Purpose of the project:

Pacific Lamprey were once prolific throughout their historical range which stretched from Alaska to northern Baja California. Over time their numbers have significantly declined in abundance and distribution, creating ripple effects to the ecological connections they have with other iconic species and the aquatic habitats we all depend on. Despite being considered the southernmost boundary of the Pacific Lamprey’s distribution, San Luis Obispo Creek boasted a healthy lamprey population when surveyed by biologists from US Fish & Wildlife Service (USFWS) and Western Fishes in 2004. Unfortunately, a return visit in 2011 resulted in the realization that the population had been extirpated, and a collaborative effort was initiated to answer the questions of why, and whether the population could be revitalized.

Following an enthusiastically attended public presentation and discussion at the local library, the Central California Coast Lamprey Working Group (consisting of California Department of Fish & Wildlife (CDFW), City of San Luis Obispo, San Luis Obispo Land Conservancy, Western Fishes, and USFWS) was formed with the mission of returning lamprey to San Luis Obispo Creek. Ultimately the cause of the disappearance of Pacific Lamprey in the creek was determined to be the 2006 installation of a tidal weir at the bottom of the drainage. The weir was intended to enhance passage for endangered steelhead, but its design resulted in a complete barrier for lamprey.

In 2013, the working group designed and installed an innovative and economical solution made from reclaimed materials – a curved piece of metal placed over the weir affectionately called a “lamp ramp”, and costing less than $315. It took a few years, but finally, in 2017 local observers reported adult Pacific Lamprey building nests in the creek, indicating that the population had recolonized without the need of human facilitated reintroduction. Not only did this natural recolonization save valuable resources in terms of time and money, it also indicated that removing barriers could open the door to natural recolonization in other watersheds, and potentially those where Pacific Lamprey have been absent for generations.

To explore this further, in 2018 the Pacific Lamprey Conservation Initiative (PLCI) contributed NFHP funding to support an assessment by Western Fishes and USFWS of habitats in coastal drainages in the southern extent of the historical distribution of Pacific Lamprey, and a consideration of suitable approaches to reestablishing their populations through either active intervention or natural processes.

In addition to the natural recolonization of San Luis Obispo Creek, the assessment also considered the recolonization of the Carmel River following the removal of the San Clemente Dam (located north of San Luis Obispo, and also in the California South Central Coast Regional Management Unit), and recent observations of Pacific Lamprey in other coastal rivers in southern California. The resulting findings indicate that Pacific Lamprey can return to coastal drainages that they were previously extirpated from, and reestablish viable populations, without active reintroduction efforts. This underscores the importance of focused conservation efforts that identify and address barriers and other factors that may have led to the loss of the species in order to facilitate natural recolonization.

Human Interest/Community Benefit:

This project and the successful return of Pacific Lamprey to San Luis Obispo Creek have sparked new local interest in the species. The working group plans to continue monitoring the return of Pacific Lamprey to San Luis Obispo Creek using a novel video monitoring system installed at the weir in December 2019. Within a few weeks of installation, lampreys were recorded making their way into the creek. With help from the California Conservation Corps’ Watershed Stewards Program, City biologists will also monitor adult lamprey returns and where they build their nests (also known as redds).

The City of San Luis Obispo is also partnering with California Polytechnic State University (Cal Poly) to study the ecological niche that lamprey fill in the stream system, including their potential to reduce pathogens in the creek.

The Central Coast Lamprey Working Group and other partners in the region are working together to better understand how and why Pacific Lamprey return, and explore how lessons learned in from this project can be implemented to assist in recovery efforts throughout the historical range of Pacific Lamprey.

Project Timeline:

2004 – Surveyed by Goodman (USFWS) and Reid (Western Fishes) and lamprey were readily encountered.
2006 – Marre Weir modified to provide steelhead passage.
2011 – Goodman and Reid surveyed the drainage and lampreys were absent. The first meeting of the working group. Identified the passage issue at Marre Weir.
2012 - 2016 – Annual surveys of the drainage with no detections of lampreys. Annual meetings of the working group.
2013 – Working group designed and installed a lamprey passage structure.
2017 – Lamprey naturally recolonized the drainage.
2017 - Ongoing – Annual monitoring of the population to track distribution, growth, reproductive timing, relative abundance, and more. Annual working group meetings.
2019 - Ongoing – installation of a lamprey specific video monitoring system tracking passage by the Marre Weir.

Economic Calculator results:

Jobs: 0.3006
Total Sales: USD 32,298.35
Value Added: USD 17,641.38
Income: USD 13,898.90

Partners:

The following partners have provided support for the development, implementation, and/or funding of this effort:
• California Conservation Corps’ Watershed Stewards Program
• California Department of Fish & Wildlife
• California Polytechnic State University (Cal Poly)
• City of San Luis Obispo
• Pacific Lamprey Conservation Initiative
• San Luis Obispo Land Conservancy
• United Water District
• US Fish & Wildlife Service
• US Forest Service
• Western Fishes