Port Snettisham is a deep glacial fjord located on the mainland (off Stephen?s Passage) approximately 50 km south of Juneau. It drains two glacial rivers?the Speel and the Whiting. The fjord is an exceptionally productive foraging area, attracting thousands of marbled murrelets per day throughout the breeding season, and hundreds of other species (loons, scoters) per day during spring migration.
The importance of Port Snettisham for Marbled Murrelets was first documented in the early 1990s. In 2005, a field camp was established to conduct systematic surveys and radio-telemetry work aimed at describing Marbled Murrelet use of the area. Those field efforts continued during summer, 2005 and 2006. Surveys consisted of daily flyway counts across the mouth of Port Snettisham. Surveys were 20 minutes long (multiplied by 3 to yield birds per hour), and on several days a week were conducted hourly from sunrise to sunset. Experiments conducted in 2006 revealed the majority of birds flying in the distant 1/3 of the inlet were going undetected, even when visibility was rated excellent. Thus, all numbers are considered minimum counts.
Within a day, murrelet flight activity is generally highest in the morning and evening, with most birds going outbound in the hour before sunset. Relatively few birds remain in Port Snettisham after dark (searches with spotlights) compared with numbers present during the day. Seasonally, murrelet numbers increased from early May through late July, and declined in August. Combining years, the peak 10-day period was 19-28 July, with an average of 698 murrelets counted per hour (N = 139 surveys). This equates to 12,656 murrelet flights per 18 hour day. Assuming each bird makes one flight in and one flight out per day, the flyway data reflect a population of approximately 6,300 Marbled Murrelets during the peak attendance period of the summer.
In 2006, at-sea surveys were conducted to assess the number of murrelets on the water in Port Snettisham. Surveys were conducted from a 7 m vessel, with trained observers counting all murrelets within a fixed width (200 m wide) strip over 15 permanent transects. Surveys were only conducted when sea state was 2 or less, and most transects had sea state 0 or 1. We assumed all birds within the strip were detected. Transects were oriented to sample the entire surface area of Port Snettisham at relatively high sampling intensity (transect area/surface area = 13.7%). From these surveys, the mean population size at Port Snettisham was 5,742 Marbled Murrelets - in rough agreement with the population size projected from flyway counts for peak 10-day periods. The maximum density of Marbled Murrelets on the water in Port Snettisham was 118 per square kilometer on August 1st, 2006
Port Snettisham also attracts large numbers of other species, including loons (several species), Harlequin Ducks, scoters (2 species), Pigeon Guillemots, and Common Murres. Of these, the numbers of loons were most significant, especially during spring migration when Port Snettisham serves as an important stopover and foraging area. During a 10 day period in 2006 (May 10-19), an average of 201 loons were counted per hour flying in and out of Port Snettisham (N = 65 surveys). Counts on individual days were even more impressive. Over a 2-day period (18-19 May), an average of 536 loons per hour were counted (N =19 surveys). This is equal to 8,040 counts per 15 hour day. If we assume that each loon makes one flight in and one flight out, >4,000 loons visited Port Snettisham each of those 2 days. Although loons could not be identified to species in distant flight, observations of large feeding flocks on the water revealed the birds to be mostly Pacific Loons. Intermixed in smaller numbers were Common Loons, Red-throated Loons, and Yellow-billed Loons.
The area is closed to gillnet fishing through most of the summer (to protect the sockeye run), but opens in late July?early August for several weeks. At that time, there may be 20-35 commercial fishing boats in the inlet, each fishing a 1200? long monofilament gill net. An unknown number of Marbled Murrelets may be entangled during that time. It is unlikely that there is a population effect due to the limited fishing window, low entanglement rates, and the large numbers of birds. An oil spill in Port Snettisham (or adjoining Stephen?s Passage) could have very damaging effects, and could kill thousands of birds.
Port Snettisham is contained within the Tongass National Forest. There are two very small private parcels in Port Snettisham, one on the south shore of the main arm, and another on the west side of the Whiting River, near the mouth. The land that houses the hatchery and the power plant at the head of Speel Arm is either state or city owned. Non-federal land probably makes up less than one tenth of one percent of the watershed area. The marine waters are not owned by any entity, but state and federal regulations define the allowable uses.
Upland habitat is a mix of old-growth hemlock-spruce forest below 300 m elevation, and treeless alpine above. The terrain is generally steep and rugged. The waters in Port Snettisham are strongly influenced by 2 glacial rivers, the Speel and the Whiting that flow into it. The fiord is very deep, except for Gilbert Bay, which is relatively shallow and turbid
The land is relatively pristine. There is a power station and fish hatchery at the extreme end of Speel Arm. A power transmission line runs along the hillside from the power station to Juneau, 30 km away. The upland habitat has had some selective beach logging in early years, but there are no logging roads or clear-cuts. No commercial tourism. Some private boats visit. There is a popular sockeye subsistence fishery (cast nets and dip nets in fresh water) at Sweetheart Creek in Gilbert Bay in mid-late July.