Shared Flashcard Set


Animal Science
Undergraduate 1

Additional Agriculture Flashcards





Name examples of each of these:


Diadromous Fish
Demersal Fish
Pelagic Fish

Diadromous Fish – fish that migrate between fresh and salt water; sturgeon, eel, trout, salmon
Demersal Fish – fish that live on or near the sea bottom; flounder, cod, shark
Pelagic Fish – fish that live in the middle or surface of the sea; herring, tuna, mackerel
Crustaceans – crabs, lobster, krill, shrimp
Molluscs – bilaterally symmetrical invertebrates, calcium shell, muscular foot and gills; abalone, oyster, mussels, scallops, clams
Cephalopods – within mollusca, well developed head with prehensile tentacles; squid, octopus, cuttlefish

Trends: Aquaculture production is increasing by _%, 'catch' increasing _% per year


US ____ metric tons grown


In extensive systems ___ to ___ kg per hectare

intensive ____ to _____ (very intensive)


Trends - world aquaculture production is increasing by 8% per year; world 'catch' is increasing 1% per year
In US - 340,000 metric tons grown last year; most widely raised fish is Channel Catfish in Southeast (Mississippi, Arkansas, Alabama,Louisiana). In US there are 1,320 catfish farms with 177,360 acres of ponds. Live catfish production 447 million pounds
c) Rough production data:
In extensive systems of aquaculture (low input systems) one typically produces 300 to 500 kg of fish per hectare of pond surface per year (1 acre = .4047 hectares); with more intensive production this can be raised into 1000 kg /hectare/yr and way up into 10,000 kg per hectare for very intensive production; in tank aquaculture with oxygen added to tanks, ultra filtration of water one could attempt to produce 2,000,000 kg per hectare per year but such production is not sustainable in large systems.
Differences between Terrestrial Animals? (4)
Differences from Terrestrial Animals:
1) body density of fish = density of water; they do not expend energy 'standing'; oysters don't even move, they are sessile
2) fish are poikilotherms (cold-blooded) - they do not have to expend energy to keep their body warm; in this way fish can hit feed:gain ratios of 1.5:1 (when correcting fish meat for water content feed:gain ratios are more like 3:1 and 4:1)
3) fish can be reared in a 3-dimensional environment, permitting more biomass for a given 2-dimensional acreage
4) fish can be reared in polyculture (not common among terrestrial animals), that is, more than one species in a tank or pond (top, middle and bottom feeders); including integration with terrestrial animals as consumers of manure
Disadvantages of Fish Production? (4)
Disadvantages of Fish Production:
1) water is heavy, hard to manage and move
2) difficult to tell when fish are ill
3) fish food is usually expensive and human competitive
4) water quality is critical, must be kept clean and uncontaminated by human and fish pollutants

 Catfish Farming


Critical Elements of Catfish Culture (3 important)


Farm Site Selection?

Pond Design?

Raising Catfish?



1) Farm Site Selection: Properties of available water: slow growth in temps of 60 to 70 F; optimal growth in temps of 70 to 80 F; above 85 F feeding declines and less dissolved oxygen; below 60 F no growth but will live down to 32 F. Optimal ph = 6.3 to 7.5. Concern for pesticide contamination from soil runoff ruling out highly farmed areas.
2) Pond Design: No true optimum but most ponds are .4 to .5 ha (hectares) {hectare = 10000 sq m = 2.47 acres); range from .4 to 40 ha; depths range from .9 to 1.8 m in South US & 1.8 to 3.0 m in North to avoid winter kill.
3) Raising Catfish: most 'farmers' purchase fingerlings (13 to 15 cm) and grow to a typical market weight of 1 lb in 1.5 to 2 yrs (small market for 4 lb catfish). Stocking rates vary from 2200 to 6600 fingerlings per ha depending on food and oxygen.

Feeding Catfish



Feeding level?



1) Diet - catfish rely on supplementary feeding rather than living off available food of the pond; typical diet has min 32% protein (with at least half being animal protein), fat between 4 and 8%, fiber between 8 and 20%, min of 8% fish meal.
2) Feeding Level - at water temp of 16 to 21 C feed at 2% of total pond weight; at water temp of 21 to 32C feed at 3% of total pond weight; over 32 C feed at 1.5% of total pond weight or less.


