Small Update on the Fish Die-off

Dr. Dominic of the Mara Mobile Vet Crew just posted a short update on the fish die-off that occurred last month.

Investigations on the deaths of fish in Mara River

During the month of February 2011, there were reports of fish dying in Mara River; three different fish species were affected, the deaths were concentrated at the ‘Mara Old bridge”, Olonana area, Mara Buffalo area and near Little Governors area. It was a one time mass-die-off of fish that lasted only one day after a heavy down-pour.

Postmortem examinations revealed extensive haemorrhages and congestion of the liver and intestines, blood oozing from anus and mouth. The deaths were suspected to have been caused by pesticide poisoning due to pesticides washed downstream from the nearby wheat farms.

Fish samples, water and soil samples were collected from the different locations of the river and submitted to the Government chemist for toxicological analysis, results are still awaited.

The Mara Crocodiles

Check out this article for some recent pictures of a croc trying to get a wildebeest in the Mara River.  The article states that the late rains delayed the migration which in turn reduced the food availability for the crocs.  We have seen in the Mara that with lower flow levels, the crocs can not hunt as effectively.  Lower average flows and a delay in the migration could have an effect on the reproduction cycle of the Mara population.  Anecdotally, we've noted lower crocodile nesting success following years of lower flow.  During lower flow years, the wildebeest can effortless cross the river and are not subjected to mass drownings - like in 2007.

It is interesting to imagine what else is impacted by low flow levels and how those changes could cascade through a system.