Abstract.— Changing temporal 

 and spatial distribution patterns of 

 Atlantic herring Clupea harengus 

 larvae collected off southern New 

 England over two decades provided 

 early signals of large-scale changes 

 in adult spawning biomass that are 

 now a matter of record. Four con- 

 trasting spawning patterns were evi- 

 dent during the 20 yr period. Each 

 pattern covered successive multi- 

 year intervals and reflected the cor- 

 responding status of the adult popu- 

 lation. In 1971, spawning occurred 

 throughout the Georges Bank/Nan- 

 tucket Shoals/Massachusetts Bay 

 study area. The principal spawning 

 grounds of herring in the Gulf of 

 Maine region were located on the 

 Northeast Peak of Georges Bank. 

 With the collapse of the Georges 

 Bank fishery in 1976, spawning re- 

 ceded westward to Nantucket 

 Shoals. By 1979, larvae occurred 

 only in the Stellwagen Banks area 

 of Massachusetts Bay, the smallest 

 of the three subareas. After a 6yr 

 hiatus, spawning beds on Nantucket 

 Shoals were reoccupied in 1985. By 

 1988 spawning had advanced east- 

 ward to Cultivator Shoals on 

 Georges Bank, but through 1990 we 

 found no evidence of renewed spawn- 

 ing activity on the historically-promi- 

 nent spawning beds on Northeast 

 Peak. The rebuilding process was at- 

 tributed to recolonization rather 

 than resurgence. 



Larval distribution patterns: Early 

 signals for the collapse/recovery of 

 Atlantic herring Clupea harengus 

 in the Georges Bank area 



Wallace G. Smith 

 Wallace W. Morse 



Sandy Hook Laboratory. Northeast Fisheries Science Center 

 National Marine Fisheries Service, NOAA 

 Highlands. New Jersey 07732 



Manuscript accepted 8 February 1993. 

 Fishery Bulletin, U.S. 91:338-347(1993). 



338 



The Atlantic herring Clupea harengus 

 has been a target species of broad-scale 

 early-life-history research in the Gulf 

 of Maine since 1956. The initial larval 

 surveys were part of a collaborative 

 study by U.S. and Canadian biologists 

 to define the stock structure of her- 

 ring in the Northwest Atlantic (Tibbo 

 et al. 1958). This effort continued over 

 two spawning seasons and was fol- 

 lowed by annual observations on dis- 

 tribution patterns of herring larvae 

 during 1962-70 (Boyar et al. 1973b). 

 Thereafter, U.S. biologists participated 

 in a multinational field program that 

 represented the starting point of the 

 Northeast Fisheries Science Center's 

 (NEFSC) current database for larval 

 herring. This study, sponsored by the 

 International Commission for the 

 Northwest Atlantic Fisheries (ICNAF), 

 was initiated in 1971 to identify mecha- 

 nisms that influence survival of larvae 

 (Lough etal. 1985). 



With the termination of ICNAF lar- 

 val herring surveys in 1977, NEFSC 

 began a comprehensive fisheries eco- 

 system study of the Northeast Shelf 

 Ecosystem (Sherman 1986, Smith 

 1988). This program, known as Ma- 

 rine Resources Monitoring, Assessment 

 and Prediction (MARMAP), included 

 standardized year-round surveys of fish 

 eggs and larvae to provide baselines 

 against which shifts in species compo- 

 sition and diversity within the finfish 

 community could be observed and 

 evaluated. These surveys continued for 

 11 years, ending in December 1987. 



In 1988, ecosystems research em- 

 phasis at NEFSC shifted away from 

 year-round surveys of the entire 

 Northeast Shelf Ecosystem and fo- 

 cused on the Georges Bank area dur- 

 ing autumn and winter. The new ini- 

 tiative was designed to document the 

 changing status of herring and in- 

 vestigate density-dependent popula- 

 tion regulation between herring and 

 sand lance Ammodytes spp., impor- 

 tant coastal pelagic species in the 

 western North Atlantic. Wlien com- 

 bined, the three multi-year research 

 endeavors conducted since 1971 pro- 

 vide an uninterrupted 20 yr database 

 for larval herring in the Georges 

 Bank/Nantucket Shoals/Massachu- 

 setts Bay area. During this period, 

 dramatic changes occurred in the her- 

 ring population. 



Spawning biomass was relatively 

 high at the onset of the ICNAF lar- 

 val herring surveys in 1971, although 

 in decline due to intense foreign 

 fishing pressure that began in th.e 

 mid 1960s. During the 1960s and con- 

 tinuing through the mid 1970s, bio- 

 mass of herring on Georges Bank was 

 estimated at 400,000-600,000 1. An- 

 nual catches ranged from 150,000 to 

 374,000 1. Dominating the population 

 during the 1960s were three year- 

 classes, 1956, 1960, 1961, and to a 

 lesser extent 1966, although spawn- 

 ing success was poor in the closing 

 years of the decade. Despite a strong 

 1970 year-class that entered the 

 Georges Bank fishery in 1973, fishing 



