A nonlethal aging technique for threatened, endangered and sensitive fishes

Authors: Ronald Rogers, Brandon Albrecht

Year: 2009 (xli)

Abstract

Morphological structures can be used to determine a fish’s age. Typical structures used for fish-aging investigations include scales, otoliths, spines, opercular bones, vertebrae, branchiostegal bones and fin rays. We have found that many of these structures are either unreliable for aging native sucker populations, or require the fish to be sacrificed. Pectoral fin rays offer a nonlethal, reliable alternative to ageing native fishes. Since 1999 BIO-WEST, Inc., has developed, refined, utilized, and benefited from employing a nonlethal aging technique to understand the recruitment patterns of a wild, self-sustaining population of razorback sucker,Xyrauchen texanus, in Lake Mead, Arizona and Nevada. Most recently, BIO-WEST, Inc., has expanded the use of this technique to successfully age flannelmouth sucker, Catostomus latipinnis, captured from the Lower Colorado River. This aging technique has demonstrated that reliable, nonlethal aging of native sucker is possible. Furthermore, this technique can provide valuable ecological insight to a variety of threatened, endangered, or sensitive fish species. This information can be useful to formulate management actions that can contribute to species recovery.