In 2013 the NHRCP began looking deeper into the abundance and diversity of seahorse populations around Koh Tao. Later that year, we got a boost in this program by partnering up with the great team at iSeahorse.org to develop some standardized survey techniques that could be used to assess these difficult to find species. And this year we are excited to see that iSeahorse.org has written a new Seahorse Specialty Course through PADI. So, after 1 year of surveys and helping to promote the iSeahorse.org database on Koh Tao, what information is known?
The first thing we can say with confidence about seahorses around Koh Tao is that they are rare. From our 2013 benthic surveys, we searched well over 51,000 square meters of sea bed for 506 total diver hours and found 1 seahorse. Including all our other dives, we found 4 seahorses in 2013. 2014 might prove a bit better, as by June we have already found 4 individuals. But we are diving everyday, and always have an eye out for them, so it is quite safe to say that you have to be lucky to find a seahorse.
Looking at the iseahorse.org database we can get a bigger picture about the diversity of seahorses on Koh Tao based on the 21 confirmed observations listed. According to the observations submitted, we have 5 species on Koh Tao: H. spinosissimus, H. kuda, H. comes, H. trimaculatus, and H. barbouri. The most abundant species by far is the Hedgehog seahorse (H. spinosissimus), making up 71% of all observations from Koh Tao.
We also find that the locations of seahorses tends to be quite transient. In part of the year one area may have multiple sightings, and then nothing more for the rest of the year. But from the observations on the iseahorse.org database, 43% of all the seahorses observed on Koh Tao where from Twins, followed by Tao Tong with 22%. Most other sites just had 1-2 sightings.
But with so many divers on Koh Tao wouldn’t we expect more sightings than this? Possibly the answer lies in that fact that most of the seahorse observed here on the island where in what are known as the ‘muck’ areas. Areas away from the coral reefs – with just sand, mud, soft coral, and other soft substrate types. These areas are generally not dived, as the majority of divers to Koh Tao spend their time in the lush coral reefs.
This means that relying only on diver observations may not give us the whole picture in terms of the management of marine areas in terms of protecting seahorse populations. The island has made great strides to protect its reefs, through marine zoning and fishing restrictions. But nothing has been done to protect the deeper waters where seahorses such as H. trimaculatus generally inhabit. These areas are still prone to being destroyed through deep sea trawling activities in the Gulf. To investigate this, we once pulled up to a trawler that was moored on Koh Tao and had our Burmese boat captain ask them if they had any seahorses. They quickly produced 4 dried individuals, all of which were H. trimaculatus.
Today, all seahorses species are listed on the IUCN Redlist as either ‘Vulnerable’ or ‘Data Deficient’. There is still a lot more that we need to understand about seahorse populations. They may not be the most important fish in the ocean, but they are something we all love. They are a unique species, with many traits that are not found else ware in nature. They are also a good indicator as to the health of our oceans, as they are sensitive to habitat destruction and overfishing.
A lot of work still needs to be done to understand and protect seahorses on Koh Tao and around the globe. One of the ways can all help with that effort is by recording observations of seahorses on the iseahorse.org database each time we dive. We also need more concentrated efforts to investigate the number of seahorses being caught by trawlers in the area. From there we would be able to design more effective fishery management techniques to protect these important and vulnerable species of marine fish.
If you would like to learn more about seahorses you can join the iseahorse.org workshop on Koh Tao and get trained and certified in the new PADI Seahorse Specialty. The workshop will be held on July 26th and 27th, and is open to all local divers. If you can’t make that workshop, then you can also get certified at New Heaven Dive School anytime of the year. You can also participate in seahorse monitoring and population’s studies project by joining in our marine conservation courses.