Fish
Interagency Ecological Program Spring Season report
Background
- Splittail are a native minnow that spawn on floodplains, so have high reproduction during high flow years when floodplains are inundated with water. They are sampled by DWR’s Yolo Bypass Monitoring Program.
- Spring-run Adult salmon returns return from the ocean during the spring. Populations are calculated by CDFW’s Fisheries Branch based on redd counts, carcass surveys, fish entering hatcheries, and live fish counts.
- Juvenile Winter-Run Chinook Salmon out-migrate to the ocean in spring, and are sampled by the USFWS’s Chipps Island Trawl, located at the confluence of the Sacramento and San Joaquin Rivers.
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Average fish abundance by species
Figure 19: picture of a sacramento splittail
Figure 20: Graph of average Sacramento Splittail catch per unit effort from 1998 to 2018. Values range from 4 to 80.
2018 was lower than the long-term average.
Figure 21: picture of an adults chinook salmon
Figure 22: Graph of average adult chinook returns from 1966 to 2018. Values range from 1000 to 250000.
In 2018, adult Chinook returns were lower than average
Figure 23: picture of a juvenile salmon
Figure 24: Graph of juvenile winter-run chinook index from 1995 to 2018. Values range from 0.2 to 6.
In 2018, juvenile winter-run salmon survival was about average.
For more information see: Kwan, N., J. Jenkins, C. Stuart, A. Shakya, and B. Schreier. 2019. 2011-2016 Yolo Bypass Fisheries Monitoring Status and Trends Report. IEP Newsletter 36(1):27-36.