Scientists galvanise to conserve Endangered Indian Ocean humpback dolphins

Like these in Dubai, UAE, humpback dolphins live very close to shore, often close to cities (Photographer: Ada Natoli).

Indian Ocean humpback dolphins (Sousa plumbea) are assessed as Endangered on the IUCN Red List, meaning they are among the species of greatest conservation concern globally.  The species range spans from the southern tip of Africa to the southern tip of India, including the Red Sea, Arabian/Persian Gulf and some islands, such as Madagascar, Sri Lanka, Zanzibar, Socotra and Mayotte. Many of the 23 range countries are low-income states.

These dolphins occur mainly in shallow water less than 25m deep, and they favour estuaries, coral reef and rocky shore habitats, lagoons, and shallow sheltered bays.  In most places where data are available, populations are small and declining because of their proximity to highly populated coastlines and exposure to numerous threats.  Significant gaps exist in knowledge, capacity and resources.

To galvanise conservation action, in early 2024, researchers and conservationists working on the species formed the Indian Ocean Humpback Dolphin Conservation Network (HuDoNet). In total, 72 scientists from 17 countries in the western Indian Ocean and Arabian Sea are now working together under HuDoNet’s umbrella.

The aim of HuDoNet is to foster and facilitate collaborative research and management efforts by sharing expertise and working together across the species range, attracting resources to support local initiatives. By unifying and amplifying the voices of individual researchers the hope is to draw attention to the needs of humpback dolphins.  The network created a logo (see below) and website: hudonet.org.

The main immediate task of the group is to set short- and medium-term targets for action in the form of a Network Action Plan. To do this, HuDoNet has established five working groups:

Indian Ocean Humpback dolphins in Tanzania (Photographer: Gill Braulik)

  • Biological Research;
  • Threats and Solutions;
  • Policy;
  • People; and
  • Network Success.

 

Each working group is undertaking the process of:
1) collating and synthesising available data to highlight gaps and opportunities for action;
2) identifying leverage points and weighing up the costs, benefits and feasibility of potential interventions, and
3) specifying the resources and capacity required for prioritised actions.

Working group meetings have been convened throughout October and November and connections are being made within this large, culturally diverse, widely dispersed group of people – a crucial step towards achieving HuDoNet’s mission of ensuring a future for Indian Ocean humpback dolphins throughout their range.  To learn more or to provide assistance or support please explore the website: www.hudonet.org.

Shipping and associated infrastructure are among the many threats to the Endangered Indian Ocean humpback dolphins (Photographer: Brett Atkins)

 

New Content Available in the CSG Online Library

 

In September 2004, IUCN convened an independent scientific review panel with a mandate to (i) assess potential threats to western gray whales from an offshore oil and gas development project called Sakhalin-II Phase 2 and (ii) evaluate and advise on mitigation measures proposed by the project operator, Sakhalin Energy Investment Company (SEIC). Thus began a 17-year oversight program involving a series of IUCN-convened panels consisting of experts from the Russian Federation, Canada, Germany, Sweden, Ireland, the United Kingdom and the United States, intended to provide guidance to the oil and gas industry to minimize the risks to gray whales and their habitat on the north-eastern Sakhalin shelf.  

 

In addition to the publication of panel meeting and task force reports, the Western Gray Whale Advisory Panel (WGWAP), and its predecessors, issued open letters to Russian government agencies, statements of concern to stakeholders and more than 600 formal recommendations directed primarily at offshore oil and gas companies but also at Russian regulatory authorities.  

 

WGWAP’s final meeting took place in Gland, Switzerland in November 2021 and its corresponding final report was finalized in January 2022 but was never officially released or posted online. In fact, following the Russian invasion of Ukraine in February 2022, IUCN permanently removed the entire dedicated, publicly accessible WGWAP body of work from its website. The Cetacean Specialist Group (CSG), with the invaluable help of DJ Shubert of the Animal Welfare Institute, has managed to recover a large portion of the IUCN panel-related material (including in excess of 80 reports and documents) and make it available once again here on a dedicated page of our CSG online Library.

