Understanding variability in growth patterns of marine mammals provides insights into the health of individuals and status of populations. Body growth of gray whales (Eschrichtius robustus) has been described for particular life stages, but has not been quantified across all ages. We derived a comprehensive growth equation for gray whales by fitting a two-phased growth model to age-specific length data of eastern North Pacific gray whales that were captured, stranded, or harvested between 1926 and 1997. To predict mass-at-age, we used the allometric relationship between mass and length. We found that on average (± SD), calves were 4.6 ± 0.043 m and 972 ± 26 kg at birth, and reached 8.5 ± 0.095 m and 6,019 ± 196 kg by the end of their first year of life (n = 118). Thus, calves almost double (2×) in length and octuple (8×) in mass while nursing, and are effectively about two-thirds of their asymptotic adult length and one-third of their maximum mass when weaned. The large sample of aged individuals (n = 730) indicates that gray whales live up to ∼48 years and have a life expectancy of < 30 years. Adult females attain a mean (± SD) asymptotic size of 13.1 ± 0.048 m and 20,758 ± 222 kg, while the smaller males average 12.6 ± 0.048 m and 19,938 ± 222 kg at ∼40 years of age. Females are thereby ∼4% longer and heavier than males. These age-specific estimates of body size can be used to estimate food requirements and assess nutritional status of individuals.

中文翻译：

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北太平洋灰鲸（Eschrichtiusrobustus）的生长发育

了解海洋哺乳动物生长模式的可变性可以深入了解个体的健康状况和种群状况。灰鲸 (Eschrichtiusrobustus) 的身体生长已被描述为特定生命阶段，但尚未在所有年龄阶段进行量化。我们通过将两阶段生长模型拟合到 1926 年至 1997 年间捕获、搁浅或收获的北太平洋东部灰鲸的特定年龄长度数据，推导出了灰鲸的综合生长方程。我们使用了质量和长度之间的异速生长关系。我们发现，小牛出生时平均 (± SD) 为 4.6 ± 0.043 m 和 972 ± 26 kg，并在其生命的第一年结束时达到 8.5 ± 0.095 m 和 6,019 ± 196 kg（n = 118）。因此，在哺乳期间，小牛的长度几乎翻了一番（2倍），质量增加了八倍（8倍），并且实际上大约是其渐近成年长度的三分之二和断奶时最大质量的三分之一。老年个体的大样本（n = 730）表明灰鲸的寿命可达 48 岁左右，预期寿命 < 30 年。成年雌性的平均 (± SD) 渐近尺寸为 13.1 ± 0.048 m 和 20,758 ± 222 kg，而较小的雄性在 40 岁时平均为 12.6 ± 0.048 m 和 19,938 ± 222 kg。因此，雌性比雄性长约 4% 且体重更重。这些特定年龄的体型估计可用于估计食物需求和评估个体的营养状况。老年个体的大样本（n = 730）表明灰鲸的寿命可达 48 岁左右，预期寿命 < 30 年。成年雌性的平均 (± SD) 渐近尺寸为 13.1 ± 0.048 m 和 20,758 ± 222 kg，而较小的雄性在 40 岁时平均为 12.6 ± 0.048 m 和 19,938 ± 222 kg。因此，雌性比雄性长约 4% 且体重更重。这些特定年龄的体型估计可用于估计食物需求和评估个体的营养状况。老年个体的大样本（n = 730）表明灰鲸的寿命可达 48 岁左右，预期寿命 < 30 年。成年雌性的平均 (± SD) 渐近尺寸为 13.1 ± 0.048 m 和 20,758 ± 222 kg，而较小的雄性在 40 岁时平均为 12.6 ± 0.048 m 和 19,938 ± 222 kg。因此，雌性比雄性长约 4% 且体重更重。这些特定年龄的体型估计可用于估计食物需求和评估个体的营养状况。