Site
is approximately 3720 hectares in open water within San Francisco Bay located
south of Alameda Island, east of San Leandro and north of the San Mateo Bridge
(State Highway 92).  It covers subtidal
substrate of mostly mud, shell and sand, and ranges from about 0-2.5m in depth.
Site hosts large numbers of migratory and over-wintering ducks, especially in
the early and late parts of the winter where they feed on invertebrates in the
subtidal sediment. The site abuts San Francisco Bay-South IBA to the north,
east and south; overlaps a known Pacific Herring spawning area in the north;
and is bisected by a navigation channel accessing the San Leandro Marina.

Ornithological Summary

The
site regularly hosts >5000 waterfowl on a given day, meeting the State D4ii
(W, California) criteria. The area tends to be most active during early
(November to mid-December) and late winter (mid Feb-March) and species seen include
Surf Scoter, Greater Scaup and Lesser Scaup. We performed a GIS analysis of
aerial survey data based on methodology described in Smith, et al (2014). This
method identified the location of this potential IBA based on regular average
counts of waterfowl in 1km2 cells. Once identified in this fashion,
the areas were checked for individual species counts greater than or equal to
1% of their North American populations (Global criteria A4i); Surf Scoter
qualified. Its location provides an open water extension of the San Francisco
Bay-South IBA.  This site and the San Pablo Bay Marine site being
nominated concurrently would be important additions to open water conservation
zone within the Bay.  The only other open
water IBA within SF Bay at this time is the Richardson Bay IBA in the Central
Bay, which at ~1270 hectares is much smaller than the proposed new areas.

Conservation Issues

The
clearest threat is small boat disturbance given the proximity to the San
Leandro Marina and the navigation channel running through the area (see
Borgmann, 2012). Major shipping does not appear to be an issue due to shallow
waters. Small vessels, however, can cause significant disturbance to resting
and feeding waterbirds as described in Borgmann (2012).  There are two major airports are in the
vicinity of the proposed IBA including Oakland (1 mile) and SFO (8 miles). Dredging
of navigation channel during winter could cause significant disturbance, but
unlikely at that time due to anadromous fish restrictions. Introduced invasive
species have the potential to disrupt food resources for birds.  Pollution, including an oil spill, can be especially dangerous for waterbirds and can result in hypothermia, sickness,
and digestive issues (plastics).

Ownership

State
and federal ownership.  Most, if not all,
was originally granted to the state of California and under the jurisdiction of
the State Lands Commission (SLC).  Nearly
two-thirds of the area within the IBA boundary was granted to the City of
Oakland by the SLC, while SLC retains control of the remainder.  A small corner of the IBA area (<1%) was
granted to the City of South San Francisco by the SLC. 

Habitat

The
site is composed of mostly subtidal lands within the southeastern area of San
Francisco Bay.  From habitat maps, the
substrate consists mostly of mud and sand. A small portion is intertidal
mudflats.

Land Use

Seasonal
fishing allowed; year-round recreational boating.  A navigational channel bisects the area in
the north and leads to a private marina on the San Leandro shoreline.

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