Hybrid Striped Bass: Spawning

Dr. Craig KasperDr. Craig Kasper

Hillsborough Community CollegeHillsborough Community College

FAS 1012 FAS 1012

Aquaculture Aquaculture

General Production• Intensive & Extensive

• Enhancing Phase-I Fish

• Ensuring Quality Products

Morone spp.:Reproduction• Broodstock

• Egg maturation

• Fry management

• Fingerlings

• Broodstock

• Egg maturation

• Fry management

• Fingerlings

HSB: Broodstock

• Wild adults collected by electrofishing or angling.• Spring spawning (55-68ºF.)

• hormones used

♀-IM 330 IU hCG/kg bwt.

♂- only 150 IU hCG/kg bwt.

Culture of Hybrid Striped BassIn the U. S.

Culture of Hybrid Striped BassIn the U. S.

Striped Bass ( Morone saxatilis )

Popular sport fish caught in U. S. marine coastal waters

Distribution of Striped Bass in U. S.

PredaciousLife History

Food habits -

Reproduction - Lives in saltwater but spawning is in freshwater ( anadromous ). Migrates up coastal rivers in the Spring. Several land-locked populations are established in U.S. Males and females reach sexual maturity in 3 years and 4 years, respectively. Life span is 30 to 40 years.

Growth - Reaches 32 kg in ocean

Commercial Fishery – Striped bass is a prized sport and food fish. The commercial catch dropped from 15 million lb in 1973 to less than 1 million lb in 1989. Presently, the commercial catch is about 6 million lb/yr. Sport and commercial fisheries are heavily regulated. Fingerling stocking programs into fresh and salt water began in the early 1970’s

White Bass ( Morone chrysops )

Life HistoryFood habits – predacious

Growth – 4 to 5 lb in freshwater lakes

Reproduction – Lives and spawns in fresh water. Migrates up rivers and streams to shoal areas in Spring to spawn. Males and females reach sexual maturity in 2 and 3 years, repectively. Life span is 5 to 6 years.

Distribution of white bass in U. S.

How to distinguish among striped, white and hybrid basses

Hybrid Striped Bass

Palmetto bass – Striped bass female x white bass maleOriginal cross first performed in the mid 1960’s

Sunshine bass – Striped bass male x white bass female

Both hybrid crosses are stocked into fresh waters to improve sport fishing. Both crosses are fertile and will reproduce in natural waters with adequate spawning habitat. The sunshine bass is the most widely cultured hybrid because it is easiest to produce fingerlings. Hybrids are better for culture than striped bass because they are more resistant to handling and warm water temperatures in culture units. Hybrids grow faster than white bass and will reach 20 lbs in natural waters.

Water quality for hybrid striped bass

Water temperature – 1 to 33o C; optimum for growth is 25 - 27oCSalinity – 0 to 25 pptDissolved Oxygen – optimum is 6 – 12 mg/l; can withstand 1 mg/l for short periodsAlkalinity and Hardness – grow best in waters above 100 mg/lpH – 7.0 to 8.5 ideal

Salt is added to freshwater with low cloride ion concentration to improve growth and survival

Reproduction in Captivity

Spawning water temperatures – 15 to 21oC

Obtaining broodfish

White bass – Some domestigated stocks but most are captured from the wild with nets and hook and line.

Striped bass – Domestigated brooders not available, all are captured from the wild. Only state and federal agencies can use nets and electrofishing. Private producers must catch brooders by hook and line and transport them to the hatchery.

HSB: Egg Collection & Staging

• Sampling begins 16 hrs. post inject.(3 mm o.d. cath.)• • Check @ 2 hr intervals (narrow window)

-2 hr sb, 0.5 hr wb

•Look at eggs microscopically- eggs = blood-free, oil droplet coalesced (transparent)

& chorion intact- eggs will be brownish

Bottom line...frequent all nighters!!

