The development of socio-sexual behavior in belugas (Delphinapterus leucas) under human care.

Although a catalog of beluga socio-sexual behavior has been established, to date, little is known about the development of beluga (Delphinapterus leucas) socio-sexual behavior. The present study explored how socio-sexual behavior developed in belugas under human care by recording the behavior of 5 belugas between years 4 and 10 of life. Overall, the presence of young male conspecifics was the most influential predictor of whether or not the subjects engaged in socio-sexual behavior, and social networks particularly emphasized the relationships between males in the social group. The subjects of the present study were also more likely to be involved in socio-sexual behavior as they matured and were more likely to be involved if they were male. Additionally, specific socio-sexual behaviors of the repertoire, including horizontal s-postures and pelvic thrusts, increased in prevalence throughout development. These findings have implications for conservation efforts as social group composition may contribute to the development of socio-sexual behavior, which in turn may influence the reproductive success of beluga populations. Furthermore, because socio-sexual behavior composes a substantial portion of a beluga's activity budget and the majority of the time spent socializing, it is likely crucial for social bonding and well-being in belugas, especially males.

Body Growth and Rapid Hematological Development Support Breath Hold of Baby Belugas (Delphinapterus leucas) during Subice Transit.

Body size and oxygen stores in the blood and muscle set breath-hold limits in marine mammals, yet these characteristics are understudied in immature cetaceans. We examined body mass and hematology from birth through adulthood in beluga whales (Delphinapterus leucas). At birth, body mass was 8% and 6% of the maximum mass recorded for adult females and males, respectively. Body mass then increased rapidly, approaching an asymptote around 12 yr for females and 18 yr for males. Interestingly, red blood cell counts, hemoglobin content, and hematocrit levels decreased after birth; this neonatal anemia was reversed as levels increased after 2 mo postpartum. Mature levels were obtained at approximately 8, 9, and 11 mo postpartum, respectively. Neonatal mean corpuscular hemoglobin also increased with ontogeny; mature levels were achieved by approximately 13 mo after birth. In contrast, mean corpuscular volume and mean corpuscular hemoglobin concentration demonstrated a significant but subtle increase throughout ontogeny. Our results indicate that postnatal maturation was required and that maturation occurred far earlier than the age at weaning (i.e., 2-3 yr postpartum). This is atypical of marine mammals, which generally achieve mature hemoglobin levels at weaning. Hematological maturation before maternal independence undoubtedly supports the prolonged breath holds of young belugas transiting under sea ice. This assessment enhances our knowledge of cetacean physiology and provides important inputs for determining age-specific dive capacity, yielding insights into age-specific flexibility to alter underwater behaviors, as will be required for future regime shifts and disturbances.

Lateralized swim positions are conserved across environments for beluga (Delphinapterus leucas) mother-calf pairs.

Research with wild belugas has indicated that, during mother-calf swims, calves spend more time on their mothers' right side, which enables the calves to maintain visual contact with their mothers using their left eye. This bias may facilitate processing of social information by the right hemisphere, much like human and non-human primates and other animals. The current study explored the social laterality of the Cook Inlet, AK beluga population in comparison to a beluga population in managed care. As expected, the results indicated that the calves spent more time on the mothers' right side than the left for both populations. We also examined the developmental trend for the belugas in managed care and found that the calves generally preferred to swim on their mother's right side across most months, although there was an inversion during the third quarter when a left-side preference appeared. Individual differences were present. The results corroborate previous research conducted with two wild beluga populations from the White Sea and from the Sea of Okhotsk in which a left-eye bias was displayed by calves when swimming with their mothers. In conclusion, a preference for a lateralized swim position appears to be conserved across wild and managed care settings, and this lateralized swim position may facilitate the processing of social information or familiar stimuli for the calves.

The first year of behavioral development and maternal care of beluga (Delphinapterus leucas) calves in human care.

The current study provides additional information for the behavioral development and maternal care of belugas or white whales (Delphinapterus leucas) in the care of humans. The behaviors and mother-calf interactions of two female beluga calves were recorded from birth to 12 months as part of a longitudinal study of beluga behavioral development. As expected, the primary calf activity for both calves involved swimming with their mothers. The calves initiated the majority of the separations from and reunions with their mothers and exhibited early bouts of independence. Both mothers bonded with their calves and displayed similar maternal care behaviors but exhibited different behavioral patterns. Despite differences in social groupings, housing, and physical health, the two female belugas followed the behavioral development of beluga calves observed previously.

