Abstract
Environmental conditions can strongly influence the growth performance of pearl oysters and affect pearl farm production schedules. Growth and condition index (CI) of two age cohorts of Pteria penguin were measured for 13 months to investigate differences in growth performance between four culture sites within the northern (Vava’u) and southern (Tongatapu) island groups of the Kingdom of Tonga. Environmental conditions were also measured at culture sites and used to explore potential effects on oyster growth and condition. Between island groups, growth performance of P. penguin was superior at northern sites and was most strongly related to higher water temperatures at these sites. Within the southern island group, growth performance varied significantly between sites and may be driven by differences in wave energy. Monthly growth rates (GM) of P. penguin also showed significant temporal variation related to age and environmental conditions. This study demonstrated significant variation in the growth performance of P. penguin at latitudinal and local scales and suggests that in oligotrophic marine environments with minimal terrestrial inputs, such as Tonga, water temperature and wave exposure may be the primary environmental conditions influencing the growth performance of P. penguin. This study therefore recommends that optimal culture sites for P. penguin in Tonga are characterized primarily by warmer water temperatures (25–30°C) and low wave exposure (<15 joules m2 day–1). Culture of P. penguin at sites with more suitable environmental conditions enables pearl production to begin up to 34.2 % (6.5 months) earlier than at less-suitable sites and this may greatly influence mabé pearl farm profitability and feasibility.
Highlights
The winged pearl oyster, Pteria penguin (Röding 1798), occurs in a diverse range of marine environments, from the east coast of Africa, throughout Asia and northern Australia, and the western Pacific (Wada and Tëmkin, 2008)
GT in wet mass (WM) of both age cohorts was significantly higher at northern sites than southern sites, while GT in DVH was higher at northern sites for “young” oysters (Table 1)
This study demonstrated significant variation in the growth performance of P. penguin at latitudinal and local scales
Summary
The winged pearl oyster, Pteria penguin (Röding 1798), occurs in a diverse range of marine environments, from the east coast of Africa, throughout Asia and northern Australia, and the western Pacific (Wada and Tëmkin, 2008). Pteria penguin is widely cultured for the production of high-quality mabé pearls (half-pearls) at both commercial and subsistence scales, supporting a range of pearl-based livelihoods (Southgate et al, 2008, 2019; Johnston et al, 2019). Subsistence-level mabé pearl farming has considerable potential for livelihood support (Yamamoto and Tanaka, 1997; Anon, 2018; Johnston et al, 2019), with small-scale farms capable of generating annual profits of more than twice the average income in Tonga (Johnston et al, 2020). No studies have investigated large-scale spatial variation in growth performance of P. penguin, yet such information is vital to inform pearl farm site selection to maximize pearl farm productivity, profitability, and associated livelihood benefits (Pouvreau and Prasil, 2001; Gaertner-Mazouni and Le Moullac, 2016; Gueguen et al, 2016)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
