FISHERY BULLETIN: VOL. 85, NO. 1 



before and after Flaxedil injection the next day. The 

 SMR was calculated as the mean of the last four to 

 six metabolic rate measurements. Water tempera- 

 ture was maintained at 25°C (±0.3) throughout the 

 experiment. 



The SMR of rainbow trout was directly deter- 

 mined in the same respirometry box as that used 

 for tunas, using essentially identical methodology, 

 except freshwater was used, inspired and expired 

 water were sampled, and oxygen levels were mea- 

 sured with a water-jacketed Radiometer oxygen 

 electrode. 



RESULTS 



Effects of Body Size on SMR 



The SMR's of 21 kawakawa (0.540-2.153 kg) and 



13 yellowfin tuna (0.585-3.890 kg) were determined 

 at 25°C. Regression lines of SMR versus body 

 weight were fitted by Gauss-Newton iteration (Bio- 

 medical Computer Programs, Program BMDP 3R), 

 rather than a log-log transformation of the data (Fig. 

 1). The advantages of the former and disadvantages 

 of the latter method are discussed by Zar (1968) and 

 Glass (1969). 

 The best fitting allometric equations are 



1) Kawakawa: 



SMR = 392.5 (±32.3) pro.496(±o.i45) 



n = 21 



2) Yellowfin tuna: 



SMR = 286.8 (±26.9) l^-573(±o.ii6) 



n = 13. 

 For comparison, the allometric equation relating 



1000 

 900 

 800 

 700 



600 

 500 



400 

 300 



o> 200 

 E 



DC 



s 



(0 



100 

 90 

 80 

 70 

 60 



50 



1 — I — I — rnr-r 



T — I — r 



SKIPJACK TUNA' 



FROM BRILL (1979) 



KAWAKAWA 

 A 



• / 

 / 

 / 

 / 

 / 



A ^'^ ^YELLOWRN TUNA 



/ 



SKIPJACK TUNA 



FROM GOODING et al., (1981) 



-SALMON 



FROM BRETT & GLASS (1973) 



• YELLOWFIN 

 A KAWAKAWA 



40 

 0.3 



_L 



J ' I I I I 



_L 



J I L 



0.4 0.5 0.6 0.8 1.0 2.0 3.0 4.0 5.0 6.0 8.0 



BODY WEIGHT (kg) 



Figure 1.— A double logarithmic plot of the standard metabolic rates (SMR) of 13 yellowfin tuna and 

 21 kawakawa. The lines represent the allometric equations: SMR = 286.8 W^°^^^ SMR = 392.5 W°^^^ 

 and SMR = 412.0 VF"^^^ for yellowfin tuna, kawakawa, and skipjack tuna, respectively, where the SMR 

 is mg Og/h and W is body weight in kilograms. The line for skipjack tuna is from Brill (1979). For com- 

 parison, the regression lines based on swimming skipjack tuna (Gooding et al. 1981) and for salmon at 

 20°C (Brett and Glass 1973) are also shown. All tuna data is from fish at 23°-25°C. 



28 



