Distribution, trapping efficiencies and feeding trials for Paranephrops zealandicus in central Canterbury
Thesis DisciplineEnvironmental Sciences
Degree GrantorUniversity of Canterbury
Degree NameMaster of Science
Freshwater crayfish are a taonga species of New Zealand waterways that are highly valued as mahinga kai by many local iwi. Crayfish can also be an important keystone species by acting as bioengineers that create habitats for other species as well as contributing to the maintenance of stream health. My research focused on the native South Island crayfish (Kekewai, Paranephrops zealandicus) and was comprised of three components; field surveys to determine the occurrence of crayfish in Canterbury streams, testing of alternative sampling techniques and investigating feeding. Crayfish distribution was patchy throughout the region, with some historic sites having possibly lost crayfish populations. Comparison of active and passive methods for capturing crayfish indicated differences in catch rates and various trapping biases. Electric fishing was the most effective method for capturing kekewai and showed no bias for sex or size. I also compared artificial and natural Māori Tau kōura traps and found that natural traps attracted a higher number of individuals than artificial traps. Feeding trials examined the palatability of various foods including macrophyte species, detritus and invertebrates (i.e. mayflies and snails) as well as investigating food preferences within food groups. Results from these trials confirm that kekewai are opportunistic omnivores and will consume a variety of food items. The results from this thesis can be used to inform management and restoration projects.