WHILE the Katherine River freshwater crocodile population was literally in the spotlight during a Parks and Wildlife Commission NT survey on August 19, it was clear that their bigger cousins were also on the minds of John Burke, Chris Heydon and Joey Buckerfield.
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The rangers were on the river to conduct a biannual count of the number of freshwater crocodiles between the Low Level and High Level bridges.
Using data collated from the survey, PWCNT biodiversity staff are aiming to identify trends related to increases and decreases in the population.
As Mr Heydon and Mr Buckerfield began the survey using a complex series of spotlight signals to locate and count the freshwater crocodiles, Mr Burke said he always lived in hope of spotting the eyes of a “saltie” in the beam of light.
“If you see eye shine midstream, everyone gets a bit excited, because it’s normally a saltie,” he explained.
“There is always a little bit of an adrenalin rush when we are dealing with saltwater crocodiles due to the fact that we do not know exactly how the animal will respond.
“In the big picture, the saltwater crocodile is an apex predator and deserves a lot of respect.”
Rangers have neither spotted nor trapped a saltwater crocodile in the stretch of river between the two bridges since 1999, but Mr Burke said experts did not know why.
“It is not known why they do not stay in this area, as we catch them approximately two kilometres below the Low Level Bridge.”
Mr Burke said his team had caught numerous saltwater crocodiles upstream from that part of the river.
“They move through this part of the system during the wet season.”
In total, 31 freshwater crocodiles were spotted during the survey, ranging in size from 50 centimetres to three metres.
In the big picture, the saltwater crocodile is an apex predator and deserves a lot of respect.
- Katherine ranger John Burke
The figure was down on the previous survey and Mr Burke explained that the disappointing wet season could be to blame.
“The wet season was shorter and the river level remained low,” he said.
“It appears that this factor has caused a lot of sediment to build up in areas of the river that were previously deeper water holes and channels.
“This may have influenced a change in the population density,” Mr Burke said.