Photo: Stuart Allen's Lake Berryessa Line

The Putah-Cache Bioregion Project:

Fish Sampling
Progress Report 1997- 98

Who | What | Where | Publications

Michael P. Marchetti (mpmarchetti) & Peter B. Moyle, Ph.D (pbmoyle)
May 12, 1998

  1. Fish Monitoring - Lower Putah Creek
  2. Larval Fish Sampling - Putah Creek
  3. Chinook Salmon Monitoring - Putah Creek
  4. Larval Ecology of Sacramento Perch and Hitch (undergraduate project)
  5. Tule Perch Mating Behavior (undergraduate project)
  6. Fish Sampling - Lower Cache Creek

Fish Monitoring - Putah Creek

This study began in the spring of 1994. The goals of the initial investigation were to determine distribution and relative abundance of fishes within the lower 23 miles of Putah Creek. Eight sites were chosen to reflect changes in downstream habitat:
  1. directly below Putah Diversion Dam (PDD),
  2. the reach where Dry Creek enters Putah,
  3. below the Highway 505 bridge,
  4. UC Davis’ Russell Ranch property,
  5. downstream of the Stevenson Road bridge,
  6. the UC Davis picnic grounds,
  7. the Old Davis Road bridge, and
  8. downstream of Mace Boulevard bridge.
Each of these sites was sampled once a month for the first year, using hand seines, electroshocking (where appropriate), and gill nets. For all subsequent years, each of these sites has been sampled once a month during late spring (May) through late summer (Oct.). The first two years of data were used extensively during the Putah Creek trial (Feb-March 1996).

At each sampling date, fish are collected using the methods above. The following data is recorded for all fish caught: species, standard length, weight, and relative number of external parasites. The aquatic habitat is evaluated (substrate, aquatic cover, habitat types) and the following environmental data is recorded: pH, turbidity (NTU), conductivity (umhos), temperature (°C) and flow (cfs). All of this data is entered into a computer database for analysis.

The continued monitoring of the fishes of Lower Putah Creek is part of a larger project to examine the distribution and abundance of native fishes and fish communities in low elevation streams in California. The study is designed to investigate the following questions:

  1. Is native fish abundance linked to stream flow?
  2. How does this link vary from year to year?
  3. How are fish communities structured in regulated streams?
  4. What factors (biotic and abiotic) influence native fish distribution and abundance?
  5. What factors (biotic and abiotic) influence non-native fish distribution and abundance?
The larger project is part of the dissertation research of Mr. Marchetti.

During the spring and summer of 1997 the standard monitoring schedule was continued. The following observations were made:

  • High flows uncovered large areas of spawning sized gravels during the winter of 1996-97. Many of these areas were in the middle reaches of the lower creek (Russell Ranch - Pedrick Rd). These gravel areas had been heavily silted in before the flows.
  • Flows in the creek were high during the early spring and continued above average through the entire summer. Much of the added flow (above releases from PDD) is believed to have originated through ground water inflow, again due to the large amount of rain early in the season.
  • The creek maintained continuous flow out into the Yolo Bypass throughout the year.
  • Native fish spawning was extensive and large numbers of juvenile fish were observed and recorded (predominately Sacramento pikeminnow, Sacramento sucker and prickly sculpin). This large recruitment may have been due to the increased spawning gravels and increased flows. A particularly large increase in native fish was observed in the Russell Ranch and Stevenson Road area.
  • Non native fish abundance was down. The decreases occurred mainly for the introduced centrarchid (sunfish) species such as bluegill, green sunfish and largemouth bass. These decreases may have been due to the large flushing flows (45 days >1000 cfs) early in the year.
  • A significant increase in smallmouth bass abundance was noted for the last two years (1996, 97). This increase was noted mainly at the Stevenson Rd and Russell Ranch sites. Smallmouth bass used to be widely distributed in the lower creek and typically require cooler water temperature and more regular flows indicative of the pre-PDD condition.
  • A number of Pacific lamprey ammocetes were captured in the PDD area. These ammocetes were extremely small and would likely have been spawned in the winter/spring of either 1996 or 1997 indicating successful recruitment in recent years. Lampreys are anadromous, like salmon.

Larval Fish Sampling

A study was initiated to describe the temporal and spatial distribution of larval fish in Lower Putah Creek. The study had four goals:
  1. describe the temporal occurrence of native and introduced fish larvae;
  2. compare species distribution and abundance at two widely separated sites (Dry Creek, Pedrick Road);
  3. compare two methods of capture (light traps and drift nets) in terms of selectivity and effectiveness;
  4. compare abundance and species composition of larvae captured in drift nets before and after sunset.
Both sites were sampled once a week for the period March 1 through Aug. 1 1997. All four of the goals were met in terms of data collected. The study used a team of ten undergraduate assistants. This study is part of Mr. Marchetti’s dissertation and is being written up for publication.

