Seasonal movement and habitat use by striped bass in the Combahee River,South Carolina

摘要

Adult striped bass Morone saxatilis (N = 30, 656-906 mm total length) were captured by electrofishing during January-March 1998 in the Combahee River, South Carolina, and fitted with radio transmitters. Their exact locations were recorded biweekly through December. From January to early April, striped bass were located in the tidally influenced lower region of the river in water temperatures ranging from 9 degreesC to 18 degreesC. The fish then moved an average of 38.5 km upstream from late April to the end of May when water temperatures ranged from 18 degreesC to 26 degreesC. Striped bass remained in the upper region of the river from late May to September when water temperatures were as much as 5 degreesC lower than in the river's lower regions. Striped bass began to move downstream and were spread throughout the river during September and October in water temperatures ranging from 19 degreesC to 27 degreesC. Combahee River striped bass appear to follow a migratory pattern typical of other southern striped bass stocks. Habitat preference appears to be strongly influenced by temperature. Combahee River temperatures are stable and remain close to the preferred temperatures of striped bass during summer extremes. Therefore, unlike northern populations, southern populations are more likely to remain within riverine habitat during the summer months. Discrete thermal refugia, such as springs, apparently are not used or are absent in the Combahee River. It is possible that striped bass in the Combahee River depend on the entire upper region of the river as a thermal refuge.