Participating organizations (WP leader in bold): P1. HCMR, P3. IRTA, P4. IOLR, P18. CTAQUA, P25. DOR, P26. GEI and P21. IRIDA
Task 23.1. Determine the cost-benefit of different weaning diets on the performance and health status of wild juveniles (led by IRTA). Weaning strategy (e.g., type of diet and length of the co-feeding period with live prey and inert feeds during the weaning period) in grey mullet early juveniles (fry) will be tested using three available commercial diets under standard rearing conditions. The period of time implemented will allow the proper adaptation of wild animals to experimental conditions and provides enough certainty that the observed results are due to the experimental design implemented. In addition, the timespan selected will allow fish to reach a significant size for tissue sampling. For achieving this goal and due to the unavailability of aquaculture produced grey mullet early juveniles, wild fry will be collected during their natural recruitment into coastal lagoons. Weaning strategies and tested diets will be analysed in terms of fish growth, survival, quality, maturation of digestive system and fish health status. The organization and functionality of the digestive system in different dietary groups will be conducted by standard histological procedures and biochemical spectrophotometric procedures for measuring the activity of pancreatic, gastric and intestinal enzymes. In addition, the economical cost/profitability of each weaning strategy will be evaluated with regards to the direct costs associated to fish rearing practices (feed and facilities) and their performance for the subsequent stages of fish rearing.
Task 23.2 Compare the effect of feeding an improved grey mullet diet on the grow-out in monoculture of F1 juveniles stocked at two different densities in cement and earthen ponds (led by IOLR). Hatchery produced F1 juvenile grey mullet will be supplied to a parner SME. These fish will be stocked at two different densities in earthen ponds and fed an improved grey mullet extruded feed. This feed will be custom-produced for all grey mullet tasks in this WP. In parallel, a 1 year density study using the project’s grey mullet feed will be carried out on F1 juveniles in circular cement ponds, where each density will be tested in duplicate tanks. Fish performance will be evaluated in terms of FCR, PER, SGR, overall weight gain and survival. In addition, analyses of lipid class and fatty acid composition of selected tissues will be carried out.
Task 23.3 Compare the effect of feeding an improved grey mullet diet on the grow-out in monoculture of wild caught juveniles stocked at two different densities in cement ponds in Greece (led by HCMR). Wild caught grey mullet juveniles will be stocked at two different densities in cement ponds where each density will be tested in triplicate tanks over 1 year. The fish will be fed an improved grey mullet extruded feed as described in Task 23.1. Fish performance will be evaluated in terms of FCR, PER, SGR, overall weight gain and survival. In addition, analyses will be carried out of lipid class and fatty acid composition of selected tissues as well as proximate analyses of the fish and diet samples.
Task 23.4 Compare the effect of feeding an improved grey mullet diet on the grow-out in monoculture of wild juveniles at two different densities in ponds in Spain (led by CTAQUA). Wild caught grey mullet juveniles will be stocked at two different densities in earthen ponds. The fish will be fed an improved grey mullet extruded feed as described in Task 23.1. Fish performance will be evaluated in terms of FCR, PER, SGR, overall weight gain and survival. In addition, analyses of lipid class and fatty acid composition of selected tissues (liver, muscle and gonads) as well as proximate analyses of feeds and fish samples will be carried out.
Task 23.1. Determine the cost-benefit of different weaning diets on the performance and health status of wild juveniles (led by IRTA). Weaning strategy (e.g., type of diet and length of the co-feeding period with live prey and inert feeds during the weaning period) in grey mullet early juveniles (fry) will be tested using three available commercial diets under standard rearing conditions. The period of time implemented will allow the proper adaptation of wild animals to experimental conditions and provides enough certainty that the observed results are due to the experimental design implemented. In addition, the timespan selected will allow fish to reach a significant size for tissue sampling. For achieving this goal and due to the unavailability of aquaculture produced grey mullet early juveniles, wild fry will be collected during their natural recruitment into coastal lagoons. Weaning strategies and tested diets will be analysed in terms of fish growth, survival, quality, maturation of digestive system and fish health status. The organization and functionality of the digestive system in different dietary groups will be conducted by standard histological procedures and biochemical spectrophotometric procedures for measuring the activity of pancreatic, gastric and intestinal enzymes. In addition, the economical cost/profitability of each weaning strategy will be evaluated with regards to the direct costs associated to fish rearing practices (feed and facilities) and their performance for the subsequent stages of fish rearing.
Task 23.2 Compare the effect of feeding an improved grey mullet diet on the grow-out in monoculture of F1 juveniles stocked at two different densities in cement and earthen ponds (led by IOLR). Hatchery produced F1 juvenile grey mullet will be supplied to a parner SME. These fish will be stocked at two different densities in earthen ponds and fed an improved grey mullet extruded feed. This feed will be custom-produced for all grey mullet tasks in this WP. In parallel, a 1 year density study using the project’s grey mullet feed will be carried out on F1 juveniles in circular cement ponds, where each density will be tested in duplicate tanks. Fish performance will be evaluated in terms of FCR, PER, SGR, overall weight gain and survival. In addition, analyses of lipid class and fatty acid composition of selected tissues will be carried out.
Task 23.3 Compare the effect of feeding an improved grey mullet diet on the grow-out in monoculture of wild caught juveniles stocked at two different densities in cement ponds in Greece (led by HCMR). Wild caught grey mullet juveniles will be stocked at two different densities in cement ponds where each density will be tested in triplicate tanks over 1 year. The fish will be fed an improved grey mullet extruded feed as described in Task 23.1. Fish performance will be evaluated in terms of FCR, PER, SGR, overall weight gain and survival. In addition, analyses will be carried out of lipid class and fatty acid composition of selected tissues as well as proximate analyses of the fish and diet samples.
Task 23.4 Compare the effect of feeding an improved grey mullet diet on the grow-out in monoculture of wild juveniles at two different densities in ponds in Spain (led by CTAQUA). Wild caught grey mullet juveniles will be stocked at two different densities in earthen ponds. The fish will be fed an improved grey mullet extruded feed as described in Task 23.1. Fish performance will be evaluated in terms of FCR, PER, SGR, overall weight gain and survival. In addition, analyses of lipid class and fatty acid composition of selected tissues (liver, muscle and gonads) as well as proximate analyses of feeds and fish samples will be carried out.