When most of us think of tuna, we think of the can. Maybe we remember "Charlie Tuna" from the old commercials. What many people don't realize is that these amazing animals are at the pinnacle of fish evolution. Tuna are capable of covering vast distances, traversing the entire Pacific Ocean in a matter of days. They are incredible athletes, described as the "Olympians of the sea." They are sleek, powerful and oftentimes, massive animals. A bluefin tuna can grow up to 1,500 pounds and 15 feet long. And for generations, they were so abundant it was thought that you could never take all the tuna from the sea. Things change. Our insatiable appetite combined with the technical advances that allow us to over-harvest have pushed tuna to the brink. Scientists are now racing to learn more about these incredible animals in the hope of saving them. Learn more at Tag-A-Giant.

Another species that TOPP (Tagging of Pacific Predators) is tracking is the Leatherback Turtle. Reaching 7 feet long and weighing 2000 pounds, leatherbacks have survived in the world's oceans for 100 million years. Now they may only have decades left. While sea turtles are not being commercially fished, they still face daunting challenges in the open ocean. They are often accidentally caught and drowned in fisherman's long-lines and nets. And pollution is also taking a nasty toll. In the water, common plastic bags look very similar to the turtles' favorite food: jellyfish. The problem is, plastic bags aren’t easy to digest. But the biggest problem the turtles face may be on land. Over harvesting of turtle eggs has long been a problem for sea turtles but now the biggest concern is over development of their nesting beaches. Turtles need a sandy beach to lay their eggs. Unfortunately, people also enjoy vacationing in the same type of places. Humans looking for that seaside getaway are quickly gobbling up the sea turtles nesting grounds. Researchers are now working hard to save these vital nesting grounds to make sure the turtles can survive.

Watch the "Tagging Pacific Predators " TV Story online, as well as find additional links and resources. Also don't miss our Web Extra: Tagging Pacific Predators Extended Interview with scientist Barbara Block of the Tuna Research and Conservation Center.

Chris Bauer is a Segment Producer for television on QUEST.

First things first: If you swim in the bay, no need to worry about sharks. None of the experts we spoke to could remember a single instance of someone getting bitten. And you can rest easy about Great Whites too; they don’t seem to have a taste for Bay waters. For more on this, see the Aquarium’s Chris Spaulding’s blog post.

The San Francisco Bay is much more of a mystery to scientists than I, at least, had realized. Why? It's simply too hard to peer into. There's no point in scuba diving. The bay is thick with sediment, much of it a legacy of gold mining explosions in the Delta. So if you want to know what's swimming around in those murky waters, you have to go fishing.

At first glance, this struck me as both laborious and tough on the animals – catch and release may spare lives, but not without putting a lot of stress on whatever's on the other end of the line. But when you think about how heavily we humans use the bay – sewage leaks, oil spills, urban runoff, coastal development — it becomes clear we have to take a closer look at how its inhabitants are faring. Sharks are at the top of the food chain, which means they're a great indicator of how everything underneath them is doing.

Of course, tagging is only worth the effort if you catch enough animals to have meaningful data – which means this project requires tenacity on the part of Aquarium researchers. For updates (as well as info on what to do if you catch a tagged shark) check out the Aquarium's website. Also, here's the radio piece we did on the same project.

Watch the "Cool Critters: Sharks of the Bay" TV Story online, as well as find additional links and resources. Also don't miss our behind-the-scenes photos for this story.

Amy Standen is a Reporter for QUEST and Radio News at KQED-FM.