mesh regulation on the effort-yield 

 relationship. At normal effort levels a 

 28 percent increase in annual landings is 

 expected. Ihe point of maximum sustained 

 yield is advanced from 75 percent to 125 

 peroait of normal. The 125 percent level 

 would not be the point of maximum net 

 economic yield, however, since a 25 percent 

 increase in effort results only in an in- 

 crease of 1 percent in fleet landings. 

 Between 75 percent and 200 percent of 

 effort the range in landings is only a 

 little over 3 percent. 



Although the data developed in table 

 III-9 is based on the 1931-h8 period, it 

 need not be revised for purposes of cost 

 analysis of the effort-yield relationship. 

 This period may be taken as typical of pr»- 

 mesh regulation fishing. Were the base 

 period to be 1931-52, average annual land- 

 ings would be 2 percent less and fishing 

 effort 2,5 percent less. Any bias, there- 

 fore, in using table II 1-9 is on the side 

 of liberality in yield "estimate. " Still, 

 it will be found that there is overfishing 

 in an economic sense. 



The effort-catch analysis serves as 

 a foundation on which to estimate the 

 number of large otter trawlers to be ex- 

 pected at each level of fishing effort. 82/ 

 This is done by making certain assumptions 

 based on actual practice and on average 

 per vessel fishing effort. These assun?)- 

 tions concern the amount of fishing versxis 

 non-fLshing time per trip out of port, the 

 minimum and maximum length of each trip, 

 the minimum and maximum number of pounds 

 landed per trip, and the total number of 

 days a boat would be out of port annually. 



Specifically these assumptions are: 

 (1) Ihat on the average each vessel will , 

 have 2,5 days non-fishing time per trip.22' 

 Non-fishing time is time spent sailing to 

 or from the fishing banks or in sailing 

 ftrom one part of the fishing grounds to 



another. (2) That a vessel captain will 

 attempt to land at lP4st 65,500 pounds 

 per average trip. 2h/ (3) When catch per 

 day is above 11,900 pounds, a vessel's 

 operations will be limited (on an annual 

 average) to an 8-day roiond trip. When 

 the catch per day is under 11,900 pounds, 

 a vessel's captain will try to Ush long 

 enough to land 65,500 potmds but not be- 

 yond the point where total trip time is 

 over 10 days. The upper limit is nec- 

 essary to prevent spoilage of the first 

 caught fish, (h) The total number of days 

 a vessel will be away from port, annually, 

 will be approximately 2ljO, 



Table III-IO incorporates the fore- 

 going assumptions with the effort-catch 

 relationship of table III-9 and thereby 

 gives an estimate of the number of large 

 otter-trawlers to be ejqsected at the 

 various levels of fishing effort. The 

 situation portrayed is one in which brood 

 recruitment has retximed to what was con- 

 sidered normal in the 1931-ii8 period. 

 Thus landings are at the level predicted 

 at the time the mesh regialation was 

 adopted. There is increasing evidence 

 that thla assumption errs on the side of 

 liberal landings. Brood recruitment has 

 been at such a low level for such a long 

 time as to make it impossible to predict 

 when it will return to the higher levels 

 which obtained in earlier years. This 

 bias toward more liberal landings than 

 are more likely to occur is explicitly 

 recognized. It can be shown, however, 

 that even with the more liberal yield 

 assumption there is uneconomic overfish- 

 ing. If such is the case, then there 

 would be even greater overfishing if 

 yields were to remain as they are at 

 present. 



Columns I, n. III and IV, on effort, 

 catch per day, and total fleet landings 

 are derived from table III-9, Columns V, 

 VI, and VIII, on days actually fished per 

 trip, trip lengths, and total days absent 



82/ Based largely upon unpublished manuscript of Mr. Clyde C. Taylor, Fishery 

 Research Biologist, Woods Hole Laboratory, United States Fish and Wildlife Service, 

 Woods Hole, Massachusetts. 



83/ Source! Data submitted by United States Fish and Wildlife Seirvice to 

 In^rnational Commission Northwest Atlantic Fisheries, 1955-1956, 



6h/ Source: Historical Data from United States Pish and Wildlife Service. 



li? 