Ecosystem regime shifts have not affected growth and survivorship of eastern Beaufort Sea belugas.

Large-scale ocean-atmosphere physical dynamics can have profound impacts on the structure and organization of marine ecosystems. These changes have been termed "regime shifts", and five different episodes have been detected in the North Pacific Ocean, with concurrent changes also occurring in the Bering and Beaufort Seas. Belugas from the Eastern Beaufort Sea (EBS) use the Bering Sea during winter and the Beaufort Sea during summer, yet the potential effects of regime shifts on belugas have not been assessed. We investigated whether body size and survivorship of EBS belugas harvested in the Mackenzie River delta region between 1993 and 2003 have been affected by previous purported regime shifts in the North Pacific. Residuals from the relationship between body length and age were calculated and compared among belugas born between 1932 and 1989. Residual body size was not significantly related to birth year for any regime, nor to the age group individuals belonged to during any regime. The percentage deviation in number of belugas born in any given year that survived to be included in the hunt (survivorship) did not show any significant trend within or between regimes. Accounting for lags of 1-5 years did not reveal any evidence of delayed effects. Furthermore, neither population index was significantly related to changes in major climatic variables that precede regime shifts. Our results suggest that EBS beluga body size and survivorship have not been affected by the major regime shifts of the North Pacific and the adjacent Bering and Beaufort Seas. EBS belugas may have been able to modify their diet without compromising their growth and survivorship. Diet and reproductive analyses over large and small time scales can help understand the mechanisms enabling belugas to avoid significant growth and reproductive effects of past regime shifts.

[Mother-infant spatial relations in wild beluga (Delphinapterus leucas) during postnatal development under natural conditions].

Elements of behavior under natural conditions, their duration, and frequency are described in three age groups of belugas calves: newborn, one-month-old, and two-month-old. The quantitative and qualitative indices of the recognized behavioral elements allowed us to evaluate the mother-infant contacts and to analyze their dynamics during calf growth. The most common calf positions relative to the mother during this period were "at the cow's tail" and "at the cow's side." The importance of behavioral responses of calf for the development of social behavior in adult animals is emphasized.

Mercury distribution in the skin of beluga (Delphinapterus leucas) and narwhal (Monodon monoceros) from the Canadian Arctic and mercury burdens and excretion by moulting.

Beluga and narwhal skin as a whole (in Inuktitut known as "muktuk") is considered to be a delicacy by native Canadian and Greenland people. Individual strata of the skin, and muscle from 27 beluga from the western, and 20 narwhal from the eastern Canadian Arctic, were analyzed for mercury and the thickness and density of each skin layer was measured. Mercury was not uniformly distributed in the skin, but increased outwardly with each layer. The concentration was only 0.29 and 0.16 microg/g (wet wt) in the innermost layer (dermis) of belugas and narwhal respectively, and 1.5 and 1.4 microg/g (wet wt) in the outermost layer (degenerative epidermis) of beluga and narwhal, respectively. There was a significant (alpha=0.05) association between age and mercury concentration in each skin layer, the regression coefficients progressively increasing from the inner layer (dermis) to the outer layer: 0.011-0.063 microg/g year-1; 0.034 microg/g year-1 for skin as a whole; 0.054 microg/g year-1 for muscle. The concentration of total mercury was 0.84 and 0.59 microg/g (wet wt) in skin as a whole (muktuk) of beluga and narwhal respectively, and 0.12 and 0.03 microg/g in blubber, respectively. The average, total mercury concentration in muscle tissue was 1.4 and 0.81 microg/g wet wt, in beluga and narwhal respectively, exceeding (except for blubber) the Canadian Government's Guideline (0.5 microg/g wet wt) for fish export and consumption. The skin surface area of an average-size beluga and narwhal was estimated (6.10 and 6.50 m2, respectively), as were excretions of mercury through moulting (13,861 and 6721 microg year-1; 14 and 7 mg year-1) for belugas and narwhal, respectively. The whole-body mercury burden (699,300 microg; 700 mg) for a 1000 kg beluga and its various tissues were estimated, as was the fraction of mercury excreted by moulting (2-0.42% of the whole-body burden). Annual mercury burden increments in beluga skin, muscle and the whole body were estimated (2750; 17,280; 40,00 microg year-1, respectively), using regression coefficients of age on mercury concentration. The annual gross mercury intake via food was estimated (131,400 microg), of which 70% was excreted.