Broodstock and Spawning





Sexing - catfish, like livestock, are usually reared in same sex groups; males have darker color, shorter wider head than females; genital opening in females is slitlike and is tubular in males; as spawning time approaches males get darker under the jaw and body, genital papillae protrude; the vent of the female loosens, swells and may pulsate.
2) Spawning (usually 3 yrs & older at 1 to 4 lbs) - for fish in a natural setting (normal, not-farmed fish) this is the term for deposition of eggs by the female and the insemination of eggs by the male, that is - mating. In nature, catfish spawn from April to July, males and females pair, male builds a 'nest', female deposits alyers of eggs for male to fertilize externally (process lasts from 4 to 12 hours), male drives away female and guards nest. In ponds, most commercial farmers let nature do the job. Put equal number of males and females together (50 to 300 per ha), provide nesting containers (old milk cans), harvest fry.
3) Fry - eggs hatch 5 to 10 days after fertilization, move to nursery pond for 2 to 3 wks fed finely groud diet, transfer to growing pond fed at 4 to 5% of total pond weight; market fingerlings 180 days later at 13 cm length and 14 g wt. Stocking approx 66000 fry per ha.

Home of the US Oyster farming industry is?

Most commonly oyster cultured in the west? East?


Home of the US Oyster farming industry is the Pacific northwest - Washington, Oregon, Alaska and parts of California
1) Species - Crassostrea Gigas (Japanese Oyster) is that species most commonly cultured in the west (stronger tasting than eastern US species; East US Crassostrea Virginica - typical oyster served on a half shell (sweet tasting and worth more $$)
Early Oyster Life Stages (5)
1 - fertilized egg - zygote
2 - larva
3 - veliger larva
4 - pediveliger larva - has developed eye spot; a 'foot' (pedi); veliger refers to the hair-like structures used to fan food (algae) into the mouth of the larva
5 - spat -metamorphosed larva into the sessile organism which becomes the adult oyster; it is at the spat stage that the oyster attaches to a piece of shell (cultch) or bay floor to begin growing

Sex Life of an Oyster

1st year?

Subsequent years?

Stored energy source is?


- mobile; oysters can change sex any number of times during their life (they are hermaphrodites - but unlike worms cannot fertilize themselves); sex is not set, for the first time, until about 1 yr of age; among Crassostrea they can only change sex once each year
1) first year of life - most oysters are males; since the investment in energy to make sperm is minimal compared to energy investment in making eggs
2) second and subsequent years - oysters will become females when environmental conditions are favorable for the investment of energy in eggs (remember oyster food is algae) Basic formula = if its a stressful environment, stay male; a good environment become a female
3) stored energy source for oysters is glycogen (a carbohydrate), unlike other animals which store energy as fat; a good store of glycogen is essential for adequate egg production
4) Spawning - collect 'fat' (well fed) oysters; maintain in fresh sea water at 18-20 C for 4-6 weeks; to bring on spawning, raise water temperature to 20 C then raise .5 hrs later to 25 C and then, if necessary, to 30 C and fluctuate temp back and forth at 25 and 30 C until the oysters spawn gametes (eggs); can also spawn by shucking oysters (opening them) and distributing gametes by hand

Growth of Oysters (5 stages) from 1 to 21 days

Ideal growing temperature?


Growth of Oysters
1) fertilized eggs - no feed necessary
2) 1-6 days - veliger larvae feeding at low level (30,000 algal cells/ml water)
3) 7-14 days continue feeding veliger larvae, increasing feed concentration to 50,000 cells/ml fed twice a day
4) 14-21 days - pediveliger larvae (eye stage) with increasing feed to 80,000 cells/ml
5) 21 days - spat; ready for setting on cultch and setting on bay bottom, racks, stick & bag, tray culture (that is, for grow out to adult form that's ready to eat) (remember, some methods have oysters raised cultchless, that is without a piece of shell or gravel to attach on and grow out)
6) ideal growing temperatures - 20 C with 25 to 35 parts per thousand salt; time to market: Alaska - 4-6 yrs; Wash. - 3 yrs; Ore. - 3 yrs; CA - 1.5 yrs
Definition - Xenomorphism - an individual where the body shape conforms to the shape of the environment (oysters are xenomorphic) (the nicer shaped oysters bring more $$)
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