Catadromous and marine fishes

Abstract

Abstract Catadromous fishes reproduce in the ocean and migrate as larvae or juveniles to coastal brackish and inland freshwater habitats before returning to the ocean as adults. Catadromous migration varies between and within marine fishes. Catadromy is pronounced in river eels, milkfish, and mullets, while other fishes are amphidromous (i.e. their migrations are opportunistically driven by trophic conditions). Aquaculture of amphidromous species includes carnivores in the order Perciformes and flatfishes (Pleuronectiformes). Two species of catadromous river eels dominate eel aquaculture: the European eel (Anguilla anguilla) and the Japanese eel (A. japonica). A. anguilla reproduces in the Sargasso Sea of the Atlantic Ocean, while A. japonica spawns at the Suruga Seamount in the Pacific Ocean. Larval development takes many months during migration toward the coasts of Western Europe and Eastern Asia, respectively. Captive eel reproduction has been advanced, but its commercial adoption is not yet feasible. Thus, river eel aquaculture depends on capture of glass eels or elvers. Semi-intensive approaches and recirculating aquaculture systems (RAS) and are used for eel aquaculture. Catadromous milkfish (Chanos chanos) is primarily a herbivore occasionally feeding on zooplankton. Advantages of milkfish for aquaculture include high stress tolerance, disease resistance, and rapid growth. Milkfish aquaculture has a long history in Southeast Asia. Specialized hatcheries produce milkfish fry for aquaculture, which relieves pressure on natural populations but requires careful genetic management. Milkfish grow-out is performed in semi-intensive ponds or cages. Despite the generally smaller ecological footprint of milkfish aquaculture, consumer preference for milkfish is lower than for carnivores.