Biology, Management, and Conservation of Lampreys in North America


doi: https://doi.org/10.47886/9781934874134.fmatter

Lampreys have the reputation of being ugly, slimy bloodsuckers that wantonly kill fish we like to eat, such as salmon. With the exception of slimy, none of this characterization is true for lampreys. Instead, they are intriguing organisms that filter-feed on benthic algae, microbes, and other organic material as juveniles, with only a few species consuming flesh and blood as adults. All are beautifully adapted for their lifestyles. Like their most distant ancestors, the ostracoderms, they spend most of their lives sucking up organic matter through jawless mouths. The jawed bony fishes eventually drove most of the jawless ostracoderms to extinction; however, the lamprey lineage persisted by adapting to prey on the very fishes that displaced their ancestors. In the process, they developed the same lifestyle that we admire in salmon—freely moving between marine and freshwater environments and being very successful in both. In fact, lampreys are an indicator of freshwater habitat suitable for salmon. Like salmon, adults build nests (redds, if they were salmon), with most dying after spawning. The young (ammocoetes) rear in the backwaters of streams and are important parts of stream ecosystems, providing food for predators from insects to fish to birds and recycling organic waste. The anadromous forms transform into big-eyed silvery “smolts” (macropthalmia), which migrate to sea (or a large lake) and attack fish larger than themselves. A few species always kill their prey, but for other species, many of their prey survive attacks, some multiple times! The large migratory lampreys are themselves important prey for sea lions and other predators, especially when lampreys concentrate in estuaries on their way upstream to spawn. For Native Americans, these fat, migrating lampreys were historically a highly valued and important food source. Lampreys are still valued by Native Americans as food and for their cultural importance. Lampreys are also part of the cuisine of some European countries (e.g., Portugal). Amazingly, most lamprey species have lost the adult predatory stage of the life cycle and metamorphose, spawn, and die in the same stream in which they were spawned. Unfortunately, the bad reputation of large lampreys and the inconspicuous nature of small nonpredaceous lampreys have resulted in a long history of ignoring the importance and special requirements of lampreys in aquatic ecosystems. If sufficient information were available, it is likely that a majority of lamprey species would be listed as threatened species under the U.S. Endangered Species Act (ESA).