Use of Haul-Out Sites by Harbor Seals (Phoca vitulina) in Bellingham: Implications for Future Development

Abstract

Harbor Seals (Phoca vitulina) have been widely studied in the Pacific Northwest for over 60 y (Scheffer and Slipp 1944; Calambokidis and others 1979; Olesiuk and others 1990; Jeffries and others 2003). In the inland waters of Washington State, Harbor Seals are the most abundant and extensively distributed pinniped, numbering approximately 15,000 individuals and thought to be nearing carrying capacity (Jeffries and others 2003). As a result of this high abundance, numerous types of interactions between Harbor Seals and humans have recently been documented, including increased disturbance from a growing number of humans recreating in the inland waters of Washington (Suryan and Harvey 1999; Johnson and Acevedo-Gutierrez 2007) and conflicts with commercial and recreational fisheries (NMFS 1997). However, little is known about the interactions of Harbor Seals and humans in Bellingham. Bellingham is an industrial city in northwest Washington State, located along the east-southeast shore of Bellingham Bay (Fig. 1). The city has an estimated population of 75,150 and an annual growth rate between 2000 and 2006 of 11.5% (US Census Bureau 2006). According to Jeffries and others (2000), Harbor Seals used to haul out on floating log booms off the southeast shore of Bellingham Bay (Fig. 1). In this decade, many logs have been removed, and seals are now hauling out on logs in a nearby industrial pond (hereafter Log Pond) that was part of the former Georgia Pacific paper mill that closed in 2001. The paper mill has restricted access with very little disturbance, and no known terrestrial predation, 2 factors determining haul-out choice by Harbor Seals (Brown and Mate 1983; Watts 1992; Suryan and Harvey 1998; Nordstrom 2002). Although anecdotal evidence suggests that seals around the city of Bellingham haul out primarily at the Log Pond, there are no current estimates on the number of seals that haul out at this site or their seasonal variation. The Log Pond is significant because it lies at the center of the proposed New Whatcom, a multistage remediation and development project to clean up and develop the Bellingham waterfront (Waterfront Futures Group 2004). The use of this site as a haul-out location by Harbor Seals presents the unique opportunity to gather baseline information to examine how seal numbers and their use of the area change, if any, after development is completed. The Log Pond is also located in the immediate vicinity of Whatcom Creek, an urban salmon stream that supports 3 main salmon runs from August through December, including Chinook (Oncorhynchus tshawytscha), Chum (O. keta), and Pink Salmon (O. gorbuscha). These runs return to the Whatcom Creek Hatchery, which in turn releases thousands of smolts every spring from March through May (Steele 2007). Anecdotal evidence suggests that seals prey on salmon in Whatcom Creek. There are, however, neither estimates on the numbers of seals involved in such events nor data on the seasonal occurrence of seals in the creek. We gathered baseline data to elucidate the current status of Harbor Seals relative to human development and the potential impact of Harbor Seals on salmon runs. Specifically, we estimated the abundance of Harbor Seals in Bellingham, examined the seasonal variation in number of seals hauled-out, and described the number of seals foraging at Whatcom Creek relative to salmon runs. We conducted observations of Harbor Seals between January 2007 and December 2007 from 6 land-based posts overlooking the study sites (Fig. 1). Sites 1 and 2 are water sections without haul-out sites at the northeast end of Whatcom GENERAL NOTES