Field Notes 



Insights into Current Sea Grant Research 



Secrets of Striper Spawning 



They call it squeezin' season. 



Every spring Sea Grant Associate 

 Director Ron Hodson and North Carolina 

 State University zoologist Craig Sullivan 

 become midwives, directing the birth of 

 thousands of hybrid striped bass finger- 

 lings. 



It all takes place at the Pamlico 

 Aquaculture Center in Beaufort County. 



And it's all part of a program de- 

 signed to control the life cycle of the 

 striped bass. With that kind of control, 

 broodstock — fish used for breeding 

 purposes — can be domesticated. With 

 domesticated broodstock. the infant hybrid 

 striped bass industry could take off like a 

 space shuttle. 



But why "squeezin' season?" 



Striped bass females and white bass 

 males are caught in the wild during 

 spawning season in North Carolina lakes 

 and rivers and brought to the center. 



There, they are injected with hor- 

 mones that will increase the spawning 

 urge and encourage the ripening of the 

 female eggs. Males are injected with 

 hormones to increase sperm production. 



Then Hodson and Sullivan begin their 

 watchful vigil. In about 36 hours, the fish 

 are ready for the careful hands of the 

 researchers. 



When their eggs are ripe, the female 

 fish are anesthetized and their lower 

 bodies are squeezed. The eggs, resembling 

 a frosty lemon-lime drink, are deposited 

 into a metal tray. The sperm from the male 

 fish is mixed with the eggs until Hodson 

 and Sullivan are sure fertilization takes 

 place. The fertilized eggs are then placed 

 in cylindrical jars where they are held in 

 suspension by circulating water, much like 

 they would be in nature. In two days, the 

 eggs hatch into "fry." 



It's a complicated process that 

 Hodson and Sullivan hope to make easier. 



The best way to simplify it, they say, 

 is to develop domesticated broodstocks 

 and methods for spawning them on 

 demand. Discovering this secret will give 

 the hybrid striped bass industry the lift it 

 needs. 



"This is what we call 'closing the 

 loop,' " says Hodson. "It means having 

 complete control of the fish, from start to 

 finish." 



Unlike most other fish that are 

 farmed, the striped bass presents some 

 unusual problems in the creation of 

 domesticated broodstock. 



"Striped bass is considered more 

 difficult to domesticate than white bass, 

 and that's what we're concentrating on," 

 he says. "The specific details of spawning 

 have been totally unknown. We don't 

 know what reproductive hormones control 

 the process. Those kinds of things." 



Hodson and Sullivan's research will 



focus on three areas: developing reliable 

 methods of reproducing broodstock on 

 demand using injectable hormones; 

 acquiring a basic working knowledge of 

 maturation of striped bass; and using the 

 new knowledge to shift the spawning 

 season to desired times. 



Gaining this much control of the life 

 cycle of the striped bass would have a 

 threefold advantage over current methods, 

 Hodson says. 



First, broodstock supplies would be 

 guaranteed. Hatchery operators would 

 have a reliable way of predicting spawning 

 times and approximating the numbers of 

 fingerlings that might be available. 



Second, the impact of hybrid striped 

 bass aquaculture on wild stocks of striped 

 bass would diminish significantly. 



And third, controlled spawning would 

 open the door to year-round production of 

 fingerlings and selective breeding of 

 superior genetic strains. % 



C.R. Edgerton 



COASTWATCH 17 



