Effects of temperature and hydrology on growth of shovelnose sturgeon Scaphirhynchus platorynchus (Rafinesque, 1820) in the lower Mississippi River

摘要

We evaluated the effects of thermal and hydrologic conditions on the growth of shovelnose sturgeon (Scaphirhynchus platorynchus) in the lower Mississippi River, USA. Duration of water temperatures 12-24 degrees C had a positive influence and temperatures below 11 degrees C had a negative influence on annual growth increment, but these two variables accounted for less than 15% of the variation in growth. Duration of water temperatures above 28 degrees C, duration of floodplain inundation, duration of low water, and minimum and maximum river stage did not influence annual growth increment. Growth of shovelnose sturgeon in the lower Mississippi River appears to be positively influenced by duration of moderate water temperatures but minimally influenced by hydrologic conditions. The low variation accounted for by thermal and hydrologic variables suggests annual growth increment may be largely influenced by additional abiotic or biotic factors.