The northeast side of San Clemente Island -- where we caught 4 makos, 5 blue sharks and one stingray today -- is one of 7 areas that we've been trying to survey 4 times each summer since 1994. We're keeping track of the numbers of juvenile blue and mako sharks.

The makos we caught today were quite large and we were able to put satellite transmitters on two. On this trip, we want to put satellite tags on larger mako sharks that are nearly mature or fully mature, instead of juvenile makos, as we have been. Mako sharks are fairly slow growing and the size at sexual maturity for males is about 71 inches (180 centimeters) fork length (from the tip of the nose to the fork in their tail), and for females it is greater than 79 inches (200 centimeters). On past cruises we have tagged many juvenile mako sharks and are starting to have a pretty good idea of how they use and live in the oceans around here. Now we want to know what the larger makos do and where they go.

The pelagic stingray is the 3rd most frequently caught species during our survey. This year we are collecting a few live rays for a graduate student from UCLA who will bring them to the marine science lab on Catalina Island to study their sensory biology. Here's a photo of the pelagic ray we caught. We first removed the sharp, toxic stinger from its tail so nobody would be hurt and then removed the hook before placing it into a large holding tank. We will transfer the ray to Catalina Island on July 6.

We interrupted our work this afternoon with a BBQ on the back deck to celebrate the 4th of July with the ship's crew. It was a Happy Independence Day!

[ed. note: Noted ecologist Carl Safina, author of New York Times Notable Book Song for the Blue Ocean, is also on board and is blogging the cruise.
Here's what he had to say in his blog about the stingray below: The stingray is a strange animal to be a wanderer of the open ocean. It looks like it should be a bottom dweller, and it’s hard to imagine it catching open-water prey, which it apparently does by cloaking it with its wings. It’s also dark above and dark below, which would seem to make it an easy mark for Makos. Whether they indeed attack or avoid the stinger-equipped rays, I don’t know. Our captive, being studied by one woman on board, is spending an extended visit in a large plastic box about 4-feet x 4 x 4, on deck.] -- ABOARD THE R/V DAVID STARR JORDAN, near San Clemente Island, California.