Stressed by the threat of capture, a young lemon shark retaliates against the camera.

10:30am, March 24, onboard the Research Vessel SEWARD JOHNSON (RVSJ) -- Once again, it was gillnetting time in Brazil...same concept as before, new location. Last night, the master plan called for a non-stop, 24-hour sharking session. By this morning, mercifully, the plan changed. With the 29 researchers available, it made a lot more sense to split up into two teams. Less fatigue makes for fewer mistakes. The "night team" rested up while the "day team, " me included, swung into action.

We had to capture as many young sharks as possible. This would be our last chance! Tomorrow evening, the expedition leaves the pristine waters of Atol das Rocas for the island of Fernando de Norhona, 70 miles east of the Rocas shark nursery.

The day team didn't have time for lunch. We got directly to work loading our a small boat with gear on the open-ended stern of the RVSJ. I jammed down a few calories in the form of a Powerbar, reading the label as I chewed. "...drink with 8-16 oz. of water," it commanded. Being surrounded by countless gallons of sea water and having nothing at hand to drink is THE textbook example of irony, and there I was being ironic. I ran inside, grabbed a healthy draught from the ship's water fountain, then double-checked the water packed into our boat.

The RVSJ truly is an amazing vessel. The water for drinking and cooking and showering all comes from the sea itself. A onboard reverse-osmosis water filtration unit sucks the salt from the briny ocean water, purifies it, and delivers it -- fresh and cold -- throughout the ship. No one takes for granted the fact that they can drink from a water fountain or take a hot shower at this remote, desolate location.

3:30pm, Atol das Rocas -- The day gillnetting team made their way through the shallow waters of the lagoon and landed on Rocas's beach. The tide was slack (the brief period of calm between high and low tides) -- a perfect time to get the nets into position...and wait.

After several hours work we caught only two sharks. Low tide drained the shallows of the lagoon, leaving behind small tidal pools, rippling sand, and shimmering reflections of the sky. The setting was beautiful, but not ideal for shark wrangling.

As we packed up the nets, New Zealander Damian Chapman confided in me, "Even on 'unsuccessful' days like this, we are still learning a lot. This whole project is an experiment in what this place is like and what we can do out here. It's not like any other place that we've worked before."

It is a refrain I have heard echoing throughout the science crew. Scientists, better than anybody, understand that progress doesn't always follow a predictable path. Science is rigged for success, because success is measured by how much you learn, not by what you learn. A research project succeeds whenever it proves an idea, disproves an idea, OR simply helps scientists to further refine the project itself.

Our shark wrangling was providing loads of valuable data, but some of the most substantial progress we've made is toward the next visit to Atol das Rocas. Every successful encounter with IBAMA, the Brazilian conservation group, establishes trust for future and paves the way for a return to these waters. Every day that passes without any injuries to the protected local species assures the guardians of Rocas that our team does their work with care and respect. Every shark that escapes the nets or bypasses the bait provides valuable ideas for improved capture techniques.

4:50pm, just off Atol das Rocas -- After another ulcer-inducing run through this tiny island's treacherous channel -- after adding a few new rock scars to our propellor -- we met up with the night team just outside the lagoon. The companies deftly switched boats, transferring gear on the rolling ocean with a precision that only comes after two-weeks of practice.

11:00pm, the bridge of the R/V SEWARD JOHNSON -- The last I heard from the night team, they had laid their nets at 9:00pm and captured only four baby sharks so far, two of which were true babies (less than one year old). Nevertheless, the island at night was proving to be an amazing place with huge green turtles laying eggs and hatchlings working their way to the surf.

Morning light will guide the night team back to the RVSJ. The sunrise will mark our expedition's last day at Atol das Rocas. Tomorrow, we set sail for Fernando de Norhona, a new environment for science and adventure, a day of shore leave, and another chance to capture adult lemon sharks.

After low tide ended a round of gillnetting, a group of researchers returns to shore.