Session: Fish Response to Implementing ROD Flows
Wednesday, February 7, 2007 - 8:25 to 10:45 AM
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| In this session: | |
| Anadromous Salmonid Escapement/Total Run-size Responses | Wade Sinnen & Nina Hemphill |
| Juvenile Salmonid Abundance and Emigration Timing Relative to Trinity River Discharge | William Pinnix & Paul Petros |
| Adult Chinook Salmon Migration Behavior: Implications of Flow Management in the Trinity River | Josh Strange |
| Mercury Transport During High Flows in the Lower Trinity River | James Rytuba |
| Discussion Session: Fish Response to Implementing ROD Flows | |
Anadromous Salmonid Escapement/Total Run-size Responses
Wade Sinnen, CA Dept. of Fish and Game wsinnen@dfg.ca.gov (707) 822-5119
Nina Hemphill, Trinity River Rest. Program nhemphill@mp.usbr.gov (530) 623-1812
The Trinity River Restoration Program in Northern California is in the process of assessing the effects of restoration activities, especially flow on salmonids. Many of the restoration activities are aimed at increasing fry survival. Direct studies on fry or smolt populations have encountered large variances around the population estimates. The best data allowing for assessment of the response of populations to changes in flow is from returning adults. Of the three salmonids present in the system, one appears to be declining and two appear to be increasing. How much of this can be attributed to changing conditions associated with flow is very much a question because of the state of earlier and present datasets on juveniles.
We have conducted annual geographically stratified basin wide estimates of adult escapement and total run size since 1977. Since the onset of Constant Fractional Marking for hatchery chinook and marking of all hatchery steelhead and coho, the ratios of natural to hatchery fishes can be analyzed. Changes in summer and winter base flow released from Lewiston Dam changed from 150 cfs to 300 cfs in 1980. Throughout the 1980s and 1990s safety of dam releases and experimental high releases were made. We present the data on total run size separated in to grilse (2 year) and adults (3, 4, and 5 year) from 1977 to 2005. From 1991 (1997 for coho), we present the runs separated into natural and hatchery fishes.
Within the Klamath basin, we will compare natural and hatchery escapement in the Trinity and Klamath Rivers . Over the long term, the Trinity River frequently produces similar return numbers of adult fall chinook when compared to the Klamath mainstem. We will also present information on Trinity River Hatchery return rates for various release strategies and investigate how these return rates may be used as a surrogate for naturally produced populations.
Long-term data on adult Coho, Oncorhynchus kisutch indicate that conditions have improved since 1994. Escapement increases may be due cessation of harvest and the strong influence of hatchery practices on survivorship of hatchery coho. However, part of the increase is due to current improvements in river conditions on the Trinity River . We will present information on the interactive effects of flows and probable bottlenecks on adult returns for coho.
Natural steelhead, Oncorhynchus mykiss , has shown increases as indicated by adult long-term datasets from weirs. Many of the returning adults are of hatchery origins but these data indicate a change in the natural percentage over time. We will present information on the interactive effects of flows and adult returns for steelhead.
Our analyses looked for the effects of the flow changes in 1980, 1995, and again in 2001. We examined the effects of increasing summer and winter base flow to 300; increasing summer base flow to 450 and increasing spring flows. We first used multivariate Trees method to separate out which factors explained the most variation in the data. A wide range of variables was loaded into these analyses for each species to account for possible sources of variation from in- river condition, climate or upwelling. Factors included mean annual flow at Lewiston, Hoopa, and Terwer; mean flow at Lewiston in JFMA, MJJA, SOND, ocean temperature in March or April, and lastly an El Nino Index. We will present analyses on the effects of flows on adult returns for fall and spring chinook, coho, and fall run steelhead in the Trinity River.
Presentation notes:
Sinnen presented returns data of adult fish to counting weirs as follows: spring Chinook: 18,714, fall Chinook: 42,777, coho: 18,249, steelhead: 11,816. Using return rates for smolts, and estimates of fecundity, he back-calculated the numbers of smolts that are naturally produced per year in the Trinity River as follows: spring Chinook 1.2 million, fall Chinook 4.6 million, coho 63,000. Hatchery fish compose large proportions of the returning adults, up to 90 % of the coho. Hatchery fish appear to comprise a progressively larger proportion in recent years. Target returns are not being met for fall Chinook. However, coho returns may be the better indicator of improving river conditions, as they are not subjected to harvest losses; they are returning at above target levels.
