Blog | Oceana USA

[editor's note, by Jason] Jon Warrenchuk is currently participating in NOAA's 2004 Gulf of Alaska Seamount Expedition.

August 11, 2004:Today was the last day on Welker seamount. Some interesting things have been documented during our 4 days of exploration. Huge fields of glass sponges, a fleeting glimpse of a deep-sea anglerfish, and corals, corals, corals. Bamboo corals, bubblegum corals, red tree corals, and black corals. Shortspine thornyhead, sablefish, scarlet king crab, grooved Tanner crab, spider crabs, squat lobsters, Pycnogonid deep-sea spiders, crinoids, grenadiers, and brittlestars (to name a few).

These names roll off our tongues easily now; we've seen varying amounts of these critters on each and every seamount. But on Welker seamount another creature left behind signs of its presence. Lying amongst the corals and sponges was a lost "longline"; commercial fishing gear baited with hooks. Was it lost during a scientific survey of fish populations? Or during exploratory commercial fishing activity?

[editor's note, by Jason] Jon Warrenchuk is currently participating in NOAA's 2004 Gulf of Alaska Seamount Expedition.

August 10, 2004: Last night a few of us made an amazing discovery: big squid will hit a "pixie" fishing lure! On light line, it's quite sporting. They're hard to keep on, and we fail to land one, but boy, its fun! These babies are at least 3 feet long, fast, and furious. I just wish we could get one in the boat!

I don't know what species they are; the closest I can think of are the "majestic" squid, Berryteuthis magister, but those only get about 18 inches long. The big squid below us are fun to watch, streaking through the schools of forage fish (sandlance? capelin?) attracted to the deck lights. Then something large and grey makes the squid scatter. Is it a salmon shark? It disappears too fast for confirmation, but it's a likely suspect. These smaller relatives of the Great white have been recorded throughout Alaskan waters, but much of their life history remains unknown.

[editor's note, by Jason] Jon Warrenchuk is currently participating in NOAA's 2004 Gulf of Alaska Seamount Expedition.

August 7, 2004: Rocketing up from the depths, the 'crab elevator' breaks the surface. We set the crab elevator the day before, it's been soaking for a day, and we're eager to check out today's catch.

The 'crab elevator' is essentially a platform loaded with crab and fish traps. Yummy herring and cat food (the quintessential crab bait) will attract critters to the sample traps on the seafloor. We dropped it over the side yesterday and sank it down to 550 meters deep on Dickins Seamount. The elevator is equipped with remote-activated floats, and when these are triggered, the elevator shoots up to the surface under its own power.

Unfortunately, the catch is pretty sparse. The lone "megafauna" in the larger traps is a female scarlet king crab, Lithodes couesi. The smaller traps fare better, and contain several dozen shrimp of an unknown species.

We measure the king crab (standard measurements are across the widest part of the carapace and the length of the claw) and perform some basic dissections. She's not carrying any eggs, and when we dissect her we see that her ovaries are quite full: it's apparent that she hasn't yet extruded. This is interesting, because in other samples we've seen female crabs of the same species carrying eggs.

This kind of asynchrony is evidence of the lack of seasonality in the deep-sea. Crabs in shallower waters generally brood their eggs for 1 year and release their larvae around the same time, to coincide with things like spring blooms of phytoplankton.

[editor's note, by Jason] Jon Warrenchuk is currently participating in NOAA's 2004 Gulf of Alaska Seamount Expedition.

August 6, 2004: Last night we launched the CTD. Marine biology is fairly light on acronyms, but this is one we throw around often. "C" stands for conductivity (a measure of salinity), "T" for temperature, and "D" for depth. Perturbations and combinations of those 3 factors (salinity, temperature, and depth) are primarily responsible for patterns of life in the ocean. This particular CTD also measures dissolved oxygen, another important limiting factor for marine life.

The CTD device is tethered to the Atlantis with fiber optic cable, and displays real-time data to the computer lab as it's lowered to the ocean floor. What's surprising is that dissolved oxygen decreases significantly after 200 meters depth and the water actually becomes quite "hypoxic" (low in oxygen). But after 1300 meters depth, dissolved oxygen increases. On seamounts that transcend this depth range, zonation of organisms is as evident as it is on a tidal seashore. It's cold on the bottom too, a consistent 1.6 to 2 degrees Celsius.

The best part about launching the CTD at night is that the boat is stationary and all the deck lights are on. When this happens, you never know what might ascend from the depths. Schooling forage fish, attracted to the lights, flash about in silvery streaks. A squid, about 3 feet long, quietly ascends, hovers, then disappears out of sight. I waited patiently for a salmon or two to make an appearance, but no luck.