Coastal movements of a critically endangered wedgefish species and the importance of transboundary conservation

Wedgefishes represent a threatened group of elasmobranchs with limited
knowledge on their ecology and habitat use. In order to improve our
understanding on their movement ecology, 28 whitespotted wedgefish
Rhynchobatus djiddensis were acoustically tracked for up to seven years
along a ~900 km stretch of the South African and Mozambican coastline.
While detection rates were low, site fidelity was evident (the majority of
detections occurred within 50 km of tagging location). However, there was
intraspecific variability in the scales of movement, with individuals
tagged in the northern extent of the study region displaying restricted
movements (< 100 km), while individuals tagged in the southern
extent made significant longshore movements (up to ~500 km). Movements
lacked seasonal trends in directionality, suggesting they were not
migrations, and the drivers of these movements remain unresolved. This
study confirmed for the first time that whitespotted wedgefish undertake
transboundary movements between South Africa and Mozambique, highlighting
the need for international cooperation and the benefit of the
transboundary Marine Protected Area in the conservation of this Critically
Endangered species.