Rhino ray recce in West Africa

Our key objective is to improve the conservation of five imperilled rhino rays in West Africa by developing new molecular tools sensitive enough to detect these exceptionally rare species and collecting valuable data on their current distributions through surveys in Guinea-Bissau, Mauritania and Senegal.

Very few recent records exist for sawfish, wedgefish and giant guitarfish in West Africa, but anecdotal evidence suggests severe declines in their populations. Knowing where a species occurs, how it uses its habitat and how its populations are changing over time is often a prerequisite for effective conservation management. Greater understanding of the extent to which these species persist in Guinea-Bissau, Mauritania and Senegal, and the identification of any priority areas, could serve as a catalyst for conservation action.

Rhino rays are a group of bottom-dwelling shark-like rays that include sawfish, wedgefish and giant guitarfish. Out of the 21 assessed species in these three families, 18 are listed as Critically Endangered on the International Union for Conservation of Nature’s Red List of Threatened Species and a further two are listed as Endangered. There are several reasons for the increased vulnerability of this group. Firstly, rhino rays tend to inhabit the shallow coastal waters of the tropics, habitat that is prone to being degraded by human activities. Secondly, many rhino rays grow slowly, are late to mature and produce few offspring. And thirdly, these species are targeted by fishers for their meat for local consumption and their high quality ‘white’ fins that fetch a very high price. Because of their long, toothed rostrum, sawfish are unusually prone to getting entangled in fishing nets. Five species of sawfish, wedgefish and giant guitarfish have been present in West Africa in the past. However, their continued presence in this region is unclear, as very few recent records exist for these species, making it likely that severe population declines, or even local extinctions, have occurred. Traditional survey methods (like gill-netting) are generally ineffective, time-consuming and costly for exceptionally rare threatened species, since the animals occur in such low numbers. Using DNA collected from environmental water samples, a technique called ‘eDNA’, has two advantages: you do not need to locate or handle the target organism, and it can detect minute traces of DNA present in the sea water.

• To develop two highly sensitive molecular tools capable of detecting five exceptionally rare rhino ray species in West Africa.
• To use these tools to survey for two sawfish, two wedgefish and one giant guitarfish in Guinea-Bissau, Mauritania and Senegal.
• To collect valuable distribution data on these Critically Endangered species for use in future conservation and management plans.
• To raise awareness of these species and their plight with local stakeholders in Guinea-Bissau, Mauritania and Senegal.