Catfish

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Whiskers are called Barbels

Catfish culture

1.     global catfish production = 980,000mt just over 3% of the annual global fihs production of 28,200,000mt

2.     US – channel catfish lctalurus punctatus; > 300,000mt =31% of the global catfish production

3.     An important US aquaculture industry = 47% of all the US fish aquaculture production (2004 farm gate sales estimated to be ~440 million dollars)

A walking catfish (clarius batrachus) – does it have legs?

1.     Invasive potential very high

2.     Native to Asia

The U.S. Catfish Industry

Mississippi top producer 75% followed by Arkansas

US catfish production is centered in the Mississippi Delta

Catfish life cycle

Fertiziled Egg > Larva (absorb yolk) > Fingerling > stock size (harvest in 1-2 years)

Catfish reproduction

1.     spawn once a year in the spring

2.     For reliable spawning, broodifhs should be >3lbs. in size and > 3 years of age

3.     Channel catfish weighing between 4-8 lbs are prime spawners

4.     Females produce 3000-4000 eggs/per lb of weight and continue producting for about 12 years

5.     Fish larger than 10lbs are difficult to handle and thus are replaced by younger fish

6.     Commercial fingerling producers use male/female ratios of 2:3 or 1:2 in spawning ponds

Carps, the most popular fish

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Carp aquaculture originated in ancient China

Oracle bones – 1,500 B.C.

First aquaculture text – Fan Lee – “treatise of pisculture”

Carp species diversity

-Carp form the largest family (cyprinidae) of all fish

-Carp species vary in size > 6 ft., to < 1” in length

-Many of the smaller cyprinids, i.e. “goldfish” (domestic strains of carassius auratus) are important as ornamentals

- The common carp (Cyprinus carpio) is he most popular for culture and is farmed throughout the world where the temperature is appropriate

Koi (domesticated carp in Japan)

-Koi (domestic carp) is the most popular fish in Japan because of its gorgeous, magnificent, and colorful style.

-In Japanese culture, the Koi represents strength, courage and success in life.

-On international Children’s Day (June 1), Carp windsocks are flown from each home. This tradition symbolizes the parents wishing success for their children’s lives in the future.

Common carp (cyprinus carpio)

1.     Temperature optimum; 20-33 C

2.     Survives 4C (overwintering, metabolic depression)

3.     Tolerates low oxygen levels but optimal growth at > 3 ppm DO (dissolved oxygen)

4.     Algal crashes and resulting complete oxygen depuration are a common cause of carp mortalities

Carp reproduction

1.     Collection of eggs and milt for artificial fertilization

2.     Natural spawning (Dubisch method)

3.     Small (120 – 300 m2) shallow ponds (30 – 60 cm deep) kept grass-covered and dry when not used

4.     When the temperature warms to 18-20C ponds are flooded to 25-3 cm deep

5.     Ponds are then stocked with spawners (broodstock = 2-3 females and 4-5 males)

6.     Spawning occurs within 1-2 days and fertilized eggs are collected from substrate

Lowering egg adhesiveness after Artificial Fertilization

1.     Mixing ration ~1 part milt (sperm) : 100 parts eggs (weight not numbers!)

2.     Urea .3% plus sodium choloride .4% is used as a saline solution for multiple washes, 1 part solution : 10 parts fertized eggs, over a period of 1.5 hours to remove the “stickness” from eggs

3.     A final rinse uses tannin to complete the process lowering adhesiveness of the eggs

Eggs are incubated in upwelling jars (10 I) for 3-3.5 days at 24C

Aftering hatching larvae are reared in upwelling tanks (200 I) 3-4 days at 20-24C

During this time the air bladder inflates and swimming commences

Rearing of carp fry

Fry ( post-yolksac larvae) are reared in small ponds

-If outside, then Predator removal

-Quicklime (pH > 11) CaCO3 + H2O -> Ca(OH)2 + CO2

-Bleach

Pond fertilization

-2 weeks prior to stocking to promote algal growth (food source)

-3:1 to 6:1 N:P ratio

Stocking of fry

-200-400 larvae/m^2

-grow in 30 days to fingerling size

Grass carp (Ctenopharyngodon Idella)

