More recent tagging developments relate to marks which will be visible on a free-swimming animal. Large whales, for instance, may be tagged with color-coded streamers, such as that shown in Appendix Figure A2. The tags, which are modified versions of the spaghetti tags first constructed for use on fishes, consist of a small stainless steel head for attachment to the blubber and a colorful streamer (sometimes stamped with information on agencies to which tags should be returned) which is visible above the surface of the animal. These tags may be applied by using either a pole applicator or a crossbow and crossbow bolts. Both applicators are equipped with a stop to limit the depth of penetration into the animal's blubber. Extensive experimentation indicates that the tags do not harm the animals and that their application is not traumatic. With the continued reduction in whaling activity, it is hoped that the use of such markers in the study of movements of big whales will be increased.
Because they often ride the bow wave of a moving vessel, thereby making themselves accessible for tagging and capture, small porpoises and dolphins have been tagged with a greater variety of marks than large whales. In recent years, at least three kinds of static tags, including spaghetti streamers, have been placed on small and medium-sized cetaceans.
Spaghetti tags, placed in the animal's blubber near the base of the dorsal fin as it rides the bow wave, stream to conform to the contour of the animal's body as it swims (App. Fig. A3). It is not possible to identify the numbers on the spaghetti tag of a moving animal, although color codes may be used to indicate different species, populations, or tagging areas.
Button tags and freeze brands are placed on captured animals prior to their release. The button tags (App. Figs. A4, A5) are placed in the dorsal fin and should be visible as the animal surfaces to breathe or as it rides the bow wave. At close range, the number, letter, or design may also be visible. Freeze brands (App. Fig. A6) are placed on the back or dorsal fin with a supercooled branding iron, apparently without pain or discomfort to the animal, and provide a permanent mark which leaves the tagged animal free of encumbrances. The use of freeze brands shows promise and should come into more extensive use.