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Presentation TitlePOSTER: Seasonal Movements of Sunshine Bass in the St. Johns River, FL
Presenting Author NameAndrew Marbury
Presenting Author AffiliationFlorida Fish and Wildlife Conservation Commission
Presenting Author EmailEmail hidden; Javascript is required.
Presentation Number11
Unit MeetingFlorida Chapter
General TopicFreshwater telemetry
Type of PresentationPoster

Sunshine Bass (M. chrysops x M. saxatilis) have been stocked into the St. Johns River since the 1980’s, creating a recreational fishery. This species can generally be caught throughout the river and its tributaries in cooler months, but due to high water temperatures (>25°C) during the summer they are confined to cool-water refugia. While restricted to thermal refuge, fish have little, if any, available forage especially when confined to mostly barren spring boils. Biologists have identified Silver Glen Springs (SGS) as one of the largest summer aggregations of Morones in the St. Johns River system, however fish health has shown to decline throughout their confinement here, lasting upwards of 6 months. In 2018, a pilot telemetry study in SGS showed a surprising amount of Sunshine Bass movement in and out of the SGS system during summer residency. With average river water temperatures well above 29°C, it was presumed that fish were likely utilizing nearby alternative thermal refugia. As a result, a new study was initiated in 2019 with an expanded receiver array to include other potential thermal refugia and seasonally-important habitats. A total of 25 Sunshine Bass were captured before their migration to thermal refugia and internally fitted with an acoustic transmitter. Initial results show a high proportion of fish (72%) utilizing SGS, along with documented use of four other spring systems. Rates of movement varied between fish, but fish tended to move less throughout the spring/summer and more in the fall/winter. Data collection is currently ongoing and is up to date through December 2019.