BROODSTOCK, SPAWNING, AND EGG HANDLING 149 



A hybrid striped bass was developed by fertilizing striped bass eggs with 

 sperm from white bass. The hybrids had faster growth and better survival 

 than striped bass. The chief advantage of the reciprocal hybrid, from white 

 bass eggs and striped bass sperm, is that female white bass are usually 

 more available than striped bass females and are easier to spawn. Under 

 artificial propagation, the reciprocal mature hybrids can be produced in 2 

 years, while 4—5 years are required to produce hybrids when female striped 

 bass are used. White bass and most male striped bass mature in 2 years, 

 but female striped bass require 4—5 years to mature. 



Both hybridization and crossbreeding of various species of catfish have 

 been successfully accomplished at the Fish Farming Experimental Station, 

 Stuttgart, Arkansas. Hybrid catfishes have been tested in the laboratory for 

 improved growth rate and food conversion. Two hybrids, the white catfish 

 X channel catfish and the channel catfish x blue catfish, performed well. 

 The channel catfish x blue catfish hybrid had a 22% greater growth rate 

 than the parent channel catfish and 57% greater growth rate than the 

 parent blue catfish. When the hybrids were mated among themselves, 

 spawning usually was incomplete and spawn production was relatively 

 small. Growth of the second generation channel catfish x blue catfish hy- 

 brid was inferior to that of the parent hybrid. 



Various hybrids of sunfish species also have been successful and some 

 are becoming important sport fish in several states. The most commonly 

 produced hybrid sunfish are crosses of male bluegill x female green sunfish 

 and male redear sunfish x female green sunfish. They are popular for farm- 

 pond stocking because they do not reproduce as readily as the purebred 

 parental stocks and grow much larger than their parents. 



It is advisable for any hatchery manager to consult a qualified geneticist 

 before starting either a selective breeding or hybridization program. 



Spawning 



Obtaining eggs from fish and fertilizing them is known as spawning, egg 

 taking, or stripping. The two basic procedures utilized for spawning fish 

 commonly are referred to as the natural and artificial methods. Natural 

 spawning includes any method that does not entail manually extracting 

 sexual products from the fish. 



Natural Spawning Method 



Fish are placed in prepared ponds or allowed to enter channels resembling 

 their natural habitat to carry out their reproductive activities naturally. 



