The Southern flounder "dream team" test their 

 scientific findings at North Carolina State 

 University. The determined team members are 

 (left to right) Russell Borski, Adam Luckenbach, 

 Harry Daniels and John Godwin. 



including World Aquaculture (March 2002), 

 Evolution and Development (January-February 

 2003); and Aquaculture (January 2003). 



The team has been invited to present their 

 findings at the N.C. Aquaculture Development 

 Conference in late January, and at both the 

 Aquaculture America and World Aquaculture 

 conferences later this year. 



Importantly, their research has won respect 



Hatchery Production 

 of Flounder 



Incubation 



c 



I 



t 



Larviculture 



3»< 



The protocol begins with crossing male and 

 female broodstock Larvae undergo a 

 metamorphosis into bottom-dwelling flatfish. 



and ongoing 

 support from 

 prestigious funding 

 institutions, 

 including North 

 Carolina Sea Grant, 

 the National 

 Science Foundation, 

 the National 

 Institutes of Health, 

 the National Marine 

 Fisheries' 

 Salstonstall- 

 Kennedy Program, 

 the Golden LEAF 

 Foundation, as well 

 as the NC State College of Agriculture and Life 

 Science. 



Still, the researchers are not resting on their 

 laurels, Godwin says. In the coming months, they 

 will challenge their own science to test methods 

 and replicate results — and perhaps even 

 streamline and refine procedures. 



The first step is harvesting egg and sperm 

 from wild-caught Southern flounder broodstock, 

 using techniques developed by NC State 

 colleagues Craig Sullivan and Hodson. Next 

 comes fertilization and managing larval 

 development to fingerling stage. This is where 

 timing — and temperature — gets critical. 



The team will re-examine their gynogenetic 

 protocol to manipulate 

 chromosomes to produce pure 

 populations of Southern 

 flounder XX female offspring 

 on a large scale. They will 

 incubate ripe eggs in ice-cold 

 seawater to retain an extra X 

 chromosome and then fertilize 

 the eggs with ultraviolet- 

 irradiated sperm (which 

 destroys the chromosome 

 contributed by the sperm) to 

 produce pure populations of 

 XX flounder. 



When these fish are 

 reared at the male-determin- 

 ing temperature of 28 C, XX 

 males with functional sperm can be produced 

 (Normal male flounder possess XY chromo- 

 somes.) These animals then can be bred with 



Reproduction 



Growout 



normal females to produce 100 percent female 

 offspring when reared at the control or female- 

 deteimining temperature (23 Q. 



The researchers will continue to probe the 

 precise body size or developmental window of 

 temperature-sensitive sex determination — and 

 establish the critical body size at which 

 temperature no longer alters the sex of the 

 flounder. 



In the coming months, they also will be 

 considering the best methods for keeping larger 

 fish healthy during grow out and examining the 

 DNA of stock progeny. 



Beyond economics 



In the case of prospective large-scale 

 commercial flounder farming operations, there 

 are two sides to the economic coin. One side 

 shows great promise as a farm-to-market 

 economic success story. Fish farmers can 

 provide year-round "crops" with consistent size, 

 quality and flavor. 



The other side of the coin holds economic 

 potential for traditional commercial fishing as 

 well. Reports of dwindling Southern flounder 

 stocks by both national and state marine fisheries 

 groups have resulted in more regulations and 

 less profit for commercial fishing fleets. 



In Japan, natural fisheries get a boost from 

 the annual release of hatchery-reared juveniles. 



Here, Southern flounder produced using 

 the flounder project team protocols could be 

 considered for stock enhancement without 

 environmental concerns, the researchers say. 



"These fish are not transgenic. We are not 

 changing genes. They have the very same genes 

 as their mothers," Borski says. 



While the potential for using farm-reared 

 fish for stock enhancement may be under 

 scientific scrutiny, it is not on the National 

 Marine Fisheries Service's policy agenda. 



Popular fare 



So, while the experts work out the most 

 effective methods to protect and enhance 

 fisheries stocks, there is little evidence that the 

 demand for flounder will diminish any time 

 soon. Health-conscious consumers are eating 

 more fish as a protein source. 



As it turns out the Southern flounder may 

 be too popular and versatile for its own good. Its 



14 WINTER 2003 



