Figure 9. Monthly mean abundances of brown shrimp and spot caught in trawls in LDWF Coastal Study Areas 

 (l-VII) and GCRL Mississippi Sound (MS) stations. 



a. brown shrimp 



i 



is 



S 



3 

 c 



E 



& 



E 



3 

 C 

 C 



Months 



b. spot 



1 



2 



900^ 



E 



C 



Months 



Coastal Study Area 



Data Content and Quality 



An important aspect of the ELMR program, especially 

 since it is based primarily on published and 

 unpublished literature and consultations, is to 

 determine the quality of available data. For many 

 species, gearselectivity, 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 

 abundance information organized by species, life 

 stage, and estuary are presented in Table 4 (pp. 49- 

 56) of the Data Summary Tables section. Data 

 reliability was classified using the foltowing categories: 



Highly certain: Considerable sampling data available. 

 Distribution, behavior, and preferred habitats well 

 documented within an estuary. 



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 availableon shrimp because 

 they are highly valued both commercially and 

 recreationally . For most species, the least amount of 

 information available and poorest quality of data are 

 forthe spawning, egg, and larval life stages. Except 

 for a few species (e.g. , brown shrimp), very little data 

 has been generated on particular habitat preferences 

 and environmental ranges. This is particularly true 

 for the smaller forage and/or non-commercial fishes 

 and invertebrates. Gear selectivity, inability to 

 correctly identify larval stages, and difficulty of 

 sampling various habitats limits the development 

 and reliability of this information. In addition, life 

 history data are lacking on some of the commercially 

 important sciaenid and pelagic species. 



Data reliability was also based on the number of 

 studies conducted on a species within an estuary 

 and whether they represented a time-series data set 

 or were designed to identify and quantify a species' 

 particular life stage. For example, LDWF used 

 different gear types to sample various habitats 

 accurately (Barrett etal. 1978). These data are more 

 reliable due to sampling of specific habitats with 

 consistent and efficient gear. In the case of limited 

 studies, information was occasionally inferred. An 

 opportunity exists to refine the data presented based 

 on additional reviews. 



11 



