by Nan Frobish
April 1, 2022
Juvenile Chinook Salmon lack rearing habitat in the Central Valley due to pervasive land use change and altered hydrology. Historically, juvenile salmon (or parr) had access to roughly four million acres of seasonal floodplain which provided ideal growth conditions before transitioning to the ocean. Managed wetlands and flooded off-season agricultural fields can provide surrogate habitat to mitigate some habitat losses. A pilot program by fishery agencies and the PGA has turned their attention to a previously untapped habitat by stocking immature salmon parr to golf course wetland ponds to increase habitat and population. The program, coined “Parr for the Course”, serves to increase the salmon population after their decline. This could be salmon conservationists’ mulligan for past failures.
Golf course ponds are ideal habitats for juvenile fish due to their higher than average food productivity, protection from predators, and overall comfort. Compared to the remaining habitat that has long endured pervasive land use change and altered hydrology, these ponds create a sort of oasis in the habitat desert, sheltering parr from their long history of abuse. While discussing new mitigation efforts for these threatened fish, biologists at the Center for Watershed Sciences realized the potential for using these areas for fish conservation, piloting the effort at a local golf course. The River Redwoods Golf Club in Sutter County was chosen for its location near migratory pathways for Feather River and Butte Creek, allowing fish easy access back to the river for outmigration. Fish were planted at the Golf Club in February, during the time of year when juvenile salmon would need to access historic floodplain habitat (photo 1). Over the next several weeks, the fish were monitored and growth rates were measured, comparing them to other rearing habitats in the area. Parr for the Course fish that had reared in these golf ponds grew at faster rates compared to fish planted in canals and rivers, growing at about 0.5g/day. This might not sound like a lot of weight, but for a juvenile salmon, this can make the difference between surviving the journey to the ocean or being consumed by a predator. A real hole in one for the fish!
Faster growth occurs in the ponds due to a highly productive detrital food webs. Jeffres et al., (2020) found that juvenile salmon in floodplain habitats are feeding primarily from a detrital based food web. In golf courses, grass clippings from the course’s constant upkeep are a source of nutrients in the pond to kickstart the detrital pathway. This supports a more productive environment, filled with zooplankton for the fish to consume. These detrital food webs also create a distinct isotopic fingerprint that can be permanently archived in tissues such as fish eye lenses. When fish return to spawn as adults, researchers can take the fish eye lens to see which fish used golf ponds and who didn’t (Tilcock et al. 2021). Knowing how many salmon from these golf ponds returned to spawn, allows researchers to quantitatively evaluate the success of Parr for the Course.
Fish planted in these ponds don’t need to worry when they hear “birdie”, because golf ponds also provide excellent predator refugia. Many perils exist in the wild for juvenile salmon as they migrate to the ocean, including predation by many different birds. Golfers swinging their clubs and yelling “Fore!” naturally prevents birds from wanting to land near the water, preventing predators from accessing the ponds. This decrease in bird activity also contributes to higher numbers of insects present in the ponds, establishing another important food source for these juvenile salmon and, again, contributing to the productivity of this environment. In addition to birds being removed from the ponds, these ponds lack other natural predators. This allows the fish to grow in a stress-free, rich environment, before being released into the river.
Along with being a predator-free habitat, the ponds have trees on their borders to shade growing salmon. Since the water in the ponds is not straight from the mountain snow melt, it is vital that the water remain cool for fish to survive, especially later in spring. Rain from the winter should be enough to keep the waters at an ideal condition.Underwater roots of trees also give fish safe havens from rogue golf balls.
In return for giving young salmon a better chance of survival, the fish assist by suppressing pests. Chinch Bug and Sod Webworms are among the most common pests for golf courses. They eat grass, leave tunnels under turf and lead to brown patches. These bugs will one way or another fly across the ponds and when they land on the water, they are snatched by hungry young salmon. This mutualistic relationship benefits both the ecology and economy.
Because of the tee-rific success of this pilot year, these fishery agencies are committed to strike while the iron is hot to implement golf course habitats all across the Central Valley. This would provide opportunities for researchers from across the state and for diverse stakeholders to participate in conserving this important species. Parr for the Course has shown us a unique way research can be incorporated into everyday life and give hope for fish conservation.
Jeffres, C.A., Holmes, E.J., Sommer, T.R., & Katz, J.V.E. (2020). Detrital food web contributes to aquatic ecosystem productivity and rapid salmon growth in a managed floodplain. PLoS One, 15(9): e0216019. https://doi.org/10.1371/journal.pone.0216019
Bell-Tilcock, M., Jeffres, C.A., Rypel, A.L., et al. (2021). Advancing diet reconstruction in fish eye lenses. Methods Ecol Evol, 12: 449– 457. https://doi.org/10.1111/2041-210X.13543
Holmes, E.J., Saffarinia, P., Rypel, A.L., Bell-Tilcock, M.N., Katz, J.V., et al. (2021) Reconciling fish and farms: Methods for managing California rice fields as salmon habitat. PLoS One, 16(2): e0237686. https://doi.org/10.1371/journal.pone.0237686
Bell-Tilcock, M., Jeffres, C.A., Rypel, A.L., Willmes, M., Armstrong, R.A., et al. (2021) Biogeochemical processes create distinct isotopic fingerprints to track floodplain rearing of juvenile salmon. PLoS One 16(10): e0257444. https://doi.org/10.1371/journal.pone.0257444
Cordoleani, F., Holmes, E., Bell-Tilcock, M., Johnson, R.C., & Jeffres, C. (2022). Variability in foodscapes and fish growth across a habitat mosaic: Implications for management and Ecosystem Restoration. Ecological Indicators, 136, 108681. https://doi.org/10.1016/j.ecolind.2022.108681
Nan Frobish is the nom-de-blog, in this case, for the team of Miranda Bell Tilcock, Abigail Ward, Francheska Torres, Scott Smith, Alexandra Chu, Eric Holmes, and Carson Jeffres.