The status and trends of small cetacean landings at Dixcove artisanal fishing port, western Ghana

Abstract

One of the largest documented takes of small cetaceans in western Africa occurs in Western regional coastal waters of Ghana. This temporally coincided with steadily decreasing catches of finfish, especially small pelagics (sardinellas, anchovies, mackerel) over the past decades, attributed to both climate change and indiscriminate exploitation methods. Dixcove, a key fishing port for cetacean landings was surveyed during 96 days between 12 September -17 December 2018. Our goal was to update insights from our earlier surveys, especially on catch rates, catch per unit effort and species composition. A total of 57 delphinids of 10 species were observed landed: Stenella attenuata (28.1%), Stenella clymene (17.5%), Lagenodelphis hosei (10.5%), Steno bredanensis (10.5%), unidentified stenellids (8.8%), Grampus griseus (3.5%), Delphinus sp. (3.5%), Pseudorca crassidens (3.5%) and single specimens of Tursiops truncatus, Stenella longirostris and Stenella frontalis. The observed cetacean catch per diem (cpd =0.59) at Dixcove was low compared to earlier rates for this port (e.g. cpd =2.82, in 2013-2014). However, fishing effort, measured as the number of canoes landing per diem (range 0-25; mean= 8.82 ± 6.05; n=22) was also reduced. Poor fish catches forced many canoes to remain in port. The prevalence in landings of common bottlenose dolphins and common dolphins has significantly decreased in the period 2000-2018. The prevalence of Fraser's dolphins and false killer whales increased. Indications are that a higher proportion of cetacean carcasses may be utilised offshore as shark bait. Hooks baited with cetacean parts are deployed in auxiliary longlines set longside large-mesh drift gillnets with a shark aggregating purpose, a first report in Africa. Shore-based incidental sightings of humpback whales suggest the potential for small scale whale-watching ecotourism in Ghanaian coastal waters, as pertains in the nearby waters of the Republic of Benin.

Outlining the causes and effects of Algae bloom at Ghana’s West Coast

“…The harvesting of dolphins and toothed whales as bycatches have seen an increase in the last couple of years, thus according to marine scientist (Ofori-Danson P.K., Van Waerebeek K., Debrah, J. (2003); Ofori-Danson, P.K., Debrah, J., Van Waerebeek, K. ( 2019)).…”

Recent Survey for Delphinids at Tristao Islands, Guinea, Reinforces Concern for Bycatches and Marine Bushmeat Use

“…In western Ghana, declining fish catches occurred concurrently with increasing landings of dolphins, commercialised as marine bushmeat 1 , a phenomenon thought correlated (e.g. Van Waerebeek and Ofori-Danson, 1999;Debrah et al, 2010;Ofori-Danson et al, 2019). A similar trend may be developing also in other coastal nations of West Africa (Van Waerebeek et al, 2017 ;Segniagbeto et al, 2019) and central Africa (Collins et al, 2019) but has not been studied in any detail.…”