The primary purpose of the laboratory, says Giedrius Macernis, the acting director, is to gather fisheries data from the Lithuanian exclusive economic zone in the Baltic Sea, as well from the high seas where Lithuanian vessels are active – the north Atlantic, the south Pacific, and off the coast of Africa. The data are analysed at the laboratory and the results sent to the European Commission, where they provide the basis for calculating fishing quotas. The data collected include biological information such as sex, maturity, length, weight, and age, which is calculated from the otoliths. These are small stones in the head of the fish that record how old the fish is in a series of lines, similar to those seen in tree stumps. Each line represents a year. Otoliths play a role in the fish’s sense of balance. In the Baltic these data are collected mainly for the four species that are of commercial interest to Lithuania, Baltic cod, herring, sprat, and flounder. The information is used in three programmes, the national data collection, national environmental programme, and a programme to research the status of fish stocks in Lithuanian waters.
Aquaculture research to benefit farmers, restocking programmes
The research being carried out at the laboratory includes the study of recirculation aquaculture systems. There are three such systems in operation, one of which simulates conditions in a hatchery. Fertilised eggs can be collected and placed in incubators and once the larvae reach a minimum size they are moved to bigger basins. The systems can be used with freshwater, saltwater, or brackish water. As on a commercial fish farm, the larvae are fed with artemia or brine shrimp, small pelagic organisms that are often used as the first feed for fish larvae. The artemia are obtained as eggs which are introduced into in an incubator, a glass tube, the base of which is angled at 45 degrees. Artemia prefer water that is highly oxygenated, so oxygen is pumped in and the angled base allows the water to circulate better in the tube. The eggs hatch and the nauplii go through several stages before achieving maturity, when they can be collected and fed to the fish larvae. The aquaculture section also contains vertical incubators for salmonid eggs. These include Arctic char, rainbow trout, and Baltic salmon. Over the last year however, the laboratory has produced the first generations of pike-perch, perch, barbel, asp, and roach. These fish are being bred for experimental purposes. For example, together with researchers from Klaipeda university, the scientists at the laboratory are planning to test certain probiotics. Another fish that is also considered interesting is sturgeon and the researchers are planning to start breeding this fish too.
The broodstock for these experiments are caught in the wild and the eggs and sperm obtained from the females and males respectively. These are then mixed together and the fertilised eggs placed in the incubators while the parents are released back into the wild. The purpose of these activities is to improve fish breeding techniques, which will benefit the work done at the Fisheries Service’s seven restocking centres. At these centres fish are bred for release into the wild to maintain stock populations for the benefit of the environment, commercial fishers, and anglers. At the laboratory on the other hand scientists carry out experiments that are intended to reveal why, for example, fish are either born with or develop certain kinds of defects. Fish that exhibit these problems in the wild usually do not survive for very long. In the laboratory, however, they can be kept alive, observed, and analysed to try and find the cause of these problems.
Creating a pool of broodstock
In a brackish water system fed with water from the Baltic Sea coast perch, pike-perch, barbel, roach, and even a single carp are being grown. Many freshwater species thrive in brackish water as long as there is enough feed. The Nemunas river brings several varieties of fish into the Curonian lagoon, where it discharges. An invasive species, the round goby (Neogobius melanostomus), is also found in these waters, and is a popular feed for pike-perch. Other tanks host fish that have developed from eggs that have been collected from the wild. These fish will be grown until they mature and will then provide the eggs and the sperm for the next generation. The advantage is that broodstock will not have to be captured from the wild and that because the fish have spent a lifetime in captivity they are already partly domesticated and therefore easier to handle. On the other hand, since they have been raised in captivity these fish would have a very low survival rate if they were to be released into the wild as they would not be able to hunt for food or avoid predators. To avoid these problems when restocking fish are released after two or three weeks.
Sophisticated equipment for the study of nature
In the basement several water cleaning systems are maintained. The purpose of these is not just to filter and clean the water, but also provide a basis for experiments that should ultimately result in better and more efficient cleaning technology. The results of these trials conducted at the laboratory are passed on to the aquaculture industry for them to improve their systems. The cleaning systems include typical filtration systems of the type found in recirculation aquaculture plants, and include biological filters, mechanical filters, degassing systems to remove carbon dioxide from the water, protein skimmers, UV filters etc. At the laboratory a significant space is dedicated to mesocosms, which are a series of large tanks that simulate a natural aquatic environment such as in lakes, the Curonian lagoon, or in the Baltic Sea. Within the tanks certain parameters (temperature, salinity, pH, gas content, etc.) can be adjusted to study the impact of these changes on the environment that is being modelled. The tanks are constructed in such a way that it is possible to have the upper layer of water at one temperature, the lower layer at another (lower) temperature and a thermocline (where the temperature changes more rapidly than in the upper or lower layers) in the middle. The mesocosms can simulate physical conditions but replicating a biological environment is more difficult. Because the water in the tanks is not recirculated only the most basic living creatures can survive, bacteria, some phytoplankton, some zooplankton, and fish larvae, and only for 2-3 months. In theory this could be prolonged by adding oxygen to the water, but that would then set other processes in motion and the mesocosm would no longer accurately simulate the environment it was supposed to. Other equipment in the laboratory are tanks where water flows can be simulated which can contribute to studies on sedimentation patterns, habitat restoration, and to research on fish behaviour, for example, in rivers.
A symbol of international scientific cooperation in the Baltic
The laboratory has an agreement with Klaipeda University so that researchers from there also have access to the facilities available. There are also international project proposals that seek to make use of the facilities to carry out experiments. The laboratory is currently among the best equipped and is certainly one of the newest in the Baltic Sea region and the laboratory administration as well as the Fisheries Service plan to encourage international collaboration that will make the laboratory a lively centre for international fisheries and aquaculture research in the region.
Director: Giedrius Macernis