Local management to support local fisheries: Rāhui (temporary closure) and bag limits for blackfoot abalone (Haliotis iris) in southern New Zealand

Abstract

Spatially discrete stocks that vary in life history traits on a reef‐to‐reef scale present a challenge for fisheries managers. Nationally or regionally applied one‐size‐fits‐all approaches to management fail to account for this variability, and when coupled with fishing pressure this can result in serial depletion and localized extinction. Where mechanisms for local management exist, as they do in New Zealand via customary protection areas (Taiāpure Local Fisheries, Mātaitai Reserves), managers have the opportunity to trial tools on scales relevant to the stocks managed. This study assesses the effect of bag limits and a rāhui (temporary closure) in managing the spatially discrete, and culturally important, blackfoot abalone (Haliotis iris, pāua) in the East Otago Taiāpure, in southern New Zealand. Using surveys spanning 8 years and 26 sites, the rāhui was found to have had mixed results: halting the decline in pāua density at 0 m but not 0.5 m depths. The rāhui did, however, result in an increase in the percentage of individuals above the minimum legal size at both depths. Where bag limits alone had been applied, pāua densities and the percentage of legal‐sized individuals continued to decline over the 8‐year period, with the loss of large individuals, translating into a decline in estimated egg production. Growth estimates from mark–recapture and surveys of juvenile abundance at sites inside and outside the rāhui highlight the fine‐scale variability in pāua life history even within this local area. This suggests there may be biological impediments to pāua management using bag limits alone. Though pāua restoration efforts have had mixed results to date, this study highlights the potential for legally empowered local managers and communities to respond to fisheries declines in their own local area in an action‐driven, adaptable, and timely way.

Constraints to effective comanagement of New Zealand's customary fisheries: experiences of the East Otago Taiāpure

“…Through the Committee, the local hapū has been provided an avenue through which to work toward restoring this taonga species (Jackson et al 2018; Table 1). A longterm monitoring program has been established and runs every four years (Hepburn et al 2008, Richards 2009, Gnanalingam 2013Hepburn et al 2016), bag limits have been reduced and areas closed (Gnanalingam et al 2021), and active restoration strategies have been trialed (Gillies 2013, Bennett-Jones et al 2021. Management of pāua within the Taiāpure has proven successful regarding many aspects of comanagement; community efforts are focused at a small scale (25 km of coastal habitat), enabling reefby-reef management and restoration that observes and accounts for the fine scale variability of pāua and the management goals of the community.…”

“…Management of pāua within the Taiāpure has proven successful regarding many aspects of comanagement; community efforts are focused at a small scale (25 km of coastal habitat), enabling reefby-reef management and restoration that observes and accounts for the fine scale variability of pāua and the management goals of the community. Recent surveys indicate that several reefs, protected by rāhui (temporary closure), have seen sustained population densities over time, whereas other reefs have witnessed significant increases (Gnanalingam et al 2021). However, despite these efforts, population decline has also been witnessed across reefs that remained open to fishing (East Otago Taiāpure Management Committee, unpublished data), demonstrating the small-scale variability of pāua, the impact of sustained fishing https://www.ecologyandsociety.org/vol27/iss4/art38/ pressure, and the requirement for management that can account for this.…”

Benefits of collaboration between indigenous fishery management and data-driven spatial planning approaches: the case of a Polynesian traditional design (rāhui)

“…To go further, any data driven planning (not only SCP) would ideally require to model several cycles of opening/closing to fishery, to assess the full impact and value of such a rotating closure, as carried out for sea cucumbers in Australia (Plagányi et al, 2015), or abalones in New Zealand (Gnanalingam et al, 2021). In other places, some key biological and ecological parameters of invertebrate species targeted by artisanal fisheries have been specifically studied to inform management strategies (Cumplido et al, 2022;Martino et al, 2021).…”

“…An additional precious source of reliable information could be toxicity tests conducted on randomly-caught fish, but these are very costly; 3. Monitor the marine resources on a regular basis (as in Gnanalingam et al, 2021) to assess its status and to allow for potential adaptive planning. The Raivavae population expressed interest in assessing the impacts of rāhui implementation on the stocks/abundance of resources on a regular basis, so as to understand its impact.…”

Environmental DNA reflects common haplotypic variation

“…Traditionally, Māori exerted kaitiakitanga (guardianship) over the marine environment for the harvest of kaimoana (seafood) using mātauranga (indigenous knowledge) and tikanga (practice), but European colonialism and centralized management have since undermined efforts for sustainable harvest (Bennett‐Jones et al, 2021; Bess, 2001; McCarthy et al, 2014). Harvesting of blackfoot pāua is managed using a variety of tools including total allowable catch and minimum legal size for commercial fisheries, and daily bag limits and minimum size for recreational fishing and authorisations for traditional fishers guided by local mātauranga (Gnanalingam et al, 2021). However, like most wild abalone populations, blackfoot pāua populations are still declining (Cook, 2016).…”