Shellfish Farm Module in EEMS10.2
The new shellfish sub-model in EEMS10.2 was used to replicate the Kobayashi et al., (1997) test case for shellfish growth over time in a water quality simulation. This test case is described in the paper “A population dynamics model for the Japanese oyster, Crassostrea gigas”. The goal of DSI’s testing was to verify that the EEMS model can accurately replicate the measured data from this paper.
The study by Kobayashi was performed in mariculture fields in Hinase, Japan, in 1990 and involved measurements performed on the growth of the Japanese oyster. The data obtained were used to calculate regressions between shell length and live weight as well as between wet meat weight and dry meat weight. An oyster population model was also developed to describe the time-dependent evolution of post-settlement oyster populations. The relationships from the measured data were then used as input into the model. It was found that the growth rates in the simulated oyster populations were in agreement with the measured values when a lower respiration rate was used.
Kobayashi concluded that the model his team developed could be used to investigate the effects of oyster density and local environmental conditions. Areas that could be investigated include flow fields around the mariculture rafts, the distribution of the rafts, and the impact of cultivation practices on the growth and development of the Japanese oyster. Potential oyster yields from individual mariculture fields can also be predicted.
With a simple EFDC+ model comprising three horizontal grid cells and one vertical layer, DSI replicated the characteristics of the Hinase waters using the time series of salinity, temperature and chlorophyll-a measured by Kobayashi. Comparison of the measured results with the model simulation are shown below for shell length and dry weight per individual. It was found that EEMS matched the data well, as can be seen in the table of statistics. The model files will be provided for free download from our website after EEMS10.2 is released. The model can be run with the free demo version of EEMS. DSI welcomes feedback from users who try out this new module.
DSI appreciates the ongoing collaboration of the Marine Environment Research Division of South Korea’s National Institute of Fisheries Science in developing this module.
Kobayashi, M., E.E. Hofmann, E.N. Powell, J.M. Klinck, K. Kusaka (1997).A population dynamics model for the Japanese oyster, Crassostrea Gigas. Aquaculture.Vol. 149, Iss. 3–4, p. 285-321.
|Mean Error||Root Mean Square Error||Coefficient of Correlation|
|Shell Length||-1.00 mm||6.4 mm||0.77|
|Dry Weight||0.05 g C||0.18 g C||0.95|
Table 1. Statistics comparing observed data and modeled results.
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Nghiem Tien Lam, Ph.D