Zambezi (bull) shark research: Expedition 01_2011

From January 6-14 the South African Shark Conservancy (SASC) undertook our first Zambezi shark research expedition of 2011. With the assistance of experienced recreational anglers from Triton Angling Club in Mossel Bay and community members from Witsand on the Breede River, we spent many long hours on the river attempting to capture and tag Zambezi sharks.

In possession of three acoustic tags, and armed with a VR100 for manual tracking, we were hopeful that the capture of three additional sharks would add valuable data to our ongoing project. Unfortunately, however, we had our first ever January miss and were unable to catch any sharks.

Although they outsmarted us this time around, there was certainly evidence of the sharks in the system as our dedicated team of anglers witnessed a shark depredating the lines of angler’s next to their fishing boat, and conservation officers from the Lower Breede River Conservancy (LBRC) photographed a 26kg dusky kob that had been taken by a shark.

The biggest hurdle on this trip was the weather which wreaked havoc with our fishing time. Blowing a constant gale force Southeaster, fishing conditions were poor to say the least. Many anglers will attest to the fact that most fish don’t bite in such conditions, and perhaps it was exactly this that deterred the sharks from our lines.

Interestingly, however, anecdotal reports from Breede River residents suggest sharks of approximately 1.2-1.5m total length (TL) were frequently seen around 15km upriver. This lends credibility to our hypothesis that Zambezi sharks may be pupping in this river, as a shark of that length would be between 0.5-1.5 years of age. Additionally, we have received anecdotal reports of a Zambezi shark that was killed ~42km upriver in 1974 which gave birth to 6 pups when she was landed. We are currently attempting to verify this report and are hopeful this will prove the Breede River is a previously undocumented pupping and nursery ground for this species in South Africa.

We will be heading back to the river in late January or mid-February and are confident that this next trip will yield the capture of three elusive sharks! Please stay tuned to this spot for updates on the project or contact SASC directly (info@sharkconservancy.org) for more information on the project.

We extend a special thanks to all those who contributed to this trip, including the Save Our Seas Foundation for funding the research, and to Triton Angling Club, Helen Heyns (Central Developments Property Group), Mark Woof Charters, Alison Kock, Ali Towner, Mudlark Lodge, Rens Bindeman, Paul Van Nimwegen, Paul Cowley and the Lower Breede River Conservancy for all the invaluable assistance.