A Niche for Nasty Nippers: Exploring Harvest Management for Control of Invasive Asian Paddle Crabs in Aotearoa New Zealand

Abstract

The invasive Asian paddle crab Charybdis japonica continues to expand its range across northern Aotearoa New Zealand, raising ecological, social, and economic concerns. This study theoretically assesses whether harvest‐based management—potentially including commercial, recreational, or customary fisheries—could contribute to population suppression. Five key factors were examined: consumer demand, fisher willingness to supply, population abundance in Whangarei Harbour, comparison with the native Ovalipes catharus fishery, and legal constraints, making up a theoretical framework within which to assess the feasibility of harvest exploitation as a management tool. Consumer surveys revealed strong interest in purchasing invasive crab products, with respondents valuing both taste and the ecological benefits of control. Fisher surveys indicated moderate to strong willingness to harvest C. japonica , though uncertainty remains around saleability and regulatory permissions. However, a stratified trap survey in Whangarei Harbour found unexpectedly low catches of the crab, suggesting the current population there cannot sustain a fishery. Comparison with the declining O. catharus fishery highlights potential market space, but also underscores ecological risks. Legally, regional vs national pest designations under the Biosecurity Act, as well as fishery regulations, present significant barriers to the ability to enact harvest control. Overall, while market and fisher interest appear promising, biological and regulatory constraints currently limit the feasibility of a harvest‐control fishery for C. japonica . This study contributes to the ongoing discourse of methods available for invasive species management.

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