Brown M R, Corkeron P J, Hale P T, Schultz K W, Bryden M M
Department of Veterinary Anatomy, University of Sydney, N.S.W., Australia.
Proc Biol Sci. 1995 Feb 22;259(1355):229-34. doi: 10.1098/rspb.1995.0034.
Existing population models for humpback whales assume that all individuals within a population undertake the annual migration from feeding areas in high latitudes to breeding areas in tropical waters. An excess of males was recorded in the commercial whaling catches near breeding areas in the southern hemisphere, but no account of this was taken in developing population models, because it was believed that this bias was a result of whalers selecting against females with young calves. Here we demonstrate that the sex ratio of migrating humpback whales near a breeding area is highly skewed towards males. A biopsy study carried out in 1992 throughout the northward and southward migrations revealed a sex ratio of 2.4 males: 1 female in the population of humpback whales migrating along the east Australian coast (n = 180). A reanalysis of the catches made during commercial whaling in this and other areas of the southern hemisphere gave a sex ratio of the same order. The most plausible explanation, supported by some evidence, is that some females remain in the feeding areas throughout winter. The results reported here show that existing management models require major revision to take account of these findings.
现有的座头鲸种群模型假定，种群中的所有个体都会进行一年一度的洄游，即从高纬度的觅食区前往热带水域的繁殖区。在南半球繁殖区附近的商业捕鲸渔获中，雄性的数量过多，但在构建种群模型时并未考虑这一点，因为人们认为这种偏差是捕鲸者对带着幼崽的雌性进行选择性捕杀所致。在此，我们证明，在靠近繁殖区的洄游座头鲸中，性别比例严重偏向雄性。1992年在整个向北和向南洄游过程中开展的一项活检研究显示，沿澳大利亚东海岸洄游的座头鲸种群中，雄性与雌性的比例为2.4:1（n = 180）。对南半球这个区域和其他区域商业捕鲸期间的渔获进行重新分析后，得到了相同比例的性别比。有一些证据支持的最合理的解释是，一些雌性会在整个冬季留在觅食区。本文报告的结果表明，现有的管理模型需要进行重大修订，以考虑到这些发现。
