CORDIO samples Tanzania

FinPrint Spotlight

Author: Clay Obota, MSc

Organization: CORDIO East Africa

Biography: Clay joined CORDIO as an intern working under the Fishery Aggregating Devices project and advanced to a research assistant working on marine biology/ecology, fish population dynamics, fish stock assessment, and fisheries management.

On March 13th 2017, representatives from Kenya and Mozambique set off by road from Mombasa on the Kenyan coast to Tanga, 175km south of Mombasa, in Tanzania, to learn how to do baited remote underwater video surveys (BRUVs) to record shark populations as a part of the Global FinPrint project. The travelers were myself, Clay Obota, Kennedy Osuka, and Melita Samoilys from CORDIO, Benedict Kiilu from Kenya Fisheries Service, and Gelica Inteca from Uni Lurio in Pemba, Mozambique. That evening we met at the Mkonge Hotel in Tanga with our three Tanzanian counterparts: Hassan Kalombo, the Regional Fisheries Officer, January Ndagala, Acting Warden of the Coelacanth Marine Park, and Hakim Matola from TAFIRI in Dar es Salaam, as well as the lead trainer, Dr. Jordan Goetze, from Curtin University in Perth, Australia.

All the participants were guileless and eager to learn about BRUVs, in particular how to analyze, interpret, and use the data collected from the videos. Jordan kicked off the training with a day on land including lectures, discussions, and hands-on practice with the equipment. The lectures covered how to survey fish abundance using BRUVs with detailed procedures on calibration, deployment, and field data management. This was followed by hands-on training setting up all the equipment for deployment. This consisted of five GoPro cameras mounted in housings on a light aluminium frame or rig, and meters of rope.

Since most of us were new to using BRUVs, this was set to be a hard day for Jordan, but we worked against all odds and managed to do 15 drops. Just like experts, we picked up the science quickly. After multiple one hour deployments, we managed to deploy the BRUVs at two sites: Nyuli (2 sets) and Mwamba Nyama (1 set). Seven connected reef systems were mapped and marked for sampling on the rocky and fringing reefs along the coast of Tanga, North of Tanzania. The success of the first day was a clear indication of future productivity. The following days were a walk in the park where each team worked efficiently with smiles and laughter lighting up the experience. 

From bait preparation to BRUV deployments and pick-ups, everyone worked hard as a team on the second day of sampling the reef systems of Fungu Tangoni and Karange, where we set 20 BRUVs. We almost lost one video frame due to strong currents on the third day while sampling Karange and Jambe. We had to pull it out and redeploy it in shallower water. Mwamba Nyama, Mwamba Wamba, and Chundo Kiroba reef systems were successfully sampled on the fourth day, with the deployment and retrieval of 20 BRUVs before 4pm, the fastest day since the beginning of the field trip thanks to low currents and smooth deployments.

Chundo Kiroba and Mwamba Wamba reef systems were sampled on the fifth day. Although the team was eager to deploy as many BRUVs as the previous day, the tides were strong making this goal challenging. The last deployment for the day at Chundo Kiroba reef was set to a depth of 40m. It had to be retrieved and re-set at 35m since the currents were strong and the rigs were drifting. Even with the strong currents, the team managed to maintain 20 drops on this day as well.

On the last sampling day, the BRUV team worked without Jordan for a half day. The team completed 10 more drops for a total of 105 drops over the course of the entire sampling trip, 15 drops more than the initial target of 90 on Tanga’s reefs. This was a great achievement thanks to the excellent team spirit and enthusiasm from everyone who learned efficient BRUV techniques.

As we felt confident in this methodology, the idea of using BRUVs as a tool for estimating population size of large fishes including sharks became increasingly popular across the participants from the three countries. The team is now looking forward to opportunities to use these acquired skills. CORDIO will be coordinating reef sampling in Kenya and Mozambique later this year to estimate shark populations, again as part of the Global FinPrint project.

Global FinPrint

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