Researcher(s)
- Clare McLaughlin, Marine Science, University of Delaware
Faculty Mentor(s)
- Edward Hale, School of Marine Science and Policy, University of Delaware
Abstract
Oyster aquaculture provides economic and societal benefits, but the environmental impacts of these activities are not well understood. Specifically, habitat provision for juvenile fishes and invertebrates around aquaculture gear remains unknown and poorly characterized. Our study compared the habitat provisioning of oyster rack and bag aquaculture to explore trends in invertebrate and juvenile fish abundance, and connectivity in response to the presence of aquaculture gear in Delaware Bay. Weekly fish trap deployments on aquaculture installations were conducted at two locations within the estuary with replication at each. Three target species were selected for examining abundance and movement including: American Eel, Atlantic Croaker and Black Sea Bass. Juvenile fish over 60 mm were tagged with Biomark MiniHPT8 Passive Integrated Transponder (PIT) tags and released. American Eels and Atlantic Croakers were more frequently captured near rack and bag systems, demonstrating an ecological “halo effect,” with higher fish abundance at distances of 0 m and 3.5 m from the oyster structures compared to 7 m and 14 m. Conversely, Black Sea Bass, which generally prefer structural habitats, were captured more often at greater distances from the structures. These results suggest that oyster structures can create a favorable environment attracting more fish to the immediate vicinity, enhancing abundance around gear for some species. However, this relationship varies by location. In Lewes, significant differences in diversity (Shannon, Simpson, Species Richness) were observed across rack and bag structures (p-values: 0.0008109, 0.0009109, 0.0006418) but not by proximity to aquaculture gear (p-values: 0.7652, 0.7293, 0.8167). However, diversity metrics remained consistent across stations and trap proximity at Port Mahon suggesting stable diversity patterns across location. Overall, high site fidelity was observed in American Eels and Black Sea Bass when compared to Atlantic Croaker. Our study demonstrates juvenile fishes concentrate around oyster aquaculture gear, potentially utilizing these areas for feeding or predatory refugia.