Blue bioeconomy projects at DTU Aqua

Starfish are an example of a resource from the sea so far not exploited in the Danish fishery, as they are usually thrown out when caught. The number of starfish has increased substantially in several of the coastal areas, and as their preferred food is mussels, they can make considerable cuts into the mussel stocks.

In an attempt to exploit a resource otherwise simply wasted, DTU Aqua and a number of partners in the STARPRO project have studied the possibility of turning starfish into animal feed. In the project, the starfish were dried and ground to a powder, and it was found that it can be included as a high-protein ingredient in chicken and pig feed. The research results form the basis for a factory from 2018 processing starfish, which may be caught sustainably.

Microalgae have great potential in blue bioeconomy. They are already used as mini factories to produce, e.g., pigments, vitamins, proteins and omega-3 fatty acids. Researchers at DTU Aqua attempt to take advantage of the algae's uptake of nutrients from nutritional waste water from the biotech industry to produce biomass, which may be dried, processed and used for fish feed.

The microalgae remove nutrients from the water, which in this way is cleaner when discharged or reused, and the nutrients become products that may be exploited in other industries. If the trial is successful, the production of fish in aquaculture, which is in great and rising demand, could be made more sustainable.

In the project SORTMUND (in English: BLACK-MOUTH, from the Danish word for "round goby"), DTU Aqua and a number of partners have studied whether the round goby, an invasive fish species, can be made into a resource for local fishermen instead of only posing a problem. Round goby originates from the Back Sea and was observed for the first time in Danish waters in 2008. It has most likely been introduced with ballast water from ships. In many coastal areas, round goby is a tough competitor for other fish species and may even threaten local coastal fisheries in areas where they occur in great numbers.

Among other things, the project has shown that it is most profitable to fish for round goby from April to June and that the goby is a healthy and tasty fish for humans as well as minks. The challenge is to turn the project's positive results into a financially sustainable product. The fishermen cannot charge the price needed if the catch is to be sold as mink feed, and according to first indications, it is not profitable to fillet the fish, as it is too small. However, pilot tests have shown that the fish may be used profitably for ground fish meat (e.g. for fishcakes) and that further development of this product should be carried out. 

The use of nutrients must be made more circular so that surplus nutrients (nitrogen and phosphorous) from agriculture do not go to waste when flowing from land into coastal waters. Consequently, DTU Aqua carries out studies in, e.g., the Limfjord to find out to which degree mussel farming can absorb the nutrients emitted from land to the aquatic system and thus become a tool to mitigate the effects of eutrophication.

When the mussels are harvested to be used as healthy and climate-friendly food or as an animal feed ingredient, the nutrients emitted to the coastal waters are brought back on land in the form of mussel meat. In this way, mussel production could contribute to creating a nutrient cycle in which nutrients from land do not end up in the sea but come back on land and are exploited there.

In order to optimally take advantage of the possibilities of the blue bioeconomy, society must have knowledge about the ecosystems in the sea, lakes and streams—which types of ecosystems do we have, how do they work, and how will they evolve in the future? DTU Aqua deals with such things in the form of basic research as well as applied research. The institute assesses, among other things, the consequences of climate change on the sea's production and the consequences of new animal species and works with the development of fishing methods and aquaculture systems promoting a sustainable exploitation of resources.

An important element of DTU Aqua's work is to give advice on fishery and the exploitation of marine living resources. This takes place through DTU Aqua's research-based advisory services to the Ministry of Environment and Food of Denmark and in close international cooperation with the International Council for the Exploration of the Sea (ICES), which is among EU's external advisers on fishery. The advice helps authorities and other stakeholders to identify the potential of blue bioeconomy and to assess where legislation may be necessary.

Blue bioeconomy also includes experience economy building on the human use of nature as a recreational resource. Here, the living organisms are the starting point for experiences, e.g. in the form of recreational fishing, oyster harvest, snorkelling and diving as well as seal, bird, fish and whale watching.

Research at DTU Aqua reveals the best ways to restore nature, e.g. by restoring rocky reefs in coastal areas or by restoring trout spawning areas in streams. The primary objective of these projects is to restore the natural biodiversity and productivity, but the projects are also likely to support the recreational economy. For example, DTU Aqua studies show that each little trout succeeding at migrating from its native "childhood" stream and into the sea to become a sea trout represents an economic value of approx. DKK 500. This is due to the fact that sea trout are in high demand by recreational fishermen along the Danish coasts and streams.

Danish Shellfish Centre, which is part of DTU Aqua, is a dissemination centre on the island of Mors at which tourists, associations, businesses and educational institutions may gain insights into how the fishery and the production of shellfish and seaweed take place, as well as how the environment and the production interact. For a fee, the Danish Shellfish Centre offers, among other things, lectures and adventure trips on and around the Limfjord.

The centre also involves citizens in its research projects, so-called citizen science. Such is, e.g., the case in a project, in which commercial fishermen and anglers contribute knowledge about the lobster stocks and lobster fishery in the Limfjord.

DTU Aqua has participated in several studies of the socio-economic benefits of angling. Among other things, they show that consumption per fishing trip for spring fish such as sea trout along the coasts of Funen is DKK 300, while for German tourists it is around DKK 900.

DTU Aqua is also investigating the human dimensions among anglers. The results show, for example, that anglers are a complex group whose participation in fishing is driven by a number of different motivations, many of which are not directly related to the recreational resource of catching a fish. However, it is also clear that participants' satisfaction is largely conditioned by the fact that there are fish to catch. Through a better understanding of participants' expectations and behaviour, we can better advise on how recreational resources such as angling can be managed with respect to biological, economic and social sustainability.