in the rearing of larvae since, while they are active 

 and feed, they do not grow. 



FINFISH 

 Salmonids 



One of the oldest research efforts in the United 

 States directed toward developing improved strains 

 of seafood organisms is that at the University of 

 Washington under Lauren R. Donaldson. Over a 

 period of 40 yr. through a selective breeding pro- 

 gram, several species of salmon and hybrids of trout 

 have been developed, and eggs from this program 

 have been provided to organizations all over the 

 world. Currently Donaldson and his co-workers are 

 working with rainbow trout, rainbow-steelhead hy- 

 brids, and Chinook and coho salmon. Oncorliynchus 

 tsfunvyscha andO. kisiitch. Millions of eggs are pro- 

 duced each year, some being used in the breeding 

 program, some irradiated for studies of the effects of 

 radiation exposure, and others used or provided to 

 other organizations for other types of research or for 

 aquaculture. 



In an associated program, other University of 

 Washington fisheries biologists are attempting to 

 demonstrate the practicality of rearing salmonids in 

 floating pens, in brackish water ponds, and in saltwa- 

 ter estuaries. In this work, which is being conducted 

 cooperatively with private industry, the salmon are 

 being reared for two uses: 1 ) direct marketing and 2) 

 release at an advanced stage for support of sport and 

 commercial fisheries. This same project also in- 

 cludes studies of the effects of environmental 

 parameters on the success of rearing salmonids in 

 seawater, the training of salmon to come to an 

 underwater sound source for effective feeding and 

 harvesting, and feasibility studies on enhancing pro- 

 duction of 20 species of flatfishes indigenous to 

 Puget Sound by improved cultural techniques. 



A team of researchers at Oregon State University 

 is investigating several problems associated with 

 salmon culture. New hatchery methods which simu- 

 late natural spawning beds are being developed. The 

 system involves raising salmon alevins (larvae) in 

 darkness on a gravel substrate instead of on screened 

 trays or smooth tank bottoms. Water velocity is 

 similar to that in good quality natural spawning beds. 

 Several hundred thousand chum salmon. O. keta, 

 are being produced annually by this method at an 

 e.xperimental hatchery located at Netarts Bay. The 

 fry from the gra\el incubator are considerabh larger 

 than frv from standard hatcherv incubators and do 



not exhibit malformed yolks which are common in 

 hatchery chum salmon alevins. In the laboratory at 

 Port Oiford, Chinook salmon are being exposed in 

 rearing tanks to increasing salinities to determine the 

 feasibility of releasing juveniles directly to seawater 

 after only a brief period of adaptation. If successful 

 this could significantly reduce the mortalities which 

 now occur in freshwater areas. 



Other work at Oregon State University on salmon 

 includes attempts to: improve certain strains 

 through hybridization and selective breeding; de- 

 velop methods for rearing in power plant effluents; 

 determine the effects of infection by the trematode, 

 Nanophyetus scilmincoUi; and develop techniques 

 for cryopreservation of gametes. Sperm frozen for 7 

 days at -I96°C were thawed and used to fertilize 

 80% or more of fresh eggs from coho salmon and 

 steelhead trout, Salnio gtiirdnen. 



Seafood scientists at Oregon State University are 

 working with several salmon diet formulations in 

 order to develop new rations, as well as to learn more 

 about the nutritional requirements of the salmon. 

 Experiments now completed indicate that a pelleted 

 fish food utilizing 40% dewatered and comminuted 

 shrimp wastes provide results as good as those ob- 

 tained with the commonly used Oregon moist pellet. 

 Thus, a use for large quantities of raw shrimp wastes 

 has been identified. 



Coho and chinook salmon are being reared in net 

 enclosures in the open waters of Puget Sound in a 

 project being conducted by a private firm. Ocean 

 Systems, Inc. This project is an outgrowth of work 

 by the National Marine Fisheries Service whose 

 scientists continue working on associated problems. 

 Assistance has also been received from the 

 Washington State Department of Fisheries and the 

 University of Washington. The eggs were hatched 

 and the fingerlings placed in a freshwater pond. 

 When they reached the desired size, the fish were 

 transferred by truck to small net enclosures (7.5 x 

 7.5 X 4.5 m) in the Sound and later transferred to four 

 larger (15 x 15 x 7.5 m) growing pens which are 

 attached to an anchored raft. The enclosures are 

 covered by a net to protect the fish from bird pred- 

 ators and surrounded on four sides and the bottom 

 by a 6.4-cm stretch mesh gill net to protect the fish 

 from dogfish and other predators. 



At the present time, approximately 230.000 coho 

 and 270,000 chinook salmon are growing in the pens. 

 They are fed a dry salmon pellet ration which is 

 hand-cast over the enclosure. .Although some of the 

 salmon have reached potential market size in 8 mo. 



47 