Hemphill ran several statistical models to search for relationships of flow with adult returns. She noted that the change in flow since 1980 has had positive effects on fish returns, particularly spring Chinook.
Questions: What about ocean conditions? These were noted to be a big covariate factor on fish returns. Fall Chinook return trends do not relate to flows as well, and these fish need a lot of cover. It was noted that the run size of Chinook, coho and steelhead have increased over the period 1995 to 2005, but the hatchery component dominates.
Juvenile Salmonid Abundance and Emigration Timing Relative to Trinity River Discharge
William Pinnix, USFWS, AFWO, bill_pinnix@fws.gov , (707) 822-7201
Paul Petros, HVTFD, ppetros@pcweb.net , (530) 625-4267
Juvenile salmonid emigration from the mainstem Trinity River has been monitored by the Arcata Fish and Wildlife Office since 1988 with rotary screw traps used as the primary gear type since 1989. The Hoopa Tribal Fisheries Department (HVTFD) has operated rotary screw traps on the Trinity River annually since 1997, primarily to monitor juvenile salmonid emigrating from the 40-mile reach below the Lewiston dam. This presentation describes monitoring conducted by USFWS from 1992 through 2006 at the lower Trinity River trap site near Willow Creek , California , and by HVTFD from 2002 through 2006 at the upper Trinity River trap sites near Junction City and Helena , California . Catch data were used to calculate abundance indices for juvenile Chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch), and steelhead (O. mykiss). In addition, population estimates of juvenile Chinook salmon were derived via an intensive mark-recapture procedure from 2002 through 2006.
Chinook salmon emigration is characterized by a number of distinct emigration periods: late winter (January through early March); spring (mid-March through July); spring-hatchery (June through July); and fall-hatchery (October through November). Due to variation in installation dates, the late winter emigration period has only been adequately sampled by the upper trapping site 2 out of the 7 years presented. The late winter emigration period has not been adequately sampled by the lower-river trapping site over the period of record; however, in all years, age-0 Chinook salmon are caught the first day of sampling. The spring and spring-hatchery emigration periods was adequately sampled by both the upper and lower river trapping sites over the period of record. The fall-hatchery emigration period was sampled at the lower river trap site 10 of the 15 years presented, and 5 of the 7 years presented at the upper trap site.
Upper Trinity River spring emigration population estimates of natural age-0 Chinook salmon derived from mark-recapture and ad-clip analyses ranged from 799,000 in 2003 to 1,392,000 in 2002. Lower Trinity River spring emigration population estimates of natural age-0 Chinook salmon derived from mark-recapture and coded wire tag analysis ranged from 98,478 in 2006 to 1,991,560 in 2005. There was no clear relationship between spring river discharge (measured at Lewiston and Hoopa) and population estimates or abundance indices at either the upper or lower river trap sites, suggesting that factors other than river discharge play a larger role in regulating spring emigration period age-0 Chinook salmon population size.
Emigration timing of age-0 Chinook salmon at the lower river trap site appears to be related to river discharge and temperature, with fish emigrating earlier in the year in drier warmer years and later in the year in wetter colder years. There is no clear relationship between age-0 Chinook emigration timing and river discharge or water temperature regimes at the upper site.
Presentation notes:
Pinnex noted that the estimates were "flow based" for 1992-2006 and mark recapture for 2002-06. Emigration goals for timing are being met: 80 % of run is completed by July 9 for Chinook, June 4 for coho, and May 22 for steelhead. Paul Petros noted that, at upper river sites ( Junction City , and Pear Tree Gulch), coho leave quickly (March through June), natural steelhead leave March through May, and Chinook Late leave winter and spring. Abundance estimates were 4 million Chinook but with high year-to-year variation. These estimates were close to Sinnen's of the previous presentation. They recommend sampling in winter and creating a clear statement of objectives.
Questions on lower river trap efficiencies: 2% for Chinook. When flows are lower, the efficiencies are 4%. Efficiencies are up to 5% at the upper site.
Adult Chinook Salmon Migration Behavior: Implications of Flow Management in the Trinity River
Josh Strange, Yurok Tribal Fisheries Program, and School of Aquatic and Fishery Sciences - University of Washington, strange@u.washington.edu
Since the spring of 2002, the Yurok Tribal Fisheries Program has led a collaborative telemetry study of adult Chinook salmon (Oncorhynchus tshawytscha) migration in the Klamath Basin. The overarching goal of this research project is to comprehensively determine and understand adult Chinook salmon migration behavior throughout the spectrum of run-timing. Specific objectives included determining migration rates, thermal experience, estuary residence, run-timing, migration behavior patterns, and behavioral responses to environmental variables such as water temperature and river flow. This presentation will discuss results from this research with a focus on the effects of flow management in the Trinity River and potential opportunities for improvement.
