Stone and Jessop: Seasonal distribution of Alosa pseudoharengus and A. aestivalis 



387 



although the Scotian Shelf has not been surveyed dur- 

 ing winter months (i.e., November-February). The 

 main summer concentration extends northward from 

 southwestern Nova Scotia into the Bay of Fundy. 



Other members of the clupeid family also exhibit 

 spatial and temporal discontinuity in marine distribu- 

 tion patterns. American shad winter off Florida, the 

 mid-Atlantic Bight, and in the Scotian Shelf-Bay of 

 Fundy region (Neves and Depres 1979, Dadswell et al. 

 1987), while summer concentrations occur off New- 

 foundland and Labrador (Hare and Murphy 1974), the 

 inner Gulf of St. Lawrence (Dadswell et al. 1987), the 

 Gulf of Maine (Neves and Depres 1979), and in the in- 

 ner Bay of Fundy (Dadswell et al. 1983). Atlantic her- 

 ring populations in the Gulf of Maine-Scotian Shelf 

 region have several geographically separate areas for 

 summer feeding (southwest Nova Scotia, Georges 

 Bank, Bay of Fundy) and overwintering (Long Island 

 Sound, Chedabucto Bay) (Sinclair and Isles 1985). 



Seasonal movement patterns of river herring infer- 

 red from American and Canadian survey data involve 

 a north-south progression and an inshore-offshore 

 movement similar to that described for American shad 

 populations along the Atlantic coast of North America 

 (Neves and Depres 1979, Dadswell et al. 1987). Dur- 

 ing spring, river herring from the Middle Atlantic Bight 

 move north as far as the Nantucket Shoals, Georges 

 Bank, coastal Gulf of Maine and even the inner Bay 

 of Fundy for the summer, then return south to the mid- 

 Atlantic coast in winter and early spring (Neves 1981, 

 Rulifson et al. 1987). The spring aggregation of mature 

 river herring observed in Canadian survey catches from 

 the southern Gulf of Maine likely consists of fish which 

 will move inshore to spawn in rivers along the eastern 

 seaboard of the United States, although some may 

 enter Canadian rivers. A large component of the over- 

 wintering population on the Scotian Shelf moves in- 

 shore during spring to spawn in rivers along the Atlan- 

 tic coast of Nova Scotia, the Bay of Fundy, and perhaps 

 the Gulf of Maine. American shad tagged in rivers in 

 Nova Scotia (Melvin et al. 1986) and in Quebec (Vlady- 

 kov 1956) were recaptured on the Scotian Shelf in 

 winter. The large aggregation of river herring in the 

 eastern Gulf of Maine, apparent during spring sur- 

 veys, may include fish in transit from overwintering 

 areas on the Shelf to spawning rivers along the Bay 

 of Fundy-Gulf of Maine coast. Considering their pref- 

 erence for water temperatures above 5°C, the migra- 

 tion route would occur along the Shelf Slope and into 

 the eastern Gulf of Maine through the Northeast Chan- 

 nel. Postspawning river herring probably feed during 

 summer in the Bay of Fundy-eastern Gulf of Maine 

 before returning offshore to the central Shelf in the 

 fall to overwinter. Some may move offshore soon after 

 spawning, as indicated by the presence of large fish 



(x FL 30.4cm) in the summer bycatch from the silver 

 hake fishery along the shelf slope. Another component 

 of the Shelf overwintering population may move north 

 around Cape Breton to the Gulf of St. Lawrence in 

 spring to spawn in natal rivers, returning in autumn 

 to the Scotian Shelf to overwinter. This hypothesis is 

 supported by the fall concentration of river herring in 

 the Sydney Bight area and movement of an alewdfe ac- 

 cidently tagged in the Sydney Bight fall fishery for 

 Atlantic herring, to the Margaree River (southern Gulf 

 of St. Lawrence) where it was recaptured the follow- 

 ing spring (Jessop, unpubl. data). 



Most river herring overwintering on the Scotian 

 Shelf probably originate in the Canadian Maritime 

 Provinces and U.S. Gulf of Maine region. Some river 

 herring of Canadian Maritime origin evidently migrate 

 south to overwinter off the Middle Atlantic Bight as 

 do American shad (Melvin et al. 1986, Dadswell et al. 

 1987). The tagging of over 50,000 river herring in the 

 Saint John River, New Brunswick, produced two recap- 

 tures off North Carolina the following spring and other 

 recoveries along the intervening coast (Jessop, unpubl. 

 data). In another study, most recaptures from over 

 19,000 river herring tagged during summer and fall in 

 the upper Bay of Fundy occurred in spring fisher- 

 ies in Nova Scotia rivers, but one occurred off Mas- 

 sachusetts and several came from North Carolina 

 (Rulifson et al. 1987). Summer aggregations of river 

 herring in the Bay of Fundy-eastern Gulf of Maine 

 may therefore consist of a mixture of stocks from the 

 entire Atlantic coast, as do similar aggregations of 

 American shad (Dadswell et al. 1987). 



An understanding of the seasonal movements, stock 

 composition, and exploitation of river herring popula- 

 tions which overwinter on the Scotian Shelf may help 

 fishery managers to explain high variability in the 

 returns of spawning fish regionally and to particular 

 river systems. Stock composition and migratory routes 

 remain to be examined. 



Acknowledgments 



We thank M. Dadswell and K. Frank for critically 

 reviewing earlier drafts of the manuscript. We also 

 wish to thank J. McMillan and C. Harvie for their 

 assistance in data analysis and G. Black for helping 

 with the offshore distribution plots. The constructive 

 comments of the anonymous reviewers are also 

 appreciated. 



