PREDICTING BENTHIC EFFECTS FROM MARINE CAGE AQUACULTURE- NEW DEPOMOD  

Kenneth D Black*, Trevor Carpenter, Kevin S Black (Partrac Ltd.)
 
SAMS, Scottish Marine Institute, Oban
Scotland, UK, PA37 1QA
kenny.black@sams.ac.uk

Fish-farms discharge wastes (faeces, uneaten food and medicines) that can accumulate on the seabed which can lead to conditions inimical to macro-infaunal animals. DEPOMOD/MERAMOD is a model which predicts the impact of fish-farm discharges on the seabed in order to optimise farm scale and configuration to match local assimilative capacity. First published in 2002, the software presently has 168 licenced users in 25 countries.

Although it has good predictive power for the majority of Scottish sites, DEPOMOD is poor at predicting impacts at highly dispersive and steeply sloping sites.  In addition, it is written in obsolete code, was designed to work within the limitations of 1990's PCs and operating systems, and has critical dependencies on third party closed source commercial software making the model increasingly difficult to execute.

We present New DEPOMOD, the result of a 3 year Scottish Government funded project which aimed to:

Rewrite the software in a modern language (java)

Refactorise the software to improve modularity, aiding future developers

Remove all third party dependencies

Produce more effective input and output interfaces

The project involved field research which allows better characterisation of the resuspension process and improved performance at dispersive and steeply sloping sites. The model is designed to accommodate 3D flow fields from hydrodynamic model outputs and so domain size is limited only by run time/computing power.

The model is released with an open source-code licence with a requirement to distribute any improvements under a similar agreement, which will allow a much more rapid development of the model than hitherto, utilising the skills of the international user community for which we aspire to provide a networking hub.

Cromey, C.J., Nickell, T.D. and Black, K.D. 2002. DEPOMOD - modelling the deposition and biological effects of waste solids from marine cage farms. Aquaculture. 214. 211-239.

Cromey, C.J., Thetmeyer, H., Lampadariou, N., Black, K.D., Kogeler, J. and Karakassis, I. 2012. MERAMOD: predicting the deposition and benthic impact of aquaculture in the eastern Mediterranean Sea. Aquaculture Environment Interactions. 2. 157-176.