Presentation notes:
There appears to be four distinct groups of Chinook: spring, summer, Klamath fall Chinook, and Trinity fall chinook. Spring fish come in when flows are high and temperatures are low, but not during floods. They target the month of April when temperatures are rising and flows are decreasing. Once they come in, they migrate steadily until Burnt Ranch Gorge where it is tougher going. Many did not make it past the gorge, especially if they were migrating during the rapid descent of the spring flows. Strange suggests that rapid decreases are harmful and a more gradual descending limb is recommended. Summer fish migrate very rapidly and starting early to late August. These summer fish could be actually be Trinity River Hatchery spring Chinook. Highest water temperatures they experience are 24o C. They migrate fast to get to cool water reach of 16o C at about river kilometer 175. Trinity fall Chinook start migrating in late August. They experience temperatures mostly below 20o C due to later run timing and therefore travel more slowly. They delay at Willow Creek Weir up to 30 days where water temperatures can be higher. If managers would pull the racks out, they can reduce delays. Klamath fall Chinook have more consistent migration behavior than Trinity River Fall Chinook. They tend to hold in cool water areas near Blue Creek to Weitchpec. They do not seem to respond to Trinity pulse flows. They are at greater risk of disease by Ich.
Questions: Strange recommends that the TRRP think of the Trinity system as ending at the Pacific Ocean . The TRRP needs to consider lower-Klamath effects on migration, emigration and pre-spawning mortality of Trinity fish.
Mercury Transport During High Flows in the Lower Trinity River
Dr. James J. Rytuba, U.S. Geological Survey, jrytuba@usgs.gov , 650-329-5418
Historic dredge and placer gold mining has left a legacy of mercury-enriched mine tailings and sediment in the Trinity River watershed. Under high flow conditions, tailings and mercury-enriched sediment are eroded and mercury and monomethyl mercury (MMeHg) are released into the river. Dredge tailings located in the flood plain consist of coarse-grained stacker cobble tailings and underlying sluice sands that are only rarely exposed. Mercury concentrations are highest in the sluice sands and grain-size analysis indicates that mercury values are highest in the finest size fraction, < 45 m, as much as 2500 ppb as compared to 70 ppb or less in the bulk sample.
Mercury concentrations in lower Trinity River waters are a function of both flow and location. In a given flow regime, lowest total mercury concentrations occur immediately below Lewiston dam and concentrations increase downstream to Hocker Flat. Under base flow conditions, 400 cfs, total mercury concentrations in the Trinity River water are very low, 0.43-0.78 ng/L near Lewiston , and increase downstream to 1.05-1.83 ng/L at Hocker Flat. Mercury concentrations in the filtered fraction (<0.45 um) range from 0.33-0.52 ng/L near Lewiston, and are only slightly higher downstream, 0.49-0.60 ng/L at Hocker Flat indicating that most of the Hg is associated with particles. MMeHg concentrations are very low under base flow conditions, 0.02-0.03 ng/L throughout this stretch of the river.
Under high flows established from controlled releases from the Lewiston Dam, total mercury concentrations increase with increasing flow and concentrations increase downstream from the Lewiston Dam to Hocker Flat. At an 11,000 cfs, total Hg concentration is 1.4 ng/L at Lewiston and increases to 8.7 ng/L at Hocker Flat. During ramp-up to higher flows, total Hg concentration peaks as a given flow is established and then decreases through time. There is a positive linear relationship between total suspended sediment and total Hg concentration, indicating that mercury is primarily transported sorbed to particulate phases. All measured values for total Hg are below the 12-ng/L water-quality objective for protection of wildlife.
Total Hg concentrations in waters from tributaries are lower than concentrations in the Trinity River, which indicates that mercury in the Trinity River is primarily derived from tailings and sediment in bank deposits. The relatively low Hg concentrations in Trinity River waters at Lewiston under all flow conditions at Lewiston reflect depletion of fine-grained sediment in this part of the river because of entrapment of mercury-enriched sediment behind the Lewiston Dam. The downstream increase in total Hg concentration under all flow conditions results from erosion of fine-grained sediment from dredge and placer tailings in the river stretch from Douglas City to Hocker Flat.
