Do fish sleep? After continuous observation aboard the Odyssey, we are only able to prove that Multimedia Producer, Chris Johnson, is able to sleep where he falls.
Photo: Roger Payne
December 13, 2000
Do Fish Sleep? - Rainbow Runners:Part IV
One of the things we can now answer thanks to this remarkable voyage of nearly a thousand statute miles with rainbow runners by our side is that fish don't need to sleep. Or if they do they must be able to sleep while swimming hard and keeping pace with a boat. That's the way science often works: it takes an altogether extraordinary set of circumstances like the one that presented itself to us with the rainbow runners, and then it takes ten days of watching to be sure about a very small point: whether or not fish need sleep. Well, now we know they don't-well, maybe not all fish, but rainbow runners, anyway-don't have to sleep. But at least we know that for sure.
Or do we? Let's be careful here. Though there is not a person on this boat who wouldn't be shocked if we were to find out that this group of fish is actually a parade of different individual rainbow runners that joined the boat for short periods, the fact remains that we only have two fish we can recognize by their natural markings, and we only know for sure that one of those fish was seen at the beginning and end of a 72 hour period. The totally unusual aspect of the behavior of this group argues that it is made of the same individual fish, as does the fact that although the number of fish has swollen from time to time the low end of our estimates, about 20 animals, has remained quite constant. And, all members of the school are of the same size as the members of the group we saw when they first joined us. But none of that makes it solid proof. We are stuck with the limitations of our data. And that data says that we can only be sure about the one recognizable fish that was seen at the beginning and end of a 72 hour period. Still, I'm pleased. I think we have added something to human understanding about fish.
One argument at the meeting I mentioned before (about whether to collect a few rainbow runners for samples) was that we might not be doing them a favor by delivering them to Tarawa where lots of fishermen await, and therefore that we ought perhaps to try to devise some method of driving them away. Which raised another interesting point: if we are indeed seeing the invention by rainbow runners of a new hunting technique it will never survive if they or their successors take up station behind a boat full of fishermen. I suppose there is a wider lesson in this: that as long as people kill fish there will never be a way to find out what kinds of companionships might develop between humans and free swimming fish. Even so, we are at this moment at least moving towards a better understanding of some of the limits.
Though our reference library aboard Odyssey is necessarily small, it reveals that other fish have followed boats for many days. For instance, a pilot fish, a fairly close relative of rainbow runners, once accompanied a sailing vessel for 80 days.
It is interesting that whales also sometimes stay with boats for long periods. Consider the following account from a voyage in 1850 on the ship Plymouth from San Diego to Realejo, Central America. There was one Dr. Stillman aboard who wrote in his journal:
"November 13: ...A week ago today, we passed several [whales], and during the afternoon it was discovered that one of them continued to follow us, and was becoming more familiar, keeping under the ship and only coming out to breathe. A great deal of uneasiness was felt, lest in his careless gambols he might unship our rudder, or do us some other damage. It was said that bilge-water would drive him off and the pumps were started but to no purpose. At length more violent means were resorted to; volley after volley of rifle-shots were fired into him, billets of wood, bottles, etc., were thrown upon his head with such force as to separate the integument; to all of which he paid not the slightest attention, and he still continued to swim under us, keeping our exact rate of speed, whether in calm or storm, and rising to blow almost into the cabin windows. He seems determined to stay with us until he can find better company. His length is about eighty feet; his tail measures about twelve feet across; and in the calm, as we look down into the transparent water, we see him in all his huge proportions.
November 29: [They are approaching their destination] ...This afternoon he left us. It is now twenty-four days since he attached himself to us, and during that time he has followed us as faithfully as a dog an emigrant's wagon. At first we abused him in every way that our ingenuity could devise to drive him off, lest he might do us some mischief; but, save some scratches he received from our ship's coppering, and numerous sloughing sores, caused by the balls that had been fired into him, no damage was received by either of us from his close companionship. ...We long since ceased our efforts to annoy him, and had become attached to him as to a dog. We had named him 'Blowhard,' and even fancied, as we called him, that he came closer under our quarter, when I felt like patting his glabrous sides, and saying: 'Good old fellow.' As the water grew shoaler he left us, with regret unfeigned on our part, and apparently so on his. This story of the whale is so remarkable, that were there not so many witnesses, I would not venture to tell it, lest I be accused of exaggeration. There were a number of experienced whalemen among our passengers, who said the animal was a 'Sulphurbottom.'"
From Marine Mammals of the Northwestern Coast of North America, by Charles M. Scammon, Dover
A Sulphurbottom is a blue whale, which is most plausible since the trip Dr. Stillman was on passes right through a well known population of blue whales now being studied by both American and Mexican biologists.
A whale also accompanied Tim Severin's leather curraugh during his trans-Atlantic "Brendan Voyage." The crew thought the whale might be trying to mate with their boat. I have seen the boat in the flesh, and it does, indeed, look very whale-like from beneath, and the hides of which it is made give it something of the same texture and feel of whale skin.
I also once met one of the sailors who had sailed the Mayflower replica from England (where it was built) to the Plymouth, Massachusetts harbor where it now resides. He said that on the trans-Atlantic crossing they had a whale beneath Mayflower for several days. He claimed that at times it was belly uppermost embracing the boat with its flippers (which he thought might be an attempt by the whale to mate with the round-bottomed, whale sized Mayflower). Which sounds reasonable to me as well. From his account I thought it was perhaps a humpback whale, but he wasn't sure of the species, and neither am I.
I likewise read, many years ago, an account of a humpback whale following a ship all the way from Cape Horn through both South and North Atlantic oceans to near Europe. Because this whale had to cross the equator, the account seems suspect. However, there is now solid evidence of humpback and blue whales crossing the equator in the eastern tropical Pacific, so perhaps this really did happen.
But all of these accounts, save the one about the pilot fish, are about whales. I wonder how often fish do what these rainbow runners are doing. I would guess: very frequently since it seems to be a good way for a pelagic predatory fish to make a living.
This is Roger Payne about a day South of Tarawa Island, in the blue Pacific.
Log by Roger Payne