Studies of Eulachon Smelt in Oregon and Washington: Project Completion Report, July 2010-June 2013
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Studies of Eulachon Smelt in Oregon and Washington: Project Completion Report, July 2010-June 2013

Category: Fish/Shellfish Research and Management - Fish/Shellfish Research

Date Published: September 2014

Number of Pages: 168

Author(s): Edited by Christine Mallette


Report A. We report on our progress at developing annual eulachon spawning stock biomass (SSB) estimates for the Columbia River population based on egg and larval production surveys from January 2011 through and including May 2013.

  • We sampled the Columbia River 29 days during a 20-week span in 2011 (weeks-of-the-year 3-22), 34 days during a 25-week span in 2011-2012 (weeks 50-21), and 43 days during a 30-week span in 2012-2013 (weeks 48-25).
    • Sample densities, and corresponding egg and larvae outflow estimates, peaked during week 12 (March 13-19) in 2011, during week 12 (March 11-17) in 2012, and during week 18 (Apr. 28 ¡V May 4) in 2013.
  • We sampled the Grays River 13 days during a15-week span in 2011(weeks-of-the-year 4-18), 13 days during a 22-week span in 2011/2012 (weeks 51-20), and 19 days during a 20-week span in 2012/2013 (weeks 52-19).
    • In the Grays River, eulachon egg and larvae outflow peaked during week 13 in 2011, during week 16 in 2012, and during week 14 in 2013.
  • Mainstem Columbia River SSB was: 3,300,000 pounds (1,500 metric tonnes) in 2011; 3,200,000 pounds (1,500 metric tonnes) in 2011-2012; and 9,650,000 pounds (4,400 metric tonnes) in 2012-2013.
    • These estimates are conservative.
      • If we had assumed there was egg to larvae mortality more females would have been needed to produce the larval production observed.
      • If we had assumed one of the more commonly reported gender ratios favoring males then the observed larval production came from a larger spawner estimate.
    • The main stem Columbia River SSB estimates are many times greater than the corresponding SSB estimates for the Fraser River (31 metric tonnes for 2011; 120 metric tonnes for 2012; and 100 metric tonnes for 2013).
    • The mainstem Columbia River SSB estimate does not capture spawning in Grays River or smaller watersheds like Skamokawa Creek which are downriver of the Clifton Channel/Price Island transect.
  • Grays River SSB was 700 pounds (0.3 metric tonne) in 2011; 900 pounds (0.4 metric tonne) in 2011-2012; and 2,300 pounds (1 metric tonne) in 2012-2013.
    • The Grays River SSB estimates are only about 0.02% of the values for the Columbia River.
    • However, the well document variability in eulachon spawning distribution in the Columbia River makes it prudent to continue to monitor the Grays River.
  • Having a long-term stock assessment program in the Columbia River would benefit the recovery effort and fisheries management.
    • The egg and larval production needs to be monitored over a 6-month or longer period (if possible starting in November and running through May).
    • Annual collection of adult eulachon in the estuary and lower reaches of the Columbia River is needed to properly parameterize the estimation.

Report B. We report on activities to characterize the freshwater distribution of eulachon eggs and larvae in: (1) the main stem of the Columbia River, (2) known or putative spawning tributaries of the Columbia River and (3) coastal streams in Oregon and Washington. The report summarizes work conducted from January 2011 through and including May 2013.

  • Biologists from the Oregon Department of Fish and Wildlife sampled eulachon eggs and larvae at fixed locations in the main stem Columbia River below Bonneville Dam using artificial substrates and ichthyoplankton nets from 10 January¡V31 May 2011 and 21 November 2011¡V24 July 2012.
    • The vast majority (93%) of eulachon larvae encountered by ODFW staff were collected during March of 2011 at sites between Cathlamet and Longview, Washington
  • Sampling to assess the current freshwater spawning distribution of eulachon also was conducted opportunistically in the Sandy River at several locations between approximately 3 and 5 river kilometers from the confluence with the Columbia River from 27 January¡V2 June 2011.
    • During the period sampled, two eggs were captured on artificial substrates while six eggs and seven larvae were encountered in oblique ichthyoplankton tows; no eggs or larvae were identified as eulachon.
  • District biologists opportunistically conducted 12 artificial substrate sets and 16 larval tows in the Umpqua River during 20 January¡V8 June 2011.
    • During this effort, no eggs were observed on artificial substrates. One egg and 15 larvae were collected in ichthyoplankton tows; however, none of these specimens were identified as eulachon.
  • Biologists from the Oregon Department of Fish and Wildlife set artificial substrates (nine sets) in the Coos River 24 January¡V28 February 2011.
    • No eggs from any species were encountered.
  • Biologists from Washington Department of Fish And Wildlife sampled 41 sites in 21 water bodies in the state of Washington (tributaries of the Columbia River and costal water bodies), and opportunistically at several sites in the main stem Columbia River near the ports of Longview and Kalama during 20 January 2011¡V7 May 2013.
    • Eulachon larvae and/or eggs were encountered at each site during all sampling events in tributaries of the Columbia River.
    • Eulachon larvae and/or eggs were encountered at 21% of the sites sampled in coastal water bodies.
    • As in tributaries to the Columbia River, eulachon eggs and/or larvae were encountered at each site during opportunistic sampling of the main stem Columbia River.

Report C. We report on our progress from April 2011 through and including October 2012 on determining and evaluating various factors influencing the catch of eulachon (Thaleichthys pacificus) by Washington ocean pink shrimp (Pandalus jordani) trawl vessels, in response to the listing of the southern Distinct Population Segment of eulachon as threatened under the Endangered Species Act. The shrimp trawl fishery was listed second among the severity of threats impacting the recovery of eulachon stocks. With bycatch data lacking for the Washington pink shrimp fleet, the Washington Department of Fish and Wildlife sought and was granted funding to place observers onboard vessels to collect catch composition data at the tow level. We present project results for eulachon; an expanded WDFW technical report (in process) addresses results for other species or categories of species (rockfish and flatfish) encountered during the study.

  • In 2011, 24% of trips landing in a Washington port were observed. Following reduced funding in 2012, 16% of trips landed in a Washington port were observed.
  • Eulachon bycatch was estimated at 7.8 metric tons (17,132 pounds) in 2011 and 171 metric tons (378,011 pounds) in 2012.
    • During both years, pink shrimp production was comparatively strong.
    • The increase in bycatch in 2012 also occurred at the same time as fishery regulations reduced the allowable bar spacing for fin fish excluders to 0.75 inch (19mm).
    • Results indicate a significant interaction between gear type (excluder bar-spacing) and month and a significant month effect on bycatch.
    • Generally, spatial distribution results point to the co-occurrence of eulachon and pink shrimp. The depth-bycatch relationship was statistically different in each month and overall, but not biologically significant.
    • The average time per tow was approximately 100 minutes. There was no significant interaction between tow time and month and the overall time-bycatch relationship was significant and the same across all months, but not very strong.
  • 3,311 total eulachon were randomly sampled at the tow level for length; 2,355 in 2011 and 956 in 2012.
    • Reduced funding and comparatively greater bycatch account for the lesser amount sampled in 2012
    • Eulachon fork length ranged from 74 to 231mm during the two years of observation
      • 2011 had a median fork length of 181mm while 2012 had a median fork length of 127mm.
      • 2011 had a mean fork length of 178 mm while 2012 had a mean fork length of 128mm, suggesting that within year length variation is low.
    • No significant difference in eulachon size by tow depth or by bar spacing are evident.
    • Using the scheme used by Fisheries and Oceans Canada (DFO), we were able to determine that different age ranges were present in 2011 and 2012; age 1+ and age 2+ in 2011 and only predominantly age 1+ in 2012.
  • Genetic samples were collected from many length-measured eulachon and, pending funding for analysis, could contribute further to our understanding of eulachon in the marine environment. These samples are archived with the WDFW Genetics Unit in Olympia.