HSB: Stripping/Fertilization

• Wet method-strip eggs into metal pan with H2O-add milt (sperm)-sperm is activated by salinity shock due to water exposure

•Dry method -strip eggs, add sperm, stir eggs (turkey feather)-add water

Striped bass eggs

shortly after fertilization

prior to cell division.

HSB: Incubation/Hatching

• Eggs are sticky (good in wild, but <fucundity) -Add bentonite or tannic acid

• Incubate in MacDonald Jars/100K eggs/jar

• Continuous flow of O2 water

•2-4 days = hatch

• Fry “swim-up” and into traugh

•Stock @ 4 days post-hatch (250K/ha)

Future: Physiology and Biochemistry

• Broodstock• Determination of Essential Fatty Acids (EFA)• Egg Quality • Fry Survivability

• Phase-I, II, III Fishes • EFA’s• Isoflavones• α-Tocopherol • Phosphatidylcholine

• Metabolism

Spawning – Males and females are injected with hormones to obtain eggs and sperm. Eggs can be checked to determine if they are ripe and ready for fertilization.

Spawning - Eggs are stripped from females and mixed with sperm from the males. White bass eggs are adhesive and must be treated to remove adhesiveness before placement in incubators. Striped bass eggs are non-adhesive and need no treatment.

Egg incubation – McDonald jars are used to incubate the eggs. Eggs hatch in 40 to 48 hr after fertilization in 15 to 18o C water. Fry begin to feed 4 to 8 days after hatch. Fry are about 1mm at hatch.

Nursery Phase First food:

Palmetto bass – large zooplankton ( daphnia )

Sunshine bass – small zooplankton ( rotifers )

Ponds must be carefully filled and fertilized to prepare the proper food organizm for the type of hybrid fry stocked

Stocking rate – 250,000 to 500,000/ha

Nursery Phase

Survival to 35 to 50 mm in 3 to 4 weeks of culture:

Palmetto bass – 40 to 50 %

Sunshine bass – 10 to 25 %

Feed training: In ponds – Crumbled feed can be fed to 14 to 21 day-old

fingerlings. Bass will learn to eat feed.

In tanks – Remove 4 week-old fingerlings from ponds and stock them at high densities in tanks

receiving flowing water. Feed them nutritionally complete crumbled diets.

Growout Phase I Grading – fingerlings must be graded to reduce cannibalism before stocking.

Stocking density – 20,000 to 50,000/ha in earthen ponds

Feeding – Bass are feed a 40 % protein floating diet 1 to 3 times/day starting a 5% body weight/day, reduced to 3 %/day as the bass grow.

Harvest – Bass are harvested in the winter when water temperatures a cold. Survival is 85% and average weight is 125 to 225 g.

Growout Phase II Stocking – Bass are graded and stocked at 3,000 to

4,000/ha into earthen ponds.

Feeding – Bass are fed 1 to 3 % body weight daily with a 40 % protein floating diet.

Harvest – Bass reach 1.25 to 1.5 lb with a survival of

90 % by October - November.

Yields – 4,000 to 5,000 kg/ha with aeration. 55% of the hybrid striped bass harvest in the U. S. are grown in ponds.

Growout Phase II

Hybrid striped bass are also grown in tanks at high density

45 % of the hybrid striped bass harvested in the U. S. are from tanks

Markets - 1999

Live – 11 % of U. S. harvest is marketed live as food fish or for fee fishing. Price to farmers is $3.30/lb ( $ 7.26/kg ).

Fresh – 89 % of U. S. harvest is sold whole on ice. Price to farmers is $2.53/lb

Constraints

1. Competition from striped bass commercial fishery

2. High cost of production; high market price

3. Difficulty obtaining broodfish

4. Legal restrictions to sell cultured hybrid striped bass in many states because it is considered a sport fish. Each fish must be individually tagged.

U. S. harvest - 1999

Weight - 9.7 million lbs (4.4 million kg )

Value - $28 million

Hybrid striped bass is 5th in weight of food fish harvested in the U. S.

THE END