Dr. Michael McGowan presented a question to us. The green sturgeon are in trouble as a species. But for a 100 million year old fish, how critical is a bay which is only 8,000 years old?
The problem is that San Francisco Bay is now demarcated as being habitat for this fish – a demarkation that makes certain aspects of human activity more difficult. The question sparked an interesting debate, about the need for good science to be behind decisions, about how much protection could be a good thing, and the possibilites of how the Bay might be critical habitat for future populations, and how driving decisions based on bad data might be ultimately harmful.
It seemed clear from Dr. McGowan’s presentation that there wasn’t a lot of good science to back up the idea that the Bay is critical habitat for green sturgeon – in particular large swaths of the south bay where the fish is rarely if ever found. Both green and white varieties of sturgeon can be found in the bay at large, but mostly for the green, the bay is just a transitional space heading from river to sea: green sturgeon spawn upstream, and the larva swim downstream and out into the ocean where they spend most of their lives. White sturgeon hang about longer (and are now doing okay in the Bay after having suffered a fisheries collapse in the late 1800s, early 1900s). But white sturgeon data was used to guide the decision about the green sturgeon — a fish that has quite a different life cycle.
Declaring the Bay critical habitat, at the end of the day, looks like it may do nothing for the fish – we ultimately need to be finding out what other causes there might be for the fish’s problems: gravel mining, overfishing, etc. Maybe habitat is the issue, it just seems likely that it is not what is going on in the bay that is the issue.
All in all it was a great talk – lots of detail about these fascinating species of fish and our interaction with them (official caviar is technically the eggs from a particular species of sturgeon that swim the Volga). We all hope they stay around for another 100 million years at least!
SF Natural History Series 