Fish Story : This Summer, as He Has for 10 Years, Marine Biologist Bob Warner Will Journey to the Tiny Man-Made Island of Ukkup Tupo to Watch His Research Subjects Change Sex
THE WARM SEA, THE PALM TREES ON the horizon, the mighty breakers crashing on the beach . . . hold on, forget that last part. That’s back in Santa Barbara, where Bob Warner, a marine biologist at the University of California, lives most of the year. No, this is Ukkup Tupo, a Panamanian island that isn’t on any map. There aren’t any mighty breakers on this shore, and there’s no beach either. This island, for which Bob Warner gives up his Cape Cod-style house in Santa Barbara every summer, rises just inches above sea level. You’d have to call it organically artificial: It was created by Kuna Indians, who dragged in the necessary sand in their dugout canoes.
Warner, a bearded scientist with a sense of humor, was drawn to Ukkup Tupo because of his interest in the reason that fish change sex, a subject he has pursued since his graduate-student days at Scripps Institution of Oceanography in the early ‘70s. Scientists had known of the peculiar phenomenon since about 1930. In some species, all fish are born female, becom-ing male if they live long enough to reach a certain size. There are also species in which males become females. How they do this wasn’t the question. Fish are pretty simple creatures, and changing sex is a minor retooling of their physiology. What mattered was why . Warner hypothesized that sex change is an evolutionary response to their inherited mating patterns.
When he finished at Scripps, Warner received a postdoctoral fellowship at the Smithsonian Tropical Research Institute in Panama in order to work in the San Blas Islands, where Ukkup Tupo is located. It was the perfect place for his research: an archipelago on the north coast of Panama, protected by a barrier reef, out of the hurricane path, full of postage-stamp coral islands. The water is 82 degrees the year around and crystal-clear. “It’s like having an aquarium,” Warner says, “without the trouble of maintaining it.”
If it is a place apart, it is inhabited by a people apart--the Kunas. They have the highest rate of albinism in the world and are among the world’s shortest people (most stand under five feet). Legally they are Panamanians, but as a result of a series of rebellions they are virtually autonomous. They govern themselves by a sort of nationwide parliament, the congreso , that convenes every three or four months. In the interim, each village holds a congreso every night, a combination of town meeting, gossip-fest and party.
The Kunas fascinate anthropologists. Not only do they have a close social life, but they are aggressive entrepreneurs as well. They will gladly pose for photos, but it will cost you 25 cents a shot, every shot. They don’t have much else to sell but molas , the famous blouse panels the women make using a technique of reverse applique. They stack and sew together several bright pieces of cloth and then spend weeks creating designs by artfully cutting through the upper layers to expose the colors of the cloth below. When a tourist ship coming from the Panama Canal docks at Carti, one of the larger Kuna islands, dugout canoes from all over the archipelago swarm there to sell molas .
The Kunas are basically a serious people who don’t smoke or drink, but whenever a girl reaches puberty, they celebrate with a fiesta that involves not only secret ceremonies but also a three-day blowout of eating, smoking tobacco and drinking chicha , the local sugar-cane wine. “He who does not get drunk on chicha at the fiesta,” a Kuna proverb says, “will not enter into the house of Baba Dummad, God the Father.” When a fiesta is on, the Kunas drink with religious intensity and a surprising degree of organization. One morning is the specific time for the old women to get drunk; the afternoon is the men’s shift.
A couple of years after Bob Warner arrived in the San Blas Islands, in the mid-’70s, a Kuna named Juan Garcia figured that the Smithsonian researchers were there to stay and decided to build a private island to rent to them.
How do you build an island? You fill a dugout canoe with sand, broken coral (which looks rather like Cheetos and which the Kunas call chiwi ) and hanks of sea grass. You dump the mixture in a shallow spot. Half the sand washes away almost immediately, but you keep bringing more sand and more chiwi and more sea grass, and some rocks to anchor the edges. This is how Ukkup Tupo, also known as Sandy Island, came into being.
