PRINCIPLES OF AQUACULTURE (AKU3201) 20May 2012 Biosecurity & predator control

Unwanted predators Bird Wild fish Frogs Reptiles (snakes, turtle, alligators)

Birds

Crabs - marine

Aquatic weed Filamentous algae/scum Floating weed Emergent weed Submerged weed Marginal weed

Water lily

Hydrilla

Duckweed

Prevention of aquatic weeds Avoid shallow pond. Why? Use grass carp Proper fertilization to establish phytoplankton bloom Manual harvesting Herbicides

Factors causing disease 1) Stress e. g Factors causing disease 1) Stress e.g., physical injury 2) Pathogen 3) Environment e.g., pollution 4) Sometimes nutrition Disease Disease agent Env. Fish