Research and innovation
Currently research is dealing with:
- Development and optimization of high quality larval fish food
- Triploidisation
- Development of breeding methods for rare or endangered fish species
- Disinfection of fish eggs
- Development of new tank and rearing systems for fish larvae s
- Testing of different fish species concerning their usability in commercial aquaculture
Development and optimization of high quality larval fish food
Breeding of fish larvae requires special fish food; grain size and nutrient composition are dependent on the physiology of different fish species. Larvae of many fish species need living food, mostly zooplankton. It is very labour-intensive and cost-intensive to breed or catch living food. Therefore, we conduct research on the development of alternative fish food.
Dry food with special emphasis on the feeding of larvae of Thymallidae, Coregonidae and Salmonidae was developed. Additionally, breeding conditions have been adjusted for intensive aquaculture.
The development of larval food is based on biochemical analyses of digestive enzymes, digestibility of food components, and the biochemical composition of living food. Moreover, the influence of food components on water quality is analysed regularly.
Another aspect of food development is the sustainability of food components. The suitability of insect-meal as a new sustainable protein source is tested at Kreuzstein. We mix the meal of soldier fly and mealworm into our special food for testing growth and health of larvae of different fish species.
Triploidisation
Triploid organisms have a triple chromosome set and according to current scientific knowledge they don´t develop sexual organs; they are sterile. This is an advantage in aquaculture because —not putting energy into growing sexual organs— sterile fish grow continuously. If a triploid fish escapes, hybridization with native fish is not possible.
Triploidisation of different salmonid fish, as the Lake trout for example, could be of interest in aquaculture for production of large fish. Those fish filets might be an Austrian alternative to Atlantic Salmon. To establish triploidization as a routine method two factors have to be full filled: The method has to be effective and reliable and it has to be established that triploidisation does not affect animal health and product quality. Methods for triploidization of native Salmonids have been developed in 2017. Different tests on stress- and physical performance on triploid Lake trout and Brook trout in comparison with diploid trout were carried out in 2018. Differences in physiology and metabolism have been detected but they did not have a negative impact on the triploid fish. Differentiation and development of gonads and growth performance of triploids are documented, too. In the course of these investigations we found that gonad development is age and sex specific. Males develop testes and a small percentage of fish can produce semen with an age of 3 years. Contrary “females” develop only small hermaphroditic gonads. Currently triploid fish are investigated on growth parameters, filet size and possible skeletal deformations.
Development of breeding methods of rare or endangered fish species
We preserve endangered native fish populations and species by developing suitable breeding programs and restocking strategies.
We are currently working on breeding programs for the European minnow. Genetic conform broodstocks have been established for different Austrian minnow populations. Spawning of minnow in aquaculture comprises difficulties; they are not stress resistant and need specific environmental cues for stimulation of spawning. At the fishfarm Kreuzstein the brood fish are kept in circular tanks with spawning substrate on the bottom. Spawning activity is regulated by temperature and photoperiod. Spawned eggs are collected through the tank´s drain. Using this technique, about 200.000 eggs for re-stocking in Austrian are produced per year.
The European sturgeon (Huso huso) and the Fringebarbel sturgeon (Acipenser nudiventris) are nearly extinct species. For these species, we have also breeding programs at the fish farm Kreuzstein. Escpecially rearing of European sturgeon is challenging due to its cannibalistic behavior during specific larval phases. In accordance with the Pan-European Action Plan for Sturgeons establishment of sterlet broodstocks and fingerling production, will be done in the following years.
Disinfectants for fish eggs
In aquaculture fish eggs are incubated in high densities, therefore it is necessary to control and reduce the number of pathogenic germs on the egg`s surface and inside the egg.
Disinfection non-hardened eggs: For the reduction of pathogenic germs inside the eggs, we apply special methods using iodine products. The disinfection of the egg internal is only possible if the egg has not yet been in contact with water and it is still permeable. We take special emphasis on the effective concentration, and disinfection time to decrease the pathogenic load inside the eggs. This method plays an important role to avoid the transfer of pathogenic germs from broodstock fish to eggs.
Development of new methods of keeping fish larvae and fingerlings
Fish larvae are tiny and vulnerable vertebrates. Larvae from many species don´t tolerate manipulation procedures, necessary in fish culture (for example tank cleaning) and water currents during their first live stages. We are currently researching the development of new keeping and feeding methods for perch, pike perch and other sensitive fish larvae. We test systems without water current and turbulences, and fish food with minimal negative effect on water quality.
Fish species which are not yet produced in aquaculture are tested on their suitability for fish culture. This research focusses on sustainable production, growth, product quality and resistance to stress and diseases. In cooperation with Hofer AG we conducted a research project on the commercial production of burbot as a new fish for aquaculture. This fish species has excellent flesh quality and almost no fish bones. However, production of burbot is difficult. Newly hatched larvae of burbot are very small, their length is about 3 mm. During their first life stages they have to be feed with living food, as for example copepods. The larvae raised and conditioned to living food must be adapted to commercially produced dry feed, suitable for edible fish. The transitional phase between living and industrial food is very critical, as the fish refuse dry feed and starve. We found that dry food is only accepted when special chemo attractants as salt (NaCl) are added to the food, for a period of circa two weeks. Compared to salmonid species the growth is slow. This problem has to be overcome when the fish should be introduced in aquaculture.