(Sweeney 1992). Due to the amount of handling the dolphins received 

 additional to the biopsies, it was impossible to interpret behavioral reactions 

 to the biopsies alone. 



DORSAL FIN NOTCHES 



Our data indicate that a dolphin's notching pattern may change over 

 time. While this conclusion should come as no surprise to others applying 

 similar methods of photo-identification (notch accumulation over time by 

 individuals has been mentioned by Scott et al. [1990] and Wiirsig and Harris 

 [1990]), it would be imprecise to conclude from our data that all dolphins are 

 bom with no notches and steadily accumulate them throughout life. These 

 data represent a "snapshot" of 36 different dolphins, not a longitudinal study. 

 Male dolphins could, for instance, accumulate the majority of their notches as 

 juveniles, while assimilating themselves into the social system. The tendency 

 for female dolphins to have more notches with increasing numbers of female 

 affiliates implies that some notching may occur as a result of social 

 interactions. 



CONCLUSIONS 



The Texas coast, spanning 2.5° latitude, with its unique cycling of tropical 

 and temperate conditions and sparse coastal beaches punctuated by 

 productive estuaries, presents an interesting yet little understood blend of 

 bottlenose dolphin life history patterns. Bottlenose dolphins on the Texas 

 coast have movement and social patterns similar to those of other coastal 

 bottlenose dolphir\s, yet the pattenis are not simply a duplication of findings 

 from other, better understood study sites. 



With resp)ect to mass mortalities, the Matagorda Bay dolphin population 

 seems to be physically healthy (Sweeney 1992) and numerically robust, 

 occupying all surveyed regions of the bay. The resident dolphins are probably 

 susceptible to local anthropogenic cmd naturally occurring toxins. Post-1992 

 die-off population numbers appear not to have changed from earlier 

 estimates (Gruber 1981). However, statistical power to detect a decrease in 

 numbers between this and previous studies is probably low, given the erratic 

 survey effort and large confidence intervals. The handful of exeimples of 

 travel between Texas bays, in spite of the low level monitoring effort which 

 produced the observations, suggests to us that an individual Texas bay 

 ecosystem could recover numerically from localized dolphin mortalities. 

 These regional, within bay, dolphin populations do not appear to be truly 

 isolated. 



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