size: 5036KB - Crocodile Specialist Group

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be removed sustalnably, provided a number of juvenile animals are released each
year. Survival values of wild and released crocodiles have been assumed for
modelling and requirc field evidence.
- There has always be€n a provision for the subsequent release of juveniles as a
condition of the per it for egg collection. P or to 1990 this was not invoked, apart
from small scale releases above Victoria Falls in the 1960s and at Sinamwenda
Lale Karjba in the early 1970s.
- Releasesta ed in 1990 and a number of animals equivalent to 2 % of the number
of eggs found 2 years previously are being released annually at a size which it was
anticipated have a low level of mortality.
- The Zimbabwean policy of crocodile anagement has been emulated by several
other African countries although none of these have yet reached the stage of releasing
animals. Validation of the successful integntion of released animals is thus essential
for successful crocodile management in Africa as a whole.
This pap€r constitutes a progress report covedng nearly six months of opention. As such
it is descriptive and does not attempt to provide calculated estimates for the parametels
studied. Insufficient data have been collected to provide more than indications of the pattem
that may finally be expected.
KEY QUF,STIONS AND METHODS
The key questions to be answered are;
l) What is the survjval rate of captive mised animals released to the wild ?
2) How does acclimatisation to the wild habitat progress ?
3) What behaviourial changes occur among released animals ?
These questions are also addressed to the wild population to provide a basis for compadson.
The Gachegachestuary, Irke Kariba, was chosen as the initial study area as access is
relatively easy and the area is representative of much of the Ka.iba envircnment, with
recrcational boating, line fishing, illegal gill netting and a rcsident human prcsence.
Mapping of the estuary at the present low water level and placement of position markers at
250 m intervals along the shoreline was carried out before the release began (See Figu.e 1).
The captive nised animals released in this project were supplied by l,ake Crccodile Park,
Kariba (82 animals) and Rokari Crocodile Farm, Bumi (67 animals). A pool of animals for
release had alrcady been made by management at both farms. Selection for rclease was
effectively mndom as none of the animals were identified and no previous history was
known. OnIy competent animals without injury or deformities were selected for release,
Processing included basic data collection on each animal. Mass, seven mqNurements of
body size and sex werc recorded for each animal. These parameters were selecied to
investigate possible moryhological co-variates of survival and to investigate possible
differences betwe€n farm and wild raised animals.
Individual identification was madc by attaching a numbered tag to the web of the left rear
foot and by partial mutilation ofa coded sequence of paired tail scutes. This duplication was