Seahorses; their appealing charisma is also what gets them in trouble. The Ria Formosa Nature Reserve is home to what’s probably the world’s largest population of Hippocampus, but in recent years there has been a massive decline, due to habitat changes and human influence. How to ensure the survival of this fish species? Enjoy the Algarve talks to marine biologists Miguel Correia and Jorge Palma about seahorse breeding and the conservation of these mythical creatures that are unfortunately still considered good luck charms.
See the original article in Enjoy the Algarve – magazine May 2017
Tails intertwined, two seahorses dance through the 250 litre tank, performing their mating ritual while the rest of the colony holds on to the ropes in the water. A closer look reveals hundreds of tiny seahorses floating around as well, each only about 1cm long. Born last night, the baby long-snouted seahorses (Hippocampus guttulatus) are proof of the successful breeding programme that goes on at the Ramalhete Field Station in Faro. Originally a facility for keeping tuna fishing gear, it’s now used by the Universidade do Algarve. Outside, there are giant water filters (water from the Ria Formosa is filtered, used to serve all tanks and gets pumped back into the lagoon afterwards), whereas in the facility’s main room, sea bream, sole and sea bass are bred and studied for agricultural purposes. In one of the smaller rooms are the seahorses, divided over dozens of aquariums. Currently there are about 1200 of them, including the around 300 new-born H. guttulatus. Back in 2007, PhD researchers Miguel Correia (pictured below on the right, 39) and Jorge Palma (pictured below on the left, 48) were among the first people in the world to successfully and continuously breed this species in captivity.
“It was a struggle for the first few years,” admits Miguel. “Mainly because of nutrition, although setting up the system of tanks was also an issue. First, we tried applying what we already knew from other fish species, but that didn’t work as seahorses are very specific; they only feed on crustaceans for example.” The adults eat small shrimps and mysids (small shrimp-like crustaceans) whereas the juveniles need to be fed with copepods (microscopic aquatic crustaceans that are barely visible to the naked eye). In 2016, the marine biologists also began to breed the short-snouted seahorse (Hippocampus hippocampus) in captivity, which instantly was a big success. The reason for this late start? “H. hippocampus are smaller when they’re born, so they’re not so easy to feed as the bigger H. guttulatus.” Also, the biologists have found way more long-snouted seahorses in the Ria Formosa than short-snouted ones. The ratio between these species in the lagoon is about ten to one.
So how many sea horses currently live in the Ria Formosa? “It’s impossible to tell,” answers Jorge. “It’s not that we don’t want to give an accurate answer to this question, it’s that we can’t,” explains Miguel. This doesn’t have anything to do with the fact that the seahorses look so alike – on the contrary: look closely and you’ll see the tiny white spots on their body, which are as individual as a human’s fingerprints – but rather with the fact that there isn’t enough funding for this research. A study done by Canadian researchers back in 2001 estimates there are around two million seahorses in the lagoon, which makes it the largest seahorse population in the world. Fact is that between 2001 and 2009 there was a dramatic decrease in numbers: 94% for the long-snouted Hippocampus guttulatus and 73% for the short-snouted Hippocampus hippocampus. Although the population started to recover afterwards, numbers still fluctuate. Which is strange, because the seahorses don’t have any natural enemies in the lagoon. The fact that they’re full of bones doesn’t exactly make them a nice snack for a fish. “We’ve even found them close to octopus and cuttlefish without any problem,” reveals Miguel.
The exact reason for the recent decline of the seahorse population is unknown, but it’s potentially associated with habitat degradation. Contributing factors likely include an increase in water temperature (seahorses are happiest between 19 and 23˚C), underwater noise, fishing, anchors and nets being dragged along the sea bottom, sun and UV light, silting (when sand that’s swept inside the lagoon covers the sea grass), and sometimes too strong currents which drag the animals away from their home. Another big reason unfortunately: humans. Illegal fishing for seahorses and sea cucumbers especially increased in the last few years. They are caught, dried and sold to Southeast Asia where they’re used for ornamental purposes, as aphrodisiacs and and in all kinds of traditional medicines. Back in November 2016, a family from Olhão was busted as they tried to trade 2,133 dried seahorses, stolen from the Ria Formosa. Although all seahorse species are protected by law, the fact that they’re small and easy to hide makes it hard for authorities to control. But human beings also do harm with a more innocent intention. Like people causing the seahorses stress while snorkelling or picking them up for a closer look. Which is easy to do as they aren’t fast movers and mostly stay in one place.
Seahorses, who live from the South British Islands up to the Canary Islands, prefer what is called a complex habitat, with lots of stuff to hold onto, like seagrass, sea urchins, shells and even abandoned fish traps. In the wild, they curl their tail around bits of seagrass and let the current bring them their food. In the aquariums, Miguel and Jorge have tested different artificial holdfast units; plastic strips that mimic sea grass, fishing ropes in various thickness that mimic codium (a type of seagrass) and thick plastic objects. “That last one they hated,” reveals Miguel. Happiest are they with the fishing rope structures, as can be seen in all of the 41 tanks, where most of the seahorses have their tails wrapped around the bits of slightly uncurled nautical rope. All tanks are numbered, indicating not only the species, but also the different generations. “They start breeding when they’re three months old and can live up to three years. The average brood is between 300 and 400, so if they’re unable to keep a steady and healthy population, then there’s really a problem,” explains Miguel, who has done his PhD thesis on seahorse ecology in the Ria Formosa, back in 2015.
