792 



Fishery Bulletin 90(4), 1992 



• = DOLPHIN CARCASS 

 «« = SWING BRIDGE 

 ICC = INTERCOASTAL CANAL 



M = ACCESS CHANNEL 



• PALACIOS 

 15 mi 



Figure 1 



Map of East Matagorda Bay. 

 Texas, showing location of 

 recovered bottlenose dolphin 

 carcasses. 



Total Length 



Site 1) Dorsal midline 10cm to 15cm caudal to the blow hole. 



Site 2) Dorsal midline 10cm to 15 cm cranial to the insertion of 

 the dorsal fin. 



Site 31 Lateral midline at the midpoint of the dorsal fin. 



Site 4) Ventral midline 10cm cranial to umbilicus. 



Site 5) Dorsolateral aspect of tail stock at level of the anus. 



Site 6) Lateral midline at level of the anus. 



Figure 2 



Blubber measurement sites on bottlenose dolphins collected 

 in East Matagorda Bay, based on Naval Ocean System Center 

 collection procedures. 



females (MF) (4 with fetus), and 5 immature females 

 (IF); 2 females and 1 male were from outside the Bay 

 on East Matagorda Peninsula. I could not make an ac- 

 curate determination of time of death because decom- 

 position varies markedly depending on environmental 

 conditions. The condition of the carcasses at necropsy 

 suggested that death occurred ~5-10 days prior to 



siting, with the exception of one freshly dead animal 

 collected outside the Bay on East Matagorda Peninsula. 



Table 1 shows blubber thickness measured at NOSC 

 (site 2), length, sex, and weight data from 24 East 

 Matagorda Bay dolphins for which there were complete 

 data, and from a comparison group of 16 Texas coast 

 dolphins which stranded over the period 1981-89. 

 Average blubber thickness for 21 stranded dolphins 

 recovered in the Bay was 12.7mm, while the average 

 thickness for the comparison group of 16 dolphins 

 recovered on the Texas coast during the winter months 

 of November-March 1981-89 was 18.6mm at the same 

 measurement site. This difference was significant (Stu- 

 dent's t test, P< 0.001). In addition, the subcutaneous 

 fat layer that is prominent between the blubber and 

 skeletal muscles in healthy robust dolphins (Ridgway 

 and Fenner 1982) was greatly reduced or absent in all 

 of the dolphins taken from inside the Bay. 



A linear regression was used to (1) show the relation- 

 ship of blubber thickness (mm) to weight (kg) for the 

 comparison group of dolphins stranded along the Texas 

 coast during winter months and (2) test the similarity 

 of slopes between the Texas-coast and East Matagorda 

 Bay groups (Fig. 4). In Texas coast strandings, there 

 was a significant positive correlation between blubber 

 thickness and body weight (r 0.9); while in the Bay 

 group, blubber thickness decreased with increased 

 weight (r -0.38). 



