are identifiable by natural markings {e.g., Brager 1992). Roto-tags, freeze- 

 brands, and radio transmitters (and subsequent transmitter hole marks) 

 provided reliable means of photographic recognition for those 35 dolphins 

 which had been freeze-branded in July 1992. While radio-tracking was only 

 possible for a part of summer 1992, the naturally and artificially marked 

 dolphins of the area provided a long-term data source by photographic 

 recognition. 



A dolphin group was defined as one or more individuals exhibiting the 

 same behavioral state(s) in the same geographical area (sometimes up to a 

 one to two hundred m^ area, probably within acoustic commurucation range), 

 usually following a 10-m chain rule. Total number of individuals including 

 neonates and other calves were recorded. Neonates were recognized by fetal 

 folds and uncoordinated surfacing behavior. Non-neonate calves were 

 recognized by their small size (generally a body length < 0.75 that of 

 accompanying adults). 



Information was gathered on the broad behavioral categories "traveling", 

 "feeding", "feeding behind shrimpboat" (FBS), "socializing", "milling", 

 "bowriding", and "unknown" (and all combinations). Traveling was 

 indicated by steady movement in one direction. Feeding was indicated by 

 behavior oriented towards visible fish, such as chasing or tossing them in the 

 air. Feeding also was suggested by repeated long dives in one location, 

 without seeing fish, though this was often in the presence of feeding seabirds. 

 FBS was indicated by dolphins following a trawling shrimpboat, or feeding on 

 discarded bycatch (Fertl 1994). Socializing was active behavior, indicated by 

 leaps, breaches, and other aerial behavior; sexual, play, or aggressive behavior; 

 and much body contact at the surface. Milling was indicated by low activity 

 levels and lacked components of the above behaviors. Dolphin behavior was 

 evaluated in the few minutes while approaching the group and/or while 

 taking photos. 



As part of the health evaluation of captured dolphins, a wedge biopsy of 

 approximately 1 gram of tissue was taken from the dolphin's left flank, 

 approximately 10 cm posterior to, and 10 cm below, the posterior base of the 

 dorsal fin (Sweeney 1992). From photogrammetry, we estimated the shallow, 

 oval shaped biopsies to have been approximately 30 mm long by 20 mm high, 

 though the dimensions varied by several mm among individuals. Healing of 

 biopsy wounds was monitored for the periods of July 1992-December 1993, 

 from photographs of biopsy wounds taken opportunistically during the 

 regular photographic surveys. 



