Terje L. Jahnsen. (Norway)
One of the main reasons to regulate the aquaculture industry is to limit the environmental impacts. International agreements have to be followed up, and in Norway we have additional national environmental objectives that have to be considered.
Even if the amount of production will influence the environmental impact, the amount of fish itself is not necessarily the responsibility of the authorities. If you can't sell the fish it's your problem. If you pollute the environment it's everybody's problem, no matter what quantity of fish it was that caused the problem.
The amount of fish you can produce without causing problems will depend on the potential of the locality (current, depth etc.), technical solutions, and your own skills. If a great potential exists, why not realise it and attain a cost effective production? This will also stimulate the farmers to find the best localities, often resulting in selecting sites in the outer coastal areas.
In Norway we have a regulation based on volume. Most farmers have a 12,000 m3 permission combined with a limitation of 25 kg/m3. The volume is calculated as 85% of the cage area multiplied by 5 m depth. The maximum biomass therefore is 300 tonnes of fish, resulting in a production potential of around 500 to 600 tonnes, no matter what the carrying capacity of the locality.
In real life however the average cage depth is around 12-13 m, resulting in better water quality for the fish when the biomass increases. Problems that may occur are seldom related to water quality because the general conditions are ideal for aquaculture. The current is typically 12-18 cm/s and the temperature varies from 4°C in the wintertime to around 15°C in the summertime. Even if the depth usually is 30 m or more, problems in relation to sedimentation may occur, at least in a longer perspective. The processes responsible for this are often predictable, assuming you know something about the physical conditions and have a some sort of clue of what's taking place at the fish farm. This is the point where computer simulations come into the picture.
What if we could give the farmer an environmental forecast and prevent a breakdown of the bottom life? Adjustments could be made to adjust the production to the carrying capacity of the locality. We could do this before fish production starts, based on general information and measured parameters. Later on we could measure the real effects and relate them to standard official quality demands for aquaculture activity. If the development is bad we could give a warning, and if necessary we could demand a full stop in production. We would gain experience and be able to make adjustments to the simulator, bringing it closer to the real life step by step. Detailed information about production, amount of feed used, feed waste, etc. is already available to the Norwegian authorities.
A suggestion for a national environmental aquaculture standard has been made. A appurtenant standard monitoring program is being tested, and we have developed a computer model for determination of the carrying capacity at different sites. Further testing will tell us into what degree these tools are working together. Then we will consider the possibility of an integration with existing regulations.
In a nearby future maybe the farmer will have a permission either in volume, number of fishes, production in tonnes, or most likely an area in m2 combined with environmental standards. He will have permission to utilise the production potential of salmon so long as he doesn't harm nature. If such a danger exists, we will probably know in time to prevent a breakdown.
A simulator combined with environmental standards could represent a new way of regulation. First of all we could focus on the effects of what's been done instead of talking about how much feed is given. Next we could use a simulator for coastal planning and to make calculations about relationships between selected characteristics of the localities and their carrying capacity. Example: What is the optimum depth of a cage at a locality with depth = 30 m and with a current = average? Maybe we should not allow cages more than 1/3 of the total depth. What would be a reasonable density in a cage that is 10 m deep? The simulator could give us the answer, leading to a table of the relationships between total depth, cage depth and the maximum density permitted. Are there other connections that could be useful in an attempt to develop a more scientific based set of regulations?
The knowledge about biological processes taking place in fish farms has increased. They are complicated for sure, but still it seems possible to describe a lot of them mathematically. Giving these equations a user-friendly interface could represent a possibility of using them in public administration, often by people who don't have a detailed knowledge of the processes behind.
May be this is believing in Father Christmas, but then again its Christmas time the moment this is written.