To revise the ELMR data, Massachusetts Coastal Trawl 

 Survey data were acquired through a cooperative 

 agreement. A "quantile analysis" was applied to six 

 recent consecutive years (September 1991 to May 

 1997) of the data. Survey locations were identified 

 within the boundaries of ELMR estuaries (Buzzards 

 Bay, Massachusetts Bay, Cape Cod Bay). Species were 

 separated into juvenile (J) and adult (A) life stages 

 based on length class. The analysis was applied only 

 to the "demersal fishes" guild, susceptible to the trawl 

 survey sampling gear. Total catch-per-unit-effort for 

 individual species/life stages was summed for six 

 years, but kept separate for May and September, and 

 any catches of were excluded from analysis. Catches 

 for May and September were "stacked," separated 

 into percentiles, and converted to ELMR relative abun- 

 dance categories using the standard criteria as de- 

 scribed on page 48. 



Based on this quantile analysis of 1991-1997 trawl 

 survey catch, ELMR data were revised for several 

 species (skates, scup, weakfish, spiny dogfish, silver 

 hake, red hake) in Buzzards Bay, Cape Cod Bay, and / 

 or Massachusetts Bay. The revised ELMR data and 

 salinity zone boundaries were then merged with a 

 1 :24,000 shoreline boundary to generate seasonal spe- 

 cies maps using Arclnfo® software. The seasonal 

 species maps were carefully reviewed in a series of 

 meetings with local and regional fisheries biologists. 

 Final revision of the ELMR data was based on the 

 comments of these experts. Figure 21 depicts the 

 distribution of winter flounder adults in Massachu- 

 setts estuarine waters, combining both ELMR and 

 MDMF trawl survey data. 



In summary, the ELMR digital maps and associated 

 data base are revised and updated in a four-step 

 procedure: 



(1) Map the species catch distribution. 



(2) Model the species distribution throughout sea- 

 sonal salinity zones. 



(3) Link the fishery-independent monitoring data with 

 modeled data via GIS. 



(4) Peer-review the revised data and associated maps. 



ELMR Applications 



The methodology and data developed through the 

 ELMR program have been applied to analytical stud- 

 ies, and to specific problems in natural resource man- 

 agement. A few of these applications are described 

 below. 



An index to assess the sensitivity of Gulf of Mexico 

 spiccies to changes in estuarine salinity regimes. This 

 study developed an index of biological sensitivity to 

 changes in freshwater inflow for adult and juvenile 

 life stages of the 44 ELMR fish and macroinvertebrate 

 species in 22 Gulf of Mexico estuaries (Christensen et 

 al. 1997). The BioSalinity Index (BSI) provides an 

 innovative approach to quantifying the estuary-spe- 

 cific sensitivity of organisms to changes in estuarine 

 salinity regimes, based upon knowledge of species' 

 salinity habitat preferences, the availability of this 

 preferred habitat, and the relative abundance and 

 spatial and temporal distribution of species. It was 

 found that a significant difference exists between adult 

 and juvenile life stage sensitivity, with juveniles ex- 

 hibiting a lower sensitivity to salinity changes than 

 adults, and that a considerable disparity exists in 

 species-specific sensitivities among Gulf estuaries. 

 Likewise, when the full complement of 44 species- 

 level BSIs are averaged, marked differences in assem- 

 blage-wide sensitivity are evident across estuaries. 

 The availability of preferred salinity habitat had a 

 greater influence on the BSI for estuarine species than 

 did their relative abundance and temporal distribu- 

 tion. In 1995, participants in a Gulf of Mexico freshwa- 

 ter inflow workshop applied the BSI to identify a 

 subset of estuaries that appear more sensitive to 

 changes in freshwater inflow, and are candidates for 

 further study. 



Estuarine-catadromy: a life history strategy couplittg 

 marine and estuarine environments via coastal in- 

 lets. This investigation was undertaken to develop a 

 better understanding of estuarine-catadromous spe- 

 cies' larval utilization of estuaries and inlets along the 

 U.S. East Coast from Buzzard Bay, MA to Biscayne 

 Bay, FL (Bulger et al. 1995). Estuarine-catadromous 

 species spend most of their adult stage in the marine 

 environment and spawn there, and in their early life 

 history stages migrate to, and reside in, estuarine 

 environments. This group of species accounts for a 

 large portion of the Gulf and East Coast fisheries 

 harvest, and their larvae's migration through the in- 

 lets is of paramount importance. ELMR data were 

 used to characterize 12 larval species' utilizations of 

 29 estuaries and 59 inlets. A Theoretical Inlet Utiliza- 

 tion (TIU) Index was developed as a series of maps to 

 provide a biogeographic perspective. These species' 

 larval abundance rankings were modeled against the 

 physical characteristics of ocean inlets, via ordered 

 stepwise logistic regression, to provide a better un- 

 derstanding of the relationships driving these utiliza- 

 tion patterns. The average concordance between lar- 

 val relative abundance rankings and nine estuarine/ 

 inlet physical variables was 82.6%. The models indi- 

 cated that additional estuarine /inlet independent vari- 

 ables, such as tidal plume characterizations (e.g., ex- 



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