Temperature-, Salinity-, and Size-Dependent Winter Mortality of Juvenile Blue Crabs (Callinectes sapidus)

Abstract

At midlatitudes within its range, overwintering mortality may play an important role in regulating blue crab (Callinectes sapidus) populations. We conducted a 121-day experiment to estimate winter mortality that used realistic temperature acclimation periods prior to and light levels during experiments. A 2 × 2 × 2 factorial experimental design was used to test for the effects of temperature (3°C, 5°C), salinity (10, 25), and sediment (sediment, no sediment) on the survival of juvenile crabs (14-68-mm carapace width) of both hatchery and wild origin. The presence of sediment did not significantly alter crab survival, while hatchery-raised crabs experienced significantly lower survivorship than wild-caught crabs. An accelerated failure time model fit to the survival data indicated that time to death increased significantly with increasing temperature, salinity, and crab size. These results suggest that winter survival varies with winter severity, is spatially dynamic, and that small juveniles are more at risk of dying over the winter than larger juveniles.

Spatial and Interannual Variability in Winter Mortality of the Blue Crab (Callinectes sapidus) in the Chesapeake Bay

“…A central assumption in this calculation is that all crabs survive the winter. Previously (Bauer and Miller 2010), we demonstrated that survival of juvenile blue crabs is dependent upon temperature, salinity, and size. Crabs were least tolerant of low temperature at low salinity, and survival significantly increased with increasing temperature, salinity, and crab size.…”

“…Previously in the laboratory, we have quantified interactions among temperature, salinity, size, and sex in regulating overwinter mortality in the blue crab Callinectes sapidus (Bauer and Miller 2010). The blue crab is an important benthic predator and scavenger in estuarine ecosystems (Hines 2007) and serves as a link between the benthic and pelagic communities (Baird and Ulanowicz 1989).…”

“…Additionally, considerable spatial variation within years might be expected as a result of variation in temperature and salinity within estuaries, as both factors have been shown to influence susceptibility to overwinter mortality (Rome et al 2005;Bauer and Miller 2010). Together, these sources of variation can give rise to both large-scale differences among populations across a latitudinal gradient (Fullerton et al 2000) and to small-scale spatial patterns .…”

“…Because temperature, salinity, and the sex and size of crabs overwintering vary spatially, our laboratory results suggest that there is the potential for considerable spatial variability in overwintering mortality. Here, to assess the potential impact of this spatial variability on estimates of crab abundance, we combine the survival model generated in Bauer and Miller (2010) with empirical data on bottom winter temperatures and salinities measured in Chesapeake Bay to generate spatially explicit estimates of winter survival in the blue crab.…”

An evaluation of the synchronization in the dynamics of blue crab (Callinectes sapidus) populations in the western Atlantic

“…Because of inconsistencies in the length of the sampling period for each stations of the survey, data from the three tributaries (York, James, and Rappahannock) should be used to create indices (Miller et al 2011). When water temperature falls below ~10°C growth ceases and blue crabs become dormant for the winter, burying into sediments (Brylawski & Miller 2006;Bauer & Miller 2010 region, and depth strata into account and using a geometric mean catch per area swept approach (Bonzek et al 2010).…”