Status of Eulachon in Washington: Annual Report July 2018 – June 2019

The National Marine Fisheries Service (NMFS) listed the southern Distinct Population Segment (DPS) of Thaleichthys pacificus, also known as “Eulachon,” as threatened under the Endangered Species Act (ESA), effective May 17, 2010 (74 FR 13012; 50 CFR Part 223: 13012-13024; March 18, 2010). The southern DPS consists of all eulachon spawning south of the Dixon Entrance/ Nass River, BC. The Columbia River has been identified as one of the primary spawning rivers of the Southern DPS. For over a century, the status of the eulachon run to the Columbia River was measured by the number of pounds of fish landed during commercial fisheries. Larval sampling in the Columbia River was first attempted in 1946 (Smith and Saalfeld 1955). A few other eulachon larval sampling events occurred in the decades that followed (Hymer 1994). In 1994, Washington Department of Fish and Wildlife (WDFW) began to consistently monitor the peak outmigration larval density in the Cowlitz River. Over the next few years monitoring was begun in other tributaries of the Columbia River. The first survey in the Grays River was done in 1998 (Table 19 in JCRMS 2014). In 1995, eulachon larval sampling was initiated in the mainstem Columbia River downstream from the mouth of the Cowlitz River. In 1997, a transect across the lower Columbia River from navigation marker number 35 at Price Island and across the downstream end of Clifton Channel (near Columbia River kilometer 55) was established as an index to be sampled systematically every year (WDFW and ODFW 2001). Until recently, sampling in the mainstem Columbia River and the tributaries was concentrated around the estimated time of peak larval outflow.

In the “Summary of Scientific Conclusions of the Review of the Status of Eulachon (Thaleichthys pacificus) in Washington and Oregon” (Status Review; BRT 2008), the Biological Review Team (BRT) concluded that, “…eulachon are a relatively poorly monitored species….” The spawner biomass estimates established in Canadian rivers were, “regarded by the BRT as constituting the best scientific and commercial data available for recent eulachon abundance in the DPS.” The Canadian approach was to systematically sample the eulachon larval density at multiple mainstem sites throughout the whole period of larval outflow, expand that by the river discharge to obtain an estimation of total season outflow of larvae, and then back calculate how many adults must have produced that larval outflow. This adult equivalent was expressed in metric tonnes (megagrams) and hence referred to as the Spawning Stock Biomass (SSB).

In the Federal Recovery Outline for Eulachon Southern DPS of June 21, 2013, NMFS states that it has been difficult to evaluate the status of eulachon “due to the lack of reliable long term data”, and that available abundance data “are confounded by intermittent reporting, fishery-dependent data, and the lack of directed sampling” (NMFS-NWR 2013). The Federal Recovery Outline for Eulachon Southern DPS, identifies “in-river spawning stock biomass surveys to develop long-term eulachon spawner abundance estimates for all four sub-populations.”, as the first item in the list of recovery tasks to improve potential for recovery.

The Endangered Species Recovery Plan for Southern Distinct Population Segment of Eulachon (Thaleichthys pacificus) was published on September 6, 2017. In this document, the first recovery action is to, “establish a Eulachon Technical Recovery and Implementation Team.” The second action item is to, “Implement outreach and education strategies.” Action 3 is near-term research priorities. The first of the eight research priorities (3.1) is to, “conduct annual in-river spawning stock biomass surveys in spawning areas with high-to-moderate spawning frequency to develop long-term high-resolution abundance estimations for each subpopulation of eulachon.”