http://www.thevlm.org/jellyfish.aspx, the moon jelly (Aurelia aurita), but a local cold -water species common this time of year, the lion's mane jellies (Cyanea capillata) . Unlike moon jellies, the lion's mane jellies have a noticable sting, are more difficult to maintain, and eat each other on exhibit, making them less than ideal to care for.
But they are currently everywhere in the rivers - and they are beautiful (above picture by Chris Crippen, VLM jelly exhibit) - making the opportunity to display them simply too good to pass up. As the weather warms, they will head out of the Bay and its tributaries, but for now they are an interesting change for our exhibit.
So how do we collect these jellies? With buckets. Yeah it's low-tech, but it prevents any damage to the jellies, damage that is usually done by lifting their fragile bodies from the water with a net or seine. Also it is a simple method to avoid physical contact with them because even broken off tentacles can carry an irritating sting. Lion's mane jellies are a little more work, but worth it.
A good on-line source of information about all aspects of jellies can be found at http://www.jellyfishfacts.net/. Chad Widmer, the former jelly expert at Monterey Bay Aquarium wrote a useful book entitled How to Keep Jellyfish in Aquariums: An Introductory Guide for Maintaining Healthy Jellies. The book does not fully cover professional level information on life support systems, but provides excellent feeding and propogation techniques and about every jelly species available, and is more than enough for almost all applications.
The following video is of the VLM's lion's mane jellies on exhibit now: