Alameda Point’s harbor seal population fluctuates between single digits and 50 during most of the year on the specially-built harbor seal float. But when the Pacific herring arrive in the winter to lay their eggs, many more seals arrive to feast on the herring, causing a sudden spike. Last winter, a spike in seal numbers to a record 70 came on January 5, 2017, in the midst of the herring run. This winter, the herring arrived sooner, in December, and so did more harbor seals, causing a spike to a new record of 73 on Christmas Eve and Christmas Day.
In the brief time span since the new harbor seal float was set in place, local monitors have assumed that it was simply the colder water temperatures that enticed greater numbers of seals to use the float in the winter. But in fact, they discovered it’s not the full story.
It turns out that dropping water temperature indeed has an effect, but the effect is on the herring. Ideal water temperature for herring spawning is between 50 and 53.6 degrees Fahrenheit. The water temperature at Alameda Point dropped below 54 degrees the afternoon of December 16 and continued dropping another 2.3 degrees, according to data collected by the National Oceanic and Atmospheric Administration. This brought on the herring run and, in turn, the voracious seals.
The rain ended, the sun came out, and so did the harbor seals at Alameda Point. So many of them came out of the water to warm up on their new float on January 5, hardly any of the structure was visible. The number has many observers asking for a second float.
The regional ferry agency installed the new float after removing an old Navy dock used by the seals, in order to make way for a ferry maintenance facility.
“I nearly keeled over when I saw the platform,” said Lisa Haderlie Baker, harbor seal monitor and Alameda resident. “So many seals packed cheek by jowl, literally, that I had to count them four times using binoculars to make sure there were 60 of them, at least, basking in the sun, which I knew had to be close to a record. It was a tremendous thrill.” Continue reading “No vacancy on float for harbor seals”
Location, location, location! But for a fenced-off dilapidated navigation light stand on a jetty at the Seaplane Lagoon, ospreys would not have had a successful nesting season this year.
In late August two adult ospreys took flight from their Seaplane Lagoon perch for parts unknown with two healthy offspring. It was a welcome sight because for the past three years a series of frustrating avian soap operas featuring other ospreys and unwanted nesting attempts aboard the maritime ship Admiral Callaghan were marked with failure. Previously in 2012 they had raised one chick, the only other recorded case of osprey reproduction at Alameda Point.
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.
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.Continue reading “Harbor seals adapting to new float”
Conservation of wildlife isn’t just important at Crab Cove
Visitors flock to Crab Cove, a State Marine Conservation Area, to learn about and experience the Bay’s sea dwellers. The educational lessons at the Crab Cove Visitor Center are equally relevant throughout the waterway south of the USS Hornet at Alameda Point where even more creatures thrive in relative obscurity.
The area encompasses an interconnected web of vegetation, birds, seals, fish, mollusks, crustaceans and worms. Ghost shrimp, bat rays, leopard sharks, striped crabs, mussels, California sea hares and fish with light-emitting diodes are just a sampling. A 36-foot-wide rock wall, known as a breakwater and built by the Navy in 1945, forms the mile-long southern boundary.
Three thousand tons of sand was added to the nesting grounds for the least terns at Alameda Point in late February and early March. In the weeks that followed, volunteers from St. George Spirits and the Boy Scouts and Cub Scouts came out to help make the site ready for the arrival of the terns in mid-April.
The Water Emergency Transportation Authority (WETA) paid for enough sand to cover half of the 9.6-acre nesting area with three inches of sand, as well as for grading. The weeklong delivery of sand was a conservation mitigation requirement for the impact that WETA’s new ferry maintenance facility will have on the terns’ feeding area. As many as 12 ferries will make up to four passes per weekday through the Alameda Point Channel where the terns frequently dive for small fish.
Wind and water erosion take their toll on the sand substrate lying atop old airfield taxiway pavement, requiring periodic replenishment. This latest delivery of Angel Island coarse sand has built up the sand depth on much of the site to the point that it’s starting to feel like a real beach underfoot. Beaches are the traditional nesting habitat for terns.Continue reading “Ferry agency, volunteers help the least terns”
The Water Emergency Transportation Authority (WETA) is aiming for the delivery of a new dock for harbor seals at Alameda Point as early as April, ahead of the start of construction of its new ferry maintenance facility this summer.
Because the maintenance facility’s new berthing dock would displace the seals’ current resting spot, a provision was approved for a new harbor seal dock as a condition for permitting the new facility. WETA, the city council, and the Bay Conservation and Development Commission (BCDC) approved the provision at the urging of community activists.
WETA issued design specifications for its 12-berth maintenance facility and administrative offices to prospective contractors in December. It expects to award the contract on March 31, with work commencing as soon as May 6. The estimated cost is pegged at $45 million, $9 million of which is for design work and the remaining $36 million going for construction, according to Chad Mason, senior planner at WETA. Funding for the project is coming from federal, state, and regional funds.
The facility will include a 70-foot-tall four-story building and is expected to be complete in 2018.
The project will also fund other benefits, among them, a new water line from Main Street, park enhancements, and sand for the least tern nesting area on the airfield.
WETA will construct a shoreline viewing terrace, bicycle parking, interpretive signage, improved lighting and landscaping, and seating on an adjacent half-acre of parkland on West Hornet Avenue.
WETA will also be providing some assistance for the California least terns, an endangered bird species that nests at Alameda Point and dives for fish in surrounding waters. As a mitigation for the impacts of the new ferry traffic on the terns’ foraging waters, WETA will be delivering enough truckloads of sand to the terns’ nesting area on the airfield in February to add a few inches of depth. Erosion of the 9.6-acre beach-like nesting landscape necessitates periodic replenishment.
The replacement harbor seal dock, also referred to as a haul-out, will be the first time such a structure has been built on San Francisco Bay specifically to retain or attract harbor seals. It will be located a short distance to the east of the old dock. Time will tell whether this experimental effort is successful.
“Meeting the permitting requirements for the new harbor seal haul-out is underway,” said Mason. BCDC is the state permitting agency for all Bay shoreline and in-water projects. It requires assurances from other agencies that the harbor seal dock does not introduce any unwanted environmental impacts before granting approval.
“With the help of the environmental consulting firm Dudek, the harbor seal haul-out is on a fast-track approval timeline,” said Mason. “The only regulatory delay is due to the herring spawning season. Regulations require that the pilings for the new haul-out be installed after the end of the herring spawning season in late March of 2016.”
“We are currently reviewing two options for providing the new harbor seal haul-out: Build a new one from scratch, or modify an existing mobile dock if we can find one that meets our needs,” said Mason. “We hope to issue the contract for the haul-out in January.” WETA will be responsible for constructing, maintaining and replacing the harbor seal dock when necessary for the 60-year term of its lease.
WETA has been working with a citizen advisory group of local harbor seal advocates who spearheaded the effort for the new haul-out. The group gained the support of the Sierra Club and the Audubon Society. The location for the new seal dock was chosen with the help of marine mammal expert Dr. Jim Harvey, Director of California State Universities’ Moss Landing Marine Laboratories.
This winter, the seals favor the afternoon for getting out of the water. Their numbers can vary from a dozen to a recent high of over three dozen. It is the only haul-out site in the East Bay between Yerba Buena Island and the marshlands of Fremont and Newark near the Dumbarton Bridge, both of which require watercraft for public viewing access. The seals at Alameda Point can be viewed from the Bay Trail.