. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. I I \ l IMI AM) CAME. Figure 142. Defective tags. The single disk in the top row is Vinylite and broke while on a striped bass {Roccus saxatilis). Note the sharp fracture, which is typical of this material. The three tags in the bottom row are cellulose acetate ( inch thick, Vie inch diameter). They were recovered from spawned-out king salmon (Oncorhyn- chus tshawytscha) and are all too typical of thin acetate tags recov
. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. I I \ l IMI AM) CAME. Figure 142. Defective tags. The single disk in the top row is Vinylite and broke while on a striped bass {Roccus saxatilis). Note the sharp fracture, which is typical of this material. The three tags in the bottom row are cellulose acetate ( inch thick, Vie inch diameter). They were recovered from spawned-out king salmon (Oncorhyn- chus tshawytscha) and are all too typical of thin acetate tags recovered on the spawn- ing beds. Photograph by D. H. Fry, Jr. hatchery pen will damage tags but usually the collective damage is not as severe as on the spawning grounds. Vinylite While men working with salmon were having trouble with cellulose acetate tags, another crew was tagging striped bass with Vinylite disks of the sort used earlier for this species on the Atlantic Coast (Merriman, 1941). They proved to be unduly brittle. Sharply cracked disks were returned frequently. The one shown in the top row in Figure 142 is typical. Use of this material has been discontinued in favor of cellulose nitrate, for which a source has recently been found. However, if the latter cannot be obtained in the future, it will be desirable to compare the qualities of the thicker ( inch) acetate tags with Vinylite ones of the same thickness. The brittleness of the latter material may prove to be less of a disadvantage than the weakness of acetate. CORROSION OF METAL WIRES Corrosion tests have been performed at the Steinhart Aquarium on Monel wire of two types, nickel pins of two batches, nickel wire, stainless steel wire and tantalum wire. Some Monel strap tags were also tested. Of these, only stainless steel and tantalum show real promise. The tests were carried out by tagging striped bass (Roccas saxatilis) about 15 inches long, and examining them at such irregular intervals as our other work
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