The bio-economic model can be used to identify and summarise potential production scenarios for Atlantic Salmon.
Users can specify an initial fish weight, time of year and desired harvest weight; the model would then return the Time to Harvest for this scenario. Furthermore the model can optimise the time spent in an intermediate system such that the time in net pens is reduced below (eg) 12 months.
The model is one of the key outputs of a project, funded by the Scottish Aquaculture Research Forum, which aimed to investigate the potential for shortening the pen-based phase of the salmon on-growing cycle in order to meet approved targets for increasing Scotland's annual production of salmon from 160,000 to 210,000 by 2020. By reducing the length of time spent in net pens to below 12 months, stocking marine net-pens with larger fish would reduce the grow-out period to harvest, thereby allowing additional harvests from existing sites, and providing an alternative to increasing the number of net pens.
One strategy with potential to reduce the on-growing period in marine net-pens is an intermediate system between freshwater nurseries and marine net-pens. Through literature reviews and consultation with industry partners, pump ashore (PAS) and recirculating aquaculture systems (RAS) were considered currently the most suitable intermediate systems for reducing the pen-based phase of the salmon on-growing cycle.
Data relating to specific growth rates (SGRs) for salmon at a range of temperatures and weights were obtained from Skretting, which allowed the estimation of the time to harvest (TtH) under various scenarios. The Excel model was developed to provide a user-friendly interface whereby users could determine and assess potential production scenarios for Atlantic Salmon; the tool also includes the ability to compare the costs of various systems.