DISEASE PEST MANAGEMENT objectives Explain aquaculture diseases and

DISEASE & PEST MANAGEMENT [objectives] • Explain aquaculture diseases and pests and how they cause problems • Discuss how fish show signs of disease • Explain diseases and how they are managed • Explain parasites and how they are managed • Explain predators and how they are managed • Describe trash fish and the problems they cause • Explain what to do if fish appear unhealthy • Discuss regulations in disease and pest control

AQUACULTURE DISEASES AND PESTS – chapter 6 • A disease is a condition that develops in an organism and then damages it in some way. • A pest is a plant, animal, or other organism that is detrimental to a species. • Aquacrops need a healthy environment; one that is free from diseases and pests. • Diseases and pests cause losses.

EXAMPLES

KINDS OF LOSSES • Direct losses occur when aquacrop is attacked or injured. • Water birds and predators (eat crop) • Diseases (reduce growth or death) • Parasites (reduce growth, produce stress) • Poaching (theft by humans)

KINDS OF LOSSES • Indirect losses result in less than ideal environments. • Weeds (make harvesting difficult) • Trash fish (compete for food and oxygen) • Rodents or other burrowing animals (may cause water leaks)

SIGNS OF DISEASE IN FISH (SYMPTOMS) • Not eating (going off the feed) • Skin abnormalities (ulcers, lesions, abscesses) • Lack of vigor (sluggish, drooping fins) • Abnormal body shape (growths, swollen belly, bulging eyes) • Behavioral change (rubbing, gulping) • Dead fish

KINDS OF DISEASES • Infectious diseases – may be transferred from one individual to another (examples – bacterial infections, fungal and viral diseases, parasite infestations) • Noninfectious diseases – not transferred from one individual to another (examples – nutritional, environmental, chemical and physiological disease)

INFECTIOUS DISEASES Fungal Bacterial Viral Parasitic fish lice

NONINFECTIOUS DISEASES • Nutritional diseases – inadequate diet • Environmental diseases – water gases, improper temperatures and water quality • Chemical diseases – contaminants such as pesticides or heavy metals • Physiological diseases – organ malfunctions from sudden changes

DISEASE CONTROL • Prevention – the practice of keeping aquacrops healthy and disease free • Sanitation – practice of keeping water and facilities clean • Quarantine – isolation of aquacrops not known to be disease free from those that are

DISEASE TREATMENT • Dipping – immersing fish in concentrated medication • Feeding – using medicated feed • Bathing – similar to dipping but less concentrated for longer period of time • Injecting – only for fish large enough to hold • Indefinite treatment – low dose of medication added to tank or pond

PARASITES AND THEIR CONTROL • Ectoparasites (external) – found on skin, gills, or fins • Endoparasites (internal) – live in organs, flesh, or digestive tract • Examples – tapeworms, flukes, leeches, roundworms, protozoans, crustaceans.

PARASITE CONTROL • Quarantine - isolation • Treatment of facilities – dry ponds and sterilize • Dipping – salt solution, formalin • Bird elimination – birds often transfer parasites • Indefinite treatment

PREDATORS AND THEIR CONTROL • Birds – cormorants, kingfishers, herons, grebes, and mergansers • Fish – some prey on other fish, some prey on eggs • Snakes – do not eat large amount of fish • Insects – can destroy eggs or fry • Turtles and alligators – usually only eat trash fish (gars, carp) • Bullfrogs – eat fingerlings (crawfish, too!)

BIRDS

FISH, SNAKES, INSECTS, BULLFROGS