Shark Chronicles 083 – Not only chumming
Posted by Rachael Cashman & Karina Harum on November 26, 2010
As with any research project, there are factors that cannot be controlled.
Midway through this month we had trouble finding white sharks. Due to big swells and high winds we were unable to stay out for long, if we made it out at all. Instead of chumming we put in some extra hours at the office, entering tracking data from previous years and writing articles for Beyond Blue. Beyond Blue is an online magazine founded by Oceans Community. The magazine is for everyone and focuses on marine research, conservation, and exploration.
We also had a presentation by Enrico about the Great White shark research projects going on at Oceans, their findings, and the importance of those findings. He stressed the value of communicating the results to the general public and explaining how those results affect their life. Fellow conservationists and researchers make an effort to know the current issues. However, the majority of people in the world are either unaware of current issues or believe they don’t concern them. The research going on at Oceans has helped keep swimmers and surfers safe by alerting the public to where the white sharks are and when they are in the area. As disappointing as it can be not to see our beloved Great Whites, it was good to see how the work we do furthers the research that goes on to affect the community.
On the third week of our internship month we finally had a chance to do some shark tagging as well we started seeing white sharks again during our chumming trips! After a successful shark collection at Mitch’s Reef for our benthic shark aquarium in the Shark Lab, it was finally time for us to release the old sharks. The benthic sharks are kept for four months at the aquarium and then tagged and released when we collect new ones. This is part of an ongoing project to measure the population of the benthic shark species in Mossel Bay. Two of the species, the Pyjama Jacket and Leopard sharks are priority because we think their population may be threatened.
Each shark was weighed and measured and photos of their total length, mouth, and defining features were taken. Every tag that we fitted on the shark had an identification number and mailing address for ORI’s tag and release database. The tag was fitted by making a small incision anterior to the dorsal fin of the shark. For female species we always make the incision on the right side of the dorsal fin and left side of the dorsal fin for male species. It was difficult to penetrate the tough skin of the sharks, which are composed of small denticles, or teeth like scales. One through it is fairly easy to insert the tag into the thick wall of muscle that forms the sharks back.
Two Pyjama-jacket sharks and one Leopard shark were being tagged that day. One of the Pyjama-jacket was male and two other sharks were female. As the Pyjama-jacket sharks that we have were quite feisty, it took a couple of intern to hold the shark while the incision was being made. One intern took pictures of the shark during the whole process while another intern made the incision for the shark tag. We try our best to put the least amount of stress on the shark while we fitted the tag.
After all the sharks were tagged we loaded them on to the boat and took them back to the waters off Mitch reef. We are hopeful that the catch, tag and release study will provide us information on the population of benthic sharks on Mitch’s Reef, Mossel Bay.