The blue crab (Callinectes sapidus) population in the Delaware Inland Bays, particularly Rehoboth Bay, holds significant economic and ecological importance. Callinectes sapidus is a key contributor to the seafood industry in Maryland and Delaware. This ongoing study focuses on areas associated with oyster aquaculture and pilot oyster reefs. The primary objective is to evaluate the blue crab population and identify a potential pathogenic virus affecting them. The study specifically targets Callinectes sapidus reovirus 1 (CsRV1), analyzed in the lab using PCR (polymerase chain reaction) and qPCR (q uantitative polymerase chain reaction) methods. Notably, no prior research has comprehensively examined the Callinectes sapidus population and CsRV1 within the Delaware Inland Bays. CsRV1 primarily affects the gills, impacting the respiratory system, and is associated with elevated mortality rates in aquaculture settings. Infected crabs exhibit symptoms such as lethargy, behavioral changes, and respiratory distress in natural habitats . Study sites were selected based on distinct characteristics, including areas with oyster aquaculture, artificial reefs, and control sites. The research involved deploying 18 traps across six sites, each with two large commercial cages and one small lobster pot. The summer and fall of 2022, the research team collected data from over 1,000 blue crabs. Our findings indicate stable populations of adult females at natural control sites throughout the season, with an increase in adult male abundance during the cooler months at aquaculture and reef sites. In 2023, CsRV1 was identified in the lab using PCR and qPCR techniques.
Figure 1 a-b. (a) Callinectes Sapidus population characteristics in Rehoboth Bay, DE, during the 2022 sampling season. Out of 1147 individuals around 525 females were egg-bearing. Roughly 787,500,000 eggs have been accounted for and released into Rehoboth Bay. (b) A picture of me processing blue crabs at our release and study site to minimize recapture likelihood.