PREP Publications

Abstract

This project was conducted as a contract between the City of Dover and the University of New Hampshire, with additional funding supplied by the New Hampshire Estuaries Project. The overall goal was to restore as much bottom area as possible (with available funds) of formerly productive oyster bottom in two areas, the Bellamy River and Pomeroy Cove (Piscataqua River). The restored areas were intended as a contribution to the long-term NHEP goal of restoring 20 acres of oyster bottom by 2010 (Trowbridge 2003). Five objectives were addressed: (1) site surveys, map production, and final restoration protocol development; (2) remote setting of oyster larvae; (3) bottom "seeding" with spat; (4) assessment of restoration success; and (5) education. Site surveys found substantial amounts of "shell bottom" (but only two live oysters) along a 1.2 km stretch of the Bellamy, and no oyster bottom off Pomeroy Cove. Hence, restoration efforts were designed only for the Bellamy. "Spat seeding" involving deposition onto the existing bottom (i.e. no bottom improvement via placement of additional hard substrate or other methods) of spat (young oysters) attached to shell substrate produced by remote setting was chosen as the primary reef restoration method. Larvae from native Great Bay oysters were set in tanks at UNH's Jackson Estuarine Laboratory (JEL) in July 2005, and held on a nursery raft at JEL until reef construction in November 2005. Approximately 300,000 spat-on-shell were used to construct 12 "mini reefs" (total surface area ~0.1 acre) within a 1.5-acre overall restoration area. On 26 July 2006 (9 months post-construction), 32,000 live oysters remained on the mini-reefs and no live oysters were found in adjacent natural reef areas. When considering only the 0.1 acre area covered by the mini-reefs, live oysters occurred at 64/m2, which is similar to oyster densities in other areas in Great Bay. When considering the entire 1.5 acre restoration area, live oysters were at ~4/m2. The entire 1.5-acre area was considered "restored" in the short-term. Longer-term restoration success will be dependent upon successful natural recruitment to the mini reefs as well as the adjacent bottom areas. Diver observations in July 2006 indicated that very little oyster shell (other than what was put out with the spat in November 2005) remained in the restoration area. This suggests that longer-term restoration success may require placement of additional shell onto the bottom. Longer-term success will be assessed by future sampling as funds become available.

Publication Date

7-28-2006

Publisher

New Hampshire Estuaries Project

Document Type

Report

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