The Hunt for a Pygmy Devil
January 2021
A lifeless ray laying on the tiled floor of a fish market in Senegal attracts little attention from passers-by. It is a sad sight, but one that is unfortunately common throughout many tropical countries worldwide. Manta and devil rays (collectively referred to as mobulids) are caught by targeted and bycatch fisheries in their tens of thousands annually. For most visitors to this market, it was just a normal day. However, for the Manta Trust team, it was special because this little ray may represent the beginning of a species resurrection - The East Atlantic Pygmy Devil Ray (Mobula rochebrunei). And if not a resurrection, some answers to an important conservation question.
Could this be a specimen of the illusive Mobula rochebrunei? © AMMCO
First described in 1879 by L. Vaillant, this species was named Cephaloptera rochebrunei. The genus Cephaloptera, which translates from Greek to ‘head-wings’, and refers to the species’ cephalic lobes, is now obsolete. There was little in the way of mentions of, or research on, this species following its description, until some seventy years later when more detailed data was collected on this species. It was from this point forward that the often-changing taxonomic status of the East Atlantic Pygmy Devil Ray, and the entire mobulid family for that matter, begins.
In 1953, Cephaloptera rochebrunei (now Mobula rochebrunei) was considered a synonym of the West Atlantic Pygmy Devil Ray (Mobula hypostoma), which is found across the Atlantic Ocean on the east coast of the Americas. Then, in 1973, researchers decided it was a synonym of the Spinetail Devil Ray (Mobula mobular – then known as Mobula japanica), before being separated again as its own species in 1987 based on newly acquired morphometric measurements.
In 1960, a French marine biologist by the name Jean Cadenat studied several dozen specimens of this species on the West African coast, a number of which he preserved from Senegal, but many of which have since been lost. The only remaining preserved specimen of M. rochebrunei is a stuffed holotype in the National Museum of Nature History in Paris. In 2017, Manta Trust researchers attempted to analyse tissue samples from this poorly preserved specimen as part of a global genetics study. However, the quality of the tissue was too degraded for analysis and was therefore left out of the study.
Images of Mobula rochebrunei from Cadenat’s 1960 paper. Cadenat J. (1960) Notes d’ichtyologie ouest-africaine. XXIX. Les
Mobulidae de la cote occidentale d’Afrique. Bulletin de l’Institut Francais d’Afrique Noire 22A, 1053 – 1084.
Around the same time, a different team of genetic researchers conducted a similar global mobula genetic study. It was this paper that led to the amalgamation of the Manta genus into Mobula. After genetic analysis of the same single nolotype specimen of M. rochebrunei from Senegal, these authors concluded that this species was no longer valid. Instead, the researchers believed it to once again be synonymous with M. hypostoma, the West Atlantic Pygmy Devil Ray. The Manta Trust team are not entirely satisfied with the robustness of this conclusion, and we feel more data is required before the species should be considered obsolete as the consequences of this quasi-extinction on the conservation of the population are dire. Therefore, our hunt continues to find more specimens of this species so that further genetic analysis can be undertaken.
One of a handful of images of mobula rays from fish markets in west Africa which have led the Manta Trust to believe that Mobula rochebrunei is still a distinct species. However this specimen can’t be confirmed one way or another through just this image. © Framoudou Doumbouya
Six years ago, the Save Our Seas Foundation funded a Manta Trust project to go out and search for specimens of the West Atlantic Pygmy Devil Ray. As is sometimes the case with field work, things did not exactly go to plan. The team hoped to travel to Guinea, Senegal, and other West African countries to survey fish markets in the hope of finding specimens. With Isabel Ender already in Senegal, and Daniel Fernando on route from Doha, thing quickly took a turn for the worse when an outbreak of the Ebola virus made it unsafe for the team to visit the countries they hoped. So, instead, Daniel and Isabel changed their plans and carried out surveys in Morocco and Western Sahara further to the north. Unfortunately, they did not find what they were looking for.
After the disappointment of the fieldtrip, we re-directed our remaining funding to a support a local fisheries researcher based in Guinea, Framoudou Doumbouya, to collect elasmobranch fisheries landing data for the next year, but alas, still no confirmed M. rochebrunei could be found. As a result, no specimens or tissue samples of this species have been collected since Cadenat’s study in the 1960s. Over recent years however, a few tantalising images of mobula rays from Cameroon, Gabon, and Guinea have appeared on the Manta Trust’s radar, reigniting our hopes of finding this species. In October 2020, we created a ‘WANTED’ poster for M. rochebrunei, and with the help of the African Marine Mammal Conservation Organization (AMMCO), and various other parties, we disseminated the posters in English, French, and Portuguese to researchers working in fish markets across the region.
WANTED poster for Mobula rochebrunei.
WANTED poster for Mobula rochebrunei posted in fish markets around West Africa.
Potential Mobula rochebrunei from Cameroon. © AMMCO
Remarkably, just a month later, we were sent images by the president and founder of AMMCO, Aristide Takoukam, of what we have been searching for. The little ray Aristide’s contacts had collected had been landed in a fish market in Cameroon and, from initial observations and images, we believe this is a new specimen of the elusive pygmy devil ray. The Manta Trust arranged for a fridge to be purchased and used to store the specimen. Unfortunately, now COVID-19 instead of Ebola is hampering our efforts to get this sample back to the UK to run genetic tests on.
Even if this pygmy devil ray does indeed turn out to be synonymous with M. hypostoma, this West African population is likely to be extremely vulnerable to extinction given the state of fishing in the region, and the localised and nearshore habitat requirements of this species. Therefore, the sooner we can undertake further research on this species, the quicker we can aid effective conservation management efforts.
SIMON HILBOURNE
Digital Media & Communications Manager