months and trout during the cooler fall and winter months. The 

 State of Arkansas has an arranr^.-'^nt with commercial producers who 

 lease or rent space in public reservoirs for cage culture with the 

 agreement that a certain percentage of the fish be released within 

 the reservoirs. The pen culture of salmon on the Northwest Coast 

 of the U. S. is growing rapidly. Cage and pen culture will play an 

 increasingly large role in aquaculture. 



Sea Ranching 



Sea or ocean ranching involves the release of immature fish to the 

 wild and the recapture of the fish when they return as adults. 

 Currently, only anadromous species such as salmon and striped bass 

 are being used for sea ranching. Private individuals and 

 corporations culture salmon from the egg to the smoltif ication 

 stage (smoltif ication is a physiological process that young fish 

 undergo to prepare them for migration to the sea) . At 

 smoltif ication, the young are released and migrate to sea where 

 they feed and grow to maturity. Maturation is the stimulus for the 

 adult fish to return to their release point, where they are then 

 harvested . 



Usually less than 3 percent of all sea-ranched salmon are 

 recaptured by those who released them. Commercial and sport 

 fishermen catch many of them. One advantage to this method of 

 culture, however, is that the expense of long-term feeding is 

 avoided. Sea-ranching is legal in Oregon, California, Maine, and 

 Alaska, but not in Washington, with the exception of some Native 

 American activities. 



Culture Systems for Shellfish 



Most shellfish species have suffered dramatic population reductions 

 in the past 15 to 30 years because of environmental degradation 

 from toxic wastes, sedimentation, overharvesting, dredging, and 

 channelization. Shellfish cultivation is beginning to reverse this 

 trend. Long-term problems with hatchery production and artificial 

 rearing of larval molluscs appear to have been solved. Techniques 

 for the setting of oyster spat (young oysters) on suitable 

 substrate have been greatly improved. Certain States require that 

 shells from commercially harvested oysters be returned to the 

 marine environment. The shells serve as substrates on which spat 

 adhere and grow to a harvestable size. 



Mussel culture in the U.S. on both the east and west coasts is 

 centered on the blue mussel ( Mytilus edulis) . Most commercial 

 producers are using suspended culture systems (long lines suspended 

 from rafts) . 



In California, juvenile abalone ( Haliotis sp.) are either stocked 

 in natural habitats as part of an enhancement program or reared 

 commercially in tanks. The time required to reach market size 



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