NEVES: OFFSHORE DISTRIBUTION OF ALEWIFE AND BLUEBACK HERRING 



Nantucket Shoals; catch records of blueback her- 

 ring were too infrequent to determine summer 

 occurrence. Both species were rarely captured in 

 water deeper than 100 m in summer. 



During fall surveys, catches of river herring 

 were less frequent than during the spring, even 

 though more stations were sampled (Table 1). Dis- 

 tribution of catches was similar to that in summer, 

 except that a concentration of both species was 

 evident along the northwest perimeter of the Gulf 

 of Maine (Figure 8). Catches of river herring were 

 recorded at most stations in this region. In 12 yr of 

 autumn bottom trawl surveys along the Atlantic 

 coast, river herring were never collected offshore 

 south of lat. 40° N. 



The relatively small number of winter sampling 

 stations was inadequate to define the wintering 

 area for either species (Figure 7). The few winter 

 catches were widely distributed, primarily from 

 lat. 40° N (south of Long Island) to lat. 43° N (north 

 of Cape Cod). 



Commercial Catches 



The time periods for major catches of river her- 

 ring in ICNAF divisions by domestic (primarily 

 inshore) and foreign (offshore) fisheries are sum- 

 marized in Figure 9. Domestic catches in Subarea 

 5 resulted from both inshore and offshore fishing 

 operations. The south to north progression in 

 spawning runs is reflected in the time and location 

 of commercial catches by the United States (Sub- 

 areas 6 and 5) and Canada (Subarea 4), since most 

 domestic catches occur during the upstream mi- 

 gration of anadromous stocks in each subdivision. 

 The periods of principal foreign catches preceded 

 or overlapped those of domestic catches in coastal 

 waters. The year-round occurrence of river herring 

 between Long Island and Georges Bank, as indi- 

 cated by NMFS survey data, was corroborated by 

 commercial catches in ICNAF divisions 5Zw and 

 5Ze (Figure 9). 



DISCUSSION 



Offshore Distribution 



Fish sampling during NMFS bottom trawl sur- 

 veys covers a large area in a relatively short period 

 and provides the most detailed, available records 

 on offshore distribution of fishes and concurrent 

 environmental conditions. As judged by the ac- 

 cumulated survey data, the seasonal offshore dis- 



FlGURE 9. — Seasonal distribution of major catches of alewives 

 and blueback herring in divisions of the International Commis- 

 sion for the Northwest Atlantic Fisheries, 1970-78, Cape Hat- 

 teras, N.C., to Nova Scotia. Within each division, the months for 

 major catches are showm separately for foreign vessels (upper 

 entry) and the domestic fishery (lower entry). 



tribution of alewives and blueback herring resem- 

 bles that of American shad, Alosa sapidissima 

 (Neves and Despres 1979). River herring are 

 widely distributed along the Middle Atlantic 

 Bight during spring, appear to move north in the 

 Nantucket Shoals, Georges Bank, and coastal Gulf 

 of Maine areas during summer and early autumn, 

 and then return south to the mid- Atlantic coast in 

 winter and early spring. The extent of overwinter- 

 ing in deep water off the continental shelf is un- 

 known. The similarities in seasonal distribution 

 between American shad and river herring may be 

 indicative of similar inshore and offshore migra- 

 tory patterns. However, a determination of stock 

 mixing and migratory routes is not possible, be- 

 cause no tagging studies have been conducted 



481 



