Unexpected diversity found in California's lamprey fish

A recent study led by the University of California, Davis and published in the North American Journal of Fisheries Management, has uncovered two potential new species of lamprey fish in California waters. 

This discovery suggests a greater diversity of this ancient animal in the state than previously known, which could impact how these jawless fish are managed.

Unexpected diversity 

PhD candidate Grace Auringer, the lead author of the study, emphasized the unexpected diversity found. “We found diversity that has never been reported,” she said. “We found two groups of fish in Napa River and Alameda Creek that are very genetically different from other samples along the West Coast.”

While eight species of lampreys are known in California, the study suggests that some species thought to be separate may not be, necessitating further research to define these new species accurately. 

Auringer described lampreys as a “really understudied group of fish.” These species are crucial for the food chain and contribute significantly to water quality and nutrient levels in waterways.

Unique life cycle 

Lampreys, which date back over 350 million years, have a unique life cycle. They are boneless, jawless fish with eel-like bodies, and their larval stages can last up to nine years. 

As they mature, some lamprey fish become parasitic, while others cease feeding, likely living off stored energy. Research affiliate Matthew “Mac” Campbell noted the challenges in distinguishing between species during the larval stage.

Focus of the research 

The study focused on 19 areas across various river basins in California. Researchers collaborated with staff from various districts, state agencies, and utilities to collect lamprey fin samples for analysis at UC Davis. The research also utilized archived tissue samples from the Columbia River Inter-Tribal Fish Commission.

Using DNA barcoding, specifically isolating the mitochondrial cytochrome b gene, the scientists identified species types and their evolutionary relationships. “The amount of diversity that we saw is quite remarkable,” Auringer said, highlighting the potential for future studies.

Study implications 

The research is significant as lamprey fish populations are thought to be declining in the West. The two newly discovered species belong to the Lampetra genus, adding complexity to California’s lamprey narrative. Identifying these species can aid in refining management practices, protecting populations, and supporting ecosystems.

Lampreys provide ecosystem benefits, such as improving water quality, maintaining streambeds, cycling nutrients, and serving as a food source for various predators. 

The research underscores the need for further study, including genomic sequencing, to understand and define the new potential lamprey species and the broader population.

More about lamprey fish

Lamprey fish belong to the ancient lineage of jawless fish, known as Agnatha. Unlike most modern fish, lampreys don’t have typical jaws. Instead, they have a unique, round, sucker-like mouth filled with rows of sharp teeth. This mouth structure allows them to attach to other fish and feed on their blood and body fluids, making them parasitic in nature.

Appearance

Lampreys are often recognized by their elongated, eel-like bodies. They lack the paired fins and scales that are typical of many fish, giving them a distinctive, smooth appearance. 

Life cycle

Their life cycle is also quite interesting. They begin life as larvae, living in freshwater sediments and feeding on microorganisms. This larval stage can last several years. As they mature, they undergo a significant transformation, developing their characteristic sucker mouth and transitioning to a parasitic lifestyle if they are of a species that feeds on other fish.

Habitat

In terms of habitat, lampreys are found in coastal and fresh waters in temperate regions. Some species are anadromous, meaning they migrate from saltwater to freshwater to spawn. Their spawning process is a notable event: they build nests by moving stones with their mouths, and after spawning, most species die.

Ecological impact

Lampreys have a significant ecological impact. In some cultures, they are considered a delicacy and are fished for food. However, in places where they are non-native, such as the Great Lakes in North America, they can become invasive and cause damage to the local fish populations. 

Efforts to control their numbers in such areas are ongoing and involve various methods, including barriers and targeted pesticides that affect their larvae.

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