FISH ECOLOGY, PHYSIOLOGY, & CONSERVATION
Restoration and Monitoring of Historic Habitat
The Banet Lab studies aquatic ecology, evolution, and physiology with a focus on fish conservation. Much of our current research concentrates on the ecology and conservation physiology of Pacific salmon. Below are some ongoing areas of research.
Predation on Juvenile Salmonids
Pacific salmon have seen dramatic declines in population sizes over the last century, particularly in California. Juvenile Chinook salmon and steelhead in the upper Sacramento River encounter numerous stressors that can affect their survival, including loss of floodplain habitat; loss of natural morphologic function; loss of riparian habitat and instream cover; and competition and predation.
The Upper Sacramento River Anadromous Fish Habitat Restoration Project reconnects historic side channels to the main stem of the Sacramento River, with the goal of providing suitable habitat that will increase juvenile salmonid numbers, and result in larger fish that are in better condition to out-migrate.
In order to evaluate restoration success, we implemented a monitoring plan to assess impacts on habitat availability and characteristics, as well as juvenile abundance, growth rates, and condition. This project is a collaboration with Caifornia Department of Fish and Wildife, Pacific States Marine Fisheries, Steve Tussing Ecological Solutions, Department of Water Resources, U.S. Bureau of Reclamation, U.S. Fish and Wildlife, the Yurok Tribe, the Sacramento River Forum, and many other partners.
In order to understand the underlying mechanisms driving population declines, we examine organismal responses to environmental stressors. For example, in a recent project we used tools from physiology to examine whether maternal exposure to stress can affect offspring characteristics after hatch in three species of Pacific salmon. We found that in all three species, exposure to the stress hormone cortisol at fertilization led to a significant reduction in juvenile aerobic swimming performance. This can be harmful because it reduces the amount of energy an organism can devote to activities related to survival and reproduction, such as foraging, growth, migration, and escaping from predators. Some management and conservation practices for Pacific salmon focus efforts primarily on facilitating adult spawning. However, if deleterious effects of maternal stress acquired prior to spawning persist into the next generation, consideration will need to be given to sub-lethal effects that could be imparted onto offspring from maternal stress.
Non-native, predatory striped bass (Morone saxatilis) were introduced to the Sacramento River in 1879 in order to enhance the recreational sport fishery, but the addition of these predators has placed added stress on the native juvenile Chinook salmon (Oncorhynchus tshawytscha) and steelhead (Oncorhynchus mykiss) populations. However, attempts to manage the striped bass populations in the Sacramento-San Joaquin River system have been controversial. Striped bass are a favorite of recreational anglers, some of whom oppose mitigation. Conversely, other groups have argued that predation by striped bass plays a larger role in salmon population declines than the water management practices that are often focused on. In spite of these increasingly heated arguments, little is known about the effects of striped bass predation on native salmon, especially at a time when salmon are facing increasing stress from habitat degradation and warming waters. We use hook and line sampling, gastric lavage, genetic analyses, and predation event recorders to better understand who is preying on juvenile salmonids, and how man-made structures and alteration of flow influence the probability of predation.
Photo: Karissa Cunninham