Bering-Chukchi-Beaufort Seas bowhead whale (Balaena mysticetus) abundance estimate from the 2019 ice-based survey

An ice-based visual survey of the Bering-Chukchi-Beaufort Seas stock of bowhead whales (Balaena mysticetus) was conducted in spring 2019 near Utqiaġvik (formerly Barrow), Alaska. A Horvitz-Thompson-type estimator is used to estimate population abundance from the resulting data, correcting for detection probabilities, whale availability within visual range, and whale passage during periods of missed effort. Analytical methods mirror those used by Givens et al. (2016) for the 2011 survey as much as possible; however, unlike 2011, no simultaneous acoustic monitoring was conducted in 2019, so the availability correction factor had to be estimated from past years. The estimated abundance was 12,505 with 95% confidence interval of (7,994, 19,560) and a CV of 0.228. This estimated abundance is markedly lower than the 2011 estimate of 16,820, but the 2019 confidence interval wholly encompasses the 2011 interval. We do not interpret this finding as evidence of a decline for many reasons including: highly unusual ice conditions, an unusual migration route that was sometimes too distant from observers to detect whales, failure to conduct watch because of closed leads during the early weeks of the migration when numerous whales likely passed, an unusually short perch, and hunters’ heavy use of powered skiffs near the observation perch which likely disturbed the whales during the survey. Furthermore, bowhead health assessment information for 2019 suggests that harvested bowheads did not exhibit obvious reductions in health condition, and aerial surveys in summer 2019 indicated high calf production (Stimmelmayr et al. 2020). Despite the challenges of the 2019 survey, the estimate is adequate for use with the International Whaling Commission’s management procedure and complies with the survey requirements of the Aboriginal Whaling Scheme.

Developing a Precautionary Management Approach for the Eastern Canada-West Greenland Population of Bowhead Whales (Balaena mysticetus)

Bowhead whales (Balaena mysticetus L., 1758) of the Eastern Canada-West Greenland population have been hunted by Inuit for millennia. Significant commercial harvests, conducted by European and American whalers for about 400 years, ended ca. 1915. A small co-managed subsistence harvest from this population has occurred inconsistently in Canada and Greenland, since 1996 and 2009, respectively. Since near extirpation from commercial whaling, population size has increased and the Inuit subsistence hunt now requires a harvest management framework that incorporates knowledge of abundance trends, population dynamics, and carrying capacity. Here, we use a model estimate of pre-commercial exploitation abundance to approximate carrying capacity and develop a management framework with reference points and corresponding stock status zones. When applied to recent abundance estimates, our framework indicates that the population is likely within the healthy (N50–N70) zone. Thus, an appropriate management objective is to support continued population increase, with concurrent marginal harvesting, while maintaining the population level above the target reference point (N70) of ca 12,000 whales. However, there remains large uncertainty about current population size and growth rate. The resulting data gaps require a plan for future research to monitor this population in the context of climate changes.

Identifikasi Karakterstik Molekuler Gen 16S rRNA Parsial pada Paus Sperma (Physeter macrocephalus Linnaeus, 1758)

Paus sperma (Physeter macrocephalus) merupakan salah satu mamalia laut yang dikategorikan dalam status vulnerable pada IUCN dan status Appendix I pada CITES. Identitas asli dari paus sperma secara molekuler dapat ditelusuri. Penelitian ini bertujuan untuk mengidentifikasi karakteristik molekuler paus sperma (P. macrocephalus) berdasarkan gen 16s rRNA parsial. Tiga contoh jaringan paus sperma yang dianalisis berasal dari perairan Laut Sawu, Nusa Tenggara Timur. Hasil identifikasi berdasarkan sekuen basa nukleotida gen parsial 16S rRNA menunjukkan bahwa ketiga contoh memiliki kemiripan dengan Physeter catodon sebesar 99%, dimana P. catodon merupakan sinonim dari P. macrocephalus. Pensejajaran sekuen nukleotida dengan outgroup (Balaenoptera physalus dan Balaena mysticetus) didapatkan nilai jarak genetik ketiga contoh dengan outgroup berkisar antara 0,0093–0,0726. Selain itu, didapatkan 25 nukleotida spesifik P. macrocephalus yang mampu membedakan dari spesies outgroup. Penelitian ini mampu memvalidasi spesies P. macrocephalus berdasarkan gen 16S rRNA dan dapat dijadikan sebagai marka molekuler yang kuat untuk identifikasi P. macrocephalus.