Research & Projects

Blue crabs (Callinectes sapidus) are economically, ecologically, and culturally significant in Maryland and the Chesapeake Bay. The wild population naturally fluctuates due to water conditions, disease, and cannibalism, which has led to inconsistent blue crab harvest. Blue crab aquaculture techniques were developed in 2005 by Zmora et al. (University of Maryland Biotechnology Institute), although a commercial industry has yet to become viable due to high levels of cannibalism from megalopae to adults. However, European lobster aquaculture has successfully reduced cannibalism in juvenile lobsters by culturing the lobsters in individual cells. 

Objectives

The goal of this study is to implement individual container culture in blue crab aquaculture to reduce mortality from cannibalism. Individual container culture will be trialed for megalopae and juvenile crabs, first in a recirculating aquaculture system, then moving to individual cages in the Choptank River.  Reducing the mortality from cannibalism in commercial blue crab aquaculture can reduce the strain on the wild population and has the potential to become a profitable industry in Maryland.

Updates

The first round of blue crab culture will take place in the summer of 2024. Stay tuned for updates and photos!

Abstract

European lobster aquaculture is a developing industry, currently being used for restocking depleted wild stocks. Sea-based container culture (SBCC) is currently the most cost-effective method for culture beyond post-larval life stages; where juvenile lobsters receive no artificial feed in SBCC and rely solely on biofouling organisms which inhabit or pass through their cells within the containers. Macrofaunal biofouling assemblages were examined to gain understanding of lobster diets and how environmental variables impact biofouling communities. The impact of various environmental variables: depth, tier in the container, days at sea, season deployed, lobster presence, and container type were analyzed. It was found that calcareous worms, saddle oysters, amphipods, variegated scallops, and clams (Hiatella sp.) were the most prevalent biofouling organisms over all deployments. Tier category, the vertical position within a container, was found to have the least impact on biodiversity and lobster growth. The season at which the containers were deployed had a significant role on the fouling assemblages. Increase in depth had a negative effect on the number of bivalve, annelid, and seaweed species, whereas it had a positive effect on number of bryozoan species. On average, more species per cell were found in inhabited containers than uninhabited containers. This study gives some insight into what lobsters are preying upon within the containers, and the ecological role lobsters play in shaping the biological composition within their cell by outcompeting other grazing organisms like crabs and urchins.

Conclusions

Tier and container type had limited impact on the biofouling communities and final carapace length. The impact of depth is tied with other abiotic and biotic factors, and physiological traits of fouling organisms. The seasonal fluctuations in spawning and larval supply not only drives the number of organisms on a structure, but also the subsequent settlers. It is unclear what biofouling organisms lobsters are eating, but lobsters’ diets are likely flexible and change with what food is available. Finally, biological interactions occur within a cell, and through predation, lobsters may have a significant role shaping the biological communities. This study gives insight on the seasonal and temporal impacts on biofouling communities.