A population dynamics model for the Japanese oyster, Crassostrea gigas

• Published in: Aquaculture 1997-03, Vol.149 (3), p.285-321
• Main Authors: Kobayashi, Masato, Hofmann, Eileen E, Powell, Eric N, Klinck, John M, Kusaka, Koji
• Format: Article
• Language: English
• Subjects: Animal populations; Animal reproduction; CRASSOSTREA GIGAS; CRECIMIENTO; CROISSANCE; DINAMICA DE POBLACIONES; DYNAMIQUE DES POPULATIONS; Energy flow model; Filtration rate; GROWTH; JAPAN; JAPON; Mathematical models; Numerical model; Oysters; POPULATION DYNAMICS; Reproductive efficiency; Respiration rate
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/S0044-8486(96)01456-1

Relationships that describe the growth of the Japanese oyster, Crassostrea gigas, were developed using measurements made from June 1990 to January 1991 in mariculture fields located in Hinase waters of the Okayama Prefecture, Japan. These relationships show that shell length increase for Hinase oyster populations of 50–100 mm in size was similar to that measured for C. gigas populations in the UK; however, the Hinase oysters were lighter for a given length than oysters found in Israel, Canada, Australia and Korea. Increases in live weight were greater in smaller oysters and lower for larger oysters than those observed for C. gigas populations in other areas. This suggests that the linear increase in live weight is a feature of artificially cultured C. gigas populations in Hinase waters. These data were used to calculate regressions between shell length and live weight, wet meat weight and dry meat weight, and dry meat weight and wet meat weight. Additionally, measurements of the gonadal condition of the C. gigas populations indicated that gonadal tissue development occurred when water temperatures were above 23 °C. These relationships were then used as input into a mathematical model that describes the time-dependent evolution of post-settlement oyster populations. A filtration rate relationship was developed for C. gigas, examined for general applicability, and used for the oyster population model. This relationship accounts for the faster growth of C. gigas relative to that of Crassostrea virginica. Similarly, two relationships for respiration rate were examined with the oyster population model. The relationships differed in the amplitude of the respiration rate, namely, one provided a rate 60% lower than the other for a given dry meat weight at 20 °C. The final biological process examined with the model was the reproductive efficiency, which determined the apportionment of net production to somatic and reproductive tissue growth. The simulated post-settlement oyster populations showed growth rates that agreed with those measured for field cultivated populations in Hinase waters when the lower respiration rate was used with a reproductive efficiency that varied from 0.0 to 0.8 between 23 and 27 °C. This modeling effort illustrates the changes that are needed to model the population dynamics of C. gigas in comparison with the similar species, C. virginica. Moreover, the model as now configured can be used to investigate effects of oyster density, local en