• Indicator of environmental stress — determined 

 from the literature, discussions with fisheries experts, 

 and from monitoring programs such as NOAA's Na- 

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

 These species are typically molluscs or demersal fishes 

 that consume benthic invertebrates or have a strong 

 association with bottom sediments. Their physiologi- 

 cal disorders, morphological abnormalities, and 

 bioaccumulation of contaminants, such as heavy met- 

 als, indicate exposure to environmental pollution and/ 

 or stress. 



• Ecological value — based on several attributes 

 including trophic level, relative abundance, and im- 

 portance as a key predator or prey species. 



Table 3 features the 153 species selected for all five 

 ELMR regions collectively. Note that some species are 

 included in one region only (e.g., dungeness crab on 

 West Coast), whereas other species are considered for 

 several regions (e.g., blue crab in the Mid-Atlantic, 

 Southeast, and Gulf of Mexico). The common and 

 scientific names of fish and invertebrate species are 

 generally those adopted by the American Fisheries 

 Society (Turgeon et al. 1988, Williams et al. 1988, 

 Robins et al. 1991). (Species lists for each of the five 

 ELMR regions are featured in Tables 8, 10, 12, 14, and 

 16). 



For the majority of species considered in the ELMR 

 program, growth and development involve a direct 

 progression through several distinct life stages. Ac- 

 cordingly, the ELMR program has compiled informa- 

 tion based on five "typical" life stages: adult (A), 

 spawning adult (S), juvenile (J), larvae (L) and egg (E). 

 Adults were defined as reproductively mature indi- 

 viduals, while juveniles were defined as immature 

 but otherwise similar to adults. Species with a larval 

 stage typically undergo metamorphosis to the juve- 

 nile 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 compre- 

 hensive classification scheme, required some devia- 

 tion from this general classification. The reproductive 

 mode of certain species differs from the norm in that 

 there is internal fertilization of eggs, ovoviviparity, 

 delayed fertilization, etc. For example, mating (M) 

 replaces spawning (S) for crab species, and parturi- 

 tion (P) replaces spawning (S) for shark species. For 

 some species, several distinct larval life stages must be 



considered collectively as "larvae," including: the 

 phyllosome and puerulus stages of lobster species; 

 the zoea and megalopa stages of crab species; the 

 nauplius, protozoea, mysis, and postlarval stages of 

 shrimp species; and the trochophore, veliger, and 

 pediveliger stages of bivalve molluscs. The lepto- 

 cephalus stage of tarpon is considered larval, as is the 

 "paralarva" stage of bay squid. Each regional ELMR 

 data summary report identifies cases in which alter- 

 nate life history stages have been considered, 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 informa- 

 tion. 



Data sheet development. A data sheet was developed 

 for each species in each estuary to facilitate the review 

 and presentation of the information. Data compiled 

 for each species/life stage included: (1) the salinity 

 zone it occupies (seawater, mixing, tidal fresh), (2) its 

 monthly distribution in those zones, and (3) its rela- 

 tive abundance in those zones. Figure 3 depicts the 

 data sheet for weakfish (Cynoscion regalis) in Delaware 

 Bay. 



The ELMR program uses the following methodology 

 to evaluate species relative abundance rankings based 

 upon available data that reflect the expected or ob- 

 served "average" rankings for selected species. As- 

 signing abundance levels is often difficult due to the 

 lack of long-term, consistent sampling surveys for 

 most species within and across many estuaries. How- 

 ever, the existing literature and the field experience of 

 local and regional reviewers provide the basis for 

 reasonably accurate synoptic abundance rankings. 

 For well-studied species, quantitative data were used 

 to estimate the relative abundance within estuaries. 

 The integration of quantitative data and expert review 

 resulted in the "final" level of abundance assigned to 

 a species. The reviews by regional fisheries scientists 

 complemented the quantitative studies, and greatly 

 increased the reliability of species relative abundance 

 information. 



Categorical spatial and temporal distribution and rela- 

 tive abundance data were compiled from data sets, 

 technical reports, and peer-reviewed literature on 

 estuarine species. Fisheries data often reveal consid- 

 erable spatial and temporal heterogeneity due to envi- 

 ronmental variation (e.g., wet year, cold year, etc.), 

 biological variation (e.g., high recruitment year, low 

 year class, etc.), and anthropogenic variation (e.g., 

 fishery mortality, sampling error, etc.). Given the 

 inherent variability in fisheries studies, this informa- 

 tion was integrated to best define current distribu- 



Text continues on p. 9. 



