The past few months have been a busy time for the Otter Project, with field work well underway. In addition to collecting otter scats for diet analysis and sign surveys for occupancy modelling, we need to have an understanding of what prey is available for otters around the Peninsula to test whether prey availability could be a contributing factor driving otter distribution.
Thus, in November last year and January this year, we sampled each of the study sites for crabs and fish – the otters main prey – using a variety of methods, including electro-fishing, fyke nets and seine nets. All fish and crabs caught are immediately identified, measured, weighed and released unharmed. After many long nights, early mornings, a few nightmares featuring large creepy looking catfish and more than the occasional nip by a feisty crab, we have successfully sampled six rivers and three vleis twice and have packed in the nets until winter when we will sample the sites again.
Although we did find a number of alien fish species, there were fewer than I had expected. All rivers had healthy populations of freshwater crabs and the indigenous fish species found included Galaxias and Cape kurper (Sandelia). Other fish included Mozambique tilapia (Oreochromis mossambicus), Banded tilapia (Tilapia sparrmanii), Carp and African Sharp Toothed Catfish (Clarias gariepinus).