The Longline Environment aquaculture consultancy produces two useful models. The Farm Aquaculture Resource Model (English only, free, Internet Explorer) uses a simple online format for input of about 20 variables on the dimensions of an offshore farm for bivalve molluscs (Mussels, Clams, Cockles), the growing conditions and the aquatic environment to predict harvestable population and biomass and impact on the environment, including estimated nitrogen removal to earn nitrogen credits. The Pond Aquaculture Management and Development is currently for shrimps and oysters, with freshwater fish under development.