Ecology of the Northeast US Continental Shelf



fall surface water temperature patterns
Figure 1. This satellite image depicts a daily snapshot of fall surface water temperature patterns on the Northeast U.S. continental shelf. Cooler temperatures are represented by darker colors shading to blue. Warmer temperatures, such as those associated with the Gulf Stream are represented by the warmer colors shading to red.

Around the world, many coastal nations are dealing with changes in marine fish and shellfish stocks as well as other sea life owing to alteration of critical habitats, over-use of ocean resources, bycatch, and the effects of climate variability. Thinking of the ocean and its life as an ecosystem provides a more realistic view of the underlying causes and effects of changes in living marine resources. Managing our use of the ocean’s resources, including fisheries, on an ecosystem basis is becoming more possible as we learn how an ocean system works. Managing from an ecosystem perspective allows us to consider the effects of multiple factors and their interactions. In addition to fishing, other activities that might be included are coastal development, pollution, shipping, and oil and gas extraction.

This site describes our current understanding of ecosystem properties of the Northeast U.S. Continental Shelf Large Marine Ecosystem (NES LME) and their importance in developing ecosystem based fisheries management for this region. This highly productive and economically important region spans the area from Cape Hatteras to the Gulf of Maine (Figure 1). We seek to convey basic principles in an accessible way to reach a general audience interested in the condition of our marine environment and its natural resources. To understand the fisheries ecosystem, we need to consider factors such as its physical structure, climate influences, oceanographic characteristics, habitat requirements, the biology of the system from the microscopic plants (or phytoplankton) at the base of the food web to the top predators (including humans), the status of protected species such as seabirds and marine mammals, human communities that depend on the fisheries and the ocean, and the connections among all of these parts. We address each of these elements and others such as the effect of introduced (non-native species) to provide some of the background information that will be necessary to move towards ecosystem based fisheries management.

This region has supported important commercial fisheries for several centuries. Fishing was one of the foundational industries of the nascent United States, and among our earliest international treaties were agreements concerning fishing rights. Today, commercial and recreational fishing contributes billions to the economy of the northeastern United States. The current concern with adopting ecosystem based fisheries management is grounded in the recognition that to protect the long-term viability of fishing communities, we need to protect the marine ecosystems on which they depend.

What is an Ecosystem?

fishery ecosystem from phytoplankton to humans
Figure 2. Representation of a fishery ecosystem from the base of the food web (phytoplankton and zooplankton) to humans. (Illustration by Michael Fogarty [NEFSC, NMFS] and Jack Cook [Woods Hole Oceanographic Institution]).

An ecosystem is a geographically specified system of organisms (including humans), the environment, and the processes that control its dynamics (Figure 2). Ecosystems are both complex and continuously changing. Humans and human institutions, beliefs and practices are integral parts of the ecosystem. Fish harvesters meet an important societal need by providing food from the sea. The ecosystems that produce seafood must be cared for both because of their intrinsic importance and to ensure this sustainable source of food for humans. Moreover, the fisheries are inextricably entwined with both the economic and cultural life of fishing communities. Also, the oceans are important for recreation, telecommunications, oil and mineral exploration, and other activities.

What is Ecosystem-Based Fisheries Management?

The recently released National Ocean Policy strongly endorses the development of Ecosystem Based Management. The action plan builds on the recommendations of the U.S. Commission on Ocean Policy which noted:

“U.S. ocean and coastal resources should be managed to reflect the relationships among all ecosystem components, including human and nonhuman species and the environments in which they live. Applying this principle will require defining relevant geographic management areas based on ecosystem, rather than political, boundaries.”

Important building blocks for ecosystem based management now exist within our current management structures. These include provisions for protecting essential fish habitat, reducing bycatch, and elements related to overall conservation goals and requirements for consideration of fishing communities under the Magnuson-Stevens Fishery Conservation and Management Act for protecting non-target species under the Marine Mammal Protection Act and the Endangered Species Act, and for managing coastal resources and balancing economic development with environmental conservation under the Coastal Zone Management Act.

By drawing on the lessons of the past showing the importance of biological interactions and bycatch, and combining them with the ecosystem management elements now in place, we can make substantial progress toward defining ecosystem based fisheries management for the NES LME. Because the properties of an ecosystem are different than those of its parts, this approach will necessarily differ from single-species based management. It will require us to consider tradeoffs in management — for example between forage fish and their predators, between allocations to commercial versus recreational fishermen, or economic efficiency and employment – but past experience shows it can be done.

The development of a full ecosystem based fisheries management in this area will require a dialogue among all interested parties in order to define specific objectives. Tapping the ecosystem knowledge of different groups is essential to help specify goals, to evaluate the current state of the system, and to explore the options for management. Choosing the right management tools with wide support among all parties will be critical.

The development of ecosystem based fisheries management, as one component of an overall ecosystem-based management strategy, will entail a collaborative effort among different stakeholder groups. Because of this, perhaps the most critical aspect of an ecosystem approach is designing the governance system. Progress will be substantially enhanced through the development of Fishery Ecosystem Plans (FEPs). A FEP provides background information on the ecology of the system to guide the development of management strategies. The information contained in this site provides much of the information required for the descriptive overview of ecosystem structure and function required for an FEP (see the accompanying text box for the steps involved in constructing an FEP). But agreement on the elements of these plans can only be gained through careful planning of the process by which input is received and decisions are made, in order to assure that all parties have reached some form of consensus.

An extensive scientific information base on the ecology of the NES LME is available to take these steps as illustrated throughout this site. This, coupled with the ecosystem knowledge of fish harvesters and others, provides an important stepping-stone to developing an ecosystem-based management strategy. It will also be necessary to integrate information for the NES LME with that for the immediate coastal and estuarine areas, to develop a fuller picture of ecosystem influences from the watershed to the edge of the shelf.

Further Readings

Backus, RH, ed. 1987. Georges Bank. Cambridge, MA: MIT Press

Ecosystem Principles Advisory Panel. 1999. Ecosystem-Based Fishery Management: A Report to Congress by the Ecosystem Principles Advisory Panel. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Silver Spring, MD.

Sherman, K. and H. R. Skjoldal (2002) Large Marine Ecosystems of the North Atlantic: Changing States and Sustainability, Elsevier, Amsterdam

Sherman, K., N. A. Jaworski and T. J. Smayda (1996) The Northeast Shelf Ecosystem: Assessment, Sustainability, and Management, Blackwell Science, Cambridge, MA