Results and Discussion 



The 1983-84 abundance estimates of 

 all zones combined for the northwestern 

 Gulf were lowest in the winter (January- 

 February), increased during the spring 

 (April-May), and remained at that level 

 through the summer and fall (Figure 2). 

 The Texas strandings provide the best 

 sample for comparison with the 

 northwestern Gulf abundance estimates. 

 The peak in strandings occurs from 

 February-April, with monthly levels 

 approximately equal throughout the rest of 

 the year (Section 1, Figure 2). Thus, if the 

 abundance estimates represent the normeil, 

 seasonal trends, strandings occur during a 

 period when abundance is apparently 

 increasing. 



The trend in 1985-86 abundance 

 estimates of all zones combined for the 

 northeastern Gulf of Mexico differed from 

 that of the northwestern Gulf, with the 

 lowest seasonal abundance in the summer 

 rather than the winter (Figure 3). In fact, 

 the highest seasonal abundance in the 

 northeastern Gulf occurred during the 

 winter. Strandings for the northeastern Gulf 

 peak during March and April (Section I, 

 Figure 4), which would correspond to 

 spring, however a spring abundance 

 estimate is not available. Based on the 

 winter and summer abundance estimates 

 for all zones, it appears that the peak in 

 strandings occurs while there is an apparent 

 declining trend in abundance. This is the 

 opposite of the trend in the northwestern 

 Gulf. 



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Fignne 2 Estimates o( seasonal bottlenose cSolphin abundance in 

 the northwestern Gulf of Mexico (Scott et al., 1989). Error bais 

 represent 95% confldenoe intervals. 



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Fignre 3: Estimates of seasonal bottlenose dolphin abundance in 

 the nonheastetn Gulf of Mexico (Soott et aL, 1989). Error bart 

 represent 95% confidence intervals. 



Another aspect of the abundance 

 estimates to consider is the likelihood of whether or not animals which die in the different 

 zones will eventually strand. Mead (1979) discussed factors which affect the discovery of 

 cetacean strandings. He stated that "virtually all cetaceans" are negatively buoyant. Dolphins 



25 



