Double Feature
Impressions
Greetings from Xakanaxa in the Moremi Game Reserve. Some of us flew by prop plane from Guma Lagoon to this camp, watching the landscape change beneath us. The wide, deep waters of the Delta's main channel spread out, forming meandering waterways separated by woodlands.
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Red lechwe cross a shallow pool in Moremi
Game Reserve. |
Our more intrepid team members traveled to the new camp by boat, and they also saw changes during their 10-hour journey: papyrus was reduced in height the further they went, indicative that the Delta's living system was drained of nutrients in its upper reaches.
The woodlands found in the southern Delta create habitats for larger mammals seldom seen at the previous sites. Although we are studying aquatic life, we've all enjoyed the terrestrial species that call Moremi home. During our first day, we saw red lechwe and waterbuck, antelope species often found in swampy areas, as well as zebras and lions. And more than once, the presence of elephants and hippos have presented challenges to the team's efforts to collect aquatic samples.
Here at Xakanaxa, the sights are amazing, and the sounds equally so. Around our campsite at night, we hear the tinkling of reed frogs, the singing of hyena, low roars of lion, grumbling hippos and the frog-like call of the tiny African Scops Owl. No wonder I can't sleep!
– Reported by Clare Nielsen
PEOPLE: Bathami Maphanyane, protecting Moremi's wildlife.
TOOLS: Scooping, catching, and trapping aquatic species.
ISSUES: Salvinia: A Tiny Troublemaker.
SPECIES: Moremi wildlife – from snake catfish to zebras!
AquaRAP in Action: Xakanaxa Lagoon
6:30am. The sun peaks over the horizon, giving the 'OK' to start out on the water. The fish team is the first to reach the boats. Yesterday, they placed a large gill net, consisting of panels varying in mesh size, near a reed bed in Xakanaxa Lagoon. Now the team is anxious to recover the net and see what it reveals.
A sign says "Idle Zone Please!" as the boat quietly passes the luxury lodges lining the shore. Tourists are still dreaming of the lagoon's crystal waters, while the fish team is about to get their hands wet in it. The team locates the net, but so does a hippo. Trying to avoid a dangerous situation, the scientists cautiously gather the net on the opposite side of where the hippo is spotted.
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| Pulling in the gill net from Xakaxana Lagoon. |
As the net is pulled in, dominant fishes found in the large-size mesh are the African Pike (
Hepsetus odoe) and the Sharp Tooth Catfish (
Clarias gariepinus). Butter catfish (
Schilbe intermedius) are the most prevalent fishes in the sections of medium-sized mesh.
Brycinus lateralis, commonly known as the Striped Robber, is the species most concentrated in the small-sized mesh.
I ask scientists Denis Tweddle and Ben van der Waal what they think of the final sample size. Without a second thought, they concur with each other that this sample contains triple the weight of fish found at previous sampling areas.
I am interested to know more about how the catch at Xakanaxa Lagoon compares with the previous sites. Dennis explains that few fish were actually found at Guma Lagoon. This is due to the lack of oxygen present in the water, making it a habitat for only the most resilient of fish. Shakawe [the first base camp], on the other hand, had good catches, though a lack of bream and catfish was found in the large-sized mesh net. Ben speculates that these fish may be vulnerable to the large nets used by commercial fishermen in the area.
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Without a second thought, they concur with each other that this sample contains triple the weight of fish found at previous sampling areas. |
Though the scientists can only make hypotheses, it seems that the fishing industry may be an important factor as to the presence or lack of various fish in a sample. For instance, in Xaxanaxa, a large quantity of the Greenhead Tilapia (Oreochromis macrochir) was found. These fish are very valuable due to the local demand, and are often found in commercial nets. Ben suggests that since commercial fishing is prohibited in Moremi Game Reserve, this might explain why such a large number were caught. Approximately 200 Butter Catfish (Schilbe intermedius) were also found in the net. These small predators are not fished commercially or for sport, a possible indication as to why so many were caught in the sample.
When the team is finished, we head back to the camp for a quick breakfast before returning to the boats for the scheduled morning transects. I gather from the smiles on the scientists' faces that they are pleased with today's catch. The team has now identified 64 of the 72 species known to inhabit the Okavango Delta, including a species that has never been scientifically described. With yet another site still left to be explored, I think to myself, "not too shabby."
– Reported by Sharon Safran
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