Insights into Critically Endangered Mekong Dolphin Genetics and What This Means for Conservation

New research has shed light on the genetics of critically endangered Irrawaddy dolphins in the Mekong River. The results are interesting, concerning, hopeful, and a call to action. The study brought together samples collected between 2000 and 2009 and the work of a group of researchers, to look at the genetic diversity, phylogeny, and demographic history of the Mekong dolphin population, and consider what this means for conservation.

The genetic diversity of the population is low, though the results weren’t clear whether this was due to (i) recent genetic collapse from the currently small population size or (ii) the low diversity inherited from the Irrawaddy dolphins that first moved into the Mekong River long ago (with such a long life-span, dolphins evolve slowly). However the results were clear that Mekong dolphins are very distinct from other Irrawaddy dolphins, even those in nearby coastal areas in Cambodia. It’s possible that the population represents a sub-species, though more evidence is needed to clarify this.

Fig 1 – Phylogenetic relationships of the genus Orcaella based on 384bp of the hyper-variable region I of mitochondrial DNA. Numbers indicate Bayesian posterior probability values for each clade.

So what does this mean for conservation of dolphins in the Mekong? Preserving the existing genetic diversity is a high priority, and the best way to do this is by protection of the existing wild population. Ongoing work in the field to protect them through management of gillnet fishing in dolphin habitats and parallel awareness raising and livelihood diversification work with local communities is the cornerstone. These efforts need to be combined with continuing policy support to protect remaining dolphin habitat from developments like proposed mainstream hydropower dams.

See our Special Projects page for more information on the Critically Endangered population of Irrawaddy dolphins in the Mekong River.

The full article:

Krützen, M, Beasley I, Ackermann, CY, Lieckfeldt, D, Ludwig, A, Ryan GE, Bejder, L, Parra, GJ, Wolfensberger, R, & Spencer, PBS (2018). Demographic collapse and low genetic diversity of the Irrawaddy dolphin population inhabiting the Mekong River. PLoS ONE 13(1): e0189200

Cooperative Net Removal Efforts Increase to Save Vaquitas

The net removal effort, started by Sea Shepherd’s Operation Milagro in collaboration with the Mexican Navy in 2015, is building to become the biggest yet in the totoaba season currently under way. The initial Sea Shepherd/Navy effort focused on observing pangas illegally setting nets at night and on removing those nets. The effort was expanded in 2016 to systematically remove both active and inactive nets throughout the vaquita’s primary distribution. This expansion in effort has been led by the Department of the Environment (SEMARNAT) together with Sea Shepherd, the Mexican Navy and Army, PEMEX, WWF-Mexico, Museo de la Ballena, Parley, World Animal Protection, and the fishermen’s organizations PESCA ABC and Cooperativa Islas del Golfo. The Mexican Fisheries Department CONAPESCA recently started supporting the program as well.

From December 2016 through December 2017, 518 nets were retrieved, most of them active totoaba nets. Over 50 tons of net were donated to Parley for recycling (further details can be found in the CIRVA 10 Report).

With fewer than 30 vaquitas remaining and the idea of rescuing some by capturing them and placing them in human care not considered viable, conservation action is now focussed on enforcement and net removal. The current enhanced net removal effort during the totoaba spawning season will last until May. Because the net removal effort is critical to saving the vaquita, progress will be updated on this website monthly.

The map on the left shows active nets removed between October 2017 and January 2018. The graph on the right shows the number of totoaba nets removed by Sea Shepherd last year (blue) and this year (orange).

Arabian Sea humpback whale tagged off the coast of Oman crosses to India!

