Bull shark research in Mozambique - 3 Fathoms
Tagging Season is Here!
We had a lot to be thankful for this Thanksgiving. While it was a wet one in southern Mozambique, pouring down rain like there would be no tomorrow, we headed to Pinnacles, the research site, all the same. After nearly six hours at sea the deluge serendipitously broke and in the calmness after the storm, we caught and tagged the first bull shark of this summer season.
Border Control: Expanding the Ocean Tracking Network in Mozambique
In the previous issue, we were excited to report that we reached our 2012 goal of doubling the number of listening stations at our Mozambique research site. Now we are pleased to announce that these 5 listening stations have been deployed at the border of South Africa and Mozambique, officially extending the Ocean Tracking Network (OTN) into Mozambique.
New moorings and re-deployed reef stations.
We successfully retrieved all the local reef listening stations during a September fieldtrip. They were full with data hits from our tagged sharks. We re-deployed stations with new moorings compliant with international standards. The stations are looking good and hopefully picking up data from passing sharks and other creatures.
Have Tag, Will Travel
One of our sharks is quite the traveller. Last season we tagged a large female bull shark. She was the last shark of the season. We picked her up on local listening stations for a while but then silence through the winter months. In September, we were thrilled to have her back again on the local reefs. Who knows where she went?
Recently we discovered that her unique tag code was picked up by researchers in Tofo Beach, Mozambique.
As shown on the map to the left, this shark swam over 300 miles (500km) to Tofo and back, a roundtrip of over 600 miles (1000km)! But she could have gone much further - there are no other ways of tracking her past the acoustic array in Tofo... yet
Research site mapped - PINNACLES REEF: A legendary site known for its drop offs and lots of sharks
Our main research site is called Pinnacles reef. Popular with fishermen, divers and sea life, the area teems with life during the summer months. It is located 3.5km off the dunes of southern Mozambique. Because the Pinnacles rise off the ocean floor from 50m to 29m, the area acts as an oasis drawing fish to the area and it attracts large numbers of bull sharks during the summer months. We've identified 19 species of shark in the area, on Pinnacles reef and inshore on more shallow reefs.
With new GPS software we were recently able to map the site. This productive reef rises off the bottom of the sea floor from 160ft (50m) as seen in the blue and purple, to 95ft (29m). Like busy winter ski slopes, these underwater peaks teem with life from the shallows to the depths, especially in these early summer months.
This is the first time this area has been mapped and we look forward to mapping more of the reefs where our equipment and where the bull sharks frequent.
Bull sharks research
Our primary research project is on bull sharks (Carcharhinus leucas) in southern Mozambique. We're putting our innovative techniques to use with acoustic telemetry, and a unique biopsy tip used with a spear gun. Very little is known about the life histories of these bull sharks so we're expanding the knowledge through everything we learn about them. And while bull sharks aren't the most threatened shark species, they're listed as near threatened by the IUCN, we're hoping to protect them and other sharks from threats of fishing, habitat loss and the impacts of climate change.