Fussy eaters, bait loss and escapees: How reliable are baited-hook assessments of shark abundance in shallow, coastal waters?

Abstract

Sets of baited hooks decrease in fishing efficacy over time as catch accumulates and bait is lost, and this complicates the quantification of fishing effort for species abundance calculations. Although hook-timers facilitate a more accurate estimation of fishing time, they cannot provide taxonomic information in the case of escapees or bait loss, nor can they provide information on animals that approach the gear but do not physically engage with it. To overcome these limitations, the present study attached sport action cameras to baited drumlines during a catch-and-release survey of sharks in the shallow, coastal waters of the eastern Caicos Bank, Turks and Caicos Islands. Overall, the true fishing time was found to be appreciably less than the apparent fishing time and more sharks approached or interacted with the gear than were successfully captured by it. Furthermore, shark-gear interactions varied by species while the amount of bait loss differed between deployment areas. Taken together, these findings suggest that baited-hook surveys underestimate shark abundance and that the magnitude of this error varies by species and habitat type.