Johann Sigurjonsson and Thorsteinn Sigurdsson
Marine Research Institute, P.O.Box 1390, 121 Reykjavik, Iceland

It is well accepted that biological information is essential for successful management of fish stocks in addition to other important knowledge on the fishing operation in question.

The required level of knowledge varies between fish species and the intensity of exploitation. This paper discusses three different cases of fish stock management in the Northeast Atlantic, the fishery for summer spawning herring off Iceland, the Iceland cod fishery and the pelagic redfish fishery in the Irminger Sea.

The local summer spawning herring stock has been managed by adopted long-term harvest strategy based on optimum harvest level (Fo.i), resulting in full recovery of the former depleted herring stock in the last 30 years and a resource that has given relatively stable yield, not sensitive to fluctuations in recruitment, operational factors or errors in assessment methods.

The Iceland cod stock has been subject for intensive harvest for more than half a century and still constitutes the single most important fish stock exploited and managed by Iceland.

The fishery has been closely monitored and studied for decades and the last 10 years it has been managed according to a well defined and adopted long-term harvest strategy developed by biologists and economists in cooperation with fishing industry representatives. This has improved the management of the stock, while still stronger measures are needed to secure more rational utilization due to too heavy fishing pressure over a prolonged period of time and due to a greater uncertainty in the assessment of the stock than anticipated.

The international fishery for pelagic redfish in the Irminger Sea is an example of an international fishery where the knowledge base is still non-satisfactory despite considerable scientific efforts in recent years. Here answers to questions regarding stock identity and stock structure are inconclusive and knowledge on productivity is limited. This would have required a greater amount of precaution in the management than has been recognised. Thus the stock is left in jeopardy demonstrating a management failure due to shortage of knowledge and lack of responsiveness of responsible international management authorities.

The three examples discussed show how well founded biological knowledge of exploited fish stocks is important for successful management. It shows how moderately harvested fish stocks are far less vulnerable to over-harvest due to mismanagement or shortage of knowledge on critical aspects of the nature of the fish stock to be managed than overexploited fish stocks. And it shows how signals of over-harvest or shortcomings in knowledge need to be taken into account with precaution when determining management actions to be implemented.

FISHERY IN NORTH ATLANTIC: REALITY AND PROSPECTS