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Rarer shark and ray species of Ghana

By Issah Seidu, 15th September 2023

We are collecting key baseline data on sharks and rays along the coast of Ghana. The 550 km coastline of Ghana is demarcated into three divisions: the west coast, east coast and central coast. Our study focused on major elasmobranch fishing communities along the west and east coasts of Ghana. The gears predominantly used in artisanal fishing communities include drift gillnets, bottom set gillnets, longlines, handlines, trolling lines, purse seine nets and ring nets. However, sharks and rays are mostly caught with two major gears: drift gillnets completed with longlines and bottom set gillnets, respectively.

Apam community. Photo © Issah Seidu

Dixcove community. Photo © Issah Seidu

Noticing the rarer sharks in landings, interestingly the shallow water-dwelling lemon shark (Negaprion brevirostris) and the oceanic-dwelling whale shark (Rhincodon typus) are the least observed species. Lemon shark reaches a size of 340 cm in length and possibly as much as 368 cm. The largest confirmed individual whale shark had a length of 18.8 m. Lemon shark and whale shark are categorized as Vulnerable and Endangered respectively on the IUCN Red List of threatened species. In our previous landing survey in February to October 2020 we observed only one individual of both species. Our current survey has not recorded any specimen of these species. Anecdotal reports from drift gillnet fishers (n= 12) who mostly land sharks indicate that these species are rarely caught. The last time fishers caught or observed lemon sharks was between 2018 and 2021. When asked about whale sharks, fishers indicated that they rarely catch the species but some were quick to add that even if they catch the species they have to release them into their habitats. This is because some fishers still regard whale sharks as whales- their revered sea god and it is taboo to catch, trade and eat them. Fishers reported that the last time they observed or caught whale sharks was between 2016 and 2020.

Traders and fishers negotiating catch. Photo © Issah Seidu

Issah interviewing a fisher. Photo © Issah Seidu

We saw a similar pattern in the common smooth-hound (Mustelus mustelus), where only seven individuals were recorded in 2020 survey but none has been observed in fisher’s landing and market sites in our current study. For the common smooth-hound, fishers were finding it extremely difficult to give us information about them. We noticed that fishers were landing immature specimens of this species and therefore, inquiry about them was recognized to be the young or juveniles of the largest shark species they mostly catch.

The team measuring a shark specimen. Photo © Issah Seidu

Issah Seidu measuring a spineback guitarfish. Photo © Issah Seidu

Sawfishes have disappeared in Ghanaian waters and in many maritime countries across the West African sub-region and have been regarded as the least observed species in the region. The last time fishers observed or caught sawfish in Ghana was in the mid-1980s. The Giant guitarfishes have overtaken sawfishes and are known to be among the most threatened marine species worldwide. The only known giant guitarfish in Ghana, the bottom-dwelling blackchin guitarfish (Glaucostegus cemiculus) as well as the common guitarfish (Rhinobatos rhinobatos) and the whitespotted guitarfish (Rhinobatos albomaculatus) are among the rarer ray species landed. The main drivers for the target of guitarfishes are for their white fins which are lucrative and sold at a high price in the international market, whilst their meat are processed and consumed in the local communities. We did not record any specimen of blackchin guitarfish and the whitespotted guitarfish during our 2020 survey expedition in West Coast Ghana. However, between November 2020 and August 2021, an extensive survey for only shark-like rays in major ray fishing communities in Ghana resulted in the documentation of 34 individuals of blackchin guitarfish and 86 specimens of white spotted guitarfish in only Central Coast Ghana. Our current survey has recorded fewer individuals of blackchin guitarfish (n= 12), common guitarfish (n=14) and whitespotted guitarfish (n= 7). We intend to extend our survey effort to migrant fishers who possess specialized gillnets which are mostly used to target guitarfishes and other ray species. This will give us a holistic view about all the species landed and their relative catch in Ghanaian fisheries.

Spineback guitarfish specimens. Photo © Issah Seidu

Measuring a white-spotted guitarfish specimen. Photo © Issah Seidu

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