"Nytt fra HAVBRUK" newsletter no. 2/2009:
Seeking knowledge in deep waters
Over the years Norwegian aquaculture facilities have become much more environmentally sound - and much larger. Suitable placement of aquaculture sites will make them more sustainable.
Much has changed in Norwegian aquaculture over the past 30 years. The first facilities were small and placed in shallow waters with poor water exchange. Those sites caused substantial local pollution - in the form of medicines, chemicals, waste feed, faecal waste and more - all of which fell in heaps on the seabed.
While production facilities today are even larger, they are placed in deep waters with good water flow. Depths of several hundred metres beneath the cages are not uncommon. So does this solve all the problems?
(Photo: Havforskningsinstituttet)
Size matters
"Moving aquaculture sites out to deeper waters has been beneficial, but the sheer size of today's facilities negates some of the environmental gains," says Arne Ervik of the Institute of Marine Research in Bergen.
Dr Ervik is leading the project Ecosystem Responses to Aquaculture Induced Stress (ECORAIS), which will ascertain the impact of aquaculture sites on the ecosystem. Collaborating with the Institute of Marine Research are the Norwegian Institute for Water Research (NIVA) and the Bergen Center for Computational Science (a department of Unifob AS).
The project is profiled in the most recent newsletter from the HAVBRUK programme ("Nytt fra HAVBRUK" no. 2/2009, available in Norwegian only). This issue of the newsletter is focused on sustainability.
"The objective is to generate knowledge about where the sites should be located for optimal sustainability in relation to the local ecosystem," explains Dr Ervik. "There is already some knowledge about the impacts; now we need to understand and quantify the processes. The project is only in its start-up phase, so there are still far more questions than answers: How much of the waste feed and faecal waste settles on the seabed? How much is dispersed by the current and where does it end up? How is algal growth in the vicinity affected? How far are the nutrient salts transported? What happens in the seabed sediments?"
Determining critical limits
An aquaculture facility is an open system, so anything entering the cage can impact its surroundings. Contamination from chemicals and medicines is not the problem it once was, but the facilities still emit large amounts of nutrient salts, waste feed and faecal waste.
"These all end up on the seabed or are dispersed by the current; nothing just disappears," Dr Ervik points out. "But we don't quite know how waste and nutrient salts impact the environment and how much of this contamination the ecosystem can withstand. Now, in the start-up phase, we are collecting seabed samples from great depths in order to examine more closely what happens in the sediments beneath the production sites."
Sustainable management
The project's overall objective is to provide a knowledge base for sustainable management of the Norwegian coastline.
"Based on knowledge of how aquaculture sites affect the ecosystem, we will be able to make calculations on how much environmental stress a given area can withstand - and where the facilities should be placed. This is valuable knowledge not only for the sake of the environment but for the welfare of the farmed fish as well. A sustainable aquaculture facility," concludes Dr Ervik, "is one that has the least possible negative impact on the ecosystem and the optimal growth environment for the fish."
- Published:
- 27.08.2009
- Last updated:
- 27.08.2009
Other articles from "Nytt fra HAVBRUK" no. 2/2009
The newsletter (in Norwegian)
- Nytt fra HAVBRUK nr 2/2009 (PDF-336.2 KB)
Contact
- Rolf Giskeødegård +47 22 03 70 97 rg@forskningsradet.no
