Role of Crab Traps in Oyster Restoration

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Kreutzer, Allison D.
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Abandoned crab traps are a problem in many coastal areas; when left in the water and marshes they continue fishing, needlessly killing crabs, turtles, and other animals. The goal of this project was to test the utility of these crab traps as a base for artificial oyster reefs. Oyster shell, the media traditionally used for oyster restoration, is expensive to buy and can be ineffective in muddy areas. To start, treatments of crab traps and standard oyster-shell-based restoration techniques were placed at three intertidal locations around Charleston, South Carolina. After nine months, crab traps that had been coated in cement recruited a mean of 2438 oysters/m², the highest recruitment of the crab trap treatments. The oyster-shell-based restoration techniques did, however, recruit more oysters than the cement coated traps with a mean of 9140 oysters/m², and oyster density was affected by a significant interaction between site and treatment (p = 0.006). To evaluate the potential of crab traps for use in soft sediment areas, crab traps filled with recycled oyster shells already laden with live oyster spat were deployed in firm and muddy substrates for nine months. These crab traps showed no significant sediment accretion in even the soft substrate. Furthermore, the oyster spat in crab traps on both the hard and soft substrate attained mean sizes of 25.69mm and 30.89mm respectively, with survival rates of 38.5% and 34.6%. Recycled crab traps show good potential as oyster reef building blocks, particularly if coated with cement, and could allow oyster restoration in many areas which are not amenable to existing restoration techniques using oyster shell alone.
Artificial reefs -- South Carolina; Oysters -- Habitat -- South Carolina; Crab pots -- Environmental aspects -- Research -- South Carolina -- Charleston Harbor; Restoration ecology -- South Carolina