Wednesday, April 11, 2012

Rock Bluff Spring and Sturgeon-ing

A beautiful breeze and clear, sunny skies made for a perfect sturgeon fishing day on Tuesday. During our weekly sampling, we use drift nets to catch about 20 sturgeon. We haul them aboard and weigh, measure, tag, and take blood (from those over 1300 mm total length) - this week we caught 18 fish, and three were 85, 100, and 115 pounders! Our overall goal is to catch 600 fish between now and the end of the summer in order to make a population estimate for the Suwannee River. Right now there are probably about 14,000 Gulf sturgeon in the river; this population has shown huge signs of recovery since becoming a listed species after being practically fished to extinction. Once the fish are hauled aboard, we also take dorsal, ventral, and gill pictures, which I have been put in charge of because I never put the camera down anyway. Here are a few shots from this past Tuesday out on the Suwannee River:

Close-up view of a sturgeon gill. When you reach your hand on the gill cover to pull it out, it snaps shut and squishes your fingers... you really have to pull to keep it open!

My boss Ken showing our volunteers the anatomy of the sturgeon mouth. It is essentially a vacuum that they can instantaneously shoot out to suck food off the bottom. They are hoover fish! 

Calm and stoic, each sturgeon sits patiently on the scale aboard the boat while we poke and prod at it. Over years of evolution, perhaps they have learned that flailing is futile. We also dump water over the fish if it is going to be out of the water for a few minutes. 

Our new volunteer Melissa is putting T-bar tags on each fin. The tool she is using is actually the same thing used to put the clear plastic T-tags on clothes... except on the sturgeon, you really have to push to get the tag to go through.

After we haul the net, we have way too many sturgeon to keep in the boat, so we tie a rope to their tails and tie them to the side of the boat. They float patiently upside down waiting their turn but are NOT dead.  But if one does decide to swim while you're holding the rope, you'd better brace yourself or you'll fall into the brown water too and perhaps go for a little ride. 

Melissa and I with the biggest fish of the day. This one weighs 115 pounds... definitely a fall-spawning female.
 At the end of the day, we were all covered in sturgeon slime, so we headed over to Rock Bluff spring. It is a second magnitude spring accessible only by water... all the land surrounding the spring is privately owned and apparently patrolled quite strictly. There wasn't really any flow coming out of the spring (a little bit of warm water, but not much), which meant that the entire basin and spring run were veryy low, only about 2-3 feet throughout. The low flow also accounted for the yellowish green color of the water. These pictures reflect the true color of the water, although it was still clean and clear, not fuzzy, when you're swimming. During high flow, Ken said the water is usually the amazing crystal clear/blue of the spring. Sadly not today. At it's deepest, the spring was probably about 20 feet, easily free-divable with my mask and snorkel, and it made for some neat pictures from the bottom :)

Looking up at our "Sturgeon Quest" net boat from about 10 feet below the surface. Since the engine is up, it's drawing only a few inches of water and it's starting to drift over the spring.

Huge cypress trees near the bank are visible from the bottom of the spring (~20 feet).

Melissa floating over the edge of the spring after a long day of fishing.

Unfortunately there is a lot of algae in the basin. I would have loved to see the spring in it's original crystal blue form.

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