1.     Also known as the White Amur carp

2.     Herbivorous, fry feed on plankton, change to vegetation at ~6’’

3.     > 20 C grass carp feed continuously eating several times their body weight in plant material daily

4.     Rapid growth; live for as long as 10 years

5.     Meat quality is very high and preferred over other carp

Omnivore = Common Carp, bighead carp

Herbivore – Grass carp, silver carp

Carnivore –  Black carp

Bighead carp

1.     Omnivorous fish / they feed on phytoplankton and zooplankton and or pellets

2.     Fourth most important carp species

3.     Very fast growing

4.     Native to Asia

5.     Highly invasive species in the us

6.     Eyes on bottom

Black Carp (Mylopharyngodon Piceus)

1.     Native to Eastern Asia

2.     Introduced to the US in the 1970’s

3.     Black carp are carnivores (meat eater)

4.     They feed on molluscs

5.     Similar to grass carp but gill rakers are fused and hardened to enable crushing of mollusk shells

Intensification of carp monoculture

-Natural production 150 – 300 kg/ha/yr

Fertilization 500 – 800 kg/ha/yr

Supplementary feeding 1-4 mt/ha/yr (soaked grains)

Complete feeds 5-10 metric tons/ha/yr

Polyculture – Tang Dynasty (618-907) A.D.

Polyculture: Rich-fish aquaculture

Advantages

1.     Rich production improved

2.     Additional source of protein and/or revenue

3.     More sustainable, less waste

Disadvantages

1.     Not useful with high-yielding, short stem rice varieties needing shallow water

2.     Not useful with multiple rice cropping; fish growth limited

3.     Need to provide refuges during rich field drainage

4.     Limited use of common insecticides and herbicides

Polyculture: Rice-Azolla-carp aquaculture

1.     Azolla is an aquatic fern (duckweed), that floats on the water surface

2.     It can assimilate atmospheric nitrogen owing to the nitrogen fixation by symbiotic cyanobacteria (blue green alga)living in cavities of azollaleafs

3.     Less nitrogen fertilizer is needed for carp culture

Crayfish

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Crayfish Reproduction (important)

1.     Mating and reproduction are easily accomplished under intensive culture conditions

2.     Mating and egg fertilization are asynchronous (non-gravid vs. gravid)

3.     Egg-laying typically occurs in burrows

4.     Eggs (~300/female) are attached to the swimming legs of the female by glair (viscous material of egg white)

5.     Eggs hatch in about 3 weeks at water temperatures of 20 degrees C.

Decapods

1.     Ten paired legs

2.     Abdomen (tail) Carapace (body) – 5 pair of legs on each the abdomen and carapace.

3.     Legs on abdomen are swimming legs

4.     Legs on carapace are walking legs

Crayfish ponds

-Crawfish are cultured in shallow open ponds. Pond areas vary from 2 to 16 ha (LA, TX)

-Pond depth is generally 30-60 cm bud deeper ponds are required in areas that have hotter summers

-Ponds have to be located near a source of good quality surface or well

-Water hardness = ~100+ or – 40 calcium

-DO (dissolved oxygen) > 3 ppm

-Grow-out = >10 cm in total length (20-50 grams) in 3-6 months

Crayfish are omnivores – they eat everything basically

Double cropping (crayfish / Rice – Polyculture)

Rice – crawfish – rice rotation

Management Actions

March/April – Plant rice ~4 months to harvest

June – At permanent food, rice grows to 20-25 cm high // stock 50-60 kg of adult crawfish/ha in new ponds

August – drain pond over 1 week period and harvest rice

October – re-flood pond

November-March – Harvest crawfish

March/April – Replant rice. No restocking of crawfish necessary.

Single crow crawfish pond (monoculture)

-Two additional months of crawfish harvest

April/May – stock 50-60 kg of adult crawfish/ha in new ponds

May/June – Drain pond over 3-4-week period

June/August – Plant forage crop October – Re-flood pond

November to May – Harvest crawfish

May/June – Drain pond over 3-4-week period. No restocking of crawfish is necessary.

