Seahorses are a fascinating and unique group of bony fishes loved by divers and marine enthusiasts. There are 48 different species of seahorses around the globe which range from less than 1 cm tall to about 35 cm tall and come in a wide variety of shapes, colors, and styles. Seahorses are physically quite different from most other fish, and also display very different behaviors and life-cycles.
In addition to being unique, seahorses are also quite fragile and sensitive to environmental changes. Recently, seahorse populations have been on the decline around the planet due both to habitat destruction and over-fishing. This has led to the group being added to the CITES Convention on International Trade under Appendix II, meaning that their trade needs to be evaluated and assessed for sustainability. Thailand is actually one of the world’s top exporters of seahorses, sending out about 5 million individuals per year, mostly to Taiwan and China. There they are sold as food, medicine, and novelty items or souvenirs.
Hippocampus trimaculatus, one of the three species seen around the island of Koh Tao.
Hippocampus kuda, the smooth Seahorse - a muck specific species rarely observed on Koh Tao.
Hippocampus spinossissimus, the Hedgehog Seahorse.
What we are doing to monitor seahorses?
Our efforts to research local seahorse populations began in April of 2013. Seahorses have always been quite rare around Koh Tao, but after seeing only one individual in 6 months we began asking if maybe their populations where declining. At about the same time we were introduced to the iSeahorse.org group and all of the great work they are doing there, including their online global database for seahorse sightings.
We began to develop our own local survey techniques for the seahorses, that would accommodate our team of trained conservation divers. Since then we have conducted many seahorse surveys, some random, or roving diver surveys, and the others a long a transect line. At the end of the article you can see the results of our findings since our surveying began.
Although it is not very often that we find any seahorses during our actual seahorse surveys, this is still good data for us to collect. Based on this research we can conclude that seahorses are quite rare, and that possibly their fishing or trade of seahorses around our area should not be allowed, as it cannot possibly be sustainable. We have also found many interesting and rare species of fish and invertebrates on these ‘muck dives,‘ making them a favorite activity for our team, and also contributing to our other invertebrate research projects.
We have however found seahorses at other times, either during fun dives or even walking on the beach. From these occurrences we can collect data on the species that we have around our island. We have also looked at the catch from trawlers parked around the island to get an idea about what species are in the region (the trawlers will show us the seahorses, but generally not tell us exactly where they were caught).
What can you do to get involved?
In addition to conducting research, we have also begun a seahorse awareness and training program, alongside the iSeahorse.org group, which you can read all about in our most recent seahorse article.
Although our seahorses research is a budding project in our program, it is something that we are trying to move forward quickly. The threats faced by seahorses are the same as many other reef organisms (habitat destruction, over-use, over-fishing, climate change, etc.) and seahorses are an important indicator species for tracking the trends in reef health and biodiversity. Students in our program can also receive the Seahorse Ecology and Monitoring Certification card for recognition of their learning and involvement, 200 baht of which goes to support iSeahorse.org. Project Seahorse is also working on a distinctive specialty from PADI, which we will also be excited to offer.
Seahorse sightings have largely varied over the years based on where we were conducting Seahorse Surveys. From 2014 to 2015 our program conducted surveys off the reef in Sai Nuan and Three Rocks where we have found one of the healthiest populations of these shy creatures around Koh Tao thus far. The shallow sloping sea floor in this area is incredibly expansive and provides a vast ranging habitat for Seahorses to use as a habitat.
The Hedgehog Seahorse (Hippocampus spinossissimus) is the most abundant species we've found around Koh Tao thus far and the Smooth Seahorse (Hippocampus keloggi) was the next most observed species. One factor that needs to be taken into consideration in this data is the behaviour of the Three-Spot Seahorse (Hippocampus trimaculatus) as it tends to prefer to float along the ocean's surface, with its prehensile tail hanging on to bits of debris. The lack of observation of the Three-Spot Seahorse is likely affected by the fact that as divers, we are not frequently surveying areas where they inhabit.
We will continue monitoring the population health, species diversity, sizes and sexual distributions of these rarely observed, beautiful creatures so return to this page for future updates or send us an e-mail below if you'd like to join us in our efforts to track these cryptic animals. Also, check out how seahorses have influenced some of our other work, like this imaginative marine debris/artificial reef project from 2016.