Examining the Ecological Role of White Perch (Morone americana) using Acoustic Telemetry in the Great South Bay Estuary, New York.

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Divver, Martha Marie
The Graduate School, Stony Brook University: Stony Brook, NY.
Acoustic telemetry was used to investigate movement and behavior of the semi-anadromous white perch (Morone americana) in the Great South Bay system. Fifteen Vemco?? VR2 acoustic receivers were deployed in the Carmans River and another fifteen were placed in tributaries throughout the Bay. Forty fish were tagged with Vemco?? V9 acoustic transmitters from August 2010 - 2011, fifteen of which returned 28+ days of movement data. Spatial use of the River varied seasonally with an expanded range during autumn and spring and contracted range during summer and winter. Both residential and dispersive individuals existed within the population, suggesting connectivity between rivers. Activity level varied on a seasonal basis, with increased activity during pre-winter foraging and spring spawning periods, and reduced activity during the winter. Temperature was shown to influence fish activity levels, with seasonal extremes suppressing activity. Salinity had little effect on perch movement and activity, however, reduced upriver salinity variations may influence white perch to overwinter these upriver areas. Acoustic tracking revealed adult perch exhibiting diel movement behavior, which has not been previously described in adults of this species. Movements were tested for cyclical patterns using autocorrelation analysis in R. The frequency of diel behavior across individuals was found to be dependent on season, with the behavior significantly reduced in winter and maximized in summer. Directionality in diel movement was also seasonal, where nightly upriver movements were favored in summer and autumn months and nightly downriver preferred in winter. Diel behavior was also affected by temperature and salinity, with high salinities and low temperatures reducing the frequency of occurrence. Additional but uninvestigated drivers that may influence diel movement include the presence of predators, movement to preferable forage habitat, and summer declines in dissolved oxygen.
125 pg.