Jon's Journal: Day 9 - Oceana USA
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August 11, 2004

Jon’s Journal: Day 9

[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.