Edwards. Allometry of energetics parameters in Stenella attenuata 



429 



small cetaceans. Existing studies of small cetaceans 

 include only Yasui and Gaskin's (1986) energy budget 

 for adult harbor porpoise (Phocoena), in addition to a 

 few estimates for various aspects of energy processing 

 by juvenile (e.g., Anderson, 1981) or adult (e.g., Lang, 

 1966; Lockyer, 1981, a and b; Yasui and Gaskin, 1986; 

 Hui, 1987; Bose and Lien, 1989; Bose et al, 1990) 

 small cetaceans. 



Incidental mortality of spotted dolphins (Stenella 

 attenuata), a small cetacean that is inadvertently killed 

 during some tuna purse-seining operations in the east- 

 ern tropical Pacific Ocean (ETP), presents an excep- 

 tion to this problem of specimen unavailability. Speci- 

 mens of all sizes die in purse-seines (Barlow and Hohn, 

 1984; Hohn and Hammond, 1985), making it possible 

 to collect appropriate data for the entire size range 

 occurring in the natural population. 



Taking advantage of this availability of specimens, 

 spotted dolphins ranging in size from fetal through 

 mature adult were collected from the fishery and ana- 

 lyzed for morphological characteristics related to en- 

 ergy processing. I report here regression equations re- 

 lating changes in 25 energetics parameters to changes 

 in total wet weight for these specimens. The param- 

 eters can be used in estimation of three components 

 contributing to cetacean energy budgets: active me- 

 tabolism, passive heat loss, and energy density. Esti- 

 mated energy density is derived from a subset of the 

 measured parameters and is reported as the 25th pa- 

 rameter. Total energy budgets, active metabolism, and 

 passive heat loss are not estimated here because such 

 estimates depend on various assumptions about other 

 factors (e.g., environmental conditions, activity levels) 

 and other energy budget components (e.g., standard 

 metabolism, heat of digestion) not included in this 

 study. The work reported here 

 was conducted to determine the 

 extent to which allometric trends, 

 if any, could be determined from 

 simple morphological measure- 

 ments on deceased cetaceans. 



the eastern tropical Pacific Ocean (spotted dolphins 

 are about 80cm total length at birth (Hohn and 

 Hammond, 1985)). Specimens included 22 females and 

 13 males (Table 1). Males specimens included 3 fe- 

 tuses, 6 immature, and 4 mature. Females specimens 

 included 3 fetuses, 6 immature, 1 mature resting, 1 

 mature lactating, and 11 mature pregnant. Not all mea- 

 surements were made on all specimens. All specimens 

 were collected incidental to tuna fishing operations in 

 the eastern tropical Pacific Ocean. Seventeen of the 

 specimens were collected on 28 December 1985; nine 

 were collected during July and two during August 1985 

 (Table 1). Specimens were kept frozen after collection 

 and were thawed in fresh water (about 27° C) just prior 

 to sampling for energetics parameters. 



Parameter measurements 



Active metabolism Active metabolism in cetaceans 

 is the total energy cost of swimming, i.e., energy (me- 

 chanical plus waste heat production heat) expended to 

 overcome hydrodynamic drag. Cost of steady submerged 

 swimming by cetaceans can be estimated by using 

 Magnuson's (1978) procedure for estimating cost of 

 swimming by tuna (see also Webb, 1975), including 

 drag on both body and fins. Eleven morphological mea- 

 surements are required to estimate hydrodynamic drag: 

 maximum diameter of the body CD ma J; wetted surface 

 areas of the body (WSA h ), flippers iWSA fp ), dorsal fin 

 (WSAj), and flukes iWSA,,); mid-chord depths of flippers 

 (MCD fp ), dorsal fin (MCD lt ), and flukes (MCD fl ); and 

 characteristic length of flippers (CL lp ), dorsal fin (CL d ), 

 and flukes (CL„) (Table 2). 



Z) max was derived from measurements of body cir- 

 cumference immediately anterior to the dorsal fin (C 3 ; 



Methods and materials 



Specimen collection 



Measurements were taken from 

 35 spotted dolphins ranging in 

 size from 71 to 210 cm total 

 length (TL [tip of rostrum to 

 fluke notch] Fig. 1). This repre- 

 sents the entire size range ( near- 

 term fetus through mature adult) 

 of the spotted dolphins found in 



