Habitat Utilization and Home Range of Largemouth Bass in a Deep Oligotrophic Tropical Reservoir

We are assessing habitat utilization and home range of largemouth bass Micropterus salmoides in Cerrillos Reservoir near Ponce, Puerto Rico, to describe largemouth bass habitat selection in a deep oligotrophic tropical reservoir. Acoustic telemetry tags were surgically implanted into 100 largemouth bass (85 female, 15 male; TL range 304-574 mm) in May 2011.  Biweekly tracking began in June 2011. Initial data indicate that most largemouth bass fall into one of two home range classifications: small home range size (<200 meters of shoreline) or nomadic with no apparent home range. Females tend to be more nomadic than males. Home range was independent of capture or release locations, as several fish have dispersed to different locations throughout the reservoir and into the river arm. Male and female largemouth bass may segregate during non-spawning periods, although habitat preferences appear similar.  Both genders select habitat that is gently to moderately sloping (0-45° incline) and contains large rock formations, sand or silt soils, and vertical and horizontal logs. During apparent spawning activity in late winter to early spring, many females migrated to male home ranges. Using GIS technology, preferred habitat characteristics for largemouth bass home range selection and spawning sites will be identified.