Sediments deposited during the highest controlled release, 11000 cfs, on the reconstructed Hocker Flat flood plain have low Hg concentrations, 50 ppb to 90 ppb because most of the mercury-enriched (170 to 200 ppb) fine-grained sediment (<20 m m) was transported downstream.
Presentation notes:
Mercury (Hg) transport primarily occurs during high flows. Most occurs as particulates.
The river is highly impacted by placer gold mining as dredge sluice fine material was "charged" with Hg during the recovery of gold. Sluice sands with high Hg were covered by stacker-cobble tailings during the dredging process. Today, these sand dredge tailings are a source of Hg, especially in high flows.
Questions: What about tributaries? Tributaries have low Hg, except Deadwood Creek, which also has high sulfates. This suggests mining activities. Hg is re-deposited at 2-3x higher concentrations at Hocker Flats. Concentrations are high in sands at Hockey Flat-2.5 ppm in the 20-32 um size class. Water concentrations are still below 12 ng/L, but could exceed this at flows above 10,000 cfs.
Discussion Session: Fish Response to Implementing ROD Flows
Panelists: Wade Sinnen, Nina Hemphill, Bill Pinnix, Paul Petros, Josh Strange, and Jim Rytuba
Question about costs regarding Strange's recommendation for a more gradual descending limb. Strange didn't consider costs. However, he thought cues will be felt by everything. Modifying the descending limb should be straightforward without incurring too many costs.
Sinnen noted that there are more adult returns to hatchery than are needed and asked whether the current release numbers of smolts are justified. The adult returns vary over the 7 years, one would need survival estimates ahead of time in order to know it is ok to release fewer smolts--and this is difficult. The hatchery is required to release a certain number of smolts, and therefore we need forecasts of survival rates.
What are some of the most important data/information gaps? Pinnex noted that the rotary screw traps are not started early enough, the weirs are not run late enough. We need to assess the difficulties and see what information we are we losing. There is a risk of losing equipment during high flows. There is not clear guidance on which population we should target. Petros noted that they are missing up to three-quarters of the outmigrants. Strange noted that tagging adults late in the season creates problems of mixing Chinook with coho and having a greater chance of high flows. We need more monitoring wild fish; three tagged fish went up Salmon River , but we did not get too many truly wild fish. We need prespawning mortality on spawning grounds. Sinnen noted that there are certain runs that are difficult to make estimates--steelhead are fall runs from early September to November and the winter runs have poor estimates of run size. We can't use a weir during high flows. Spring Chinook at Junction City is difficult to census due to high flows. Hemphill noted that they can't assess statistical effects of flow due mostly to poor data.
What is needed to monitor and validate effects of restoration? Strange noted that there used to be a historic summer run and it is not known what habitat and area was used by this run. We need good, long-term data sets and we need to commit to long-term budgets. Hemphill noted that they are really trying to evaluate the effectiveness of actions and the Integrated Assessment is trying to do this.
How reasonable is it to try to achieve goals of 64,000 returning adults in the Trinity when up to two-thirds of the population is harvested once the 35,000 Klamath basin floor is met? Sinnen noted that 64,000 natural adults in the Trinity River was only met once. So, this is a problem. Maybe the goals and the rationale need to be re-visited. Pinnex noted that in an ideal world they would do juvenile monitoring every 10 miles and at tributaries. They would estimate abundance, and could get survival between stations. But, this would be too expensive to actually do. Strange noted that we are essentially dealing with one watershed: the Klamath-Trinity. We need to address the inter-related factors of ocean harvest, two hatcheries, and two federal agencies, among other things. We may be headed toward a healthy hatchery population, but we may be losing the natives.
What are the effects of Hg on the lower Klamath? We have no data on how far it goes downstream; it likely goes to the estuary. Bioaccumulation will be addressed later in the symposium. Any recommendations on channel rehabilitation due to Hg? The overarching question is to be careful on how excavation occurs. If you are creating wetlands, don't do in areas with large amounts of sluice sands.
About the effects of ROD flows, we can't determine increased smolts from ROD flows exactly. We can detect a doubling, but we need more data to have a solid answer.
Integration Issues: does the panel want to change flow schedules? Strange reiterated that the rapid descending limb impacts spring Chinook but not the summer run. The summer run could dilute the spring and fall and this is bad.