Advantages of Polyculture – Additional crop (rice) / Environmentally friendly

Advantages of monoculture – Ponds flooded during hot summer months / 2 harvests of crawfish

Disease, pest and predator control

1.     Primary loss of crawfish from Louisiana ponds is to bird predators, such as herons and egrets

2.     North American species carriers of a fungal disease, the “crawfish plague”. While not problematic for North American species it is deadly to many other crayfish species in the world

3.     Introduction of Louisiana crayfish into Africa and Europe have devastated native species susceptible to the “crawfish plague”

Two species dominate crayfish harvest in the US

1.     Red swamp crawfish 85%

2.     White river crawfish 15%

Trap Harvest (both fishery and aquaculture)

-       Three-funnel pyramid trap made from ¾ inch mesh PVC-coated wire

-       The ~2.0 cm mesh size commonly used to construct the traps allow escape of crawfish less than ~8cm in length (considered the minimum marketable size)

Crawfish Production

1.     40% USA

2.     40% China

3.     20% Spain

Crayfish traps

1.     Density = 25 – 50 traps/hectar

2.     Baited (1/3 lb fish or manufuactured bait) and harvest

Crawfish distribution

1.     Sacked for distribution in “onion” sacks with ¼ mesh; 35 lbs/sack (must turn onion sack over once in a while to relief pressure off bottom crawfish)

2.     Storage at 4-7 C for 5 days without excessive mortality (Q10 effect, low temperature means lower metabolism)

3.     Turned once a day, stacked no more than 3 sacks high

Oysters - Yummy in my Tummy!

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Oysters

Of all the oysters produced 4,400,000 mt (98%) are a single species – the Japanese oyster (crassostrea gigas)

WHY?

1.     Fast growth

2.     Highly adaptable

3.     Demand -> taste/size

A little bit of “Oyster history”

-       Olympia oysters is the native spcies

-       S.F. oyster beds depleted by 1851 as a result of overharvesting

-       After that east coast oysters arrived by ship in barrels and cost 6$ a piece

With the opening of the transcontinental Railroad in 1875 “relaying” of Eastern oyster seed for growout in S.F> bay was started

-       1889 1.5 mt of seed imported

-       1899 1,100 mt of oyster meat produced

-       1908 down to ~ 600 mt of oyster meat

-       1919 Eastern oyster stocks suffered a massive mortaility

-       1921 Seed shipments discontinued

-       1939 Holding of imported stock halted

Japanese or Pacific oysters

-       Tougher and more suitable for aquaculture than the Eastern Oyster

-       Grows in brackish water upwards of > 16 ppt salinity

-       Grows at temperatures between 10-30 C

-       Withstand <0C

-       Withstands period of turbid water conditions

Problem – requires temperature greater than 20C for spawning

Oyster Life cycle

Fertilized Egg > Trochophora Larvae > Veliger larva > Spat (few mm size) (all done in hatercy up to this point) > Adult stage

Cultch

-Cultch is used in shellfish aquaculture as a substrate on which oyster spat can grow.

- The clean shell (cultch) is used in the hatchery to receive larval settlement

- Oyster seed is shipped to grow-out areas a spat on cultch

- After 1-4 years the settled oysters are removed and the empty shells recycled as cultch

Development of Oyster Hatcheries on the U.S. West Coast – 1980’s

Drivers

1.     Cost of Japanese spat was rising

2.     Infrequent natural spawning of C. gigas because of low water temperature

Broodstock used in oyster hatcheries

-Broodstock is conditioned for 2-6 weeks in flow-through trays while being fed algae

- generally, 30% males (1.5 – 2 years old) and 70% females (2.5 years and older) are used as broodstock

- Each female will produce millions (60-90 million) eggs

Induction of oyster spawning

-       Temperature shock

-       Spawning = excretion of gametes (unfertilized eggs and sperm) into the water

-       Blender technique to maximize fertilization

Oyster Harvest

Oyster cultured in bags, trays and on ropes are often harvested mechanically because of their heavy weight

Grow-out in California takes 13-18 month to produce a 4-inch oyster.

Shellfish Food safety regulation

National Shellfish Sanitation Program (NSSP) under supervision of the FDA

-Requires that both farmed and wild harvest-growing areas be distinctly demarcated

- Requires that each growing area is regularly tested for pathogens and classified as to water quality as determined by fecal coliform (gut bacteria0 counts

Food Safety Problems

1.     Deadly bacteria – can infest oysters and causes lethal septicemia in individual with impaired immune system

2.     Toxic algae (Cooking does not destroy these algal toxins)