Lampreys, an unexpected desert species: their conservation status along the Southern California coast.

Authors: Stewart B. Reid, Damon H. Goodman

Year: 2012 (xliv)

Abstract

Two species of lamprey are native to California south of Point Conception, the Pacific Lamprey, Entosphenus tridentatus, and an unresolved brook lamprey, Lampetra cf. pacifica, which is apparently extirpated from its known range in southern California. The North American range of the Pacific Lamprey extends from Alaska south to the Río Santo Domingo in northern Baja California, including records from many principal streams in southern California. However, recent coast-wide surveys of streams from Canada south to Baja California suggests that there is a major change in range and population dynamics south of Big Sur. While Pacific Lamprey ammocoetes (a freshwater-resident larval stage lasting about five years) are nearly ubiquitous from Big Sur northwards, they are now absent, or extremely rare, southwards, even at sites of recent collections and known populations. The mechanisms causing this pattern remain to be resolved, but include man-made passage barriers and anthropogenic changes in the environment, as well as natural habitat constraints, such as seasonal barriers to migration and arid conditions. Historically, there was also a freshwater-resident brook lamprey in the Los Angeles Basin, including the San Gabriel, Santa Ana, and Los Angeles drainages. However, the species has not been collected from its known range in the basin since 1955. One goal of the Pacific Lamprey Conservation Initiative is to increase awareness of lampreys in southern California streams and explore approaches to their unique conservation needs.