Kōura / fresh water crayfish

The North Island Kōura Paranephrops planifrons

There are two species of freshwater crayfish or Kōura in New Zealand. The North Island species, Paranephrops planifrons has been found in the Gordonton section of the Mangaiti stream. While kōura can often be found in native, exotic and some pastoral watercourses, they are generally rare in Hamilton city streams as they are quite sensitive to urban runoff. In addition to water quality, the presence of instream structural cover (logs, undercut banks, tree roots) is crucial for supporting the presence of kōura. Cover provides shelter from aquatic and terrestrial predators and helps to trap leaves and other detritus that koura feed on.  While eels are a natural predator, if there is plenty of thick cover and undercut banks they can co-exist. The trend tends to be that the higher you go upstream and the smaller the watercourse gets, and the harder it is for fish to get to, the more kōura you find. Streams like this also tend to have lots of leaf matter and small stable pools for the kōura to eat and reproduce. In some streams where formidable waterfalls with big overhangs prevent fish access, kōura can be very abundant. Under such situations, kōura can often be observed out in the open in the middle of the day, grazing happily away on litter on the bottom stream pools, with no fish to influence their behaviour. In streams that have fish, they tend to stay much closer to cover and to only venture out into the open to feed under the cover of darkness. They have been seen grazing on algae etc on bedrock sheets out of the water, but where they can be 
kept moist.  

                                                            Koura in the Mangaiti stream.