The biologists aren’t only trying to find the precise cause of the fluctuating numbers, they’re also ensuring they have enough seahorses to introduce back into the Ria Formosa if it’d become necessary to restock the population. The underlying motivation of both men: keeping the seahorses from extinction. “They’re becoming very scarce. I’ve never seen one in the actual sea, only in the lagoons, here and in Alvor. They’re extremely sensitive animals with a low mobility. If their habitat gets destroyed, so do they,” explains Jorge (pictured above), who’s wanted to be a marine biologist ever since he was a kid. “The seahorse is considered more beautiful and cute than, let’s say, the sea cucumber, but every species has their role in the ecosystem. Sea cucumbers, for example, filter the sand,” adds Miguel. “And the seahorse’s charisma is actually also what gets them in trouble: since ancient Roman and Greek times, they’re seen as mythical creatures. Therefore, people have thought, and some perhaps still do, that it isn’t a problem to bring one home as a lucky charm.” Twenty to thirty years ago, various shops in the Algarve still sold dead varnished seahorses. And the long-time fishermen tradition of giving any seahorses they find in their nets away as a souvenir to family and friends (instead of chucking them back into the water), also still hasn’t entirely disappeared.
With lectures in local schools, Miguel (pictured below) and Jorge want to change these attitudes and raise awareness for the vulnerable marine creatures. “Conservation and exploitation often don’t go well together,” says Jorge. However, the marine biologists see no need to make the entire lagoon into a zone where fishing and boats are forbidden. He explains: “Although the Ria Formosa looks quite big, about 80% of it runs dry with low tide. Since seahorses are subtidal species, they always need water. You won’t find them in rock pools for example. Therefore, the eventually available habitat is only 20% of the lagoon. Of this 20%, the majority is unsuitable as it’s only sand and mud, without seagrass. We suspect the suitable seahorse habitat area is as little as 1% of the lagoon. So only these areas would need to be protected from disturbing factors.” Sounds like a plan. So where exactly are those areas? “Well, we wanted to research this by drone. Unfortunately, we didn’t get the necessary funding…” To ensure the survival of the seahorses, more funding and research is needed. And more work.
While Miguel gets a dip net and goes off fishing in the lagoon for shrimps, Jorge starts transporting the seahorses to a bucket, carefully unwrapping them from the rope structures in order to clean the tank. Studying the adult ones, which are about 20cm long, the dorsal and pectoral fins can be seen moving at high speed as they float upright in the tank. We’re lucky enough to witness a female transferring the eggs to one of the male seahorses (in this species, the male gives birth). Contrary to what has always been believed, seahorses don’t always mate for life. “They choose a partner for at least one breeding cycle, but if they stay together afterwards completely depends on the density of the population.” If there are many other seahorses around, the female might hook up with another male. So much for everlasting love. Still, with their horse-shaped head and fish tail, these mythical creatures (the Greek god Poseidon’s chariot is often depicted being pulled by seahorses) are the most romantic fish in the world, especially when the pair does their mating dance again.
Admiring all the seahorses at Ramalhete Field Station, it soon becomes clear that the long-snouted seahorses, H. guttulatus, are more of a greenish brown, while the short-snouted seahorses, H. hippocampus, come in a broader range of colours, from mustard to Bordeaux red. Some even seem beige. “They can change colours in a split second, a bit like chameleons,” explains Jorge. Another trait those two completely different animals share is that they seem unhurried, content with chilling most of the time, which fits perfectly to the lifestyle here in the south of Portugal. Staring over the Ria Formosa lagoon, this gorgeous place feels even more special knowing that it’s home to so many of these fascinating and cute marine creatures. Hopefully just like chameleons have become a symbol of the Algarve on land, the seahorses will soon reach this status in the water. This is certainly the marine biologists’ aim for the future. Miguel: “Seahorses have huge potential to promote the protection of the entire Ria’s ecosystem. If they become the flagship species of the Algarve, this won’t only benefit the seahorse populations, but also all the other species that inhabit the Ria Formosa.”
Look, don’t touch!
What to do when encountering a seahorse? Avoid touching or handling them, as tempting as it may be. Why? You can hurt them, cause them stress or even move them away from their habitat (which leads to them not getting enough food and dying). Whatever you do, never handle a pregnant male as he could release the eggs because of stress. Also: don’t disturb a couple as this can endanger the breeding cycle. Last, but not least, since seahorses are a protected species, you need special permission from the Instituto da Conservação da Natureza e das Florestas ((ICNF), the Institute for Conservation of Nature and Forests), to touch them.
Long story short: look, but don’t touch. Also: make sure your presence doesn’t contribute to added stress to seahorse populations by minimising your impact: snorkel without fins, mind your movements to avoid hitting seahorses and/or their habitat, and behave as calm as possible.
See the original article in Enjoy the Algarve – magazine May 2017