stranding rates along the Texas coast. These surveys were conducted by the SEFSC during 

 1988-90 along portions of the Texas coast. Bottlenose dolphin stranding data collected during 

 the beach surveys were examined to determine if the surveys detected an increase in 

 strandings between 1990 and 1988-89 during the months of January-April. The beach surveys 

 for 8 areas were examined; Table 2 lists the areas surveyed and the number of dolphin 

 strandings recorded. 



TbUc 1. Texas beach surveys conduaed from 1988-90 (Januaiy-May) by area with reported bottlenose dolphin strandings. 



The number of surveys per area varied yearly, but the total number of surveys per 

 year was similar, and ranged from 82-86. The number of miles of beach surveyed per year 

 was also similar, and ranged from 2388-2580 (Table 3). Compared to the 1988-89 average, 

 1990 strandings increased in 5 areas, decreased in 2 areas, and were unchanged in 1 area. 

 Overall, the number of strandings recorded during 1990 were about 1.9 times the 1988-89 

 average. The beach surveys provided a measure of the stranding rate; the 1990 stranding 

 rate (stranded dolphins per mile surveyed) was approximately 1.8 times the 1988-89 average.- 

 The number of bottlenose dolphin strandings reported by the Texas Marine Mammal 

 Stranding Network (TMMSN) for the beach survey areas showed an increase during 1990 

 of about 2.5 times the 1988-89 average (Table 4). 



Potential biases were apparent in comparisons of trends in strandings between the 

 beach survey data and the TMMSN data. First, the yearly number of beach surveys by area 

 was not consistent. For instance, during the first five months of 1988 and 1989 about 20 

 surveys were conducted each year at South Padre Island, while during 1990 only one survey 

 was conducted (Table 3). Second, surveys were not conducted at an adequate frequency. 

 Surveys averaged about 2 per month (range, 1-4), but during peak stranding periods 

 bottlenose dolphins stranded about once every 3 days. Third, discrepancies between the data 

 sets indicated that under-reporting was occurring in both systems. The beach survey data 

 should be a temporal subset of the Network data, but in fact some of the beach survey areas 

 reported more strandings during 1988 and 1989 than the Network reported for those areas 

 (Table 4). The Network reported 45 dolphins stranded in the Galveston area during 1988 

 while the Galveston beach survey reported none that year. These discrepancies may indicate 

 under-reporting within each data set, and/or variations in geographic definitions. Overall, the 



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