| Methods: |
Trapping and relocation at Wallace Weir and the CBDC
On a daily basis CDFW will check the fish trap at the Wallace Weir Fish Facility. The facility will impound all fish species, therefore all fish present will be identified and removed from the fish collection facility. ESA-listed species captured in the facility will be prioritized for collection, processing, transportation, and release back to the Sacramento River following the approved protocol. The Sacramento River release location(s) will be evaluated and may vary with species and time of year, but will only occur in locations where CDWR or CDFW have property rights or landowner permission to carry out fish releases.
When feasible, biological data will be collected for all Chinook salmon, steelhead, and sturgeon captured and relocated (species and or run identification, fork length, sex, physical condition, ad-clip status for salmonids, and tissue samples for genetic analysis). Captured steelhead may receive a PIT tag as part of CDFW's Steelhead Monitoring Program. When large numbers of Chinook salmon are encountered, biological data will be collected on a systematic subsample of fish (every nth fish sampled). Tissue samples for genetic analysis will be collected and will be labeled and preserved using standard techniques.
To allow information to be gathered on movement, survival, and spawning success after releases, salmonids and sturgeon that are rescued will be marked or tagged (Floy tags, PIT tags, and/or acoustic tags may be used). Species other than Target Species or Species of Management Concern that are found in the facility will be passed through to the upstream or downstream side of the weir using infrastructure incorporated into the facility.
When fish passage is thought to occur at the Wallace Weir Fish Facility, CDFW will initiate a roving survey using DIDSON imagery at known choke points within the CBDC and associated tributaries to look for focal species. A DIDSON 300 unit with a 60 meter cord will be used for these purposes. The video quality of this unit allows for images of fish and substrate characteristics in turbid water bodies. The unit has a 30 meter viewing range, critical for making observations in many of the choke points in the CBDC where fish may congregate. The DIDSON unit will be attached to an aluminum staff. Field staff will deploy the unit by hand at each monitoring location.
DIDSON sonar images will be read in real-time by field staff as images are being acquired and recorded to an associated field laptop hard drive. DIDSON image files from each site will be transferred to a dedicated electronic storage file in the CDFW Region II office when staff return from the field. Downloaded videos will be reviewed at the office the same day they were recorded to ensure presence or absence of focal species at sampling locations. If a focal species is observed while in the field or upon review of DIDSON video while at the office, field staff will immediately inform project leads who will initiate rescue operations.
Monitoring and Rescue at Fremont and Tisdale Weirs
Block nets and hoop nets will be used to capture entrained adult sturgeon. Acoustic tags will be surgically implanted by trained department staff (training by UCD/USBR staff) and data will be recorded on fish size, condition, and time of release. Additionally, abiotic data will be recorded including river conditions prior to and during entrainment and the duration of entrainment will be calculated to the extent possible. After capture, adults will be held in a fish stretcher or cradle, ventral side up. Gills will be continually irrigated with water. Fish will be quickly assessed for physical condition, then acoustically tagged and PIT tagged. For insertion of the acoustic tag, a small incision (11mm for V9 tags) will be made between the third and fourth ventral scute, approximately 2-3mm off the ventral midline. The tag will then be inserted into the peritoneal cavity and closed with a 4/0 PDSII absorbable suture. To help with external identification, a photograph will be taken prior to release and fish will be externally tagged with two Floy tags. Genetic samples may also be taken and retained by CDFW staff.
If adult or juvenile salmonids are found to be entrained, they will be captured using beach seines. Data collected will be similar to that described for sturgeon, however salmonids will not receive acoustic tags. Adult Chinook salmon will however receive two Floy tags and be sampled for tissues. Additionally, rescued steelhead may receive a PIT tag as part of CDFW's Steelhead Monitoring Program. After processing, fish will be transported to the closest accessible point on the Sacramento River to the rescue site. If this distance is less than 100 yards fish will be directly transported to the river using the stretcher. If this distance is greater than 100 yards then fish will be placed in a specialized holding tub with aerated water and transported by truck to the nearest possible release location. Fish will not be anesthetized during the tagging process since the use of MS-222 requires a 21-day holding period. Fish will then be released back into the Sacramento River at the nearest possible point to minimize transport times. Fish movement data will rely upon data collected by acoustic receivers deployed thought-out the Central Valley, Delta, and San Francisco Bay.
Upper Sacramento River Redd Dewatering Surveys and Rescue of Stranded Juvenile Winter-run Chinook Salmon
A recent effort has been made by fisheries agencies (CDFW, PSMFC, USFWS) to annually monitor Sacramento River winter-run Chinook salmon redds. Monitoring includes: searching for, identifying, marking, and repeated measuring of shallow water winter-run redds. This monitoring allows CDFW biologists to predict the flow at which redds will be dewatered on a redd-by-redd basis. Given this knowledge, it is possible to physically modify redds in danger of being dewatered to lessen the impacts to emerging juveniles in each redd. During the study, each observed redd is classified in the database from a list of five dewatering descriptors ranging from "not dewatered" to "totally dry". For the purposes of this study a dewatered redd is minimally identified as any active redd that has its highest section (the tailspill mound) exposed to the air. This would indicate that the river flow has decreased from the time when the redd was constructed and adverse impacts to egg or juvenile survival could be present. A small number of dewatered redds may be excavated to document the level of mortality resulting from dewatering eggs and/or juveniles.
