. Commercial fisheries review. Fisheries; Fish trade. 32 or if it is necessary to move them to beds protected from starfish invasions or winter storms. Growingbeds are cleaned of predators, such as starfish and oyster drills, competitors, such as slipper shells and mussels, and silt before seed oysters are spread. Seed oysters may be transplanted each spring thereafter, or, if not transplanted, thinned out. Com- panies that do not transplant or thin out grow- ing oysters each year find that they become much too dense on the bottom--in some in- stances, more then 3,000 bushels per acre. I
. Commercial fisheries review. Fisheries; Fish trade. 32 or if it is necessary to move them to beds protected from starfish invasions or winter storms. Growingbeds are cleaned of predators, such as starfish and oyster drills, competitors, such as slipper shells and mussels, and silt before seed oysters are spread. Seed oysters may be transplanted each spring thereafter, or, if not transplanted, thinned out. Com- panies that do not transplant or thin out grow- ing oysters each year find that they become much too dense on the bottom--in some in- stances, more then 3,000 bushels per acre. If a significant percentage of seed oysters is covered by silt, which accumulated during the winter, or by sand during winter storms, they must be transplanted during the following Marcher early April before water tempera- ture reaches about 43° F. (the level at which most begin active pumping), or the buried ones suffocate (Fig. 4). When seed oysters are in clusters, repeated transplanting each year alsobreaks these apart sothat almost all oys- ters are "singles" by the time they reach market size. A portion of market oysters may be attached in clusters, however, if the original set of seed oysters was very heavy. Most oysters are transplanted 3 or 4 times before they reach market size. During 1966-69, oyster companies spread seed on growing beds at lower concentrations than they had in the past. They spread 1-year- old 1968 set on growing beds at rates of 175 to300 bushels (750,000 to 1,000,000 oysters) per acre, depending on number of individuals per bushel. In the past, the rate of spreading of 1-year-olds was 500 to 800 bushels per acre. But survival rates of-oysters became much higher, so spreading rates had to be lowered to accommodate growth of the OCTOBER. JANUARY -deposit of silt Oysters marked by an x will die by Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration
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