ASSOCIATION OF MAMMALS AND BIRDS WITH VESSELS 



Table 29 shows that the number of surface vessels seen during the Pilot Study 

 followed no seasonal pattern. However, commercial fishing/shrimp boats tended to 

 aggregate within waters less than 50 m deep. Ships, including tankers, freighters, and 

 crew boats, are less likely to distort normal feeding patterns for mammals and birds 

 because they offer less food. Such craft tended to be less clustered in their distribution 

 and were sighted in waters of all depths. Thus, any effect of ships on observations might 

 be present in any part of the survey subunits, whereas fishing/shrimp boats might effect 

 only observations made in relatively shallower waters. 



The association of mammals and birds with fishing boats was common in Texas, 

 but very rare in Florida. During August organisms were found in proximity to fishing 

 boats 9 times in STEX and 15 times in NTEX. One of the nine occurrences in STEX 

 involved an unidentified Stenella ; the others involved terns and gulls. The 15 occurrences 

 in NTEX included 5 sightings of bottlenose dolphins around anchored shrimp boats, while 

 terns and gulls were sighted around boats the other 10 times. The association of 

 bottlenose dolphins with boats is well known to the fishermen in the area off Matagorda 

 Island (J. Gruber, Department of Wildlife and Fisheries Sciences, Texas A & M 

 University, College Station, Texas; pers. comm.). 



During November we found mammals and/or birds in proximity to fishing boats 11 

 times in STEX and 6 times in NTEX. The 11 sightings in STEX included one sighting of a 

 group of three bottlenose dolphins; the rest involved gulls and terns. The six sightings in 

 NTEX were all of birds, mostly herring gulls and unidentified terns. 



We found only one case of an association with a fishing boat in our four Florida 

 surveys. The single observation was of a pair of unidentified birds with a boat in NFLA 

 during November. 



Table. 29. The number of surface vessels seen during aerial surveys. 



u *" vev August November 



subunit " 



STEX 67 25 



NTEX 78 105 



NFLA 67 52 



SFLA 33 36 



56 



