| Autor: |
Phelps, QuintonE., Tripp, SaraJ., Hintz, WilliamD., Garvey, JamesE., Herzog, DavidP., Ostendorf, DavidE., Ridings, JosephW., Crites, JasonW., Hrabik, RobertA. |
| Zdroj: |
North American Journal of Fisheries Management; June 2010, Vol. 30 Issue: 3 p767-775, 9p |
| Abstrakt: |
AbstractSeveral studies have investigated the demographics of shovelnose sturgeon Scaphirhynchus platorynchusand pallid sturgeon S. albusin the Mississippi River through assessment of adult populations; however, comparatively few studies have examined the early life history of these species. Here, we describe a comprehensive 4-year study that examined the effects of water temperature and river stage on the mortality, abundance, hatch timing, and growth rates of age-0 Scaphirhynchusspp. sturgeon in the middle Mississippi River. We trawled island areas every 7–10 d from April to August 2004–2007. We captured 1,256 individuals ranging from 10 to 193 mm total length over the 4-year study. Mean age-0 sturgeon growth rates ranged from 1.42 to 1.50 mm/d over the 4 years; however, growth rates did not differ among years. Individuals hatched over a 25–65-d period, and peak hatch dates were between 10 and 20 May in all years. Moreover, hatch timing possibly coincided with optimum spawning temperatures of 17–20°C and an increase in river stage. Abundance appeared to be regulated by river stage; longer durations of high water were related to higher relative abundance. Furthermore, mortality increased with the number of days on which water temperature exceeded 28°C. Based on these data, management strategies may need to ensure sturgeon hatching success and subsequent survival through optimizing hydrologic and thermal regimes that occur during the early life stage. |
| Databáze: |
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