Figure 8. — Arterial O2 

 and Cq., tensions (Pao^ 

 and PacOj) '" ^ 9"* 

 wtiale cal'f, from se- 

 quential blood samples 

 drawn about every 15 

 sees during five respira- 

 tory cycles. 



so 60 70 



to 85 mm Hg, and the corresponding 

 Pcoo varied from 75 to 54 mm Hg. 

 We computed wasted ventilation from 

 the difference between end tidal and 

 mixed expired Pco2- " equalled '3.0 

 percent of V^ at age 3 months and 

 13.5 percent at age 13 months. 



Arterial Po2' ^C02- ^^^ P^* ^'^■'^ 

 measured on three occasions in sam- 

 ples drawn at random during the res- 

 piratory cycle. (Table I). Those values 

 also varied considerably: the differ- 

 ences between arterial and alveolar 

 Pq„ and Pcoo ^^"^^ difficult to inter- 

 pret, and were sometimes negative. 

 Therefore, we measured blood gases 

 and pH in arterial blood drawn se- 

 quentially during the respiratory cy- 

 cle (about every 15 sec); the values 

 then varied systematically (Figure 8). 



DISCUSSION 



As we are presenting data concern- 

 ing the respiratory and metabolic 

 changes in growing whales, we should 

 examine the hypothesis that their size 

 and rate of growth were normal. 

 There is ample reason to raise the 

 question, for confined animals fed 

 contrived diets should always be sus- 

 pected of exhibiting biological values 

 which would be abnormal for the 

 population in nature. There are two 

 methods of examining this question: 

 to make comparisons with other gray 

 whales; and to look for internal evi- 

 dence of abnormal growth and de- 

 velopment. 



Data from Gilmore (1961) and 



Rice and Wolman (1971) comprise 

 the first method, for they have exam- 

 ined gray whale calves similar in age 

 and size to Gigi II. Her weight and 

 length at the time of release compare 

 favorably to the other data on calves 

 thought to be yearlings (Figure 3). 

 As gray whales in the wild are thought 

 to fast during the southern migration 

 (Rice and Wolman, 1971), the obser- 

 vation that Gigi II was slightly heavy 

 for her length should be interpreted 

 with caution. 



The internal evidence relating to 

 the question consists of the observa- 

 tion that Gigi II sustained an increase 

 in body length which preceded any 

 considerable growth in body weight, 

 mitigating against an argument that 

 she was grossly overweight or overfed, 

 and which is consistent with the pat- 

 tern of early growth in other mammals 

 (i.e.. exponential for weight and linear 

 for length) (Christian, 1972; Carlan- 

 der and Ricker, 1962; Brody, 1964). 



Although there is some disagree- 

 ment (Gilmore. 196 l.andpers. comm.). 

 newborn gray whales are estimated to 

 be 4.9 meters in length at birth (Rice 

 and Wolman. 1971). Their birth- 

 weight is less certain, although Rice 

 proposes the weight of the products 

 of conception at term to be between 

 1.000 and 2.000 kg. Our estimates 

 of the birthweight of the two whales 

 at about 1.500 kg. and the birthlength 

 at just under 5 meters are therefore 

 consistent, and permit extrapolation 

 of their ages at capture to 4 weeks for 



Gigi I and 10 weeks for Gigi II. At 

 age 1 year. Gigi II had increased her 

 birthweight by about 3.5 fold, and 

 her birthlength by a little less than 

 1.5 fold. 



Comparison of growth rates be- 

 tween species may be deceptive due 

 to species differences in longevity, 

 newborn maturity, and adult body 

 size. However, since humans and 

 gray whales (Rice and Wolman. 1971) 

 have similar life spans, and are both 

 large mammals, it is of interest to 

 consider their relative growth rates 

 in body weight, respiration, and me- 

 tabolism. 



If mature female gray whales are 

 13 meters in length (Rice and Wol- 

 man. 1971; Scammon. 1874). and 30 

 to 35 thousand kg in weight, then the 

 newborn whale must increase its 

 birthweight by about 20 fold and its 

 birthlength by about 2.5 fold. The 

 fractional annual and ultimate in- 

 creases in weight of the whales are 

 similar to those in man. but the frac- 

 tional increase in length is greater 

 (Benedict and Talbot. 1921). 



Lung volume in human infants in- 

 creases as a cubic function of body 

 length (Cook and Hamann. 1961). a 

 satisfying observation considering the 

 geometry involved. The regression 

 onto body weight is not very reliable; 

 the regression onto length is approxi- 

 mately; Total Lung Capacity (liters) 

 = body length (meters) cubed. Al- 

 though we have insufficient data for 

 the whale to make firm conclusions 

 (and have arbitrarily linearized the 

 data against body weight in Figure 6). 

 calculation of resting lung volume 

 against body length suggests that an 

 equation of Lung Volume = 0.62 X 

 length' also fits the data. This rela- 

 tionship seems reasonable, as resting 

 lung volume in the whale is probably 

 less than total lung capacity. 



Tidal volume and minute ventila- 

 tion increased during the year's growth, 

 and as a first approximation, we have 

 again linearized the data (Figures 4.5). 

 We recognize that changes in res- 

 piratory function and metabolic rate 

 are probably not rectilinear functions 



