RUG and IBAP tag first critically endangered sharks and rays in West Africa

In a first for the region, highly threatened sharks and rays have been tagged and released by scientists in the Bijagos Archipelago, off the coast of Guinea-Bissau in West Africa. The main goal of the expedition was to determine why these species use the shallow waters of the archipelago. During the four-week expedition, a team of researchers from the University of Groningen (the Netherlands), in collaboration with local conservationists from the Institute of Biodiversity and Protected Areas (IBAP) and local fishers worked together to place satellite-transmitters on critically endangered guitarfish. In addition, the team studied various threatened shark species, such as hammerhead sharks, bull sharks and blacktip sharks to collect essential data to support the protection of these species within the archipelago and the wider region.

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Highly endangered fish
According to the latest estimates, approximately 31% of all shark and ray species in the world are now threatened with extinction. Within the West African region, species like the blackchin guitarfish and scalloped hammerhead shark are now in the most precarious category of the international list of threatened species: Critically Endangered. “We are afraid that these species of sharks and rays might disappear from the Bijagós Archipelago, or even from the entire West African region, just like what happened with the sawfishes” says Emanuel Dias, the Director of the Orango National Park within the Bijagós. Dias continues: “The organization that I work for, the Institute for Biodiversity and Protected Areas (IBAP), has management plans for the national parks within the Bijagós, but we see that fishing by boats from other countries are threatening sharks and rays both in and outside the parks. The Bijagós is a large area and controlling the fisheries is a big challenge. That is why research on sharks and rays is important to ensure that we can protect these species more effectively”. 

Socio-cultural value of sharks and rays
Sharks and rays have played an important historical role in the cultural ceremonies and celebrations of local Bijagó communities in Guinea-Bissau. These communities inhabit 20 of the 88 islands in the Archipelago, and all islands are lined by dense mangrove forests, extensive sand- and mudflats, and are connected through a complex system of tidal channels. During the traditional ceremonies the Bijagó communities wear shark-inspired costumes, with masks and fins resembling hammerhead sharks or sawfishes, and within some villages one can find buildings in the shape of sawfishes. Sawfish – a group of large ray species – that were once common in the region are now considered to be extinct in West Africa. The Bijagós Archipelago was one of the last places where these species could be found in the region.

The first time that a critically endangered blackchin guitarfish is released with a satellite-transmitter. This mature female named Aissa (named after the project manager of the biodiversity institute of Guinea-Bissau) will help scientists to study how these highly threatened species use West African waters.
Photo: Maarten Zwarts/University of Groningen.

Tracking guitarfish
In their most recent expedition, a team led by the University of Groningen (the Netherlands) and supported by IBAP and local fishers – managed to catch, sample and safely release over 50 sharks and rays belonging to ten different species. The biggest achievement? “Deploying the first-ever satellite-transmitters on critically endangered blackchin guitarfish and achieving this milestone in close collaboration with local fishers. They know how important these species are for the Bijagó culture” explains Guido Leurs, expedition leader and shark researcher. Leurs adds: “Based on our research over the past years, we have seen that this species is declining rapidly in the region. These transmitters will allow us to safely track and monitor these animals for almost a year, which will allow us to map where these animals migrate to and how they connect different natural areas in the wider region. This information is crucial for our local partner organizations like IBAP to enhance protection of these species across their migrations and during their life cycle. Right now we have no idea where these animals go”. 

A critically endangered scalloped hammerhead shark receives fresh seawater to enable the shark to breath during the short procedure. Scientists take minuscule tissue samples, and give the shark a tag with a unique identification number. This allows researchers to track the movements and growth of the animal over time. The procedure takes approximately five minutes after which the shark is released safely back into the water.
Photo: Maarten Zwarts/University of Groningen.

A future for sharks in West Africa
In another exciting development, the team also discovered a possible nursery area for newborn shark species, including threatened scalloped hammerhead. “We think scalloped hammerhead sharks use shallow coastal areas like the Bijagós during the early life stages and once they grow older, they move to the open ocean. The problem is that when these sharks leave the Bijagós they may be threatened by industrialized fisheries operating outside national park boundaries. We want to figure out how big that risk is for them” says Leurs. He concludes ‘’We are proud of our teams for working together to achieve conservation results that benefit local communities as well as these vulnerable ecosystems that are essential to many marine and terrestrial species’’.