NOVA Online | Kingdom of the Seahorse (2024)

Seahorse Crusader Amanda Vincent

NOVA: Can you talk a little bit about how you got interested in seahorses andwhat sort of life you lead as a scientist?

AV: I suppose I study seahorses for three reasons. Initially, I startedstudying them because I wanted to work with the sea, and I wanted to use mybrain. And I wanted to be outdoors. Then I had an academic interest in theevolution of sex differences—and in seahorses only the male gets pregnant,which of course raises a lot of questions about sex differences. And then thethird reason is that, as I began to work with seahorses, I became completelyaddicted to the little creatures and now I would find it very hard to move myattention away from them and their relatives. I did an undergraduate degreeand then I traveled around the world for quite a few years not really doingbiology just getting more experience of different cultures and differentplaces, which has been very useful in the long run. I went back and did aPh.D.. After I finished my Ph.D. I then went and did a research fellowship atOxford in England, and had a lot of freedom to explore ideas that interestedme. So I went off to Australia and did a lot of field work on the seahorses.And while I was doing that, I began to get frightened about what I perceived tobe a really big trade in these animals. I looked around and I found that thereweren't any data at all, that there weren't formal trade records, nobody knewanything about the trade, and realized I wanted to work with this. I was verylucky because National Geographic Magazine had invited me to write an articleand offered to fund a trip to look into the possible trade. So I was able togo around Asia visiting all the little fishing villages and the traders, theimporters, the exporters, the biologists, the fisheries officers asking themwhat they knew about the seahorse trade. And my goal, I suppose is very muchto alert people to the problems of marine conservation. So by working withseahorses I get to work with animals that I'm really hooked on, that I reallylike. I have some qualifications for becoming involved in a whole range ofissues in marine conservation. And I have an excuse for working in the tropicsfor part of the year, particularly during the Canadian winter.

NOVA: I know that, during your field work in Australia, you sometimes spent asmuch as twelve hours a day underwater observing seahorses. What was thatlike?

AV: Getting up in the morning at 4:30 isn't a whole lot of fun, and pulling ona wet suit that's still rather damp and smelly from the day before is even lessfun. It used to be a real struggle to get in the water. But somehow myassistants and I would make it in before dawn. And you'd float out over thisghostly set of seagrass meadows knowing that the animals you knew asindividuals were down there. And then came the challenge of trying to findthem each morning. And I have to say that it got pretty embarrassing becauseyou knew where they should be, and yet you would go round and round that littlebit of seagrass until eventually you suddenly caught sight of a little tail tipand then you'd sit and watch them. And your mind would play funny tricks.Sometimes I'd be watching the seahorses for three hours, six hours, nine hours.It was very hard not to make up a soap opera about the animals you werewatching. You knew that any moment now little Harry would put his head up andMabel would come swimming over the horizon up to him, and they'd dance togetherfor a little while holding tails and they'd be ever so happy and then they'dseparate for the rest of the day. And then you wondered whether Mabel wasgetting up to hanky-panky with anyone else. You discovered eventually that no,she wasn't. In fact, she spent her whole day feeding, and so did Harry. Sothey were a heck of a couple, really exciting for six minutes a day, andotherwise dreary as hell. Then on the day that Harry had given birth, Mabelwould appear with a load of eggs. And they'd go into this nine hour ballet.They'd just be pivoting and dancing and twirling and rising and changing colorsand lifting their heads and it was very, very beautiful, and somehow you didn'teven realize nine hours had gone past. And there they were mating. So I guesswatching seahorses requires a very calm spirit. And if you're not a calmperson, and I'm not, then I'm sure it's very good for the soul, because youbasically just go into a meditative state for the whole time.

NOVA: Are seahorses plentiful off American shores?

AV: There are approximately four species around North America down to SouthAmerica. They range in size from a very small species, sometimes known as thedwarf seahorse, which is only about an inch long, up to a species off thePacific Coast of Central America which gets to be about a foot long calledHippocampus ingens. And then there's Hippocampus reidi, which is found in theCaribbean in coral reefs. It's quite a slender, but quite large seahorse andone of my favorite species, because when they dance they turn these fluorescentneon colors. And then Hippocampus erectus is quite a big chunky seahorse andit's found from Nova Scotia all the way down to perhaps Uruguay. The seahorsesaround the Americas are often caught by mistake in troll nets, especially thosethat are seeking live shrimp for bait. They're also caught intentionally foraquarium trade. We know that Florida had at least 112,000 seahorses landed in1994. We don't know quite what was done with them. But the Taiwanese customsdata, which are the only data in the world for seahorses, show that theyimported seahorses from North America for medicines. And we think many ofthose may come from Florida.

