1. Life history and production were assessed for the crayfish Paranephrops zealandicus in three reaches of a headwater stream with a catchment of regenerating coniferous‐broadleaf forest in the south‐east of the South Island of New Zealand.
2. Crayfish density ranged from 3 to 4 m−2 in riffles and 4–12 m−2 in pools, depending on reach. Crayfish biomass (4–33 g AFDW m−2) and annual production (2–11 g AFDW m−2) were high compared with values reported elsewhere, while P:B ratio was low (0.33–0.43). This substantial production was dependent primarily upon high biomass rather than high growth rate.
3. The crayfish of this population rank amongst the longest lived and slowest growing ever recorded. Individuals estimated to be 16+ year of age were not uncommon. Females became reproductively active at 6+ year. Fewer than 4% of females carried eggs, and young remained attached to females for at least 15 months.
4. We propose that characteristics of this population are the consequence of a cool thermal regime (mean daily stream temperature = 7.0 °C, range 1.8–11.9 °C), and that low biomass turnover and poor reproductive rate precludes any sustainable commercial harvest of crayfish from streams in New Zealand with similar thermal regimes.
Within the Pacific over the last two decades there has been greater recognition of the pre-existing tools within indigenous communities for natural resource management. Periodic tambu (Tok Pisin: a prohibition) is an indigenous resource management tool often used across Papua New Guinea. On Manus Island terrestrial periodic tambu areas are characterised by a cycle of resource closure followed by instantaneous harvest. We examine the differing application of periodic tambu areas by three different clans who are using the technique to restock areas with the Admiralty cuscus (Phalangeridae: Spilocuscus kraemeri), an arboreal possum-like marsupial. We examined the plausibility of cuscus population recovery over differing closure periods at three different harvest rates using a composite female-only population projection matrix approach based on the vital rates of closely related phalangerid surrogates. The resultant trajectories suggest that commonly used closure durations may allow recovery at low to medium harvest rates (10–30%) but not at high harvest rates (50%). From this we infer that periodic tambu areas may be a sustainable strategy for customary resource use of Admiralty cuscus at low to medium harvest rates. We found periodic tambu management on Manus Island to be culturally dynamic with clans differing with respect to their purpose, adherence to tradition, and hybridisation with modern land governance practices. Given the past difficulties of imposing exogenous conservation systems in Papua New Guinea, we advocate greater exploration of the merits of endogenous systems such as periodic tambu areas.
The shell of the Manus green tree snail Papustyla pulcherrima is renowned for its beauty and is subject to international protection under CITES, having been harvested intensively in the past. To determine its threat status, and whether further conservation action is justified, an inexpensive Wisdom of Crowds approach was used to estimate the change in relative density of the snail between 1998 and 2013. Local men and women were approached around the main market on Manus Island, Papua New Guinea, and asked to map the relative abundance of the snail on an ordinal scale, based on their personal observations in 2013 and 1998 (a year of cultural significance). The spatial abundance data from 400 surveys were analysed using an information-theoretic approach. A suite of cumulative link models incorporating geographical factors was used to determine the magnitude of the change and to investigate possible biological influences underpinning the reported pattern. High abundance of the snail was associated with intact forested areas, high elevation and low population density. A slow decline was evident, with the median percentage of map cells where the snail was categorized as plentiful decreasing by c. 20% between the 2 years. On this basis a categorization of Near Threatened was advocated for the species. Although it is arguable that Wisdom of Crowds methods cannot be substituted for in situ quantification, the approach appears to have utility as a preliminary assessment for further conservation expenditure, and as a tool for determining threat status.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.