Predation on the St Joseph Callorhinchus capensis by Cape fur seals Arctocephalus pusillus pusillus in Namibia
Chondrichthyans form an important part of marine food webs as top predators and mesopredators. However, little is known about chondrichthyans in Namibian waters and the roles they play in ecosystem function.
Chondrichthyans form an important part of marine food webs as top predators and mesopredators. However, little
is known about chondrichthyans in Namibian waters and the roles they play in ecosystem function. During efforts to
disentangle Cape fur seals Arctocephalus pusillus pusillus from fishing gear or plastic debris, 11 incidents of seals
impaled by the dorsal spines of St Josephs Callorhinchus capensis (order Chimaeriformes) were recorded. These
observations overlapped with mass die-offs of the seals owing to food shortages, as indicated by large numbers of
emaciated seals and widespread miscarriages of seal foetuses. This suggests that the St Joseph is not a desirable
prey species for Cape fur seals, though this chimaera may provide a source of food, especially when preferred prey
species are unavailable. This is the first published record of Cape fur seals feeding on chondrichthyans in Namibian
waters. Documenting these types of food-web linkages between pinnipeds and chondrichthyans will allow for a better
understanding of how impacts on their populations may more broadly affect Namibia’s marine ecosystems.