Improvement of fish and pearl yields and nutrient utilization efficiency through fish–mussel integration and feed supplementation

Abstract

article A 153-day experiment wasconducted inland-based enclosuresto exploretheefficacy of fish-musselintegration in pearl yield, fish yield and nutrient utilization. The freshwater mussel Hyriopsis cumingii were integrated with either a four-fish species combination (grass carp, gibel carp, silver carp and bighead carp) or a two-fish species combination (silver carp and bighead carp). Fish in each combination received either formulated feed supple- mentation or no formulated feed. Fish yield, nitrogen utilization efficiency and wastes of nitrogen and phospho- rus were higher in the enclosures received formulated feed supplementation than in those received no formulated feed. Production performance (evaluated with pearl weight and soft tissue weight of each mussel, pearl and fish yields, nitrogen utilization efficiency and nitrogen wastes) was better in the enclosures of mussel integrated with four fish species and fed with formulated feed than in those of mussel integrated with two fish species without feeding formulated feed. The total nitrogen, total phosphorus, chemicaloxygendemand and cal- cium in the water column were higher, while the Secchi depth and dissolved oxygen were lower, in the enclo- sures stocked with four fish species and fed formulated feed than in those stocked with two fish species and without feeding formulated feed. This study indicates that formulated feed supplementation to a fish-mussel in- tegratedsystemcanenhance fish andpearl yieldsandnitrogen utilizationefficiency.Thecombination of four fish species with complementary feeding habits is more productive than that of two fish species in a fish-mussel in- tegrated system. Statement of relevance: We declare that: