, Fisheries and Oceans Canada

What is the cause of the collapse of cod fish stocks in the Gulf of St. Lawrence? Over-fishing. Yet this is too simple an answer to a very complex question. In fact this question raises loads of other questions. Have fisheries scientists considered environmental changes and their impacts on cod fish stocks in establishing quotas? Have fishermen correctly declared their takes, an essential piece of information in establishing quotas? Have fishermen foregone the practice of releasing small fish in order to replace them with larger fish which are more profitable? Have scientists taken into account the warnings of fishermen concerning changes in the abundance of cod? Have politicians reduced the fishing effort as recommended by scientists in order to protect cod stocks?

The answer to all of these questions is no. Towards the end of the 1980s cod stocks were heavily exploited. At the same time, major environmental changes throughout the Gulf of St. Lawrence due, among other things, to variations in water temperature, had a considerable impact on cod fish productivity. Scientists continued to establish quotas based on high levels of productivity of cod, which meant that we went from a situation of intensive fishing to a situation of over-fishing.

On the other hand, in order to determine the quantities of fish taken, scientists base their studies on what the fishermen declare. If fishermen take more fish than they declare, scientists underestimate takes and overestimate the abundance of cod, which, once again adds to the pressure on cod fish stocks and the creation of a situation of over-fishing. The most deplorable example of this is what is commonly known as "dumping". This consists of releasing small fish in order to replace them with larger fish that are worth more. Take the example of a fisherman, whose boat has a five tonne load limit, who, after a full day of fishing, has caught only small fish. Near the end of the day he catches about four tonnes of fish. As he brings up the net he notices that he has come across a school of larger cod that are worth a lot more. Faced with this situation certain fishermen would throw back four tonnes of small fish and continue fishing until they catch five tonnes of large cod. They would then declare a take of five tonnes while, in reality, nine tonnes of fish were taken. Once again, it’s a case of over-fishing.

At the end of the 1980s, coastal fishermen noticed a drop in their catches. Trawlers, on the other hand, noted nothing of the kind. This can be explained by the fact that the distribution area of fish diminishes as its population diminishes. A coastal fisherman will catch fish only if his net is directly in front of a school. However, trawlers use powerful sonar in order to locate concentrations of fish. For this reason trawlers, which fish only where fish are abundant, would not notice changes in abundance as would a coastal fisherman. Due to the fact that elsewhere, as far as the scientists could tell, all indications were that cod stocks were doing well, they attributed the changes observed by coastal fishermen to a simple change in distribution. Looking back, it is obvious that ignoring the warnings of one type of fisherman once again led to over-fishing.

Finally, there are the politicians. Scientists realised that by the end of the 1980s there were problems with Atlantic cod stocks. They therefore requested a drastic reduction of quotas. Unfortunately, politicians declared these reductions impossible for they would mean closing down the fishing industry in numerous regions. Hence, over-fishing continued for several years before these closures became unavoidable: there were simply no fish left to catch.

This is but brief overview of a very complex situation. Every student in fisheries or marine biology should read what is probably one of the best popularised works on the subject: Harris, M. 1998. Lament for an ocean: the collapse of the Atlantic cod fishery, a true crime story. McClelland and Stewart Inc. Toronto, ON. 342 pp.