Event Title

Using Present and Past Data to Model Predator-Prey Dynamics in Lake Powell, Utah-Arizona: A Bioenergetics Approach

Location

Space Dynamics Laboratory

Event Website

http://water.usu.edu/

Start Date

3-26-2004 8:30 AM

End Date

3-26-2004 8:45 AM

Description

Lake Powell (UT-AZ) supports a popular striped bass fishery with more than 1.5 million annual angler-hours on the reservoir. Since the introduction of striped bass in 1974, the threadfin shad forage population has fluctuated widely. The predatory striped bass population appears to respond directly to these fluctuations in the shad forage base. As a result, fisheries managers have identified a need to more explicitly understand the mechanisms driving this predator-prey cycle. We used bioenergetic-based models coupled with time series abundance data for bass and shad to quantify and evaluate this cycle. In 2003, we collected monthly field data from May to October at six sites throughout the reservoir. These data provided estimates of diet, growth, thermal history, and relative abundance of striped bass and threadfin shad. Within a year, bass consumption on shad follows a seasonal trend where consumption increases dramatically as the individual size of shad increases among the young-of-year cohort. The temporal relationship between bass and shad shows a distinct cycle where relative bass abundance and growth rates can be predicted based on annual indices of shad. We demonstrate how historical data and bioenergetics can be used as a tool for better managing and understanding the fishery.

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Mar 26th, 8:30 AM Mar 26th, 8:45 AM

Using Present and Past Data to Model Predator-Prey Dynamics in Lake Powell, Utah-Arizona: A Bioenergetics Approach

Space Dynamics Laboratory

Lake Powell (UT-AZ) supports a popular striped bass fishery with more than 1.5 million annual angler-hours on the reservoir. Since the introduction of striped bass in 1974, the threadfin shad forage population has fluctuated widely. The predatory striped bass population appears to respond directly to these fluctuations in the shad forage base. As a result, fisheries managers have identified a need to more explicitly understand the mechanisms driving this predator-prey cycle. We used bioenergetic-based models coupled with time series abundance data for bass and shad to quantify and evaluate this cycle. In 2003, we collected monthly field data from May to October at six sites throughout the reservoir. These data provided estimates of diet, growth, thermal history, and relative abundance of striped bass and threadfin shad. Within a year, bass consumption on shad follows a seasonal trend where consumption increases dramatically as the individual size of shad increases among the young-of-year cohort. The temporal relationship between bass and shad shows a distinct cycle where relative bass abundance and growth rates can be predicted based on annual indices of shad. We demonstrate how historical data and bioenergetics can be used as a tool for better managing and understanding the fishery.

https://digitalcommons.usu.edu/runoff/2004/AllAbstracts/34