California Shark Research - Nuclear Options

Question: How do you age validate sharks?

Unlike trees or even mammals sharks are cartilaginous, they do not have bones or tree rings to look over after they die.

Bones and tree rings can give you the age of your target research specimen pretty quickly. With most shark species that's a much harder proposition.

Enter some smart folks at the Pacific Shark Research Center in California who are doing age validation of sharks and rays using radiocarbon isotopes.

As it turns out above ground testing of nukes in the 50's and 60's dropped these isotopes (¹⁴C) all over the planet and for a time every living thing on the planet had higher levels in their bodies. By tracking these higher levels in cartilage researchers can get a pretty accurate look at the age of long lived sharks like the white shark.

For more information go here.

Fine News for Lemon Sharks - Florida

News Release

February 18, 2010
Contact: Lee Schlesinger, 850-487-0554

The Florida Fish and Wildlife Conservation Commission (FWC) approved a rule Thursday to prohibit all recreational and commercial harvest of lemon sharks from Florida waters. The FWC took this action to protect lemon sharks, because they have a high potential to be overharvested.

Lemon sharks are often found near shore in shallow water, especially in Southeast Florida, where they aggregate in large numbers each year. This makes them easy to locate and raises the potential for large numbers of lemon sharks to be removed from the population with minimal effort by fishermen.

Lemon sharks also are susceptible to overharvest because of their life history characteristics. They are slow-growing, reaching sexual maturity at 12-15 years of age, and have a low reproductive potential, producing 6 to 18 pups per litter every second or third year. Juvenile lemon sharks experience a mortality of 40-60 percent.

Recently, some preliminary data from an ongoing tagging study found that at least 7.5 percent of tagged adult lemon sharks from a Southeast Florida aggregation succumbed to fishing mortality in one season. At that rate, the entire lemon shark aggregation could be harvested in a few years.

In addition, recent regulatory actions for other shark species might put more fishing pressure on lemon sharks in Florida waters, where 90 percent of known lemon shark aggregations occur. The harvest of lemon sharks will still be allowed in offshore federal waters adjacent to state waters.Healthy lemon shark populations are especially important to Florida's dive charter industry which provides ecotourism trips to see lemon shark aggregations in the winter months.

The FWC's lemon shark rule takes effect on March 23. More information about recent shark-management actions is available online at MyFWC.com/Rules, click on "Fishing - Saltwater."

Image:Christy Fisher

Submarines and CICIMAR Guadalupe Island

Interesting video of submarine explorations at Isla Guadalupe with Expedition Jaytay
and CICIMAR's ongoing white shark study at this site:

When science get's "Wicked Cool" - DSN

From personal experience we can attest that deep water baiting either by submersible, or by remote camera is probably one of the most surreal experiences a human can have.

There are "things" in the deep ocean that boggle the imagination and raise the normal oceanic cool factor to 11.

So pay heed divers, ocean lovers, and those that like the things that go "bump in the night" because as the guys over at the Deep Sea News blog tell it - your world is going to get rocked August 14th:

The Eye-in-the-Sea camera will be freshly baited with a frozen sea lion carcass in a camera deployment set for August 14th, in the deep Monterey Canyon. Mark your calendars and tune in to the Ocean Research Conservation Organization (ORCA) website for updates on the event. The ever fascinating Dr. Edie Widder, the ORCA President, will be your host.

Complete Post