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Tagging Fish.--(White Metal News Letter, Sept. I933.) It may not be difficult to tag a fish but Dr. Rounsefell in charge of the Alaska Herring Investigation for the U. S. Bureau of Fisheries has had his difficulties in the past when he tried to recover the tags. The fish are tagged for the purpose of tracing their migration which is done by recording the points at which the fish and their tags are caught. Since the herring and the tags are quite small, ordinary methods of tag recovery prove rather tedious.
Accordingly, Dr. Rounsefell has developed a magnetic nickel tag and has installed a system of electro-magnets for recovering the tags. The great majority of the herring in Alaska are put through reduction plants for the manufacture of fish oil and fish meal. A powerful electro-manget was installed at the discharge end of each of the meal dryers and as the dry meal emerges from these cylinder dryers, it falls over the magnet, which catches the tags.
C.
๐ SIMILAR VOLUMES
wooden racks on a shelf in proximity to an inclosed arc light; beginning with a pure oil on the left hand side, then bottles with o.I per cent. mineral oil, I per cent., 2 per cent., etc., up to IO per cent. The standard with linseed oil serves to examine cottonseed, corn, China-wood, China-bean oil