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Fishery Bulletin 91(3). 1993 



WET WEIGHT (kg) 



Figure 4 



Relationship between wetted surface areas of fins and total 

 wet weight of body in kilograms for 26 specimens of spotted dol- 

 phin tStenella attenuata) from the eastern tropical Pacific Ocean, 

 both sexes and all ages (sizes) represented. Areas are total for 

 both sides of dorsal, both sides of both flippers, and both sides of 

 both flukes. Lines through points are fitted regressions. 



ACT = 20650 * MP/(ME*PE) 



20 40 60 80 100 



WET WEIGHT (kg) 



Figure 5 



Relationship between mid-chord depths of fins and total wet weight of 

 body in kilograms for 26 specimens of spotted dolphin {Stenella attenuata ) 

 from the eastern tropical Pacific Ocean, both sexes and all ages (sizes) 

 represented. Lines through points are fitted regressions. 



by the actual values taken on by the parameter, and 

 by the relative importance of the energy characteristic 

 in the overall energy budget. 



For example, the relative importance of the param- 

 eters WSA,, and D mta in the equation for active me- 

 tabolism is highly dependent on both parameter place- 

 ment and relationship with wet weight (trend). Active 

 metabolism (calhr ') can be estimated for steady sub- 

 merged swimming by torpedo-shaped bodies as 



where 



VL is velocity (cm. sec 1 ) and TL is total length in 

 centimeters (Edwards, 1992, following Webb, 1975). 

 Collecting and assuming constant all terms ex- 

 cept the energetics parameters WSA h and D max , 

 the expression for active metabolism can be sim- 

 plified to 



ACT = C * WSA h * 11 + ( 1.5*((D n 



(7*((D max )/TL)) :1 ]. 



,)/TL)) 3/2 + 



where C represents the collected terms. 



The effects of increasing or decreasing the 

 values used for WSA h and D mM can be seen 

 more readily in this formulation. Changes in 

 the value of WSA h lead directly to equivalent 

 changes in the estimate of ACT (e.g., increas- 

 ing WSA h by 50% will increase the estimated 

 cost of activity by 50% ). WSA h not only has a 

 direct effect on estimates of activity cost, but 

 has also a strong relationship with wet 

 weight, leading to differences of up to 80% in 

 estimates of activity costs for 30-kg versus 

 70-kg spotted dolphins (WSA h for a 70-kg 

 dolphin is 78% larger than for a 30-kg dol- 

 phin. Table 4). Differences are near 350% for 

 5-kg versus 30-kg dolphins (WSA h for a 30- 

 kg dolphin is 339% greater than for a 5-kg 

 dolphin, Table 4). 



Conversely, changes in D,„. 1X have little ac- 

 tual effect on activity estimates, both because 

 changes with size are smaller overall and because 

 of the parameter's algebraic placement in the equa- 

 tion for activity costs. The ratio D max /TL will al- 

 ways be quite small (e.g., 5/80 = 0.065 in an 80-cm 

 dolphin (D mas = 5 cm) weighing 5 kg; 11/210 = 0.052 

 in a 210-cm dolphin (D„ iav = 11cm) weighing 70kg). 

 Because this small term is made even smaller by 

 raising it to higher powers, changes in D max will 

 have little effect on estimates of ACT (e.g., dou- 

 bling D mm from 5 to 10cm for an 80-cm dolphin 



