Rare, Imperiled, and Recently Extinct or Extirpated Mollusks of Utah: A Literature Review

About 139 species of mollusks are known to occur, or within historical times to have occurred, in Utah. The number of known Utah mollusks is not fixed and can be expected to continue to change, increasing as new molluscan discoveries are made in Utah and possibly decreasing as taxonomic revisions change our concept of how many valid mollusk species exist. This report represents one of the end products of a review of literature—published journal articles and books as well as unpublished agency reports—dealing with mollusks in Utah. The goals of this review were to determine (1) which species have been documented from the state, (2) extent of knowledge of the status—abundance, distribution, conservational needs, and so forth—of each of the species in Utah, and, thus, (3) which species are of conservational concern in the state. This report summarizes the assembled information pertaining to the last goal, the 79 molluscan species that are of conservational priority—or of conservational interest in the cases of those believed to be extirpated or extinct; it is intended to help guide current management of the molluscan resources of the state as well as to identify gaps in existing knowledge that will need to be filled in order to manage these resources more effectively in the future. Some of the understanding that is important for truly effective management of Utah\u27s mollusks is lacking, especially with regard to our knowledge of threats to and population trends in these species. Threats to various species discussed in this report should be understood, in most cases, as potential threats, often based on educated guesses. Similarly, information pertaining to population trends of mollusks in Utah is largely unavailable from the existing literature. Despite the incompleteness of reported information concerning Utah mollusks, much is known, and this information obtained from the literature provides an valuable base from which to plan future work. Mollusks, as a group, are thought to be among the most endangered of animal groups that occur in North America, but this is a new awareness, and conservational management attention has only recently begun to be directed toward this group. The Utah Division of Wildlife Resources now has management authority for all mollusks in the state and is establishing mechanisms and procedures for the management and protection of the state\u27s molluscan resources