Archive for January, 2012

White Sturgeon in San Francisco Bay

The Sturgeon in San Francisco Bay:
How critical can a 10,000 year old Bay be for a 100 million year old fish?

Guest Speaker:  Michael McGowan
7:30pm, Thursday, February 16th, 2012
FREE at the Randall Museum, 199 Museum Way, San Francisco, CA 

Michael McGowan, fisheries oceanographer and aquatic ecologist, will discuss his research on how the ecology of the green and white sturgeon differ in their life history and in how they use the Bay.

White sturgeon are the largest fresh water fish in North America that can live over a hundred years and can grow to 20 feet long, and weigh 1500lbs. (more info)

Green sturgeon, up  to 7 feet long and 350lbs, seem to be a little more mysterious on the web, they are probably migratory salt water fish that probably spawn in fresh water. (more info)

Michael will fill in the details for us.

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Glen Martin started off his talk with an anecdote: coming into his garage one night to find an opossum. He poked it with a broomstick to test the notion of “playing possum,” but the opossum did not play dead, but threatened him, opening up a mouthful of the biggest looking teeth he’d ever seen.

Opossums (and introduced species) and their “cousins” skunks, raccoons and others are doing well with those teeth, living in amongst us, and living off of us. Skunks love our lawns for their grubs and worms, raccoons love our garbage cans, and opossums seem to like to eat anything. With restoration efforts some of the less human adapted meso predators are doing well, ringtail cats in riparian environments, mink in the delta, and river otters.

Meso predators are defined by a certain mass and a certain function — they are not the top tier predator, but if the top is eliminated they can actually do quite well as the apex predator. This is what has happened to the coyote where wolves have been eliminated. The apex predators are often extremely unforgiving of the mesopredators: wolves will kill coyotes, lions will kill cheetahs and hyenas.

Of course meso predators can also have devastating effects. A guest of Mr Martin’s: Dr Frank talked about his experience studying (as a FWS tech) the Aleutian Goose in the Aleutian Islands, and how a fox introduced for their fur (in 1750), wiped clean of birds island after island. The foxes managed to survive after this decimation by living off of the abundance of isopods on the beach. More details of the Foxes here.

Glen Martin discussed feral cats as being a significant cohort of this type of predator, and their potential as a force for habitat discussion.

This most interesting part of the evening was the talk around the interrelation of predators and how changing those relationships adding or removing predators can have profound impacts on the local environment. The most famous example is that of Yellowstone where the re-introduction of wolves has  kept elk moving and out of the plains, which has allowed things like river side Willows to grow, which has provided fodder for beaver who also had been gone from the park.

But if you want to find out more about the meso-predators we live with, you can get an intro to the subject through his Bay Nature article from July 1st of 2011, the Middle Way.

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The Golden Age of Mesopredators
Guest Speaker:  Glen Martin
7:30pm, Thursday, January 19th, 2012
FREE at the Randall Museum, 199 Museum Way, San Francisco, CA 

"intruder alert! intruder alert!" by slworking2

Glen Martin, former environmental reporter for the Chronicle, will recount how mid-level predators are thriving in the Bay Area.

You can get an intro to the subject through his Bay Nature article from July 1st of 2011, the Middle Way.

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