Juvenile white sturgeon (Acipenser transmontanus) habitat and distribution in the Lower Fraser River, downstream of Hope, BC, Canada

The primary objective of this study was to identify and characterize juvenile white sturgeon (Acipenser transmontanus) habitat in the Lower Fraser River downstream of Hope, BC, Canada. A secondary objective was to estimate the juvenile white sturgeon population in the Lower Fraser River. A total of 1867 white sturgeon was captured with gill nets at 26 sites in the Lower Fraser River. The greatest numbers of sturgeon were caught in three sloughs; all but three sturgeon were captured in the June to August period. These three sloughs all had water deeper than 5 m and current that was multidirectional. Turbidity ranged greatly from 1.5 NTU (Nephelometric Units) to 67.0 NTU and the substrate of most sites was fine sediments, fine sand, silt and clay. Stomach contents were mysid shrimp (Mysidacea), midge larvae (Chironomidae) and peamouth chub (Mylocheilus caurinus). We identified three of 26 sites with appreciable numbers of juvenile sturgeon, identified water quality parameters of these sites, identified any incidental species that might be prey and also determined that between 1985 and 1993 the juvenile white sturgeon population had declined.