Investigating the socio-economic impacts of the introduced Asian paddle crab, Charybdis japonica, on New Zealand’s native paddle crab fishery
Weaver, S. J. (2017). Investigating the socio-economic impacts of the introduced Asian paddle crab, Charybdis japonica, on New Zealand’s native paddle crab fishery (Thesis, Master of Environmental Sciences (MEnvSci)). The University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/11547
Permanent Research Commons link: https://hdl.handle.net/10289/11547
Despite the body of scientific research that exists on Charybdis japonica since it’s discovery in New Zealand in 2000, an investigation into the socio-economic impacts this introduced species may have was lacking. This study focuses on the potential socio-economic impacts from C. japonica on NZ’s native paddle crab (Ovalipes catharus) fishery. Charybdis japonica has spread steadily throughout the North Island of NZ, predominantly in an area that coincides with the main commercial fishing area for O. catharus (federally managed and defined as ‘PAD1’). Fishers perceptions of change and impacts in the fishery were investigated across the commercial and recreational sectors within this focus area. Qualitative, semi-structured interviews with commercial crab fishers covered three main areas: (1) background information on the O. catharus fishery, (2) perceptions of change in the fishery, (3) knowledge of C. japonica and perceived impact. Surveys with recreational fishers also covered these areas, with additional questions on their perceptions of the value of certain coastal environmental aspects (i.e., safety, cleanliness, biodiversity). Commercial fisheries catch data for the five main O. catharus fishing regions was also analysed to assess if a significant change in catch rates pre- and post- the arrival of C. japonica in NZ had occurred. Results showed significant changes in PAD1, PAD7 and PAD8 fisheries management areas. Given C. japonica has not yet been found in PAD7 and PAD8, catch rate changes within these three areas are likely due to other unmeasured variables. Commercial fishers predominantly suggested C. japonica had not yet had an observable impact on the O. catharus fishery. Recreational fishers that participated in this study had only had a short-term exposure to the fishery (the majority had started fishing for crabs less than a year ago), thus they had limited perceptions of change within the fishery. Commercial and recreational fishers were also tested on their ability to accurately identify the two crab species. Both sectors accurately identified O. catharus 95% of the time and C. japonica 55% of the time from a series of four images, with no statistically significant difference in accuracy between the two sectors. Despite some evidence of self-reported awareness of C. japonica in this study, further sustained public education to enable identification of this introduced species is needed if the public are to be incorporated into the management of this species. Commercial fishers highlighted the potential impact C. japonica may have on the flatfish fishery, an area requiring further investigation. Further research on the impacts C. japonica could have on other species of ecological, social, cultural and economic importance in NZ is required.
The University of Waikato
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- Masters Degree Theses