Catches of marine fish species such as herring, saithe and nephrops should be reduced, and cod in the Kattegat and the eastern Baltic Sea should not be fished at all. But several freshwater fish species are increasing in numbers, according to a report from Swedish University of Agricultural Sciences, SLU.
”In Lake Vättern, the stocks of common whitefish, burbot and vendace are so strong that we judge that they can handle increased fishing and the same applies to perch in Lake Mälaren and Hjälmaren”, says Eddie Von Wachenfeldt, environmental analysis specialist at the Department of Aquatic Resources at the Swedish University of Agricultural Sciences, SLU.
Every year, the Department of Aquatic Resources (SLU Aqua), on behalf of the Swedish Maritime Administration, conducts an overview that describes conditions and trends for the most fished species in the sea and the four large lakes: Lake Vänern, Lake Vättern, Lake Mälaren and Lake Hjälmaren.
The report ‘Fish and shellfish stocks in Swedish seas and freshwater’ also provides biological advice for the management of the stocks, i.e. assessments of how fishing on different stocks should be developed if it is to be sustainable in the long term. This year’s report includes descriptions of 48 species, which occur in about a hundred different populations and/or areas.
The knowledge base is based on data collected in commercial and recreational fisheries, as well as extensive monitoring of fish stocks and analyzes by national and international researchers.
“When assessing how the stocks develop, we look at the fishing pressure, how many fish are born, how well they grow and how many die from natural causes. If growth increases or if natural mortality decreases, this means that fishing can increase. If, on the other hand, the catches are greater than the addition of new fish, the fishing cannot be conducted at that level in order to be sustainable in the long term”, says Eddie von Wachenfeldt.
Inland, catches are estimated to increase for burbot in Lake Vättern, common whitefish in Lake Vänern and Lake Vättern, vendace in Lake Vättern and Lake Mälaren and perch in Lake Mälaren and Lake Hjälmaren.
“The majority of marine species such as haddock, plaice and sprat in the North Sea, North Sea and Baltic Sea have also shown a positive stock development and here the assessment is that fishing for these species can increase”, says Eddie Von Wachenfeldt.
Serious situation for cod
For other marine species, the status is worse, and the situation is most serious for cod in the eastern Baltic Sea and in the Kattegat.
“The cod here shows both a reduced individual growth and an increased natural mortality and ICES advises that no fishing for cod should take place in 2021. Also for cod in the western Baltic Sea, ICES wants to see a reduction in fishing by 18% compared to the previous year”, says Eddie Von Wachenfeldt.
For spring spawning herring in the Skagerrak, Kattegat and southwestern Baltic Sea, the advice is that the species should not be fished. For autumn spawning herring in the North Sea, Kattegat, Skagerrak and eastern English Channelkingfisher,, catches should be reduced by 15%. Catches of other marine species such as lemon sole, saithe, norwegian lobster and hake should also be reduced.
Along the coast, test fishing shows negative trends for pike, a predatory fish that is central to the functioning of the ecosystem and which is also a popular species for recreational fishing.
“We know that recreational fishing catches much more pike than commercial fishing and that it thus has a major impact on fish stocks, but here we would need even better data. Based on the downward trends we see, we believe that catches of pike should decrease in the Baltic Proper”, says Eddie von Wachenfeldt.
For perch along the coast, the trend is stable, but in about a quarter of the areas, catches of perch have decreased in the test fishery and in the coastal areas of the Baltic Sea itself, recruitment remains weak. The fish and shellfish included in the overview are important indicators of how the environment is and are part of the aquatic ecosystem.
The fish and shellfish included in the overview are important indicators of how the environment is and are part of the aquatic ecosystem. The report mainly evaluates fishing, but there may be other factors that are important and good management needs to take a holistic view and consider different ecosystem services that our seas, lakes and watercourses deliver.
“The knowledge is important to be able to implement ecosystem-based management and the work of creating a balance between conservation, long-term sustainable use and a fair distribution of natural resources”, says Fredrik Ljunghager, investigator at the Swedish Marine and Water Authority, HaV.
European eel
The European eel consists of one very wide-spread population and is managed under an EU framework, but with national implementation. In Sweden, eel management is divided into three units: the West Coast, inland waters and the Baltic Sea. Formally, however, all of Sweden consists of one eel management area covered by a national Eel Management Plan, that sets out to implement the EU eel regulation. The eel population is assessed as one unit by ICES, and has been declining for several decades to a very low level. SLU is following the ICES advice, which states that in line with the precautionary approach, all anthropogenic impacts that decrease production and escapement of silver eels should be reduced to, or kept as close as possible to, zero in 2021. The report also states that it is difficult to judge whether Sweden currently fulfils the objectives and targets in the EU eel regulation, and whether the targets in the Swedish eel management plan have been reached, as the number of silver eels leaving Swedish waters remains at low level and number of migrating silver eels has continued to decline. Unusually, this advice is contested in the report by SLU Aqua’s own eel experts, pointing to the fact that the ICES advice on annual fishing opportunities does not provide advice on the implementation of the EU eel regulation or the Swedish eel management plan.
Some well-known species in specific waters, in brief:
- The Great Lakes
In Lake Mälaren and Lake Hjälmaren, perch stocks have been stable or increased slightly. In Lake Vättern, the lake has a positive development. Vätternrödingen seems to be in a recovery phase and whitefish and vendace also show positive trends. For whitefish, a positive development can also be seen in Lake Vänern, while recruitment of trout remains weak. The bream is viable in all of the large lakes.
- Baltic Sea
In the Baltic Sea, plaice, flounder and sprat are all doing well. The herring stock is stable in the Gulf of Bothnia, but further south the spawning biomass is low and recruitment varies between years. Pikeperch and pike both show declining trends. The situation of cod in the eastern stock is so critical that there is a complete fishing closure in place, but the situation is bad even for the western stock as well.
- Skagerrak and Kattegat
The condition is good for whiting, haddock, plaice and sprat. It looks worse for monkfish, nephrops, mackerel, halibut and autumn spawning herring. The situation for cod in the Kattegat is really bad (fishing closure), while it is doing better in the Skagerrak.
- North Sea
The condition is good for haddock and plaice and sprat. Autumn spawning herring shows a downward trend.
About the report and SLU Aqua
The report “Fish and shellfish stocks in Swedish seas and freshwater” is a resource overview produced by the Department of Aquatic Resources (SLU Aqua) at the Swedish University of Agricultural Sciences at the request of the Swedish Marine and Water Authority. The resource overview is based on data collected in commercial and recreational fisheries, as well as extensive monitoring of fish stocks and analyses by national and international researchers.
The report presents current fisheries and biological advice for species and stocks that are managed nationally, as well as stocks covered by international management that are found in Swedish waters. With regard to nationally managed fish and shellfish stocks, SLU Aqua is responsible for the advice, for internationally managed stocks, SLU Aqua’s advice follows that given by the International Council for the Exploration of the Sea, ICES.