Cetaceans in the Western Indian Ocean


In early 2019 cetaceans in the Western Indian Ocean and Arabian Seas were the focus of two important scientific meetings. The first was to identify Important Marine Mammal Areas (IMMAs) within the region, and the second, conducted under the auspices of the International Whaling Commission Bycatch Mitigation Initiative, was to look at priority areas in the region for cetacean bycatch interventions.


Important Marine Mammal Areas.
Important Marine Mammal Areas (IMMAs) are defined as discrete portions of habitat, important to marine mammal species, that have the potential to be delineated and managed for conservation. The Western Indian Ocean and Arabian Seas IMMA identification workshop took place on March 4th-8th 2019. The workshop was held in Salalah, Oman, and involved 38 marine mammal scientists and observers from 15 countries, with several more scientists contributing to assessments and proposals remotely. A total of 55 candidate important marine mammal areas, (cIMMAs) were identified which is the largest number proposed from a single workshop to date. Thirteen areas of interest (AoI) were identified as locations where further research is merited. The experts identified cIMMAs for the Arabian Sea humpback whales, Indian Ocean humpback dolphins and concentrations of Omura’s whale, as well as three different populations of blue whales. The cIMMA proposals are now undergoing peer review, and those that are approved will be added to the eAtlas later in 2019. The preliminary report from the workshop can be downloaded here:


IWC Bycatch Workshop
The International Whaling Commission (IWC) held a technical workshop on Bycatch Mitigation Opportunities in the Western Indian Ocean and Arabian Sea from 8-9 May 2019 in Nairobi, Kenya. The workshop was attended by 50 participants working in 17 different countries. The workshop included a range of presentations on innovative approaches to assessing, monitoring and mitigating bycatch, as well as some hands-on sessions where participants worked together to identify potential bycatch hotspots in the Western Indian Ocean, where further research and mitigation efforts can be directed. The Report of the IWC Workshop on Bycatch Mitigation Opportunities in the Western Indian Ocean and Arabian Sea is available for download here.

It was recognised that cetacean bycatch is generally very poorly documented in the region and that this presents a major barrier to understanding the scale of the issue and making progress towards bycatch reduction. The workshop concluded that a more systematic assessment of bycatch information is critical, particularly for small-scale and medium-scale fisheries. Given the prevalence of small to medium-scale fisheries using passive fishing gears (gillnets, traps, etc) across the Indian Ocean region, and the lack of financially viable and effective mitigation solutions for these gears, the workshop concluded that further work to develop and trial low-cost and low-tech solutions was urgently needed. The utility of existing tools and approaches for assessing and monitoring bycatch in the numerous small to medium-scale fleets was also recognised, including rapid bycatch risk assessments, remote electronic monitoring and crew-based observer schemes. The workshop concluded that bycatch reduction efforts should aim to apply multi-disciplinary and multi-taxa approaches wherever possible. The workshop resulted in a number of recommendations for collaborative work to reduce bycatch in the region that can be read in detail in the final report.

Alert on the Mediterranean sperm whale subpopulation

Giuseppe Notarbartolo di Sciara has attracted our attention to recent events concerning the Mediterranean subpopulation of sperm whales, which has been red-listed as Endangered since 2006 based on an inferred continuing decline of an already reduced population (assumed to be in the low to mid hundreds). In the past, the main cause of mortality in the Mediterranean was bycatch in pelagic driftnets, which have now been banned from the region since 2001. Driftnets continue to be deployed illegally by several Mediterranean fleets, but fishing intensity has significantly decreased because of the ban and there were hopes that the sperm whale population would be recovering.

Dead mother and calf Sperm Whale photographed off Ponza, Italy in June 2019.

Unfortunately, mortality in driftnets still occurs as shown by recent reports of multiple entanglements – a social unit of 8 whales in Algeria in May 2019 and a mother-calf pair in Italy in June 2019. Also, an unusual mortality phenomenon affecting sperm whales in Italy is being investigated by Sandro Mazzariol and colleagues. Fourteen animals were found dead over a 6-month period (24/12/2018 – 01/07/2019) between Sicily and Tuscany, with a cluster near Sicily in May. Two more were reported as stranded along the French Mediterranean coast in November 2018 and one more carcass (presumed to be a sperm whale) was found floating off Liguria in July 2019. All the carcasses were in an advanced state of decomposition, most of them calves or juveniles with stomachs empty or containing plastic debris (which was not the cause of death).

Finally, Greece is issuing extensive concessions for seismic surveys for oil & gas prospecting along the Hellenic Trench, an area that hosts the largest concentration of sperm whales in the Eastern Mediterranean (about 60 individuals) and which is designated as an Important Marine Mammal Area (IMMA). The prospect of prolonged ensonification of this important sperm whale habitat is of great concern.

Northern Gulf of California World Heritage Site Listed as ‘In Danger’

When the Islands and Protected Areas of the Gulf of California were listed by UNESCO as an area of Outstanding Universal Value in 2005, it was noted that the site contained a third of the world’s marine cetacean species, most importantly, the endemic vaquita. In early July of this year, only 14 years after inscription, it was added to the list of World Heritage Sites in Danger. The reason for this change of status is simple: the well-documented precipitous decline and imminent extinction of the vaquita. It is feared that there were no more than around 10 vaquitas left (range of 6-19) in the late summer of 2018. Since then and through the first half of 2019, illegal fisheries have ramped up. Not only has illegal totoaba fishing continued and become more violent toward efforts to remove nets (see earlier vaquita updates this year), but also since the compensation program for fishermen was terminated without a readily available alternative fishing method , fishermen have returned to gillnetting for sharks, Spanish mackerel (or sierra, Scomberomorus sierra and S. concolor), chano (Micropogonias megalops), and curvina (Cynoscion othonopterus).


The World Heritage Committee stresses that the listing of a site as ‘in danger’ doesn’t represent a sanction, per se. Rather, it is meant as a way to stimulate and enhance action to protect threatened sites and endangered species. Countries, in this case Mexico, are encouraged to use the designation as an opportunity to attract funding and expertise and hence strengthen protection measures. We can only hope that Mexico acts decisively and urgently to address two of the key failures in its vaquita conservation strategy: (i) effective enforcement of laws and (ii) provision of alternative livelihoods for fishermen, including access to alternative fishing gear.