Smith and Morse Larval distribution patterns of C/upea harengus "on the Georges Bank 



339 



pressure by the large international fleet was so in- 

 tense that landings declined after 1971. From 1973 

 to 1975 the principal herring landings shifted from 

 the bank to the vicinity of Great South Channel, 

 just east of Nantucket Shoals. After 15yr of moder- 

 ate-to-heavy exploitation, and several years of quota 

 management under ICNAF, the Georges Bank her- 

 ring fishery collapsed in 1976 (Anthony & Waring 

 1980). 



This paper examines the 20 yr larval database to 

 look for early signals of the dramatic changes in 

 adult biomass that have occurred since 1971. We 

 evaluate the influence of transport mechanisms on 

 the spatial and temporal distribution patterns of lar- 

 vae to corroborate the herring stock hypothesis of 

 lies & Sinclair (1982) and Sinclair & lies (1985). 

 Finally, we search for supporting evidence that the 

 late-1980s recovery of herring in the Georges Bank 

 area resulted from population resurgence rather than 

 recolonization, a conclusion of Stephenson & 

 Kornfield(1990). 



Methods 



The 20 yr time-series began during the final years of 

 the international fishery. It included a 10 yr period 

 when essentially no fishing took place in the study 

 area, and ended with the 1990 spawning season when 

 a limited fishery was again underway. Without a di- 

 rected fishery after 1976, this dataset, along with 

 NEFSC semi-annual trawl surveys, provided the only 

 source of information to evaluate the status of herring 

 in the Georges Bank area for more than a decade. 



Sampling designs 



All three larval surveys used the 61cm bongo, fitted 

 with 0.333 and 0.505 mm mesh nets. Larval herring 

 catches from the 0.505 mm net were analyzed. Net 

 mesh selection was based on recommendations in Smith 

 & Richardson (1977) and on Colton et al. (1980) who 

 found no significant difference in retention rates of 

 herring larvae captured in the two mesh sizes. 



i. n 



Figure 1 



Station plan for (a) ICNAF larval herring surveys in the Georges Bank area, 1971-76, (b) MARMAP surveys in Georges Bank, 1977- 

 87. and (c) studies of herring/sand lance interactions, 1988-90. (d) General surface circulation in the Georges Bank area (after 

 Ingham 1982). 



