40 



During this period the primary emphasis was upon the effects of 

 mesh size on fishing mortality. Mesh size was the earliest method of 

 international fisheries regulation, and thus ICNAF scientists concen- 

 trated on this issue. It was not until later that season and area 

 closures were instituted as it became clear that mesh size, while main- 

 taining a stock, could not restore depleted stocks. 



However, ICNAF regulations regarding mesh size often failed to 

 require a mesh size limit for new fisheries. As foreign fleets entered 

 the Georges fishery, they were often able to operate on certain species-- 

 for example, redfish--with gear requiring no mesh size limits at all. 

 Yet because qroundfish species frequently mingle, a vessel harvesting redfish 

 with unregulated gear often caught other species of value, such as cod and 

 haddock. While directed cod fisheries required certain types of gear, a 

 by-catch of immature cod would result from the smaller mesh size utilized 

 in the refishery. In the late 1960s this was recognized as a serious 

 problem, but in 1962 there was only passing mention of this issue 

 throughout the assessment community. 



The Working Group went on to predict future haddock yields given an 

 increase in effort. The following table takes 1961 effort as "present" 



level of effort and predicts landings per unit effort resulting from 



(49) 

 total effort (as % of present level): 



Table IIC 



Effort 50 75 100 200 



(pr&sent) 

 Landings 86 95 100 102 



Landings per 172 130 100 51 



unit effort 