When Garcia had about 10 feet by 10 feet of dry land, he built a shack on it and rented it to another marine biologist interested in the sex life of fish. Warner came to hear about the place in the summer of 1976 while staying at a rudimentary hotel on a neighboring island. Later, the National Science Foundation awarded him a grant to study at Ukkup Tupo, and for the last 10 years Warner, his wife, Isabel Downs (who is also his research assistant), and, recently, their two children, Toby, 5, and Andy, 3, have spent their summers on Ukkup Tupo, usually joined by a couple of Warner’s grad students. He’ll be going back again this summer.
Ukkup Tupo has not stood still all this time, of course. Juan Garcia has continued to enlarge his creation. At first the Warners had to stay in a cane house built out over the water on stilts. Now the island is three-quarters the size of a tennis court and accommodates three multi-room thatched buildings. Inch for inch, Ukkup Tupo has turned out to be one of the most productive marine research stations in the world, and the Smithsonian rents it all year. Locals are starting to call it Smithsonian Tupo.
It’s an idyllic existence, to hear Warner describe it, living just above the lapping waters. Wherever you look there’s nothing but sea and sky and scattered tropical islands, “like islands in a cartoon,” he says, “a little line on the horizon with some palm trees sticking up.” The fish Warner and his assistants study conveniently spawn at the same time every day--between 1 and 3 in the afternoon--and they observe them with the aid of masks and snorkels. The island has no electricity aside from the batteries that run a small computer. Lighting is by kerosene lamp. A gas-run refrigerator holds the catch of the day; vegetables, if anybody has been to Panama City lately, and the beer that the canny Kunas keep on hand to sell to thirsty researchers.
Ukkup Tupo is just a stone’s throw from two small but densely populated Kuna islands, Nalunega and Wichubhuala--the one 50 yards away and the other about 100--”just a swim and a short walk,” Warner says, “if you don’t mind stepping on sea urchins.” The Americans are in daily contact with the Kunas, and Warner’s young sons have learned enough of the Kuna language to play games with them. Apart from beer, the Americans buy bread from the Kunas, a sort of elongated bun that is chewy like a bagel. It is perhaps the unique gastronomic specialty of the San Blas. Researchers dream of Kuna bread when they’re back in Santa Barbara.
As for Warner’s hypothesis: “It looks good so far,” he says. “It looks like there’s a close match between species that change from female to male and those in which large males monopolize matings.” His key observation is the importance of a fish’s size in the mating pattern. Among coral-reef fish of the sort he has been studying, such as wrasses and parrotfish, larger males monopolize the spawning females. In this situation a small male may not spawn at all, while a small female certainly will. Reproductively speaking, small males are just wasting their time. In these species, the females change sex once they are big enough to compete with the larger males during spawning. (At least, that’s the case on coral reefs, where there is plenty of light and visual clues are important; cold-water fish are studied less and might go about things differently.)
Warner’s hypothesis predicts that members of species that mate in random pairs tend to be male at birth. In these species, it’s reproductively advantageous for the fish to be a male while small, with the capacity to fertilize a larger female, and to be a female when it is large and has a greater capacity for egg production.
In contrast, fish that are monogamous have nothing to gain from changing sex, and generally they don’t do it. There is an interesting exception, though: the clownfish, or anemonefish. Its mating system consists of a monogamous pair, a male and a larger female--larger, according to Warner, because a female the same size as a male could not produce nearly as many eggs as the male can fertilize--together with an all-male escort of immature clownfish. If the female dies, the male changes into a female and one of the youngsters becomes the new male partner.
Bob Warner once ate one of his subjects, but only once. “They’re pretty small and don’t have much flesh,” he says, “and generally, parrotfish and wrasses aren’t very. . . .” He grimaces at the memory of the experience. In a word, so far as the Kunas are concerned, the Smithsonian people can have all the parrotfish and wrasses they want.
