(#Dolphins seen/#Hours on water, Table 2) and the October estimate, indicate 

 an autumn increase in the number of dolphins in the Port O'Connor area. 

 Gruber (1981), in the Port O'Connor area, and Shane (1977) and McHugh 

 (1989) in the Aransas Pass area 100 km south, found fall /winter increases and 

 spring/summer decreases in dolphin numbers. Jones (1988), in the Galveston 

 area, 200 km north of Matagorda, found higher autumn numbers. These 

 changing abundances may be attributable to low level, short range migratory 

 movements to warmer waters (Jones 1988) or to a reaction to changing prey 

 densities (Gruber 1981). Further radio-tracking and photographic 

 identification studies are necessary to elucidate subtleties in and sources of 

 seasonal patterns. 



Gruber's (1981) population estimates for the 75 km^ area surrounding Port 

 O'Connor ranged from 93.4 ± 5.39 (SD) dolphins (1.2 dolphins/km^) in winter 

 to 48.6 ± 19.25 (SD) dolphins (0.6 dolphins/km^) in spring, from boat-based 

 subarea counts. Our estimated papulation is assumed to range over 312 km^, 

 yielding similar densities. Note, however, that dolphins are not uniformly 

 distributed over the area but tire found more frequently near shorelines and 

 channels. Sarasota Bay also has densities on the order of one dolphin /km^, 

 and is a very similar barrier island /estuarine habitat. 



We do not know if the study area (shaded areas of Fig. 4) represents an 

 area enclosing most of a breeding population. We assume not, since 

 10 dolphins tagged in the northeast of this area were never resighted in the 

 area, and were presumably resident further northeast in Matagorda Bay. As 

 well, the extended ranges of some individuals and infrequent sightings of 

 recognizable dolphins in other than their core areas (e.g., Jones 1991), argue 

 against group isolation. 



HEALING OF BIOPSIES 



We saw no obvious signs of infection in either biopsy or tag wounds. As a 

 rule, the radio-tag (and probably rototag) wounds healed slower than the 

 biopsy wounds, though it is evident that healing of the three wound types 

 went through similar stages (Appendix 6). The radio-tag and rototag wounds 

 differed from wedge biopsies in several ways. Radio-tags and roto-tags are 

 piercings involving foreign material passing through and pressing against 

 skin and connective tissue of the dorsal fin, not blubber, for several weeks' 

 duration. Scott et al. (1990:508) note that "tags that break the skin can wick 

 bacteria into the wound and prevent it from healing". Hindered cleansing of 

 the tag wounds may contribute to slower healing rates as well. 



Bruce-Allen and Geraci (1985) report on a controlled study of 

 morphology, hematology, and ultrastructure of healing of 2 mm deep scalpel 



31 



