Basking sharks meet to eat – and show off

DIVING NEWS

Basking sharks meet to eat – and show off

Yohancha
Picture: Yohancha.

Researchers studying video-tagged basking sharks in Scotland’s Sea of Hebrides have recorded the first complete breaching event, as well as what is thought to be the first sub-surface courtship display, consisting of nose-to-tail chasing and parallel swimming. 

Their recordings included the first observations of basking shark grouping behaviour near the seabed.

The breach, captured from a basking shark’s point of view for the first time, followed a rapid ascent from a depth of 77m in 70 seconds. The display was thought to be another component  of the sharks’ courtship behaviour, of which little had previously been known, despite advances in biologging technologies.

The sharks were also observed breaching as many as four times in 45 seconds.

The study was carried out off the islands of Coll and Tiree, known to attract basking sharks (Cetorhinus maximus) in large numbers in summer and recently designated a marine protection area for this reason.

Six sharks were pole-tagged with towed cameras combined with time-depth recorders and satellite telemetry. These would automatically detach and float to the surface after a few days. The team followed the sharks for a total of 123 hours.

Groups of up to 13 sharks were recorded near the seabed swimming slowly either side by side, on top of each other or nose-to-tail, with their fins touching.

Feeding occurred only within a depth of 1m and made up 75% of the sharks’ time spent swimming near the surface. To the scientists’ surprise, they spent as much as 88% of daylight hours near the seabed.

6 August 2021

The scientists believe that the solitary sharks come primarily to forage, as previously thought, but then take advantage of the short-term opportunity of socialising with others and finding breeding partners.

Whatever their activity or depth, the basking sharks maintained similar tail beat frequencies, said the scientists from the University of Exeter, led by Jessica Rudd and Matthew Witt. Their study is published in Plos One.

Basking sharks, the oceans’ second largest fish at up to 8m, are found in temperate waters and are IUCN-classed as Endangered, having been hunted in the past for their liver oil. Other seasonal foraging aggregations occur around the Isle of Man, the south-west of England and the west of Ireland.

biggest

LET’S KEEP IN TOUCH!

Get a weekly roundup of all Divernet news and articles 🤿

We don’t spam! Read our privacy policy for more info.

Subscribe
Notify of
guest
0 Comments
Inline Feedbacks
View all comments

Related Divernet Posts

Diver Magazine Relaunch

Diver magazine needs YOU!

Are you still lamenting the demise of Diver magazine? Well now you can help resurrect an icon as we seek to bring back the magazine

Buford Springs Cave topside view

2 divers die at Florida cave site

Two men have died while scuba diving at western Florida cave-diving location Buford Springs Cave.  Three teenage swimmers found 52-year-old Todd Richard McKenna unresponsive at

Sponges fragments

Sponges: Glue of the reef

A variety of environmental threats hang over scuba attraction the Florida Keys, but a team of dedicated divers are doing their bit to shift the

nets and diver

Spanish divers battle illegal nets

Scuba divers from Spanish marine conservation group Equilibrio Marino have removed a 600m fishing net from the Mediterranean Sea off Malaga city beach. In the

Misunderstood Banded Sea Snake

Misunderstood Banded Sea Snake

Found all of the Asia Pacific Region, including Raja Ampat, the Banded Sea Snake is a deadly but misunderstood stood creature We know you share

Follow Divernet on Social Media

0
Would love your thoughts, please comment.x
()
x