Stellwagen Bank Marine Historical Ecology Final Report


Stefan H. Claesson, Ph.D. & Andrew A. Rosenberg, Ph.D.
With contributions by: Karen Alexander, Andrew Cooper, Jamie Cournane, Emily Klein, William Leavenworth, Katherine Magness

Gulf of Maine Cod Project, University of New Hampshire

This report is provided to the National Oceanic and Atmospheric Administration''s (NOAA) National Marine Sanctuary Program (NMSP) and Gerry E. Studds Stellwagen Bank National Marine Sanctuary (SBNMS), by the Gulf of Maine Cod Project (GMCP) at the University of New Hampshire (UNH). It presents the results of a 3-year survey and analysis of historical documents and manuscripts relevant to the marine historical ecology of SBNMS.

This study of SBNMS history and ecology reinforces the long-term significance of the sanctuary''s ecosystems and marine resources to the broader Gulf of Maine system. At the same time, it highlights the historical role of Stellwagen Bank''s marine resources in the development and well-being of Gulf of Maine coastal communities. An assessment of the late 19th- and early 20th-century fisheries of Stellwagen Bank, presented in this report, provides baselines for comparison with current ecosystem conditions. Through comparative analysis, long-term trends have been identified that may be useful to direct future management decisions. Our historical research revealed significant declines in animal diversity and abundance, as well as major shifts in the species composition of Stellwagen''s fisheries. These findings shift baselines established in the "Condition Report" of the 2008 Stellwagen Bank National Marine Sanctuary Draft Management Plan and Environmental Assessment, and should influence the direction of management actions needed to improve overall ecosystem integrity.

Marine animal trophic level, richness, abundance, and habitat quality in SBNMS and the Gulf of Maine declined sharply over an approximately 100-year period (1900- 2000). The result of our research into the effects of climate factors such as Sea Surface Temperature (SST) and the North Atlantic Oscillation (NAO) on these baseline shifts was uncertain. Therefore, we focused on documenting anthropogenic impacts, specifically, the effects of fishing upon the sanctuary's marine animal populations and habitats. Indirect factors such as industrial pollution, river damming, and reclamation of wetlands have interfered with spawning and migration of marine species. However, the direct impact of fixed- and towed-net fishing gears on Stellwagen Bank, which has resulted in the removal of biomass and seafloor habitat disturbance, is the primary cause for declines in species richness and abundance within the sanctuary. Based on quantitative and qualitative analysis of the historical record, our findings are as follows:

a) Nearshore and microbank fish populations were significantly deteriorated by ca. 1800.
b) Top predators in SBNMS, such as halibut and swordfish, were overfished to near extirpation by the late 19th and early 20th centuries.
c) Steady decline in the trophic level of commercial species began in the early 1900s with the advent of steam-powered bottom trawling.