Seabird Surveys in Puget Sound 1996, Report to Northwest Indian Fisheries Commission
We documented the distribution and abundance of seabirds, particularly the threatened Marbled Murrelet, in Puget Sound during fall of 1996. This was a cooperative project, with participation by Northwest Indian Fisheries Commission, Tribal members, SEI, USDA Forest Service, Washington Department of Wildlife, and the US Army (Fort Lewis). Our goal was to describe seasonal changes in distribution, and to make this information available to fisheries managers.
SEI conducted surveys from September 24 - November 23,1996, in the following
Skagit Bay and the Saratoga Passage, south to Possession Sound
Admiralty Inlet and Hood Canal, from Port Townsend to Quatsap Point
A total of 40,415 seabirds and mammals were seen on all surveys. 1492 of these were Marbled Murrelets. Hence Marbled Murrelets comprise 3.77% of the number of species observed. 899 Murrelets were observed on NWIFC sponsored surveys within Hood Canal and Skagit / Saratoga study areas only (comprising 2.2% of the number of species observed in those study areas).
Our major findings can be summarized as follows: Marbled Murrelets are concentrated in well-defined areas. However there are seasonal shifts in the location of these aggregations. Most Murrelets occur between 200 and 500 meters from shore. Information from surveys was made available to Tribal fisheries managers as data were collected. Because Murrelet distributions change during the season, fisheries managers need up-to-date information.
We report estimates of relative abundance from extensive transect surveys at 300m offshore. Intensive surveys in areas of high Murrelet density were carried out at 100, 300, 500, 800, and 1100 m from shore. In 1995, these more detailed data suggest that extensive surveys at 300m detect approximately 53% of the total number of Murrelets present.
Burrows Bay had large populations of Marbled Murrelets only on September 9. We counted 156 Murrelets within the east central part of the Bay. Most Murrelets were between 300 and 1000m from shore. This is an unusual pattern of distribution, not usually found elsewhere.
Deception Pass had a small and erratically present population of between 4 and 11 Murrelets. These were concentrated in areas close to (but not within) the Pass itself. On 1 of 3 survey occasions no Murrelets were present, suggesting that birds in this area may be transients during fall.
Within the Saratoga Passage, Marbled Murrelet distribution varied with season. These Murrelets were typically concentrated between 100 to 300 m of shore. In fall more Murrelets appeared in Penn Cove (7) and Holmes Harbor (23) in November.
Along the western shore of Camano Island, we saw few Murrelets south of Lowell Point. Port Susan contained no murrelets the entire survey season. The area immediately north of Tulalip Bay contained a few Murrelets in early fall (5). However a massive influx occurred in early November with at least 127 birds in the areas immediately north and south of the Bay entrance. Murrelets in this area were concentrated between 200 and 500 m from shore. No Murrelets were seen in and around Gedney Island this year.
One survey was carried out in Port Madison prior to the fall Chum fishery. No Murrelets were seen in the area. Western Grebes were the most abundant seabird in Port Madison.
The Hood Canal region was surveyed from October to mid November. The total numbers of Marbled Murrelets slightly increased in this region (counts of 200 in October); until late fall (400 in November). However the distribution within the region changed dramatically. Most observations of birds were within 500m of shore.
Within Port Gamble, Murrelets entered the bay in fall. These Murrelets were concentrated in the north east part of the bay, at between 150 and 300 m from shore.
Many Murrelets were found north of the Hood Canal Bridge, in the vicinity of Port Ludlow and Port Townsend. These Murrelets were again concentrated between 300 and 500 m from shore.
We have interpreted our data regarding their implications for fisheries management, but feel strongly that several years of surveys will be required to understand the annual variation in distribution and abundance in fishing areas. Overall, we feel that there is only limited potential for conflict between gill-net fisheries in Puget Sound and conservation of the Marbled Murrelet. Our results show that significant bye-catch of Murrelets is unlikely in most areas. When Murrelets are concentrated inshore, placement of nets further offshore would eliminate most bye-catch. It is our hope that our results can be used by fisheries managers to avoid potential conflicts.
Figure 5. Comparison of Marbled Murrelet Numbers in Skagit/Saratoga Study Area between years 1995 and 1996.
Figure 20. Number of Marbled Murrelets at various distances from shore combining all intensive survey data from 1995 and 1996 in Skagit and Hood Canal study areas.
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