Winter-run redds in shallow water will be identified and monitored by boat crews to determine formation date and subsequent emergence date of each redd. These redds will be repeatedly measured to determine the depth of water column above the highest point of the redd during each river flow reduction. When a redd is in jeopardy of becoming dewatered, (based on the redd depth and the schedule of flow reductions) CDFW may take action if deemed necessary to reduce the impacts of dewatering. Just prior to a Keswick flow reduction (1-2 days), a field crew will gently remove substrate from the tops of redds that are likely to become dewatered (e.g. redds in water 2-3 inches or less before a 250 cfs reduction). Crews will remove by hand the rocks from the tops of redds to a sufficient depth that will allow water to remain freely flowing over the redd top after the forecasted flow reduction. Redd tops will be removed using a slow and gentle manner to minimize abrasion impacts to fry in the uppermost area removed. Water velocity will be measured at the redd before and after the substrate removal process. Water depth measured from the redd top to the water surface will also be recorded pre and post rock removal. Photographs will document the substrate removal process. Numbers of fry observed during the redd removal will be noted. Crews will revisit and repeat this protocol if necessary on the monitored redds until after the emergence date of each redd in the effort has passed.
Juvenile stranding events and stranding sites are observed while surveying the Sacramento River and side channels by boat and on foot. Efforts to locate and monitor stranding sites are typically conducted from the Tehama Bridge (RM 229) to Keswick Dam (RM 302). Isolated and partially or potentially isolated pools are observed and marked on a handheld GPS. All stranding sites observed are also photographed. Fish present will be enumerated and identified by visual observation, including underwater observation and underwater photography. Juvenile salmonids are to be identified by species, and juvenile Chinook are classified by run based on approximate fork length relative to date. This is accomplished using an electronic version of a Central Valley Chinook length-at-date fork length table (example found in attached document - Jarrett and Killam 2014). Prior to each field survey the fork length table was referenced and the size ranges of all present Chinook runs were recorded for classification in the field. The site location and environmental conditions are also recorded.
CDFW staff will survey known stranding sites immediately following Keswick flow reductions (as feasible), to determine if a fish rescue is necessary. If determined necessary, CDFW staff will seine, net, or electrofish (in this order of priority to reduce negative impacts to already stressed fish) stranding locations based on staffs experience and feasibility at each location.
Some stranding pools are subsequently measured and environmental conditions such as temperature, dissolved oxygen levels, substrate, type of shelter present, etc., are also recorded. Likelihood of juvenile survival will be assessed at observed stranding pools and will be based on current and expected environmental conditions (e.g., if site is isolated and drying up and warm dry weather forecasted, then survival is probably unlikely for that site). The feasibility of juvenile fish rescue and removal from the observed stranding site is also evaluated. This is based on the size and substrate of the stranding site, as well as surrounding habitat. For example fish stranded in a wide, shallow pool with little aquatic vegetation, could be removed and relocated to adjacent flowing water easily using beach seines or other capture methods. Conversely, a deep bedrock pool with submerged debris such as downed logs or tree branches would be very difficult to effectively capture and remove juveniles for relocation.
Stranding sites suitable for rescues containing juvenile salmonids are identified and prioritized based on numbers of fish as well as accessibility. Rescues efforts will involve the use of seine nets of various lengths, dip nets and assorted tubs and buckets. Multiple passes will be made with seine nets at each site and captured fish will be transferred to buckets of water. Fish are then identified, tallied, and relocated to the nearest flowing river channel with minimal handling.
Another characteristic assessed at each observed stranding site is the potential for re-connection. This is based on the substrate of the stranding site and the proximity to the nearest watered portion of Sacramento River. The feasibility of re-connection includes the potential for use of hand tools (e.g., shovels), power tools (e.g., jack hammers) and more aggressive re-connection using machinery such as backhoes, etc. Both permanent and temporary re-connection techniques are considered during assessment. Documented stranding sites are regularly revisited as resources allow throughout the survey season. The status of each stranding site is evaluated to determine if and when the location reconnects to or disconnects from the main river system. Fish present are counted and identified to assess mortality of stranded juveniles over time.
When conducting rescues within Upper Sacramento River Basin Tributaries, fish will be captured using beach seines. When seining is not feasible other methods such as fyke netting, backpack electroshocking or hook and line may be used as a last resort. If conditions are not suitable for release within the body of water where fish have been rescued (due to low flows, high water temperatures, etc.) a one-ton flat-bed truck fitted with a 200 gallon oxygenated water tank will be used to transport rescued salmonids. Rescued fish will be relocated and released at the Sycamore Boat Launch downstream from the Red Bluff Diversion Dam (RM 243) or the nearest suitable release location on the Upper Sacramento River. |
