Growth of the black-lip pearl oyster, Pinctada margaritifera, at nine culture sites of French Polynesia: synthesis of several sampling designs conducted between 1994 and 1999
S. Pouvreau et V. Prasil, Growth of the black-lip pearl oyster, Pinctada margaritifera, at nine culture sites of French Polynesia: synthesis of several sampling designs conducted between 1994 and 1999, AQU LIV RES, 14(3), 2001, pp. 155-163
Between 1994 and 1999, several sampling designs were used to measure the gr
owth of the black-lip pearl oyster, Pinctada margaritifera var. cumingi at
different sites in French Polynesia. Using a common statistical method, gro
wth data were analysed for nine sites and showed significant geographic var
iability. Parameters of the Von Bertalanffy model, fitted on the nine data
sets, ranged from 147 to 186.5 mm for the H-infinity parameter and from 0.4
2 to 0.58 year(-1) for the k parameter. The phi parameter (combination of H
-infinity and k) provided a ranking classification of growth in these nine
sites: growth was low in closed atoll lagoons, such as Takapoto, whereas th
e island lagoons and ocean habitat supported a very promising shell growth.
Calculated on the basis of these models, two parameters of interest for pe
arl farming were computed: 1) the time for pearl oysters to reach a size of
100 mm (size at which they are suitable for nucleus implantation), which r
anged from 21 to 26 months, and 2) the annual shell growth increment at thi
s size (correlated to the rate of nacreous deposition on the pearl), which
varied from 19.7 to 31.8 mm.year(-1). The combination of these two sets of
results demonstrated that the time necessary to produce a comparable pearl
varied significantly according to the site. Several hypotheses to explain t
he differences observed in the growth of P: margaritifera in these nine sit
es are proposed. The most reasonable would appear to be: 1) the negative ef
fect of high temperature (> 30 degreesC), and 2) the degree of water renewa
l and food supply around the bivalve. Although this paper demonstrated sign
ificant variability in growth performance in the nine investigated sites, f
urther investigations are needed, especially concerning the flesh growth ra
te. Indeed, this highly relevant parameter, which reflects both bivalve hea
lth and the suitability of farming sites, has received very little attentio
n to date. (C) 2001 Ifremer/CNRS/Inra/IRD/Cemagref/Editions scientifiques e
t medicales Elsevier SAS.