Accomplishments not Documented in Reports A, B or C

  • Beyond preservation of genetic samples, genetic analysis was curtailed due to cuts to the project budget.
  • The following genetic sample collections are currently archived at the WDFW Molecular Genetics Laboratory in Olympia, Washington:
    • Cowlitz River (MGL code 09DI) N=108
    • Cowlitz River Tribal Sample (MGL code 13AU) N=62
    • Columbia River Adults (MGL code 13CY) N=69
    • 2011 Washington Trawl (MGL code 11DL) N=769
    • Eulachon by-catch, shrimp fishery (MGL code 12DT) N=435
  • Several hundred additional genetic samples collected from larval surveys in the Columbia River and various Coastal rivers are undergoing verification at the WDFW Region 5 Laboratory in Vancouver, Washington. After processing these will be sent to the WDFW Molecular Genetics Laboratory by October 31, 2014 for archiving.
  • The WDFW Molecular Genetics Laboratory acquired funding from a Section 6 grant from NOAA and Washington State General Funds to standardize their laboratory to the Canadian Department of Fish and Oceans¡¦ Lab.
    • WDFW Molecular Genetics Laboratory obtained 96 Eulachon DNA samples from DFO and genotyped the samples at 14 microsatellite loci. Allele bins were named according to DFO nomenclature such that genotypes developed by WDFW could be compared with original genotypes from DFO for the same individuals. We used this comparison to confirm that allele calls matched between WDFW and DFO.
      • There were 13 differences between genotypes (out of 1392 total) where one agency scored a heterozygote (two different sized alleles) and the other agency scored a homozygote (two same sized alleles). In these cases, one allele was missed in a heterozygote such that it appeared to be a homozygote. This scoring issue is known as ¡§large-allele drop-out¡¨ where the larger-sized allele amplifies poorly or not at all, and is missed during scoring. However, these differences constituted less than 1% of the data set.
      • Five Eulachon loci were hyper-variable and had between 50 and 100 alleles per locus.
    • Because the standardization data set included 23% to 73% of the alleles at any single locus, mostly from the center of the allele size distribution, a second round of standardization may be necessary to include alleles that were absent from this data set. This will ensure that allele nomenclature remains standardized throughout allele size ranges.
  • The Canadian DFO and Columbia River Inter-Tribal Fish Commission (CRITFC) geneticists have been working to develop some Single Nucleotide Polymorphisms (SNPs) for eulachon.
    • WDFW provided the CRITFC genetic laboratory at the Hagerman Fish Culture Experimental Station , Idaho, with 120 samples from the 2013 field work for use in developing the SNPs library.
    • WDFW Molecular Genetics Laboratory will be working toward having their eulachon baseline genotyped with SNPs in addition to microsatellites.
  • Under the marine life stage objective, we conducted numerous formal meetings with industry, plus produced the short project highlight video intended for posting to the WDFW website.
  • Under the marine life stage objective, the project originally proposed to conduct experiments on gear-related bycatch reduction. This work was accomplished by ODFW through another funding source. The reduced bar spacing modification to the fin fish excluder devices has been adopted by the pink shrimp trawl industry, and research continues to explore further mechanical and operational modifications to the shrimp trawl fleet that reduce eulachon bycatch levels.
  • Under the stock assessment objective, the proposed task to determine fecundity, sex, and age on adult samples was hindered by the project budget cuts, and by the closure of fisheries. Through additional NMFS regional funding (and collaboration with the NMFS Point Adams Research Station and the Cowlitz Indian Tribe) adult samples were obtained during 2013 both in estuary and lower main stem reaches of the Columbia River, and in the Cowlitz River. WDFW was able to:
    • Developed a spawning scale to differentiate eulachon gonad morphology,
    • Sent nine unusual gonad samples to the U.S. Fish and Wildlife Service (USFWS) Bozeman Fish Technology Center for histological assessment (all samples confirmed to be from spent fish and not abnormal or infected),
    • Determined that 5% by weight sampling of gonads could yield reasonably accurate and efficient estimates of the true fecundity,
    • Derived an average fecundity value,
    • Confirmed that there was a strong length-fecundity relationship,
    • Discovered that the age composition was overall younger than assumed (2013 run was predominately Age 2, and 3, with some 4; versus the assumed 3, 4 and some Age 5 used in past run predictions), and
    • Observed that the Gonadosomatic Index (GSI) for female eulachon returning in 2013 was consistently 20% throughout all size classes.
  • Under the stock assessment objective, one task was to annually compile environmental correlates that may help in the prediction of eulachon adult run strength. Measures of the Pacific Decadal Oscillation (PDO) and Multivariate ENSO Index (MEI; El Nino/ La Nina) were gathered from the internet. In addition, biological information from the Canadian government was obtained such as the eulachon biomass and composition in the West-Coast Vancouver Island (WCVI) shrimp trawl surveys, and Fraser River eulachon SSB estimates.

Presentations have been made at various meetings with regional resource agencies concerning the findings of the project. A presentation summarizing the activities and results of the Section 6 grant project was made at the Washington/British Columbia Chapter of the American Fisheries Society Annual Meeting in Vancouver, Washington on March 26, 2014 (Phillip Dionne presenting, numerous co-authors).

Suggested Citation:
Recommended Citation for a Chapter or Appendix in the Report:
James, B.W., O.P. Langness, P.E. Dionne, C.W. Wagemann and B.J. Cady. 2014. “Columbia River Eulachon Spawning Stock Biomass Estimation.” Report A, In C. Mallette (Ed.), Studies of Eulachon Smelt in Oregon and Washington, prepared for the National Oceanic and Atmospheric Administration, Washington, DC, by the Oregon Department of Fish and Wildlife and the Washington Department of Fish and Wildlife. Grant No.: NA10NMF4720038.