The nursery value of discrete habitat types within an estuarine complex is variable, however, and depends on their respective quality and availability. A synoptic examination of crab abundance and growth across a broad geographic range indicated that shallow-water, unvegetated habitats presently serve as functional nurseries in southern New England tidal rivers.Įstuaries are composed of mosaics of interconnected habitats that serve as nurseries for juvenile fishes and invertebrates ( Peterson 2003 Sheaves 2009 Fulford et al.

The absolute and relative growth rates of juvenile crabs equaled 0.9 ± 0.3 mm CW/day and 1.5 ± 0.6 % CW/day, respectively, and were directly related to DO levels. In contrast, mature females were most abundant during August and years with elevated water temperatures. Peak catches of males and juvenile females occurred during the spring and mid-summer, and annual abundances were positively related to dissolved oxygen (DO) concentrations. Seasonal and interannual patterns in crab abundance also differed by sex and ontogeny. Crabs were spatially segregated along a salinity gradient with males and juvenile females prevalent in oligohaline waters (upper river salinity ~ 5 ppt) and adult females mainly concentrating in higher salinity areas (mid- and lower river salinity ~ 11-21 ppt). Males accounted for the majority of age-1+ crabs (~ 83% of cohort), yet sexually mature females were also observed (9% of cohort mean ± SD abundance = 0.04 ± 0.06 adult females/100 m 2 size at 50% maturity ± 95 CI = 129.0 ± 0.2 mm CW). The younger age-0+ cohort was numerically dominant (~ 88% of total catch) and comprised of male and juvenile female crabs (mean ± SD abundance = 0.28 ± 0.26 males/10 m 2 and 0.14 ± 0.12 juvenile females/10 m 2).

Crabs measuring 8 to 185 mm carapace width (CW n = 2,577) were collected, and two distinct age-classes occupied the rivers during the spring and summer (maximum abundance ~ 5 crabs/10 m 2). These metrics were also analyzed with respect to crab life history traits and in situ abiotic conditions to elucidate patterns of habitat selection throughout ontogeny. Crabs were collected fortnightly from May through August (2012-2016), and abundance- and growth-based metrics were used to assess riverine habitat use and quality.

This study examined the population structure of blue crabs in the Seekonk and Taunton Rivers (Rhode Island and Massachusetts, USA): two tidally influenced rivers contiguous with the Narragansett Bay Estuary and dominated by shallow-water, unvegetated habitats. The blue crab, Callinectes sapidus, has a broad geographic distribution encompassing coastal waters of the eastern United States and Gulf of Mexico, but intraspecific patterns of habitat use and quality are lacking at northern latitudes.

Blue crab habitat