Preliminary results:

  • Native larval fish occur earlier in the year (March through May) than exotic fish (May through July). This corresponds to the known information regarding species specific spawning times. The native fish may be responding to environmental cues different from the non native fish (high flows and low temperature vs. low flows and warm temperature respectively).
  • The Dry Creek site had an order of magnitude more larval fish than the Pedrick Road site in the drift nets. The Dry Creek site also had two orders of magnitude more native larvae than introduced larvae using both sampling techniques. The Pedrick Road site had three times as many introduced larvae as native larvae. This information suggests that the Dry Creek site provides better (or more) spawning and rearing habitat for native fish than the downstream Pedrick Road site.
  • A preliminary comparison of the two methods of capture suggests that a sampling approach using both techniques is appropriate for a full characterization of low elevation California streams. The drift nets appear to be a more consistent method to capture larvae early in the season, when the flows are high, and larvae which exhibit a propensity to drift. The native fish both appear early in the season and are more inclined to drift than non native centrarchids. The light traps are an excellent method to sample the slow moving and pool type habitats that are more abundant later in the season. Light traps, due to their passive sampling nature, are more sensitive to placement on a local microhabitat scale and are therefore good at sampling centrarchid species which tend to be locally abundant near their nest.
A comparison between drift nets set an hour before sunset and nets set an hour after sunset at the same location suggests that larval fish are significantly more abundant in the drift after sunset. Three possibilities may account for this behavior.
  1. The larval fish are more active after dark because they are less visible to predators and find it an opportune time to move to downstream habitats.
  2. The larvae are responding to the movement of their food (small invertebrates) which may be more available after dark.
  3. The larvae lose their ability to orient visually to habitat features after dark, so are more likely to encounter currents which can sweep them away.

Chinook Salmon Monitoring

Chinook salmon juveniles were first observed in the creek during routine sampling in the spring of 1995 (at Dry Creek, Old Davis Road, and Mace Boulevard) and again in the spring of 1997 (at Pedrick Road). Adult salmon were observed spawning in the creek during the winter 1997-98 in the vicinity of Stevenson Rd Bridge, and spawned out carcasses were found. High flows early in 1998 prevented sampling for juveniles prior to late March. On 3/26/98 Marchetti and four undergraduates seined in the vicinity of Pedrick Road and caught seven juvenile Chinook salmon. On the same day, the region near Stevenson Road Bridge was sampled and two juvenile salmon were captured. On 3/31/98 the same crew collected approximately 30 juvenile salmon in the region surrounding Mace Boulevard. On 5/8/98, two juvenile salmon were captured below Pedrick Rd by Moyle and Marchetti. An irregular sampling regime for salmon will continue through May.

Larval Ecology of Sacramento Perch and Hitch

An undergraduate student (Heather Logan) began a project to characterize the temporal and environmental ecology of Sacramento perch (Archoplites interruptus) and hitch (Lavinia exilicauda) (both native species) in a farm pond located north west of Davis (the pond is on Mary Scheidt’s property near the Yolo Co. airport). The larval ecology of both species is little known. The pond was created by Ms. Scheidt in 1995; in 1995 and 1996 we stocked it with adult hitch and adult Sacramento perch. In the early spring of 1997, Ms. Logan began a weekly sampling of the larval fish in the pond that continued until early summer. She has sorted all the samples and has begun the task of identifying the larval fish. The data will be collected in a data base and will be used to characterize the ecological and temporal aspects of both species of fish. The project is expected to be completed by the end of spring quarter 1998.

Mating Behavior of Tule Perch

An undergraduate student (Ryon Kurth) began a project to examine aspects of tule perch (Hysterocarpus traskii) mating behavior. The tule perch is unique among California’s freshwater native fish fauna, in that it exhibits internal fertilization and gives birth to live young. The mating and courtship behavior of this species is little studied and has very rarely even been observed. After some preliminary work with the species (collected from Putah Creek), Mr. Kurth and Mr. Marchetti were able to get the fish to mate within an observation tank. Mr. Kurth began an experiment to address the question of whether color dimorphism within the species has an effect on mate choice. He designed and implemented the study to address this question and we are writing the results up for publication.

Fish Sampling of Lower Cache Creek

During June and July, 1997, a fish and habitat survey was conducted on lower Cache Creek, from Capay Dam downstream to the Cache Settling Basin. The survey was conducted by three undergraduates (Josh Pederson, Brennan Mulrooney, and Andy Fecko) who were supervised by Melody Mathews. Ms Mathews is a recent UCD graduate in fisheries who was hired for this project by the Cache Creek Conservancy. Seven sample sites were chosen and systematically sampled for fish (using seines, electrofishers, and angling) and the habitats characterized. Five of the 18 species captured were natives but they accounted for only 10% of the total fish. An exotic minnow, the red shiner (Cyprinella lutrensis) accounted for 77% of all fish captured and it was abundant at all sites. This species has probably been in the creek less than 10 years. The most abundant native fishes were Sacramento sucker and hitch. An unexpected capture was of a few speckled dace (Rhinichthys osculus), a native normally associated with cool, permanent waters. Only 6% of the fish were over 100 mm (4 inches) total length, indicating the lack of deep pools and complex cover in most of the creek. Most of the creek consisted of shallow riffles in a wide, exposed channel, that dried up in places as the season progressed. The native fishes are most likely limited by the lack of habitat for adult fish and the low summer flows. The final report on this project has been written by Josh Peterson. The results have also been summarized in the newsletter of the Cache Creek Conservancy.

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