For well-studied species such as penaeid shrimp, 

 quantitative data were used to estimate abundance 

 levels. For many species, however, reliable quantita- 

 tive data were limited. Therefore, regional and local 

 experts were consulted to estimate relative abun- 

 dances based on the above criteria. Several reference 

 or "guide" species with abundance levels con-esponding 

 to the above criteria were identified for each estuary. 

 These guide species typified fishes and invertebrates 

 belonging to a particular life mode (e.g., pelagic, dem- 

 ersal) or occupying similar habitats. Once guide spe- 

 cies were selected, other species were then placed into 

 the appropriate abundance categories relative to them. 

 These data represent relative abundance levels within 

 a specific estuary only; relative abundance levels across 

 Gulf of Mexico estuaries could not be determined. 



The final level of abundance assigned to a species was 

 determined by asking regional and local biologists for 

 expert opinions based on their knowledge of individual 

 species within an estuary. This effort complemented 

 quantitative studies, the ELMR relative abundance 

 categories, and greatly increased reliability of abun- 

 dance infomiation. The quality of relative abundance 

 information varied between estuaries as well as spe- 

 cies. As a result, temporal resolution was greater in 

 well-studied estuaries. Nevertheless, the relative 

 abundance data shown in the data summaries are the 

 best that could be synthesized from agency reports, 

 academic studies, and expert reviews. 



Data verification. Approximately two years were re- 

 quired to develop the 1 ,364 data sheets (Figure 4) and 

 consult with regional and local experts for the 31 

 estuaries studied. Nearly all of the data sheets were 

 carefully reviewed during consultations or by mail. 

 These consultations complemented the literature and 

 published data sets compiled by NOAA. Ninety-four 

 scientists and managers at 44 institutions were con- 

 sulted. Local experts were especially helpful in provid- 

 ing estuary/species-specific information. They also 

 provided additional references and contacts, and iden- 

 tified additional species to be included in the ELMR 

 data base. The names and affiliations of these experts 

 are listed in Appendix 3. 



Data summary tables. The information compiled for 

 each species and estuary (1 ,364 data sheets) was 

 organized in three data summaries (pp. 19-191). Tables 

 4 and 5 provide graphic presentations of the spatial and 

 temporal distribution and relative abundance by life 

 stage for each species and estuary. The information 

 shown represents the usual spatial and temporal distri- 

 bution of a species in a particular estuary. Table 6 

 ranks the relative reliability of the information pre- 

 sented for each species and estuary. 



Spatial distribution and relative abundance. Table 4 

 (pp. 19-59) summarizes the distribution and relative 

 abundance for each species by life stage, in each 

 estuary by salinity zone. The highest level of abun- 

 dance during the year in each estuary is depicted. 



Temporal distribution. Table 5 (pp. 61-149) summa- 

 rizes the temporal distribution of each species by 

 month and life stage for each estuary. This table 

 combines data over the three salinity zones, showing 

 the highest level of abundance for a particular life stage 

 by month. 



Data Content and Quality 



An important aspect of the ELMR program, especially 

 since it is based primarily on published and unpub- 

 lished literature and consultations, is to determine the 

 quality of available data. For many species, gear 

 selectivity, difficulty in identifying larvae, and difficulty 

 in sampling various habitats has limited the amount of 

 reliable information. Therefore, a deliberate effort was 

 made to assess the overall reliability of the data base 

 so that it could be used appropriately. 



Estimates of the reliability of the distribution and abun- 

 dance information organized by species, life stage, 

 and estuary are presented in Table 6 (pp. 151-190) of 

 the Data Summary Tab/es section. Data reliability was 

 classified using the following categories: 



• Highly certain: Considerable sampling data avail- 

 able. Distribution, behavior, and preferred habitats 

 well documented within an estuary. 



Results 



Presence/absence. Table 3 (pp. 16-17) was devel- 

 oped to readily convey the occurrence of each of the 44 

 ELMR species in each of the 31 Gulf of Mexico estuar- 

 ies. The highest level of abundance during the year for 

 the adult or juvenile life stages is depicted. The 

 spawning, egg, and larval categories are not consid- 

 ered. This table suggeststhezoogeographicdistribution 

 of species between Gulf of Mexico estuaries. 



• Moderately certain: Some sampling data available 

 for an estuary. Distribution, preferred habitat, and 

 behavior well documented in similar estuaries. 



• Reasonable inference: Little or no sampling data 

 available. Information on distributions, ecology, and 

 preferred habitats documented in similar estuaries. 



The quality and quantity of available data vary by 

 species, life stage, and estuary. For example, a large 

 amount of information is available on the blue crab 



