determined by consulting regional experts and NMFS 

 reports, e.g., Atlantic salmon (Salmo salar) and striped 

 bass (Morone saxatilis). 



• Indicator of environmental stress — determined from 

 the literature, discussions with fisheries experts, and 

 from monitoring programs such as NOAA's National 

 Status and Trends Program (O'Connor 1990). These 

 species are typically molluscs or demersal fishes that 

 consume benthic invertebrates or have a strong asso- 

 ciation with bottom sediments, e.g., blue mussel (Mytilus 

 edulis)ar\dw\r\\erttour\der(Pleuronectesamericanus). 

 Their physiological disorders, morphological abnor- 

 malities, and bioaccumulation of contaminants, such 

 as heavy metals, indicate exposure to environmental 

 pollution and/or stress. 



• Ecological value — based on several attributes includ- 

 ing trophic level, relative abundance, and importance 

 as a key predator or prey species, e.g., silversides 

 (Menidia species) and sevenspine bay shrimp (Crangon 

 septemspinosa). 



For the majority of species considered in this report, 

 growth and development involve a direct progression 

 through several distinct life stages. Accordingly, the 

 ELMR program has compiled information based on 

 five "typical" life stages: adult (A), spawning adult (S), 

 juvenile (J), larvae (L) and egg (E). Adultswere defined 

 as reproductively mature individuals while juveniles 



were defined as immature but otherwise similar to 

 adults. Species with a larval stage typically undergo 

 metamorphosis to the juvenile stage, hence larvae 

 usually differ from juveniles and adults in form. In 

 addition, most species rely on external fertilization via 

 spawning, when gametes combine externally after 

 being released by males and/or females. Therefore, 

 spawning adults were defined as those releasing eggs 

 or sperm and larvae and eggs included most early life 

 history stages. The complex life histories of some 

 species, and the subsequent difficulty in placing them 

 into a comprehensive classification scheme, required 

 some deviation from this general classification. For 

 example, mating (M) or parturition (P) replaced spawn- 

 ing (S) for some species (e.g., green crab and spiny 

 dogfish respectively) because the reproductive mode 

 of certain species differs from the norm in that there is 

 internal fertilization of eggs, ovoviviparity, delayed 

 fertilization, etc. In addition, egg and/or larval stages 

 are not applicable for certain species because the 

 stage(s) is either absent or better defined by the 

 presence of gravid females. Refer to Appendix 3, 

 Species life history notes, for a discussion of these 

 deviations for individual species. This section identifies 

 cases where the ELMR program has considered alter- 

 nate life stages, cases in which two or more species are 

 considered as a single unit, comments on specific 

 habitat preferences and behaviors, and other pertinent 

 life history information. 



Figure 3. ELMR North Atlantic estuaries and associated salinity zones. 



Salinity 

 Zones 

 Present 



ItImIsI 

 ItImIsI 

 ItImIsI 

 ItImIsI 

 ItImIsI 

 ItImIsI 



SMsj 

 ItImIsI 



Kennebec/Androscoggin Rivers , , , 



Casco Bay JTJMJ SJ 



Saco Bay JTJMJ SJ 



Wells Harbor I * M SJ 



Great Bay JTJMJ SJ 



Merrimack River MM * 



Massachusetts Bay and * , , 



Boston Harbor subestuary I * ImI Si 



Cape Cod Bay I * ImI si 



S = Seawater zone * = Salinity zone not present 



Estuaries 



Passamaquoddy Bay 

 Englishman/Machias Bays 

 Narraguagus Bay 

 Blue Hill Bay 

 Penobscot Bay 

 Muscongus Bay 

 Damariscotta River 

 Sheepscot River 



Legend: T =Tidal fresh zone M = Mixing zone 



