Marine Farming and Enhancement

The recognition of an animal or a group of animals within a population is important for many reasons in fisheries research. Many types of tags and marks have been developed to aid biologists in recognizing animals (Rounsefell 1963, Farmer 1981). Unfortunately, no one technique has been totally satisfactory from a biological or technical standpoint. In 1983, the National Marine Fisheries Service began a study supported by the Bonneville Power Administration to evaluate the technical and biological feasibility of adapting a new identification system to salmonids. The system is based upon a passive integrated transponder (PIT) tag. This tag has the promise of eliminating some of the inherent problems with present tagging and marking systems. In addition to the research with salmonids, preliminary tagging studies have also been conducted with two crustacean species. This paper provides an overview of the basic tag operation, biological acceptability in test animals, field testing results, and a discussion of some of the possible applications of the PIT tag. Integrated circuit chip Antenna Glass tube ~ (((((((((((((((((((((((( (((((((((( Tag operation _ Figure 1 PIT tag. The PIT tag consists of an antenna coil that has about 1,500 wraps of a special coated, 0.0254-mm diameter copper wire. The antenna coil is bonded to a integrated circuit chip. The electronic components of the tag are encapsulated in a glass tube about 12 mm long and 2.1 mm in diameter (Fig. 1). Each tag is preprogrammed at the factory with one of about 34 billion unique code combinations. The tag is passive, having no power of its own, and thus must rely upon an external source of energy to operate. A 400-KHz signal energizes the tag, and a unique 40-50 KHz signal is transmitted back to the interrogation equipment where the code is immediately processed and displayed, transmitted to a computer via an RS-232 interface, and/or placed on printed hard copy. A portable hand reader (Fig. 2) or a fixed tag-monitor system is used to interrogate and display the tag code information. Data transfer rate is 4,000 bits/so The interrogation range of the tag varies with the monitoring equipment used: Using a hand reader the reading range is up to 7.6 cm, while with a fixed full-loop interrogator the reading range of detection is about 18 em (Fig. 3). The tag can be read through ~-------12mm--_ An ongoing cooperative agreement between the Bonneville Power Administration and the National Marine Fisheries Service was initiated in 1983 to evaluate the technical and biological feasibility of adapting a new identification system to salmonids. The system is based on a passive integrated transponder (PIT) tag. Each tag measures 12 mm in length by 2.1 mm in diameter and is uniquely coded with one of 34 billion codes. The tag's operational life is unknown at this time; however, it is thought to be 10 or more years. The tag can be detected and decoded in place, eliminating the need to anesthetize, handle, or restrain fish during data retrieval. Biological tests indicate the body cavity of juvenile and adult salmonids is biologically acceptable for tag implantation. Comparisons between PIT-tagged and traditionally tagged and marked juvenile salmonids are discussed. Laboratory and field tests showed that the PIT tag did not adversely affect growth or survival, nor was there any appreciable tissue response to the tag. No evidence of infection due to tagging procedures was observed. Video-taped swim-chamber tests showed no significant effect of the PIT tag on respiratory rate, tail beat frequency, stamina, or post-fatigue survival of juvenile salmonids. Tag retention within the body cavity was near 100% for salmonids weighing from 2 to 10,000 g. Previously PIT-tagged mature salmon which were hand stripped of sperm and eggs showed high tag retention with no adverse tag-caused effects. During their outmigration, PIT-tagged juvenile salmonids were successfully interrogated at two dams using automatic tagmonitoring equipment. All data were automatically recorded and stored by computer. PIT-tag reading efficiency was 96 to 100%, while reading accuracy was over 99%. The tag-monitoring equipment proved to be reliable under field conditions. Special tagging considerations with Crustacea and preliminary testing ofthe PIT tag with two crustacean species are discussed, along with future applications of the PIT tag to fisheries research. 300 350 250 / / / / /