 

Additionally, a large portion of the Marine Mammal Holarctic Conference proceedings is now publicly accessible on the CSG website here under the ‘Useful Links and References’ section of our CSG online Library. The CSG is grateful to Vladimir Burkanov for providing those materials. 

Update: Threats to Taiwanese white dolphins from offshore windfarms

By Qingyi Zeng1 and Chiawen Kuo2
with input from John Y. Wang, Randall Reeves, Gianna Minton and Gill Braulik
1 Ph.D. student at University of Michigan, Ann Arbor
2 Researcher at Wild at Heart Legal Defense Association, Director of Matsu Fish Conservation Union

 

With the aim of reaching net-zero emissions by 2050, Taiwan has committed to achieving a total offshore wind power capacity of 5.6 GW by 2025 and 40–55 GW by 2050 (National Development Council, 2022). This energy policy has led to the rapid expansion of offshore windfarms along Taiwan’s west coast, all situated adjacent to or even within the habitat of critically endangered Taiwanese white dolphins (Sousa chinensis taiwanensis), thereby exacerbating the pre-existing threats to their survival from entanglement in gillnets, habitat loss, pollution etc.

Since 2003, this individual dolphin has been photographed almost annually (Photograph by: John Y. Wang / CetAsia Research Group Ltd.).

By the end of 2023, four windfarms, comprising 201 turbines, had been completed and were in operation. Six more offshore windfarms were under construction and another five were expected to be completed by 2027. While most of the windfarms are located more than 5 km away from shore, marine construction activities that include pile driving and cable laying, especially for the cables that must cross Taiwanese white dolphin habitat to reach the energy grid system on land, intrude into dolphin habitat.

In 2011 the Forestry and Nature Conservation Agency commissioned scientists to delineate Taiwanese white dolphin critical habitat, and an official announcement came into effect in September 2020. The designated critical habitat spans a total of 763 km2, from Miaoli County to Waisanding Zhou, Chiayi County.

Large offshore windfarm projects are under construction in and adjacent to the habitat of critically Endangered Taiwanese white dolphins (Photograph by: John Y. Wang / CetAsia Research Group Ltd.).

While the designation has helped to protect the dolphins’ habitat, the area does not encompass the entire known area used by the dolphins (see Figure below) nor does it extend to other areas of suitable dolphin habitat. These shortcomings were pointed out by teams of international scientists in 2014 and 2020, and the Ocean Affairs Council has been looking into the matter since then.

In addition to continuing habitat degradation and loss, large-scale offshore windfarm construction has resulted in a major surge in vessel traffic as well as increased construction activities, including sea-floor profiling and pile driving, which contribute substantially to underwater noise. Although pile-driving noise is typically low-frequency, research has shown that it can be broadband, with peak sound energy at frequencies of up to 10 kHz, meaning that the sound is well within the frequency range of humpback dolphins (Sousa spp.).

Figure 5 from Ross et al. (2010) showing “priority habitat” for the subspecies

Current regulations concerning offshore windfarm construction in Taiwan mandate that underwater noise within a 750 m radius of a pile-driving site should be kept below 160 dB re 1Pa for 95% of the monitoring time. However, this mitigation measure may be inadequate given that the onset of temporary hearing threshold shifts for certain high-frequency cetaceans can be lower than 160 dB re 1Pa. Also, the threshold for the onset of behavioral disturbance caused by continuous underwater noise, such as that from vibratory pile driving, can be as low as 120 dB re 1Pa.

Increasingly, offshore wind turbines are being installed in the dolphins’ habitat (Photograph by: John Y. Wang / CetAsia Research Group Ltd.).

Although the hearing thresholds of Sousa chinensis at low frequencies have not been tested empirically, there is considerable evidence to suggest that stricter regulation of anthropogenic underwater noise along the west coast of Taiwan is needed to provide a healthier soundscape for the critically endangered Taiwanese subspecies. Despite that evidence, for nearly the entire first 5.6 GW of wind power installation off western Taiwan, no effort was made to assess the impacts on dolphin behavior.

 

For relevant literature, see https://iucn-csg.org/csg-focal-taxa/eastern-taiwan-strait-humpback-dolphins/