In November 2017, a research team led by the Environment Society of Oman (ESO) and Five Oceans Environmental Services placed a satellite tag on a humpback whale in the Gulf of Masirah, Oman. First observed, photographed, and biopsied close to the same site in October 2002, the whale was genetically determined to be a female, and was named Luban – the Arabic word for Frankincense – due to the tree-like pattern in the centre of her tail fluke. She was one of 14 whales to have been satellite tagged off the coast of Oman since 2014, of which only two were females. Tagging was supported through sponsorship from Renaissance Services SAOG.   In the first three weeks following her tag deployment, it appeared that Luban would follow the pattern of previously tagged whales, that all remained in waters off the coast of Oman or Yemen. Around day 21, however, Luban began a journey that would captivate all of the members of the research team and all the members of the Arabian Sea Whale Network for the next several weeks.   True to her name, Luban followed one of the ancient routes of the Frankinsense trade, crossing from Oman to the west coast of India, where she slowly made her way south and has been engaged in small-scale localized movements off the southernmost tip of India since late December.

Data hosted by SeaTurtle.org. http://www.seaturtle.org/tracking/index.shtml?project_id=1295

Static Map | Zoom Map | Animated Map (66KB)

Photograph of Luban’s tail flukes. Notice the tree-like pattern in the center, from which her name, the Arabic word for Frankincense tree, is derived.

Research teams on both sides of the Arabian Sea have been speculating as to the reasons behind this ocean crossing. Satellite imagery has revealed areas of high phytoplankton productivity along the west coast of India which is a potential indicator of where prey may be found, and interviews with fishers on the coast are detailing good landings of the one of the humpback’s favoured foods, sardines. However, given that the crossing occurred during the beginning of the population’s breeding season, some are speculating that she may have also been driven by a search for mating or calving grounds rather than feeding opportunities. By late December the overwhelming interest in Luban’s movements motivated a community of marine scientists along the west coast of India to collaborate and conduct fisher interviews as well as boat surveys to try and locate Luban or any other whales in the area, as well as to document the conditions around the area of her track. At the time of writing none of the parties have yet sighted Luban in Indian waters. However another team will begin surveys off the southern tip of India on January 31st to further investigate the waters where the telemetry data indicate she has spent the last month. It is hoped these surveys will feed into regional efforts to better understand the conservation status of this unique population of whales.

Arabian Sea humpback whales were designated as Endangered on the IUCN Red List of Threatened Species in 20081. At the time, reviewers considered the case for a Critically Endangered Status based on the very low numbers and threats documented off the coast of Oman, but decided that too little was known about the rest of the population’s suspected range. Questions have since remained as to whether whales taken on both sides of the Arabian Sea during illegal Soviet whaling operations in the 1960s2 represented a single management unit with frequent exchange, or two separate sub-populations isolated from each other.   Luban’s crossing provides the first recent indication that there may be regular movement between Oman and other areas of the Arabian Sea, and increased efforts to collect opportunistic data from fishing, tourism and coast guard platforms in India and Pakistan indicate that humpback whales are still present on the Eastern side of the Arabian Sea.

Participants to a workshop in Oman introducing a regional online data platform that will facilitate collaboration on whale conservation throughout the Arabian Sea.

The crossing provided extra excitement and motivation for researchers from a number of Arabian Sea humpback whale range states who met in Muscat from January 21-24th for a workshop focusing on the introduction of a new regional online data platform that will facilitate collaboration throughout the region. It has also confirmed that collaborative regional efforts, such as the recently approved Concerted Action under the Convention for Migratory Species are needed to effectively protect and manage this endangered population.

For more information consult Suaad al Harthi of the Environment Society of Oman: salharthi@eso.org.om, or Andrew Willson, of Five Oceans Environmental Services: andy.willson@5oes.com

References

  1. Minton, G. et al. Megaptera novaeangliae, Arabian Sea subpopulation. IUCN Red List of Threatened Species http://www.iucnredlist.org/details/132835 (2008).
  2. Mikhalev, Y. A. Humpback whales Megaptera novaeangliae in the Arabian Sea. Marine Ecology Progress Series 149, 13-21 (1997).

 

Luban – Renaissance Whale and Dolphin Project 2017 Arabian Sea Humpback Whale Satellite Tagging

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