30 November, 1999
I caught a big fish! How big was it? It was so big that when we went ice fishing, we had to pull the ice auger with a bulldozer. It was so big; we had to use 1000-pound test steel cable for line. It was so big; we used a power winch to haul it in. It was so big; it took 4 people to carry the live box. Does this sound like a fish story? It is and it is all true. This fisherman never lies.
I had the opportunity to join a group of fish researchers to collect a species of fish known as Dissostichus mawsoni. This fish is also known as the Antarctic Toothfish or, more commonly, the Antarctic Cod. These fish are very fascinating animals. They live in waters that have temperatures below the freezing point of fresh water (-2C and lower). The blood of most fishes would freeze at this temperature. Some cold blooded organisms that live in the cold oceans have body fluids that have the same salt concentration as sea water, so they have the same freezing point as the surrounding water and therefore won't freeze even when the temperature of the sea water is below 0C. Warm-blooded animals, like seals and penguins, keep from freezing by producing heat and insulating themselves with blubber, fur, feathers, etc. Fish, however, are cold blooded (their body temperature is the same as their environment.), but they have a salt content in their blood much lower then sea water. Most fish would freeze if they were put in the water below the ice in the Ross Sea. The d. mawsoni, along with several other species of fish, have evolved a number of unique antifreeze compounds called antifreeze glycoproteins (AFGP). The AFGP prevent the d. mawsoni from freezing in the cold Antarctic waters. As I discussed yesterday, researchers in the McMurdo area do a lot of research on the AFGPs in the fish.
The Antarctic Cod is a relatively deep-water fish living in depths of 90 to 1600 meters (300-5000ft). We fished for them in about 470 meters (1500 feet) of water. Mawsoni eat other fish and are preyed upon by seals and probably other large fish. I went out with fish researchers Andor Kiss, Nelyn Soto, Terri McClain and Kevin Hoeflag to collect some cod for use in their AFGP research. Lines with bait had been set out the night before. The cable was lowered into the sea using a power winch. At 10-meter intervals from the bottom 9 large hooks are clamped onto the cable. Bait fish (Pagothenia borchgrevinki) about 8 inches long are placed on each hook. The next morning, we went to haul the fish in. The cable was pulled in using the winch and the catch, if any, was hauled in. It takes quite a while to pull up the line from 1500 feet. After about 15 minutes or so a large shape started to appear in the hole. We had one! It was a 67 pound, 55 inch Antarctic Cod. What an impressive sight! Kevin carefully lifted the fish out of the hole and removed the hook. The fish was weighed and measured and placed in the "fish coffin", an aerated live box built to hold two or three of these big fish. We continued to raise the line. The next fish was 80 pounds and 61 inches long. It was the largest we caught today. I got to hold this one and measure it. The next hook was empty but the one after that had a cod on it and I got to land and handle this one myself. It was quite a thrill! Of the 9 hooks set, we got 6 live fish between 80 and 32 pounds. The last hook had a cod on it, but it had died on the hook. It was covered with small shrimp-like scavengers called amphipods. They can consume the entire carcass in a short period of time.
After we pulled all the lines up, a trap for baitfish was attached to the line and lowered into the water. Terri had also designed a special trap to capture an Antarctic species of fish that has never been studied before. So far the fish has avoided capture, but Terri is going to keep trying. We loaded the 6 cod into the aerated carrying boxes and it took 4 of us to carry them to the Sprite for the trip back to the aquarium. Once back at McMurdo, we placed some of the fish into tanks for further study. Blood and tissue was extracted from others in order to isolate and identify the AFGP's in the fish. Andor collected blood, liver and gill samples while Nelyn took the rest of the guts for sampling. Lot's of information will be gathered from these samples.
There are lots of Antarctic Cod in McMurdo Sound and surrounding waters. The fish can only be killed for scientific studies. However, each year poaching of these large, good tasting fish becomes more and more of a problem. The Patagonian Toothfish, a close relative of d. mawsoni that lives closer to the southern tip of South American, is being fished to extinction. Enforcement of the Antarctic Treaty that prohibits commercial fishing of Antarctic species is hard to enforce in such a large ocean. Some countries have not signed the treaty and may continue to try to exploit the animals of this fragile region.
I was very fortunate to be part of the group studying these magnificent fish. I want to thank Andor, Nelyn, Kevin and Terri for letting me part of the team for a little while. I wish them luck with their future research.
I am scheduled to leave Antarctica on Saturday, December 4th, weather permitting. The C-141 that I flew me here can no longer land on the sea ice runway because it only has wheels and is too heavy for the deteriorating sea ice. I will be flying home in a C-130 Hercules aircraft operated by the 109th Airlift Command of the Air National Guard. Tomorrow we will look closer at these cool aircraft and the crews that fly them.
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