ESTONIA
Eutrophication in the Baltic Sea complicates the development of marine aquaculture
Mussel farming may be the answer Interest in farming fish in the sea is growing in Estonia but there are challenges to be overcome before the activity can really take off.
E
stonia has a modest production of farmed fish that has, however, been growing fairly steadily. From around 385 tonnes (not counting eel and carp) in 2008, output from aquaculture has increased to 870 tonnes in 2017 with some hiccups along the way, according to data from Statistics Estonia. This corresponds to an average growth rate of 8.4 per annum. For data protection reasons figures for the production of farmed carp and farmed eel are not included in the 2017 data. Rainbow trout accounts for 80 of the production; other species include eel, common carp, sturgeon, African catfish and crayfish. The Veterinary and Food Board recognised 55 farms in 2017 of which 30 produced fish and the rest crayfish, production of which amounted to 800 kg. Apart from the production of farmed fish for commercial purposes by private companies, there is also a state-run production for a restocking programme at the Põlula Fish Farm, a division of the State Forest Management Centre. At the fish farm, various species of fish are bred for release into the wild at different maturities. Salmon has been bred here since its founding in 1994. In 2017, juvenile salmon (180,000), sea trout (2,500), European whitefish (7,000), European eel (318,000), and crayfish (3,500) were released in to Estonia’s natural water bodies.
Countries around the Baltic are committed to reducing nutrient inflows Aquaculture as it is currently practiced in Estonia is land-based, but interest in marine farming is growing as technologies develop. However, there are issues that constrain the development of this field as Dr Georg Martin from the Estonian Marine Institute, University of Tartu points out. For one, the lack of experience with marine farming in Estonia, where only a few isolated projects have been carried out. For another, the Baltic Sea is eutrophic, a significant problem caused by an excess of nutrients. The issue is being addressed – countries around the Baltic have committed to reducing their inputs – but farming fish, which would be a source rather than a sink for nutrients, would be a step in the wrong direction. This is the contradiction that researchers at the institute are trying to find a way round, the increasing interest in marine aquaculture on the one hand and the need to remove nutrients generated by this activity or prevent their production, on the other. Rivers are the main source of nutrients in the Baltic Sea, which has some 500 cubic km of fresh water from rivers (and net precipitation) entering it from the north and the east. The source of the nutrients is a combination of agriculture, industry, and municipalities as well as atmospheric depositions. Thanks to a regular reporting
process, scientists have a good idea of the extent of the different countries’ contributions to the nutrient loads in the Baltic. The HELCOM Baltic Sea Action Plan includes a nutrient reduction scheme which allocates reductions in nutrient inputs to the individual Baltic countries. The trend since 1995 for both nitrogen and phosphorus is one of falling inputs, but further reductions are still needed to reach the targets set for a clean Baltic Sea.
Legacy nutrients should also be dealt with With this background, starting a business such as fish farming that will add to the problem is an issue in itself. The situation is further complicated by the presence of legacy nutrients, says
Dr Georg Martin, Estonian Marine Institute, University of Tartu
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Dr Jonne Kotta also from the Estonian Marine Institute, which are present in the sediment of the Baltic Sea as a result of decades of pollution. Reducing the inputs alone is not enough, he adds, measures are required to remove the nutrients from the system, because the Baltic Sea is so enclosed and the water exchange so limited. A potential solution may be to cultivate blue mussels in the Baltic Sea as the technology to do this now makes it commercially feasible, which it was not 10 or even 5 years ago. The Baltic Blue Growth project, which has partners from six Baltic countries including research bodies (among them the University of Tartu), municipal authorities and private companies, is in fact dedicated to the removal of nutrients from the Baltic Sea
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13/06/19 9:17 AM