Harbor seals adapting to new float

A new concrete float for harbor seals was delivered to Alameda Point on June 22. It is the first-of-its-kind on the West Coast. With seals starting to use the new platform, a milestone has been reached culminating two-and-a-half years of citizen advocacy to maintain a resting site for harbor seals at Alameda Point. A ferry maintenance facility is slated to begin construction this summer where the seals have been finding solitude for over a decade. The new float will be anchored 300 yards away to the east.

Harbor seals on new float Alameda

In an effort to acclimate the seals to their new float and surroundings, the float is being moved in stages to its permanent location. It will be anchored a hundred yards offshore from the Bay Trail near the soccer field on West Hornet Avenue.

Harbor seal climbing onto new float at Alameda Point.
Harbor seal climbing onto new float at Alameda Point.

The old wooden dock that the seals had been using for a decade was demolished on July 11 in order to prompt the seals to start using the new float. On July 28, the float underwent its first move, followed by a second move on Tuesday, August 9. Two more moves are scheduled in the next four weeks.

The number of seals in the harbor in mid summer is typically in the single digits, with seal monitors recording a high of seven in recent weeks. During the winter, two dozen or more seals have regularly made use of the old wooden dock. The new cement float appears small, but it can comfortably hold up to 30 seals.

The design and location of the new harbor seal float was selected with the assistance of marine mammal expert Dr. Jim Harvey, director of the Moss Landing Marine Laboratories. Dr. Harvey recommended a location near the old wooden dock in order to stay within the seals’ known comfort zone. He said that ferries moving about nearby would not alarm the seals. Kayaks and canoes approaching too closely, on the other hand, will arouse the seals.

Permanent location of harbor seal float indicated on image, along with ferry maintenance facility. Groundbreaking for maintenance facility Sept. 15, 2016.
Permanent location of harbor seal float indicated on image, along with ferry maintenance facility. Groundbreaking for maintenance facility Sept. 15, 2016.

During the winter months at Alameda Point, it was not uncommon to see two dozen seals hauled out on the old wooden dock and some odd planks tied to the dock pilings. The inner harbor at Alameda Point is the only harbor seal haul-out site in the East Bay between Yerba Buena Island and Fremont. The sheltered harbor with good food foraging makes the area ideal for seals.

The floating structure provides an additional benefit beyond that of traditional land-based resting areas – it is available for use throughout the tide cycle. Harbor seals need to come out of the water periodically to warm up and also to shed their coat, called molting. Unlike their marine mammal cousins the sea lions, harbor seals become worried when people get too close. Repeatedly rousting seals from a resting site could lead to abandonment of the area. It is a violation of the federal Marine Mammal Protection Act to harass or disturb resting harbor seals. Fines can be in the tens of thousands of dollars.

Harbor seals on new float Alameda Point

The new float is 20 feet by 25 feet. One side is sloped to make it easier for the seals to haul out. The float is made of reinforced concrete. Styrofoam enclosed within the concrete keeps the platform afloat. This custom-designed structure was built by Kie Con Inc. in Antioch, based on a patent held by International Marine Flotation Systems of Vancouver, British Columbia, at a cost to WETA of $68,000.

Two harbor seals on new float Alameda Point

Local harbor seal advocates have established a Facebook page called Alameda Point Harbor Seal Monitors. Community members interested in contributing their observations of the harbor seals are invited to contact the group. The agency that issued the permit, the San Francisco Bay Conservation and Development Commission, is interested in knowing whether the float is being used for its intended purpose. They will rely on citizen science. More than a year of data has already been recorded by volunteers on the behavior of the harbor seals at Alameda Point.

Author: richard94501

My blog is Alameda Point Environmental Report covering environmental issues from wildlife to cleanup at the former Navy base in Alameda now called Alameda Point. Articles on my blog are frequently printed in the Alameda Sun newspaper. I also host a Twitter site and a Flickr photo site. I hope you find my stories and photos of interest. Richard Bangert Alameda, California

One thought on “Harbor seals adapting to new float”

  1. Nice to hear about the progress and what to expect. Thanks to all those who helped prevent the seals from leaving the harbor.


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