The Downeast Institute, the Maine Department of Marine Resources, and University of Maine Sea Grant Extension worked with Jonesport and Beals Island scallop fishermen to test a plan the fishermen developed to enhance the region’s scallop fishery from May 2007- May 2009.
With commercial populations of sea scallops, Placopecten magellanicus, at or near record low catch levels in eastern Maine, DEI conducted three independent field trials to study the effectiveness of managing the scallop fishery using closed areas that are enhanced with wild scallops. It also studied the best method for moving wild scallops into a closed area and whether it is possible to collect wild scallop spat (seed) using collectors that have been very successful in Canada, Chile, and Japan.
Closed Areas: The first trial was conducted over 30 days (May-June) in 2007. Two 1-km2 zones in the scallop grounds that lacked commercial quantities of scallops were created in the Beals-Jonesport area and closed by rulemaking to scallopers (both dragging and diving). Plots (15 m x 15 m; n = 8) within the closed areas were seeded with legal and sub legal scallops dragged from a nearby area (Englishman Bay in Jonesport) at a density of 2.5 individuals/m2. Another objective of the trials was to determine the best methods to collect, handle, transport, and deploy wild sea scallops (5-70 mm SL). One-half of the plots in each area received scallops that had been stored for ca. 7 hours in commercial fish totes on board two commercial draggers, while the other half of the plots received scallops that had been held in flow-through containers (modified Xactic box) for the same period of time. The fate of the deployed scallops was followed for thirty days by SCUBA divers. Scallop recovery and survival in all plots in both areas was excellent and independent of handling treatment. These results may be related to the fact that both air and seawater temperatures were less than 10oC during the time when dragging occurred and the experimental plots seeded.
The results from the field trials suggest that enhancement of bottom plots is feasible using legal and sub-legal individuals; however, it remains to be seen whether dragging animals from open areas to seed into closed bottom areas is a sustainable activity.
Spat Collection: The second (2007-2008) and third (2008-2009) field trials focused on collecting wild spat to be used to enhance the bottom plots in both closed areas (juveniles < 20 mm in shell height). These tests were conducted to determine if it is possible to collect wild scallop spat using collectors similar to those that have been used with great success in Canada, Chile, and Japan.
DEI deployed total of 1,200 bags were deployed in late summer 2007 and 2008, and were retrieved in the spring of 2008 and 2009, respectively. Each year, one half of the bags were placed on the eastern and western side of Great Wass Island. On each side of the island, one-half of the bags were deployed in shallow (< 20 m) and deep (> 30 m) water. Less than 40% of the gear was retrieved in both years.
In 2008 the bags captured 2.8 ± 0.43 individuals (n = 460 bags) and in 2009 they captured 18.6 ± 2.04 individuals per bag (n = 383 bags). The 2009 amount captured was approximately 6.5x higher than the previous years. In both years, more scallops settled into bags deployed in deep vs. shallow water and scallops size remained higher on the western vs eastern side. In 2008, the scallop density per bag was significantly higher on the western vs. eastern side of Great Wass Island, but in 2009 no significant difference in scallop density was found between sides of the island.
These amount of spat captured in these field trials was in stark comparison to the amount that were captured in the Canadian Maritimes in similar size bags, where researchers captured > 3,000 animals.
The discouraging results from the spat collection trials suggest that commercial scallop populations are recruitment-limited and that, at least in the Jonesport- Beals area, other methods to collect wild spat or produce culture spat should be explored.
Funding for this research was provided by the Northeast Consortium (which is comprised of the University of New Hampshire, the University of Maine, Massachusetts Institute of Technology, and Woods Hole Oceanographic Institution), DEI, the University of Maine Sea Grant Extension, and the Maine Department of Marine Resources.
