Brandon et al.: Neonatal growth ot Eumetopias /ubatus 



249 



was used to estimate total body water (TBW in kg and 

 %TBW as a percentage of BM). Background concentra- 

 tion of deuterium was determined from blood samples 

 taken from pups that were subsequently injected intra- 

 muscularly with 10 mL deuterium oxide (D._,0) (99% en- 

 riched, Cambridge Isotope Laboratories, Andover, MA). 

 After a two-hour equilibration period (Costa, 1987), 

 blood samples were taken to determine the dilution of 

 injected deuterium in total body water. 



Pups were recaptured at approximately two-week 

 intervals over periods ranging in length from 18 to 

 38 days (average measurement period was 29.6 days) 

 (Table 1) and were weighed, measured, and a blood 

 sample was taken from each pup. Similar protocols were 

 used at all rookeries, except Marmot Island in 1990 and 

 1991, when only BM and SL were measured, and the 

 age of pups was not estimated. Therefore, no growth 

 rates were obtained from these data. 



Labeled water sample analysis 



Blood samples were centrifuged in the field in serum 

 separator tubes, and the serum was transferred to cryo- 

 vials that were frozen at -20°C until analysis. Isotope- 

 ratio mass spectrometry was used to determine the 

 ratio of deuterium ( 2 H) to hydrogen (H) (Laboratory of 

 Biochemical and Environmental Studies at University 

 of California, Los Angeles, CA). The hydrogen-isotope 

 dilution space was calculated from this ratio by using 

 Equation 3 in Schoeller et al. (1980). However, the hydro- 

 gen-isotope dilution space has been shown to underesti- 

 mate TBW in a number of pinniped species (Reilly and 

 Fedak, 1990; Arnould et al., 1996b), leading Bowen and 

 Iverson (1998) to develop a single predictive equation to 

 estimate '/'< TBW from hydrogen-isotope dilution space in 

 pinnipeds for which data on the accuracy of the hydro- 

 gen-isotope method are lacking. The equation 



9cTBW = 0.003 + 0.968 H-dilution space 



(1) 



was used in the present study to correct the overesti- 

 mated %TBW by 3.3% (Bowen and Iverson, 1998, Eq. 5). 

 Percent total body lipid (%TBL, as a percentage of BM) 

 was calculated by using predictive equations derived 

 from the relationship between %TBW and 7cTBL for 

 Antarctic fur seals (Arnould et al., 1996b): 



%TBL = 66.562 - 0.845 %TBW. 



(2) 



9cTBL was then compared between male and female pups 

 and among rookeries. 



Statistical analyses 



Statistics were performed by using Systat (version 11, 

 SPSS, Inc, Chicago, ID, and by first treating each study 

 site and year as a separate "location," then combining 

 data for multiple years at a location (e.g., Marmot Island 

 and Lowrie Island) when no significant interannual 

 differences were found. Significance was determined 



at PsO.05. Data were examined for heteroscedasticity 

 (unequal variances) before analysis (Zar, 1984). A\\ post 

 hoc pairwise comparisons were made with the Tukey 

 multiple comparison test. Data from the first capture 

 (1-5 days of age) were analyzed for comparison by loca- 

 tion and sex by using two-way ANOVA. Pup growth rate 

 was estimated by performing a linear regression for each 

 pup and extrapolating to t = to estimate birth mass. 

 Differences among means of pup growth rate and birth 

 mass were then analyzed by using two-way ANOVA to 

 determine differences by location and sex. 



Results 



Neonatal size 



There were no significant differences by rookery in 

 pup mass at 1-5 days of age (Table 2) and no signifi- 

 cant interaction between rookery and sex. The only 

 significant difference in SL of 1-5 day old pups was that 

 both genders were significantly longer on Seguam and 

 Yunaska Islands than on Fish Island (P=0.0395). Pups 

 on Chirikof Island had significantly smaller AG than 

 pups on Lowrie, Fish, and Seguam and Yunaska Islands 

 (P<0.02). Male and female pups were significantly differ- 

 ent for all three morphometric measurements. Overall, 

 male pups averaged 22.6 kg (±2.21 SD, ?i=71) and female 

 pups averaged 19.6 kg (±1.80 SD, ;?=74) at first capture 

 ( 1-5 days of age). 



There was no significant difference by rookery or sex 

 and no significant interaction between rookery and sex 

 in %TBW or %TBL of pups at first capture. When all 

 pups at all rookeries were combined ( « =116), %TBW 

 was 72.1% of BM (±3.17 SD) and %TBL was 5.6% of 

 BM (±2.68 SD). Male pups had a significantly greater 

 absolute TBW than female pups (P<0.0001), as would be 

 expected because of the difference in BM at birth. There 

 was a significant correlation between TBW and BM 

 (Pearson r=0.945, P<0.001, ra=116; TBW (kg) = 0.6895 

 xBM + 0.6618). 



Neonatal growth 



Growth rates were treated as linear over the period 

 monitored; there were not enough data to determine 

 if growth was nonlinear. Male and female pups on the 

 same rookery grew at the same rate (in BM, SL, and 

 AG) during the first six weeks after birth (Fig. 2). When 

 compared by rookery, BM increased at a faster rate for 

 pups on Chirikof Island (P=0.0005) and on Seguam 

 and Yunaska Islands (P= 0.0002) than on Lowrie Island 

 (Fig. 3 and Table 3). The increase in BM for pups on 

 Fish Island did not differ significantly from that at 

 other rookeries. Marmot Island pups grew significantly 

 more slowly than pups on Seguam and Yunaska Islands 

 (P= 0.0382) but did not differ significantly from growth 

 of pups at other rookeries. 



Standard length increased at a faster rate for pups 

 on Chirikof Island (P=0.0068) and Seguam and Yu- 



