Oyster Research and Restoration in U.S. Coastal Waters: Abstracts

two oyster shells - top one showing inside and bottom showing outside of the shell

Oyster Research and Restoration in U.S. Coastal Waters: Strategies for the Future

Abstracts
Workgroup: Oyster Fisheries Management and Restoration

Oyster Predator-Prey Interactions: Roles of Different Predators, Seasonality, Spatial Variation and Deterrents.

Principal Investigator(s):

Kenneth Brown, Department of Biological Sciences, Louisiana State University, kmbrown@lsu.edu

Co-Investigator(s):

Gary Peterson, Coastal Ecology Institute. Louisiana State University
Mike McDonough, Department of Biological Sciences, Louisiana State University
and Charles Ramcharan, Department of Biological Sciences, Louisiana State University

Funding Period: 1999

We conducted both small-scale laboratory and large-scale field experiments to study the roles of scent deterrents, snail versus fish predators, estuarine versus coastal conditions, and seasonality in explaining mortality rates of oysters (Crassostrea virginica). Preliminary laboratory experiments at the Grand Terre Marine Laboratory indicated that small, single oysters, such as those planted on oyster leases, are extremely vulnerable to predation by black drum (Pogonias cromis) . Experiments in 20,000 L raceways indicated the scent of dead conspecific drum reduced mortality rates from feeding fish by 46%, but variation among experimental trials was so large that the effect was not significant. In large-scale field experiments at both estuarine and coastal locations in Barataria Bay, Louisiana, we tested whether the scent of dead conspecifics would lower mortality rates to fish in separate experiments in the fall and spring. Percent survival of oysters varied from 2 to 66%, and tended to be highest in the fall at the estuarine site. Percent mortality caused by fish varied from 61 - 99%, and was highest in the spring at the coastal site. Percent mortality caused by oyster drills (Stramonita haemastoma) varied from 1 - 38% and was highest in the fall at the estuarine site. Scent significantly reduced fish feeding rates only at one of the sites, and then only for one of four weeks in the fall experiment. We conclude that oyster drills and black drum pose serious predation risks for oysters, both when seed oysters are planted in the fall, and before oysters are harvested in the spring. However, the scent of dead conspecifics, considered a deterrent by local lease holders, does not seem effective in reducing mortality rates caused by fish. We are currently investigating whether acoustic cues are effective deterrents for fish predation.

PROJECT PUBLICATIONS

Brown, K.M., C. Ramcharan, B. Lezina, G. Peterson, and P. Banks. 2001. Novel deterrents to black drum predation on oyster leases. World Aquaculture Society Meeting at Lake Buena Visata, FL, p. 91 (abstract).

Kenneth M. Brown, 1* Gary Peterson2, Mike McDonough1, and Charles Ramcharan1. 1 Department of Biological Sciences, 2 Coastal Ecology Institute. Louisiana State University. Oyster predator-prey interactions: roles of different predators, seasonality, spatial variation and deterrents. 31st Marine Benthic Ecology Meeting, 21-24 March 2002, Orlando, FL. Hosted by the Florida State University.

UM-SG-TS-2003-01 www.mdsg.umd.edu

This publication was supported by funds from
the NOAA National Sea Grant College Program and the
Maryland and Virginia Sea Grant College Programs

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Abstracts Workgroup: Oyster Fisheries Management and Restoration

Oyster Predator-Prey Interactions: Roles of Different Predators, Seasonality, Spatial Variation and Deterrents.

Abstracts
Workgroup: Oyster Fisheries Management and Restoration