Experimental production of natural zooplankton and the quality of stored eggs
Plankton is the most important food for our juveniles' main fish stocks and redfish is the most common species of plankton in Iceland, but Acartia species can also be found in plankton almost all year round. The aim of the project was to cultivate selected species of natural zooplankton that are common in Iceland (redfish and Acartia) and produce hibernation eggs to ensure its supply all year round. In connection with the project, facilities have been set up for the cultivation of zooplankton and live algae that were used as feed for the plankton. Wild zooplankton has been collected using various methods and breeding experiments performed under different environmental conditions. Experiments have also been performed with the hatching eggs of Acartia tonsa in two separate experiments. The main results indicate that the animals are very sensitive to any kind of treatment as well as temperature changes during collection. There were large losses in the first days after collection and it proved difficult to keep the animals alive for more than a few weeks. Nutrition has a far-reaching effect on animal reproduction, performance and productivity, and the results indicate that the algae concentrate used was not suitable for the cultivation of zooplankton, but much better results were obtained with the use of live algae. The hatching of the laying eggs went well and they managed to get the animals to produce eggs. Subsequently, it is planned to investigate the effects of various factors such as the nutritional content of food, food supply and density on the development, sex ratio and egg production of the animals.
Zooplankton is the food source of our fish stocks, with Calanus finmarchicus being the most abundant species in the marine ecosystem around Iceland in addition to Acartia that may be found in the zooplankton throughout the year. The overall goal of this project was to culture natural zooplankton species (Calanus finmarchicus and Acartia) for production of eggs that is the basis for commercial production of copepods. Facilities for culturing zooplanktonic species and live algae have been set up as part of the project. Natural zooplankton has been collected using various approach and attempts have been made to culture copepods under various conditions. Eggs of Acartia tonsa have furthermore been hatched and cultured in two separate experiments. The main results indicate that zooplankton species are extremely sensitive to handling and temperature changes during collection and transport. Significant losses were observed during the first days following collection and the copepod cultures only survived through a few weeks. Previous studies show that nutrition profoundly affects reproduction, survival and productivity of zooplankton species. The present results indicate that the algae paste used did not fulfill the nutritional requirements of the copepods but improved results were achieved using live algae cultures. Hatching of dormant eggs proved successful and eggs have been collected from the experimental units. Further experiments are planned with the aim to study the effects of nutrition, food supply and copepod densities on the development, sex ratio and productivity of the cultures.