Reference | Buckley, R. M. and H. L. Blankenship. 1990. Internal extrinsic identification systems: overview of implanted wire tags, otolith marks, and parasites. American Fisheries Society Symposium 7:173-182. |
Abstract | Implanted wire tags, otolith marks (induced by variation in temperature, feeding, or photoperiod), and natural parasites are internal extrinsic systems used to identify fish for recovery of specific information after considerable time and growth. The validity of these systems depends upon the assumptions that identified fish are representative of the species with regard to behavior, biological functions, and mortality factors, and thus provide unbiased data. The histopathology of fish tagging, and the long-term failure of percutaneous devices, indicate that internal identification systems are superior to external tags for validating the assumptions and for long-term recovery of information. These three internal identification systems can be applied to fish of almost any size, although otolith marks require retaining fish in controlled environments for limited periods. Coded wire tags have a large data capacity and can identify groups or individuals in all fishery situations. Tags implanted in transparent tissues are externally detectable without the use of an external indicator. Otolith marks and parasites enable the identification of groups of fish, most practically in confined fishery situations. All three systems can be used for within-season management of fisheries. The lack of widespread use of internal extrinsic identification systems for many species is based on a preconceived idea that small, obscure identifiers are not recoverable in fisheries. This bias appears to be base on the historic use of external identifiers and not on any in-depth analysis of their reliability and accuracy. |
Tag | Coded Wire Tag (CWT) |
Objective | Evaluate tags |