Objectives Identify propagation methods of fish. Describe how to care for fry. Identify strategies for marketing fish. Identify factors that affect selling fish.
How are fish propagated? Propagation –Process of man controlling fish reproduction. Fish reproduce by spawning. –Female lays her eggs and then the male deposits sperm over the eggs. Method of propagating fish varies by species.
Catfish propagating Often allowed to naturally spawn –Without the intervention of man. –Female seeks hollow log or other structure to lay eggs. can use farm spawning –Occurs when male and female catfish are moved to a spawning container. Artificial nest –Fertilized eggs can be left in pond or moved to hatchery. –Eggs will hatch in 6 to 10 days. www.esd.ornl.gov/programs/ bioindicators
Tilapia propagating Usually spawned in ponds, tanks or aquaria. Spawning controlled by photoperiod. –Number of hours of sunlight during a day. Spawn when days reach 10 to 16 hours. Light can be controlled by artificial lights. www.avapub.com/testimonials.htm
Tilapia propagating Mouthbrooders –Lay eggs in nest. –Allow eggs to be fertilized. –Female will incubate eggs in mouth until hatch. Substrate spawning –Lay eggs in their nests on bottom of pond. –Eggs are fertilized. –Eggs remain on the bottom to hatch.
Trout propagating Can spawn naturally. Trout eggs take 80 days to hatch. Often propagated by artificial spawning. –Eggs are removed from female. –Milt (sperm) is removed from male. –Humans mix the eggs and milt together. –Fertilized eggs placed in incubators. –Eggs are monitored and controlled. www.whitefishchamber.org/ fishing.html
How should fry be cared for? Fry –Immature fish –Must be protected by predators. –Dietary requirements are different than adult fish.
How should fry be cared for? Fingerlings –Young fish slightly larger than human fingers. –Ready to be stocked in ponds. www.jas.com/rik/falke/foto.html
Catfish fry Born with an egg sac that gives nutrition for a few days. After egg sac is gone fed 49% protein feed that is finely ground. Protein percentage is reduced as fry matures. Fry kept in troughs or other protected areas for 1 year. Then are fingerlings.
Tilapia fry Cared for in similar way as catfish. Started on feed that is as high as 60% protein. Feed is usually ground into a fine meal or pellets that disintegrate in water.
Trout fry Cared for similar to catfish and tilapia. Very small. After hatching moved to troughs. Fed a nutritious feed. Continuously graded to keep fry of similar size together. Done to prevent larger fry from eating the smaller ones.
What are some strategies for marketing fish? Sell broodfish to hatcheries –Fish used for breeding. Fish hatcheries –Produce eggs, fry and/or fingerlings sell these to other producers. Obtain eggs or fry from hatcheries. –Raise them to fingerlings size. –Sell them to producers to stock ponds.
What are some strategies for marketing fish? Raise the fingerlings to harvest size. –Sell the fish to processors, fee lake operators, or live haulers. Live haulers –Buy fish from growers and then resell to fish markets or fee lakes.
What are some strategies for marketing fish? Fee lake operators –Obtain fish from growers. –Stock ponds. –Charge people to fish in their ponds. www.dgif.state.va.us/fishing/lakes/ occoquan_reservoir/gallery.html
What factors affect selling fish? Size of the fish –Should be marketed at optimum size. –Varies with species and stage they are marketed. –Need uniform lots. –Separate fish by size. –Numerous mechanical devices can be used to sort fish.
What factors affect selling fish? Grading Fish –Remove fish that are diseased or injured. –Graded on color. –Uniform looking lot of fish is desirable. www.al-kabeer.com/freshfish.htm
Review / Summary How are fish propagated? How should fry be cared for? What are some strategies for marketing fish? What factors affect selling fish?
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