SECnON I 



STRANDING RATE AND TRENDS 



Lany J. Hansen 



Southeast Fisheries Science Center 



Miami Laboratory 



75 Virginia Beach Drive 



Miami, FL 33149 



Methods 



Since the mortality event under investigation appeared to have occurred between 

 January through May, 1990, the 1990 stranding records for January through June were 

 compared to those from prior years for the same months. Unless otherwise noted, references 

 to aimual or yearly strandings refer to strandings that occurred during January through June. 

 In those cases where the number of strandings were compared, strandings from 1986-89 

 were used for comparison (except when comparing the highest number stranded, then 

 records from 1984 on were used). This was done since stranding recovery effort in several 

 areas of the Gulf was probably relatively consistent during those years, although this effort 

 cannot be measured. Prior to 1986, stranding recovery effort was generally sporadic but was 

 assumed to have provided a random sample of the strandings. 



For analytical purposes, in most cases the strandings were divided into two main 

 groups, Texas strandings and non-Texas strandings. This was done primarily because a 

 consistent stranding network has been operating on 

 the Texas coast beginning in about 1986, and the 

 yearly sample size from Texas was adequate for 

 analysis. The stranding networks in the remainder of 

 the Gulf vary in consistency, and none have adequate 

 yearly sample sizes. For these reasons, additional 

 analyses (sex and length structure) were conducted on 

 the Texas sample. 



400 



in MO 

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z 



i 230 



I I TEXAS 

 ?77i LOUIStMM 

 Jga MtSSSSPPI 

 m ALABAMA 

 R^ FUJRIOA 



200 



Results and Discussion 



The number of stranded bottlenose dolphins 

 examined between 1984-89 varied from 63 to 174 

 animals. During 1990, 361 stranded bottlenose 

 dolphins were examined. The number of animals 



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Figiirc 1: Bottlenose dolphin strandings 

 nonbern Gulf of Medcx). 1984-90. 



in the 



15 



