First field work – Lake Ngami

Last week, I got to do my first field work in the wilds of Botswana. I am working with a fantastic team of scientists at the Okavango Research Institute (ORI). They do regular monitoring of fish populations and water quality, so I tag along to get my own data. My main objectives are

  • catch and dissect fish
  • collect blood for assessing metabolic syndrome in fish (glucose, HDL cholesterol, and triglycerides)
  • collect liver, gonad, kidney, and speen tissues for histology and microscopic analysis
  • collect liver and muscle samples to assess heavy metal contamination
  • measure basic water quality: pH, temperature, dissolved oxygen, conductivity, salinity, total dissolved solids, depth, clarity, nitrate and nitrite levels.

I had initially proposed studying red-breasted tilapia, Tilapia rendalli. These fish have been recently reclassified to a different genus, and now they are called something far less gracious (in my humble opinion) – Coptodon rendalli. Seriously, which one sounds tastier to eat?

Speaking of – red-breasted tilapia are one of favorite eating fishes of the Okavango Delta. They are the top choice of my wonderful colleague here at ORI – Keta Mosepele.

If you live in the United States or Europe, you might have tasted farmed tilapia and decided it was, shall we say, not your first choice for dinner, with its mushy flesh and watery texture. I have yet to try Tilapia rendalli (um, I mean – Coptodon rendalli), but I did recently get to eat a wild-caught three-spotted tilapia and it was superb!

Back to the fish I am studying. Since we caught mostly three-spotted tilapia (Oreochromis andersonii) and very few red-breasted tilapia, and because my ORI colleagues assure me the three-spot is much more common, I am going to focus on the three-spot.

Three-spotted tilapia (Oreochromis andersonii) in the net
Three-spotted tilapia (Oreochromis andersonii) in the net

We also caught several predatory silver catfish (Schilbe intermedius), which I will sample next time for heavy metal analysis. Predators tend to have higher metal loads than herbivores (like tilapia) because they bioaccumulate metals from their prey.

So, here are some photos from my first fish catching expedition. I am also producing a video of the sampling process which I will post shortly.

Launching the boat at Lake Ngami
Launching the boat at Lake Ngami
Lake Ngami
Lake Ngami
Moi
Moi
African white pelicans, Lake Ngami
African white pelicans, Lake Ngami
Lake Ngami sunset
Lake Ngami sunset
Lake Ngami sunset
Lake Ngami sunset
Sunset at camp
Sunset at camp
Sunrise in camp
Sunrise in camp
My colleague, Kaelo Makati pulling in the gill net used to assess fish populations in the lake.
My colleague, Kaelo Makati pulling in the gill net used to assess fish populations in the lake.
Other uses of lake water. This truck was pumping water for brick making. You need a permit to use natural water, but permits are apparently easy to get and the water is free with the permit.
Other uses of lake water. This truck was pumping water for brick making. You need a permit to use natural water, but permits are apparently easy to get and the water is free with the permit.
Lunch! Sadza and beef stew with greens. Sadza is ground maize and a lot like thick grits. Very tasty.
Lunch! Sadza and beef stew with greens. Sadza is ground maize and a lot like thick grits. Very tasty.
Restaurant where we ate lunch in Sehithwa, a town at the western edge of Lake Ngami
Restaurant where we ate lunch in Sehithwa, a town at the western edge of Lake Ngami