1998 Lake Whatcom Survey: The Warmwater Fish Community 15 Yers after the Introduction of Smallmouth Bass

Lake Whatcom is a large body of water (surface area = 2,030 ha; volume = 936,651,000 m3) located directly east of the City of Bellingham in Whatcom County. The lake consists of three basins separated by distinct glacial sills. The northern and middle basins (Basin 1 and Basin 2, respectively) are relatively small and shallow (20 to 25 m maximum depth), whereas the southern basin (Basin 3) is considerably larger and deeper (85 to 100 m maximum depth) (Figure 1). Lake Whatcom is fed by Silver Beach, Carpenter, Olson and Smith Creeks from the east, Anderson, Fir and Brannian Creeks from the south, and Austin/Beaver Creeks from the west. Several unnamed, intermittent creeks discharge into each basin, whereas water from the middle fork of the Nooksak River is occasionally diverted to Basin 3 via Anderson Creek. Surface water exits the lake from the north, through Whatcom Creek, eventually discharging into Bellingham Bay.

The near-shore habitat of Basin 1 is comprised mostly of gravel, sand, and mud. Basin 2 is comprised mostly of gravel, sand, and exposed bedrock. Much of Basin 3 is comprised of exposed bedrock and gravel. Low to moderate amounts of coarse woody debris can be found in the shallows of all three basins (Table 1). The aquatic plant community consists of a variety of pondweeds (Potamogeton sp.), waterweed (Elodea sp.), stonewort (Nitella sp.), common naiad (Najas flexilis), and the exotic Eurasian watermilfoil (Myriophyllum spicatum) [Jenifer Parsons, Washington Department of Ecology (WDE), unpublished data]. Emergent and submersed aquatic vegetation covers up to 33% of the littoral zone of all three basins (Table 1).

Land use around Basins 1 and 2 is primarily high-density residential. Up to 30% of the shoreline is bulkheaded within these basins and the mean number of docks ranges from 2 to 3 per 100 m shoreline (Table 1). Timber and undeveloped lands comprise the dominant uses of Basin 3; however, some high-density residential areas occur as well. Less than five percent of the shoreline in Basin 3 is bulkheaded, with an average of less than 1 dock per 100 m shoreline (Table 1).

Surrounding land uses in the Lake Whatcom watershed affect its water quality (Matthews et al. 1999; Serdar et al. 1999). High development adversely affects water quality in Basin 1, which stratifies with regard to temperature and oxygen during summer and fall (Matthews et al. 1999; Table 2). Water quality in Basin 2 has demonstrated a trend towards increased eutrophication in recent years, but is currently less anoxic in the hypolimnion than Basin 1 during summer and fall (Matthews et al. 1999; Table 2). The hypoxic conditions of Basins 1 and 2 have led the Environmental Protection Agency (EPA) to consider the lake degraded based on the work of Matthews et al. (1999) [BPWD 1999]. In Basin 3, water quality is generally good with respect to hypolimnetic oxygen (Matthews et al. 1999; Table 2).

Lake Whatcom is the primary source of drinking water for approximately 66,000 Whatcom County residents. However, a recent study by Washington Department of Ecology (Serdar et al. 1999) indicated that several contaminants of concern were detected in water, sediment, and fish tissue samples from the lake and its tributaries during 1998. Fecal coliform bacteria (FCB) was the most common contaminant found in creeks surrounding Lake Whatcom. Levels of FCB exceeded Washington State water quality standards wherever water was sampled. Other contaminants included a variety of metals and pesticides, most notably polychlorobiphenyls (PCBs). For example, elevated levels of mercury were detected in smallmouth bass (Micropterus dolomieu). Furthermore, levels of dieldrin, PCB-1254, and PCB-1260 detected in smallmouth bass, kokanee (Oncorhynchus nerka), and longnose sucker (Catostomus catostomus) exceeded the EPA’s National Toxics Rule (NTR) edible fish tissue criteria to protect human health (Serdar et al. 1999).

Recreational activities at the lake include swimming, water skiing, sailing, and fishing. Historically, the sport fish community comprised of kokanee and resident cutthroat trout (Oncorhynchus clarki). Rainbow trout (Oncorhynchus mykiss) and lake trout (Salvelinus namaycush) were introduced early in the 20th century. Largemouth bass (Micropterus salmoides), yellow perch (Perca flavescens), brown bullhead (Ameiurus nebulosus), and pumpkinseed (Lepomis gibbosus) were illegally introduced in later decades. In addition to sport fish, crayfish (Pacifastacus leniusculus) occur abundantly in the lake and are harvested commercially on occasion (Fletcher 1982; Looff 1994; Jim Johnston, WDFW, personal communication).

Given the prevalence of gravel and exposed bedrock habitats throughout Lake Whatcom (Table 1), the minimal angling pressure, and the presence of a large crayfish population as a possible forage base, Fletcher (1982) proposed the introduction of a new sport fish into the lake. Subsequently, during late summer 1983 and 1984, smallmouth bass were released into Basin 1 by the WDFW, formerly the Washington Department of Game (Jim Johnston, WDFW, personal communication). Although records of Lake Whatcom’s native, resident fishes have been compiled for years (Looff 1994; Jim Johnston, WDFW, unpublished data; Paul Mongillo, WDFW, unpublished data), no recent information exists concerning the warmwater fish community at the lake, especially since the introduction of smallmouth bass. Therefore, in an effort to evaluate the status of the smallmouth bass population and to gather baseline information on other warmwater fishes, personnel from WDFW’s Warmwater Enhancement Program conducted a fisheries survey at Lake Whatcom in late summer 1998.