Abstract
Basking sharks, the world’s second largest fish, are endangered globally following two centuries of large-scale exploitation for their oily livers. In the northeast Atlantic, they seasonally gather in key sites, including the western Scottish Isles, where they feed on plankton, but their breeding grounds are currently completely unknown. Using high-resolution three-axis accelerometry and depth logging, we present the first direct records of breaching by basking sharks over 41 days. We show that basking sharks breach both during the night and day, starting at approximately 20 m depth and can breach multiple times in short succession. We also present early evidence of potential lateralisation in basking sharks. Given the energetic nature of breaching, it should have an important biological function, but this remains unclear.
Highlights
Basking sharks, the world’s second largest fish, are endangered globally following two centuries of large-scale exploitation for their oily livers
Given the energetic investment required to breach it seems plausible that this behaviour has a fitness benefit, such as securing a mate
We used accelerometer enabled animal-borne biologging tags to describe in high temporal resolution the variability and repeatability of 67 breaches made by three sharks over 41 cumulative days (Fig. 1; shark 5 m length (n = 1) 678 kg estimated mass; and sharks 6 m length (n = 2) 160 kg estimated mass)
Summary
The world’s second largest fish, are endangered globally following two centuries of large-scale exploitation for their oily livers. Breaching (leaping entirely, or almost entirely out of the water) has been noted in basking sharks in the west coast of Scotland[9] along with courtship-like behaviours such as close following, parallel and echelon swimming[9,10].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
