The nets were laid out lengthwise down the river at 6 pm the evening we arrived. At 6 am the next morning, the fish team got up bright and early to bring in the catch. Although crocodiles had destroyed some of the nets, there were still enough samples for our team to settle down to the tedious task of untangling each fish from the net. Some fish like the squeakers (Synodontis) have numerous barbs near their mouths pointing forward and backward, which can tangle up nearly 20 of the gill net's fine threads.
||"It can take up to half an hour to remove just one fish."|
|Squeaker fish (Synodontis nigromaculatus), the most common of the species caught in AquaRAP gillnets.|
It can take up to half an hour to remove just one fish, and hands numb with cold, one of the Botswanans grew frustrated and jerked a fish from the net, breaking off a spine. "Look, you've destroyed this sample," cried Ben Van Der Waal, AquaRAP scientist. "Let's not do that again!" So each team member resumed pulling the fish out thread-by-thread.
|Gillnets used by AquaRAP fish team.|
One of AquaRAP's goals is to impart these important lessons learned to local scientists, equipping them with the knowledge needed to continue monitoring these waters after the expedition concludes.
Scientist Roger Bills carefully cut a piece of the bottlenose fish and scraped the flesh into one of the 200 vials he brought for tissue storage, taking another couple of samples just in case. "It's not the sort of thing that you are going to catch frequently, so you normally take two or three samples from each," he told me. Although there is no current research project going on in South Africa about the bottlenose, he's collecting the sample for a colleague at Cornell University and will keep a few on hand in his laboratory in case other scientists are interested.
One of AquaRAP's greatest resources is the knowledge of local people, especially when it comes to the fish they depend on for protein. Some groups guard their knowledge
||"It's easier to remember fish names than people's names," Ben confided. |
closely, claiming intellectual property rights over the traditions of their ancestors, but most are happy to collaborate.
According to Ben, "most Botswanans do not think that fish (names) are that important." In a country that is three-quarters semi-desert, it's not so strange that Setswana (local language) fish names are very general. Two tribes that live in the Northern Delta, however, are fishermen: the Marmyrus (who built the round reed huts we saw on our drive out to the camp) and the Mbukushi people. Their language reflects the complexity of the fish species in the Delta and is a useful tool for conservationists trying to understand the history and ecology of this freshwater ecosystem.
How do Ben and his colleagues remember all the common and scientific names of hundreds of fish species? "It's easier to remember fish names than people's names," Ben confided. "You handle fish and you get to know each species the way you get to know a person."
– Reported by Jensen Reitz Montambault
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