Regional Results 



Data summaries. Regional ELMR data summary 

 reports have been published for the North Atlantic 

 (Jury et al. 1994), Mid-Atlantic (Stone et al. 1994), 

 Southeast (Nelson et al. 1991 ), Gulf of Mexico (Nelson 

 et al. 1992), and West Coast (Monaco et al. 1990). In 

 each regional data summary report, the information 

 compiled for each species and estuary was organized 

 in data summary tables. The information shown 

 represents the expected spatial and temporal distribu- 

 tion of a species in a particular estuary based upon 

 available data. These tables include: 



Spatial distribution and relative abundance: The highest 

 level of abundance during the year in each estuary is 

 depicted for each species by life stage, and in each 

 estuary by salinity zone. 



Temporal distribution and relative abundance: This table 

 combines data over the three salinity zones, showing 

 the highest level of abundance for a particular life 

 stage by month for each estuary. 



Regional presence/absence of ELMR species. Tables 9, 

 11,13, 15, and 17 were developed to readily convey the 

 occurrence of each of the ELMR species in the estuar- 

 ies of each region. These tables (9, 11, 13, 15, 17) are 

 derived from the regional ELMR data sets by taking 

 the maximum abundance value for either the juvenile 

 or adult life stage in any month, in any salinity zone, 

 within a given estuary. Thus, a single relative abun- 

 dance value is reported for each species in each estu- 

 ary. Although these occurrence tables provide a use- 

 ful summary of "ELMR-at-a-glance," they lack the 

 temporal resolution between months, spatial resolu- 

 tion between salinity zones, and distinction between 

 life stages that are some of the inherent strengths of 

 the ELMR data sets. The spawning, egg, and larval life 

 stages are not considered. However, these tables 

 suggest the zoogeographic distribution of species 

 among estuaries and regions. 



North Atlantic Region. The location of the 17selected 

 ELMR North Atlantic estuaries are shown in Figure 6 

 (next page), and the common and scientific names of 

 the 58 selected ELMR North Atlantic species are listed 

 in Table 8 (p. 17). Results of the ELMR study in the 

 North Atlantic region are summarized in Distribution 

 and Abundance of Fishes and Invertebrates in North Atlan- 

 tic Estuaries, ELMR Report No. 13 (Jury et al. 1994). 

 Life history summaries and tables are still being de- 

 veloped for the species in this region. 



The North Atlantic estuaries are located along the coast 

 of the Gulf of Maine, a cold, deep marine basin influ- 

 enced by the Labrador Current. Compared to areas 



further south, estuaries in the North Atlantic region have 

 colder and deeper waters, little seasonal variation in 

 temperature, significant freshwater inflow from only a 

 few large rivers, stronger tides, and a predominantly 

 cold-temperate fauna (Gosner 1971, NOAA 1990a, 

 Ayvazian et al. 1992). The Gulf of Maine consists of a 

 deep central basin enclosed by Georges Bank, with water 

 circulating counterclockwise through the gulf — enter- 

 ing through the Northeast Channel and Browns Bank, 

 and exiting via Great South Channel and Nantucket 

 Shoals. The northern coastline is mostly rocky, consist- 

 ing primarily of granite, schist, and gneiss. In many 

 areas the consolidated rocks are overlaid by glacial till, or 

 sand/gravel deposits. The estuaries of this area are 

 dominated by submerged, glacier-scoured river valleys 

 with unmodified mouths, but there are some exceptions 

 (e.g., Boston Harbor, Wells Harbor). Tides are 

 semidiurnal and peak freshwater inflow occurs during 

 April and May due to the spring runoff. Average 

 precipitation across the region generally ranges from 40 

 to 46 inches per year. 



Cape Cod is generally considered to be the biogeo- 

 graphic boundary between the Virginian province to 

 the south and the Acadian or Scotian province to the 

 north (Briggs 1974). However, it is thought to act as a 

 "selective filter" rather than an absolute barrier (Gosner 

 1971) because many of the cold-temperate and boreal 

 fauna that dominate the North Atlantic have ranges 

 extending south of the cape, and several eurythermal 

 migrants from the south enter the Gulf of Maine 

 seasonally. The 58 species selected in the North Atlan- 

 tic region are generally of the cold-temperate or boreal 

 fauna of the Acadian or Scotian biogeographic marine 

 province, with some southern seasonal migrants. Di- 

 adromous species include Atlantic and shortnose stur- 

 geon, American eel, Atlantic salmon, alewif e, blueback 

 herring, American shad and striped bass. 



Table 9 (p. 18) readily conveys the occurrence of the 

 selected 58 ELMR species in each of the 17 North 

 Atlantic estuaries. This table depicts the highest rela- 

 tive abundance of the adult or juvenile life stage of 

 each species, in any month, in any salinity zone within 

 each estuary. The spawning, egg, and larval life stage 

 categories are not considered. This table also suggests 

 the zoogeographic distribution of species among North 

 Atlantic estuaries. For example, blue mussel and 

 mummichog are ubiquitous, but scup are not com- 

 mon north of Massachusetts. Self-sustaining popula- 

 tions of Atlantic salmon are now rare or extirpated 

 through much of their former range, and have, there- 

 fore, been proposed for protection under the federal 

 Endangered Species Act (ESA) (NMFS 1997). 

 Shortnose sturgeon have been listed as endangered 

 since 1967, and Atlantic sturgeon have been consid- 

 ered as a candidate species for ESA protection. 



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