-96- 



III. B. 3. Results of Yield-per-Recruit Analysis 



Fisheries on the north Atlantic stock were realizing a 

 yield-per-recruit of about 3.8 kg in the 1970's, with a size-at- 

 recruitment of about 40 cm. Maintaining the current effort levels and 

 increasing size-at-first-capture to about 65 cm should produce about a 25% 

 increase in yield-per-recruit. This size-at-recruitment, however, will 

 likely impact the existing surface fisheries severely. Maintaining the 

 current size-at-recruitment and increasing or decreasing effort up to 20% 

 will produce no significant changes in yield-per-recruit. 1980 ICCAT 

 results indicate that changes in the surface fisheries patterns may be 

 increasing yield-per-recruit. 



III.B.4. Results of Spawner/Recruitment Analysis 



Analysis of spawner and recruit indices for the north 

 stock in recent years has caused concern at ICCAT. Current levels of 

 spawning stock indices appear to be about 15% to 20% as great as those 

 observed in the late 1950's (Figure 7). Indices of recruitment show a 

 possible declining trend with increasing variability. Recruitment as 

 measured by CPUE indices dropped from a value of about 16 in 1957 with 

 relatively little estimated variance, to a mean value of about 12 in the 

 last 5 years with variance increasing five-fold. Recent work indicates the 

 probability of a year-class failure may be as high as 10% to 20%. 



III. 8. 5. Results of Other Analyses/Simulations 

 None available. 



III.C. Current Evaluation of Stocks and the Fishery 



The available analyses indicate that the north Atlantic albacore 

 stock appears to be fished near MSY. Yield-per-recruit is not near a 

 maximum value, owing to substantial amounts of small fish in the catch. 

 However, little change appears possible without large changes in the 

 structure of the fisheries. The decline in recruitment (related to the low 

 yield-per-recruit) and apparent increases in variability, make a year-class 

 failure, as measured by the recruitment index, a real possibility. 



IV. STATUS OF CURRENT RESEARCH NEEDS AND EFFORTS 



IV. A. Major Research Problems 



1) Effort needs to be standardized to determine its effect on 

 production model results. 



