Population demographics of Tridacna noae (Röding, 1798) in New Ireland, Papua New Guinea

Militz, Thane A., Kinch, Jeff, and Southgate, Paul C. (2015) Population demographics of Tridacna noae (Röding, 1798) in New Ireland, Papua New Guinea. Journal of Shellfish Research, 34 (2). pp. 329-335.

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The recent resurrection of a Tridacna maxima sensu Rosewater (1965) ecotype as a distinct species, Tridacna noae (Röding, 1798), has raised concerns that inadvertent confusion of the two species in the past may have led to overestimates of T.maxima densities and errors in determining demographic parameters. To assess the potential impacts of such a scenario, this study examined the population demographics of T. noae within the center of its geographic distribution in the Kavieng lagoonal system of New Ireland Province, Papua New Guinea. The study found that 42% of the T. maxima sensu Rosewater population could be delineated as T. noae, with T. noae being the most abundant giant clam species at 7 of the 20 study sites. Past confusion of the two species is likely to be of the greatest concern on reef sites with high or medium levels of exposure to oceanic influences where T. maxima (2.08 ± 0.41 per 400 m², 1.86 ± 0.59 per 400 m², respectively) and T. noae (2.06 ± 0.36 per 400 m², 1.25 ± 0.28 per 400 m², respectively) densities were similar (P > 0.05). In analyzing size (shell length) frequency distributions, it was determined that the T. noae population had a larger mean size (206 ± 6 mm) than that of T. maxima (161 ±6 mm, P < 0.001). Thus, in areas where the two species have overlapping distributions and fisheries regulations are based on size, reassessment of T. maxima stocks should be considered a priority given the high frequency at which the larger T. noae may comprise historical populations of T. maxima sensu Rosewater.

Item ID: 42060
Item Type: Article (Research - C1)
ISSN: 1943-6319
Keywords: giant clam, Tridacna noae, Tridacna maxima, demographics, density, distribution, management, Papua New Guinea
Funders: Australian Centre for International Agriculture Research (ACIAR), National Fisheries Authority (NFA)
Projects and Grants: ACIAR FIS/2010/054
Date Deposited: 08 Dec 2015 13:55
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060207 Population Ecology @ 50%
07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070403 Fisheries Management @ 50%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8301 Fisheries - Aquaculture > 830103 Aquaculture Molluscs (excl. Oysters) @ 100%
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