Regulation to minimize impacts from aquaculture is of key concern in coastal zone management for the sustainability of the industry and the receiving environment. Market and consumer forces are presently driving much of this regulation and its implementation. Mathematical modelling can provide the tools for planning and monitoring as well as regulation, and a number of countries have well-developed policies and procedures in place which utilize modelling tools. The main impacts currently modelled are nutrient enhancement, organic waste deposition and the dispersion and deposition of medicines and chemicals. The release of these wastes is influenced by species- and site-specific characteristics, as well as culture and husbandry techniques. The modelling process requires consideration of definitions and limitations; standards for model development including clear objectives and justification; good technical description; use of good and appropriate data; calibration; validation; sensitivity analysis; quality assurance; auditability and consideration of the operational needs of the user, the grower and/or the regulator. Models should have simplicity and clarity; be fit for purpose; be open to scrutiny; be accessible, user-friendly and be used with caution. Current models are considered to be limited in scope but do cover the main hydrodynamic and particulate processes. The regulation and monitoring of finfish aquaculture involving the direct use of models is apparently restricted to relatively few countries where they are involved in setting holding capacity, the licensing of medicines and for assessing site applications. Different approaches have been developed in different countries as required. In contrast, many countries do make considerable indirect use of modelling techniques within the regulation process. With respect to shellfish, models are in current use to predict and optimize exploitation capacity but there is scope for studying nutrient flux, habitat degradation and deposition below suspended systems. Future developments for finfish need to better address the main question of holding capacity or exploitation capacity in relation to nutrients and medicines release, including whole water body /regional impacts. The relationship and predictability of toxic algal blooms remains some way off. Modelling the complexities of degradation, resuspension and the effect of the scavenging process on the transport of in-feed medicines is required. Keys to future developments across Europe include accessibility, setting of Environmental Quality Standards or targets, training and support for users, resources and structured research. |
