2 September, 1997

When I boarded the ship I was assigned to a small but comfortable two-person cabin on the bottom deck. The 8-ft by 8-ft space has bunk beds, a bureau, closet, and desk. All the essentials! Being close to the forward hull makes it one of the noisier places on the ship.

In the next cabin is a fish biologist who works in both the Arctic and Antarctic. He would be a good person to ask about the size difference in the cod that we were catching here compared to those I recalled seeing in Antarctica. Why should there be such a discrepancy in the same type of fish living at opposite sides of the planet?

Rich started his explanation saying the popular belief that one species has a higher metabolism than the other is not true. He noted that the water temperatures around Antarctica are very constant and the fish can't migrate north because of a circumpolar current. On an evolutionary scale, the habitat of the Antarctic Cod has remained unchanged for a much longer period than that of their northern cousins. The arctic cod are exposed to about a ten-degree change in water temperature but only show small growth sprits during the time when the water temperature is highest. Rich's theory is that the Antarctic species have had a much longer time to adapt to a constant environment! This seems to be common on our planet, if an environment doesn't change for a long enough time, some organism will adapt to it and prosper.

Compare the size of an adult arctic cod to the same Antarctic species