COASTAL ECOSYSTEM MANAGEMENT IN WELLFLEET HARBOR, MA: ADDRESSING SUSTAINABLE SHELLFISHING AND AQUACULTURE

AnneMarie Cataldo, Earth, Environmental and Ocean Science Department, University of Massachusetts Boston, annemarie.cataldo001@umb.eduAnamarija Frankić, Earth, Environmental and Ocean Science Department, University of Massachusetts Boston, anamarija.frankic@umb.edu

ABSTRACT

Wellfleet Harbor has been well known for its oyster and quahog harvests and abundant shellfish resources. Like many developed coastal areas, Wellfleet Harbor has been experiencing increased population, landuse conversions, and tourism development, while at the same time the abundance of its shellfish species has been declining. This is mainly due to fishing pressure, habitat loss and alteration, water quality degradation and shellfish diseases. However, Wellfleet continues to support a very active historical, cultural and economically important shellfishing community. This project addresses how to restore sustainable shellfishing and aquaculture development using coastal ecosystem based management. Properly sited and established shellfish spawning sanctuaries represent restorative and precautionary measures in fortifying the current spawning population and increasing natural shellfish abundance. Using GIS and existing environmental data, land use maps, and coastal and marine use zones, the site suitably and use conflict analysis were performed (Frankic, 2003). Identified areas for potential spawning sanctuaries were evaluated based on both environmental and socio-economical suitability analysis. Provided management recommendations have capacity to forecast conflicts in a system that is evolving under both anthropogenic and climatic forces.

INTRODUCTIONThe draft of the 2002 Wellfleet Harbor Shellfish Management Plan suggested several changes to the current management regime for the shellfish resource. As part of an ecosystem based approach, the establishment of 6-10 small mixed shellfish species spawning sanctuaries were proposed in this plan, with six specific sites identified (Figure 2). The present study has set out to evaluate if these suggested sites are suitable for the establishment of mixed species spawning sanctuaries (Mercenaria mercenaria and Crassostrea virginica) considering both environmental and socioeconomic factors of existing data for the harbor. Considering environmental parameters, sites selected for spawning sanctuaries must be conducive to the growth and reproduction of the two shellfish species being considered. For socio- economic factors, a use conflict analysis will need to identify areas that avoid use conflict with social and economic activities occurring in and around Wellfleet Harbor. The present study of site suitability analysis for spawning sanctuaries of Crassostrea virginica and Mercenaria mercenaria will test for both environmental suitability and use conflict in Wellfleet Harbor. Additional management considerations will also be discussed so as to provide an easily understandable range of management options for the decision maker.

METHODS

Environmental Site Suitability Analysis

• Determination of environmental conditions promoting growth, survival and reproduction for Crassostrea virginica and Mercenaria mercenaria

•The generation of maps in ESRI’s ArcGIS 9.1 of selected environmental parameters in Wellfleet Harbor using available data

•Classification of environmental parameters: a) not suitable for growth survival and reproduction, b) suitable for growth survival and reproduction, and c) optimal for growth survival and reproduction;

•Environmental data available from monitoring studies used in the analysis are: Salinity, Temperature range, Spawning temperature, Dissolved Oxygen, Bathymetry, and Fecal Coliform concentration;

• Using multiple criteria analysis in ArcGIS 9.1, performing the environmental site suitability analysis of Wellfleet Harbor based on the not suitable, suitable and optimal classification of environmental parameters;

Use Conflict Analysis (part of the Socio-economic considerations)

•Identifying and mapping present and future planned uses/activities in Wellfleet Harbor (ArcGIS 9.1) (Figure 4)

• Selection of not suitable, suitable and optimal uses:

Not Suitable: Aquaculture, Mooring areas, Dredged areas and the Marina

Suitable: Areas of the harbor not being used for the previous purposes

Optimal: Areas of Subaquatic Vegetation (SAV)

• Using multiple criteria analysis in ArcGIS 9.1, and performing the use conflict analysis to select suitable sites for shellfish spawning sanctuaries

RESULTS AND DISCUSSION According to the environmental site suitability analysis performed with available data, Wellfleet Harbor has been classified for its ability to support the growth, survival and reproduction of the oyster and quahog. The analysis was performed separately for the oyster and quahog, as their environmental tolerances differ, and then the analysis results were combined for a map displaying not suitable, suitable and optimal areas for both species (Figure 3).

Results on the Figure 3 shows that most of the harbor has environmentally optimal conditions for both species. This optimal area occurs predominantly in the deeper parts of the harbor. A large part of the harbor is also displayed as environmentally not suitable. This area covers most of the intertidal flats. The main environmental indicator for the unsuitable classification is the low temperatures and frequent ice cover during the winter that causes high mortality for oysters in particular. Two other sites were selected as environmentally suitable for oysters while optimal for quahogs, and environmentally suitable for both species.

Adding socio-economic factors in the use conflict analysis of the area resulted in expansion of not suitable areas for spawning sanctuaries (purple polygons in Fig. 3).

Considering the initially suggested sites (Figure 2) it is clear that the site suitability analysis has shown that most of these sites are not suitable for shellfish spawning sanctuaries (Figure 5). According to the analysis, only two sites: a) the deep water site and b) the creek north of the Audubon Sanctuary, should be further considered as potential sites for spawning sanctuaries. The deep water site is predicted to be environmentally optimal for both species and without use conflict. The creek north of the Audubon Sanctuary is predicted to be environmentally suitable for oysters, optimal for quahogs and without use conflict.

Further considerations should be given to the adjacent land uses and current resource management at the two potential sites: a) the creek site that is adjacent to the Audubon Sanctuary is also close to residential zones. While the sanctuary would not create a problem, residential zones create the potential for tenure disputes as well as runoff problems in the adjacent coastal area.

b) In order to use the deep water selected site for sanctuary the current shellfish management and feasibility study must be considered. Because this part of the harbor is abundant in commercially important shellfish and dredging is the main harvest method. Therefore, this might be a potential future use conflict to establish a sanctuary in a dredging area for commercial shellfishing. .

In conclusion, while spawning sanctuaries are proved to be one of the precautionary and restorative measure for improving shellfish populations, they must be placed based on environmental and socio-economic considerations in order to be effective. In Wellfleet Harbor more scientific data can help in the decision making process (e.g. currents, benthic habitats, non point sources of pollution, freshwater inputs). This approach and analysis identified gaps in knowledge about the area as well as needed scientific data and monitoring needed in the Wellfleet Harbor area.

REFERENCE:

Frankić, A. 2003. Integrated Coastal Management & Sustainable Aquaculture Development in the Adriatic Sea, Republic of Croatia. Virginia Institute of Marine Science.

ACKNOWLEDGEMENTS: Town of Wellfleet Shellfish Department, Wellfleet Health and Conservation Department, WHOI Sea Grant/ Cape Cod Cooperative Extension, Massachusetts Division of Marine Fisheries

Figure 2: Sites Suggested for spawning sanctuaries

Figure 3: Results of the environmental suitability analysis

Figure 5: Results of the use conflict analysis combined with the environmental suitability analysis

Cape Cod

Massachusetts

Figure 1: Wellfleet Harbor

Wellfleet Harbor

Cape Cod

Figure 4: Uses of Wellfleet Harbor