What are Lamprey?

Lamprey are a group of cartilaginous (boneless) fish that have been around for more than 360 million years. Ten different lamprey species call Oregon home. The species most commonly found in streams and rivers on the central Oregon coast are: the freshwater resident the Western Brook Lamprey (Lampetra richardsoni), and the anadromous Western River Lamprey (Lampetra ayresii), and Pacific Lamprey (Entosphenus tridentatus). Lamprey have two primary life histories, anadromous (life spent in freshwater and saltwater, returning to natal streams to spawn) and resident (live only in freshwater). Both start life in silty deposits, where they filter feed and gain nutrients from detritus. Anadromous lamprey migrate downstream as they change into juvenile form, developing their signature circular mouths. Then, they swim out into the open ocean where they attach to marine animals and feed parasitically. Some resident species also become parasitic within freshwater creeks. Anadromous lamprey can spend upwards of seven years in the ocean before they transform into adults, stop feeding, and migrate upriver to spawn. Here the males will construct nests (known as redds) moving gravel with their mouth. Redds attract females and up to eight lamprey may occupy a single redd as they spawn. Following spawning, both resident and anadromous lamprey die.

Why are they Important

Lamprey serve important ecological and cultural niches across the Pacific Northwest. Ecologically, lamprey act as ecosystem engineers, adding structure to creeks by building redds. They are also an important food source for birds, mammals, and other fish, with spawning runs serving as a seasonally abundant food source.

Culturally, runs of lamprey provide an essential food and cultural resource for Tribes of the Pacific Northwest. Annual runs serve as the basis for traditional harvest practices, celebrations, and feasts. Subsistence harvest continues where healthy lamprey populations exist, such as the Willamette River. 

What are Their Threats?

Both anadromous and resident lamprey face major population declines influenced by poor water quality, loss of instream complexity, and other factors. Anadromous lamprey are particularly vulnerable to fish passage barriers, which may cause them to expend excess energy, prevent them from reaching spawning grounds, or trap them in areas of high predation. In coastal rivers, nonnative predators such as smallmouth bass can consume large quantities of larval and adult Lamprey, further reducing small populations.

Why are we Using eDNA to find them?

Environmental deoxyribonucleic acid or “eDNA” sampling is a scientific technique used to determine species presence or absence in an area. This method is usually applied to species that are otherwise difficult to find by traditional surveys, and works well in aquatic environments for species with certain life history strategies. Larval lamprey occupy consistent locations (burrows in silty sediment) and provide a steady source of genetic material into the surrounding fresh water. As such, eDNA sampling is an appropriate technique to determine which water bodies have lamprey present, and which do not. Using eDNA to identify active lamprey streams can inform future conservation and restoration efforts. Their presence can also be used as a bioindicator to assess the health and complexity of streams across the central coast.

Photo- Midcoast Staff