NOVA: How hard is it to strap on a snorkel and go have a look at these littlecreatures?

AV: Well, the first field work I tried to do on seahorses was in Florida in1986. And it was a screaming embarrassment because I just couldn't find theanimals. I mean it was really mortifying. To be underwater as, supposedly, aseahorse biologist and I couldn't find them! Eventually I got better at it.

NOVA: What's so tricky about it?

AV: They're very, very cryptic animals. Seahorses can change color to matchtheir background. They grow long skin appendages so that they blend in betterwith the algae. They let encrusting organisms settle on them. They're justreally well camouflaged. You always look for the tail, because the tail wrapsall the way around whatever it's holding, whereas the head and the eye can behidden.

NOVA: What evolutionary purpose does monogamous pair bonding and malepregnancy provide for seahorses?

AV: It's always an awkward question as to why animals are monogamous. Veryfew animals stick with one partner for life. Humans are unusual in thatrespect. In fishes, monogamy is particularly rare. So it was a bit surprisingto find that seahorses were monogamous. We have evidence suggesting that whenseahorses stick with a partner for a while they get better at producing babiesas a team.

NOVA: And what about male pregnancy?

AV: Well, we tend to think of parental care as being the responsibility of thefemale, but that's because we're mammals. In birds, if you think about it,both parents usually care for the young. And in fishes, people are oftensurprised to learn that usually the parental care is given only by the male.Now parental care in fishes usually involves just guarding the eggs, fanningthe eggs, making sure they get enough oxygen and they're clean. The seahorsesare the most extreme example of fathers providing the care that we know in theanimal world. Because they guard the eggs all right, but they guard them ontheir body. They also provide oxygen through a capillary network in the pouch,and they also transfer nutrients, and they control the pouch environment sothat it changes during the pregnancy to become more like salt water. This thenis an extreme example, but presumably instead of producing many small young,the seahorses produce fewer, but better developed and larger young.

NOVA: Seahorses are not, technically speaking, endangered, are they?

AV: Well, we've listed virtually all seahorses on the 1996 International Unionfor the Conservation of Nature "red list." And the "red list" acts like aflag. It warns you that species are considered to be at risk, withoutenforcing any regulations. We know that the seahorse populations we've beenable to examine are declining quite dramatically—on the order of 25 to 50percent over five years.

NOVA: Where are all these seahorses going?

AV: There's tremendous difficulty with consumption of seahorses fortraditional Chinese medicines, for the aquarium trade and also for curiositiesand souvenirs. Traditional Chinese medicine is the biggest user of seahorses,and the numbers involved in that trade may amount to more than 20 million ayear. I should point out, it's not just ethnic Chinese communities—seahorses are also used as medicines by the Indonesians, the Central Filipinos,and a whole host of other racial and ethnic groups around the world. Hundredsof thousands of seahorses are used each year, as well, for the aquarium trade.And the aquarium trade is primarily driven by North American consumption. Mostof these seahorses are juveniles, they haven't even bred, they haven't evenreproduced when we buy them and put them in our home aquariums, where theyusually die. And then the curiosity trade is, again, hundreds of thousands ofanimals each year. It's pretty hard to justify having a seahorse on a keychain or on your mantelpiece when you know that's depleting wild populations.And seahorses live in some of the world's most threatened habitats: seagrasses, mangroves, coral reefs and estuaries. We're working very hard to drawattention to the habitat loss.

NOVA: How much are seahorses worth? How much do they trade for?

AV: Seahorses are becoming very valuable. The best quality seahorses intraditional Chinese medicine—the smooth pale, large seahorses—now sell inHong Kong for up to $550 U.S. per pound. Even the seahorses that are not quitesuch good quality are selling for a couple of hundred dollars per pound. Thereare about 39 countries around the world now involved in the seahorse trade,most of them trading dried seahorses for traditional Chinese medicine. So thisis becoming quite big business, which is part of the problem.

NOVA: Is there any evidence that, chemically, there is something unique inseahorses that is medicinal?

AV: Traditional Chinese medicine doesn't usually do western-stylepharmacological testing. Instead they tend to rely on past efficacy, pasttreatments and how they've worked. So there's a strong conviction thatseahorses are one of the fundamentals of traditional Chinese medicine, butthere's not any testing in a way that we would recognize as double-blindmedical testing. Certainly there are Chinese medical treatments which havebeen well tested in the west and are proving incredibly useful. So it would benice to investigate thoroughly the real value of seahorses.