Site
is approximately 6200 hectares in open water within San Pablo Bay in the
northern section of San Francisco Bay.  It
covers subtidal substrate of mostly mud and sand, and ranges from about 0 - 3m
in depth. Site hosts large numbers of migratory and over-wintering ducks,
especially in the early part of the winter where they feed on invertebrates in
the subtidal sediment. Site abuts San Pablo Bay Wetlands IBA to the northwest
and is just north of a major shipping lane for traffic moving to and from the
Sacramento-San Joaquin Delta and the San Francisco Bay. 

Ornithological Summary

The
site regularly hosts >5000 waterfowl on a given day, meeting the State D4ii
(W, California) IBA criteria.  The area
tends to be most active during early winter (Nov-Dec) and species seen include
Surf Scoter, Greater Scaup, Lesser Scaup, and Canvasback. 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 and Greater Scaup qualified. 
Additionally, this area repeatedly supported >20,000 waterbirds (Global
criteria A4iii). Its location adjacent to the San Pablo Bay Wetlands IBA
provides an important extension out into open water, and buffers the heavily
trafficked area just to the south. Additionally it is less than 5 miles from
the North Richmond Wetlands IBA to the south. This site and the San Francisco Bay–Southern 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
most obvious threat to the birds is disturbance by boats, especially since it
abuts the shipping channel to its south. 
However, since the area is relatively shallow (1-3 meters), it is more
likely to see use by smaller vessels such as motor boats, kayaks and
paddleboards.  While small, these vessels
can cause significant disturbance to resting and feeding waterbirds as
described in Borgmann (2012).  UAV
(drones) could develop as another source of disturbance if use increases
significantly in the near future. 
Invasive invertebrate species have taken hold and could potentially alter the nutritional resources the birds depend upon. Dredging would be limited in scope and time, since it is not likely to
occur every year and would be limited to the current navigation channels as
well as by anadromous fish restrictions. 
Pollution, including an oil spill, is especially dangerous for
waterbirds and can result in hypothermia, sickness, and digestive issues
(plastics).

Ownership

Federal, state and municipal ownership.  Most, if not all, was originally granted to
the state of California and under the jurisdiction of the State Lands
Commission (SLC).  Over half the area
within the IBA boundary was granted by the SLC to the City of Vallejo and the
US Navy, while the SLC retains control of the western 45%.

Habitat

The
site is composed of subtidal lands within San Pablo Bay in the northern section
of San Francisco Bay.  From habitat maps,
the substrate consists mostly of mud and sand. 

Land Use

Waterfowl
hunting from boats is allowed during October – January; fishing (seasonal); and
year-round recreational boating.

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