No abstract

Bottlenose dolphins, Tursiops truncatus, can be separated into coastal and offshore ecotypes based upon hemoglobin levels, packed cell volumes, and red blood cell counts, the offshore form having higher values for all three measures. Captive-bred crosses between coastal and offshore types produce animals with intermediate hematologic profiles suggesting a significant genetic basis for these differences.

The haeniatological and rheological characteristics of blood from seven marine mammal species have been examined to determine the relationship between increased haematocrit. which is correlated with the ability to increase aerobic dive limits. and blood viscosity. The species examined reflect adaptations to a variety of marine niches ranging from coastal to pelagic to iceedge environments. and exhibit a wide range of diving behaviours. Average haematocrits ranged from43–45% in bottlenose dolphins. killer whales and California sea lions to more than 60% in the deeper diving species (beluga whales and northern elephant seals). Whole blood viscosity () increased exponentially with haematocrit (= 0.96*e0‐0335*Hct). representin a two‐fold increase from 4.1 cP for killer whale blood to 8.9 cP for northern elephant seal. There was no apparent compensatory mechanism to reduce viscosity at any shear rate. The optimal haematocrit for oxygen transport was calculated to be40–50% for all species tested. The species with lower haematocrits were within optimal values for oxygen transport. while the two species with the highest haematocrits (beluga whales and northern elephant seals) were above predicted optimal oxygen transport values. On the basis of comparisons of the diving behaviour of these seven species, we suggest that marine mammal species with the greatest adaptation for increased oxygen stores via increased haematocrit have the capacity for deep, long‐duration dives, but a limited oxygen transport capacity. We predict that this compromise precludes fast sustainable swimming behaviour in these species.

Chronological age is a fundamental and yet elusive variable in studies of many wild animals. Telomeres are nucleoprotein structures on the ends of chromosomes that change size throughout the life of many animals and because of this property have been advocated as a means to estimate age. In this review, we assess the existing and potential application of using telomeres for age estimation. We argue that there are conceptual and statistical inconsistencies in previous studies and that the basis for telomere change over time is not well understood and affected by several intrinsic and extrinsic process unrelated to chronological time. Furthermore, these processes are likely to vary spatially and temporally for animal populations. We conclude that the current data suggest telomeres should not be used for age estimation. If telomere-based age estimation is to be used, more work in understanding variability in key processes affecting telomere dynamics and rigorous substantiation via blind testing is needed.

Sea World has maintained killer whales (Orcinus orca) since 1965. The total killer whale inventory has included 39 whales (25 females, 14 males); 28 were wild-caught and 11 captive-born, including one second-generation calf. As of September, 1993, there were 19 whales in the breeding program. Ten of these whales (53%) were captive-born, either at Sea World or other facilities in North America. The live wild-caught whales ranged in estimated age from 12-27 years (X * sd = 17.6 k 4.2 years). The captive-born whales ranged in age from <1 to 8 years. In the Sea World breeding program (through September, 1993), there have been nine live births and one stillbirth, with eight calves part of the current inventory. Births occurred from July to February. Calving intervals ranged from 32-58 months. Female age at birth of first calves ranged from 8 years to an estimated 17 years (% C sd = 12.7 5 3.0 years). Gestation, based on conception estimates from serum progesterone analysis, averaged 17 months (X 2 sd = 517 i 20 days), but successful pregnancies with viable calves occurred from 15-18 months (468-539 days). Females, in the presence and absence of males, were polyestrus with periods of cycling interspersed with individually variable noncycling (presumed anestrous) periods ranging from 3-1 6 months. Mean serum progesterone levels (ese) were as follows: noncycling periods = 121 -+ 20 pg/ml; peak elevations during nonconceptive ovulatory (estrous) cycles = 3,962 & 2,280 pglml; first pregnancies = 14,592 5 3,854 pg/ml; second pregnancies = 8,389 It 395 pg/ml; and third pregnancy = 8,180 t 4,556.