4.4 MIGRATORY PATTERNS 



The structure of New England fish 

 communities is dynamic and the species 

 are, for the most part, constantly shift- 

 ing position in the coastal zone. Many 

 movements can be linked predictably to 

 patterns of foraging, local and regional 

 variations in water temperature, or repro- 

 ductive activities. The frequency and 

 magnitude of migrational activities, how- 

 ever, appear to be both species- and 

 regionally-specific. 



Species in the resident (non-migra- 

 tory), nearshore fish assemblage make 

 inshore-offshore movements over small 

 distances, moving into slightly deeper 

 water to avoid extremes in water tempera- 

 ture (e.g., tomcod). Movements are also 

 linked to tidal cycles where fish move out 

 of areas that are exposed at low tide or 

 are very shallow and reoccupy the areas as 

 the tide floods (e.g., murrmichogs). Dusk 

 feeding movements are also common to many 

 species. Herring move to the surface to 

 feed at dusk (Sindermann 1979a), juvenile 

 pollock move inshore, and striped bass 

 also rise to the surface to feed at dusk 

 following their preferred prey items. 



Coastal fish migrations occur on 

 a regional scale in New England; Fig- 

 ure 11 sumn;arizes these general patterns. 

 Bluefish, mackerel, and menhaden are 

 examples of spring-summer northward mi- 

 grants. These species move along the 

 coastline and inshore to southern New Eng- 

 land and the Gulf of Maine as water tem- 

 perature increases. The timing of these 

 migrations is probably also a response to 

 increasing food supplies since during the 

 warm months pelagic and demersal food 

 organisms are abundant in coastal areas. 

 In fall and winter, the fish reverse 

 direction in response to declining water 

 temperature. Southward migrating fish do 

 not always follow the coastline, but may 

 move offshore to the warrrier continental 

 slope waters off southern New England 

 (Figure 11). Many inshore migrant species 

 (including red hake, silver hake, scup, 

 butterfish, summer flounder, and goose- 

 fish) winter there (TRIGOM-PARC 1974). 

 Some species, such as the winter flounder, 

 reside in cooler offshore waters during 

 the summer and move inshore in winter. 



Because of differences in water tempera- 

 ture variation, southern New England con- 

 tains few permanent fish residents and is 

 characterized by a continuously shifting 

 fish species composition. The Gulf of 

 Maine, conversely, is typified by more 

 resident species and less pronounced sea- 

 sonality in species composition. 



4.5 REGIONAL PATTERNS 



Since New England coastal fish commu- 

 nities are strongly influenced by water 

 temperature variation, more detailed com- 

 munity descriptions can be made by exami- 

 nation of both regional and seasonal dif- 

 ferences using Cape Cod as a biogeographic 

 boundary. Regional patterns of community 

 structure have been separated into spring- 

 summer and fall-winter periods. It is im- 

 portant to realize that within-region 

 physical and biological conditions vary, 

 and that these will in turn affect the 

 distribution and abundance patterns of the 

 fishes. The generalized patterns described 

 below are intended to convey overall 

 trends in seasonal shifts of species 

 composition and not, necessarily, the 

 dynamics of specific, localized fish 

 community structure. 



4.5.1 South of Cape Cod (Figure 12) 



During spring, anadromous species 

 such as lampreys, striped bass, and large 

 schools of certain herring (e.g., ale- 

 wives, bluebacks, and shad) begin ascend- 

 ing river systems to spawn in brackish and 

 freshwater. Although larger rivers such 

 as the Hudson, Connecticut, and Thames 

 support major spawning runs, anadromous 

 fish also enter many smaller rivers and 

 streams. Lampreys, sturgeon, and herrings 

 have spawning populations along the entire 

 northeast coast while for the striped 

 bass, the Hudson River marks the northern 

 limit of a major spawning population. 

 (Recent anadron:ous fish restoration pro- 

 jects to re-establish successful spawning 

 populations of the Atlantic salmon and 

 shad have been initiated in many New Eng- 

 land rivers.) Adults of some species die 

 following spawning (e.g., lampreys); 

 others descend rivers and feed actively to 

 regain body stores lost during spawning 

 (e.g., herrings, striped bass). In south- 

 ern New England, adults of most anadromous 



38 



