Response of Estuarine Fish to Large-Scale Oyster Reef Restoration

 In response to historic low population sizes of eastern oysters, the North Carolina (NC) Division of Marine Fisheries created a network of no-take, oyster broodstock reserves in an effort to enhance the oyster metapopulation in Pamlico Sound (PS).  In addition to oyster enhancement, restored oyster reefs increase structural refuge and provide increased feeding opportunities for fish.  Using gill nets and fish traps, we quantified transient and reef fish, respectively, inhabiting oyster reserves and nearby unstructured estuarine bottom. Moreover, a large-scale oyster restoration effort at 2 of 4 study locations allowed us to conducted a paired Before-After-Control-Impact study prior to and after restoration.   In general, catch per unit effort (CPUE) of transient fish species was higher over unstructured bottom than oyster reefs.  This relatively high CPUE of fish over unstructured bottom was influenced by schooling planktivores such as atlantic menhaden and thread herring (which made up 43% of our catch). A greater variety of fish species were found on the restored oyster reserves (51 different species) compared to the 36 different species sampled on the unstructured bottom. Two species of concern, Weakfish, Cynoscion regalis, and Croaker, Micropogonias undulates, were found in large abundances on the oyster reserves. Additionally, estuarine fish CPUE caught by fish traps were highest on relatively “old” reefs, followed by “new” reefs created in 2010, and lowest on unstructured bottom. There was also evidence of seasonal habitat use of reefs by NC species of concern, such as weakfish, as well as, recreationally important fish such as spot, Leiostomus xanthurus, and bluefish, Pomatomus saltatrix .  Analysis of bluefish stomachs indicated that oyster reserves and unstructured bottom had a moderate diet-overlap (Schoener’s index=0.64). However, the niche  breathe of prey items was greater on oyster reserves compared to unstructured bottom in bluefish diets. The results of this study will help refine the role of restored oyster reefs as essential fish habitat.