The diving from November 2013 to April 2014 has been outstanding in the Similans. We have been overwhelmed with the numbers of manta ray and whale shark sightings throughout the Andaman Sea this year. To try and understand this sudden influx of larger pelagic life, we asked our friends who work in the local diving industry what their thoughts are on the increase in megafauna this sensational season in the Similans.

The Similan National Marine Park, once a world class diving destination, has not offered anything very positive worth mentioning in the past few years. In 2010 the islands suffered from severe coral bleaching, this left a lot of the Similan’s reefs looking barren and void of life. Shark fishing and other illegal fishing activities conducted in the National Park have really taken their toll on larger pelagic species in recent years too. This combined deterioration of the coral and depletion of marine life had resulted in some disappointing diving experiences.

Whale Shark sightings, in particular, have been dropping every season since 2005. It has been only the regular Manta Ray sightings at Koh Bon and Koh Tachai over the years that has kept the Similan Island’s reputation alive.

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One diver’s logged Whale Shark sightings

That is until the current Similan diving season 2013-2014.

This season there have been a lot of surprising changes. From the very early trips in late October day trip boats and liveaboards were reporting sightings of Whale Sharks and Manta Rays. These early sightings were mainly at Koh Bon and Koh Tachai and they continued through the following couple of months until January.

It is common during the Similan’s peak season, usually in the last week of December, for seasonal winds to pick up and blow strongly from the north. This can play havoc with operators running full boats, and with the winds come higher waves, sometimes leading to cancelled trips.

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Until this season sightings like this were few and far between

New Year came and went and still the strong winds blew. Well into January some of the smaller boats were still finding it difficult or impossible to head north from Koh Tachai to Richelieu Rock. Despite clear blue skies the wind persisted. The surface temperature of the Andaman Sea dropped by one, or sometimes two degrees.

Then towards the end of January the diving conditions in the Similan National Marine Park started to dramatically improve. Divers weren’t just witnessing single, brief encounters of Whale Sharks. Divers were seeing two, or sometimes three, Whale Sharks on a dive and for the whole dive. The sharks were even seen on subsequent dives at the same location and a couple of hours later.

Could cooler water temperatures be the reason?

“Just a guess would be colder and more nutritious water this season”, suggests long term Thailand resident Tom Sorensen who has over 9 years of experience diving in the Andaman Sea and has worked on a plethora of different boats this season. This season he has had two Whale Shark sightings, these are the first two he has ever seen in the Similans.

Gianluca, owner of the MV Similan Explorer, agrees: “With water temperatures down to 27C there is more food. Or it is luck!”. Gianluca has been diving a total of five seasons in the Similan Islands and until this season had only sighted one Whale Shark back in 2002. This season he has logged 15 Whale Shark encounters, although he isn’t sure how many are repeat sightings of the same animal.

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A Giant Manta Ray at Koh Tachai

Beto Kawaguchi has more experience than most Similan liveaboard tour leaders, with a total of 13 seasons diving in the Similans. His last Whale Shark encounter was in April 2012, he claims, “stronger currents and more food, mainly lots more jelly fish this season” are the reasons why he has enjoyed more than 20 Whale Shark sightings and more than 20 Manta Ray sightings this season.

It seems that most divers we have spoken to are in agreement; cooler water temperatures are one of the main reasons behind the turn around in megafauna sightings. The same can be said for the coral life in the Similan Islands. There has been a notable improvement in coral regrowth over the last couple of seasons, since the unfortunate bleaching outbreak in 2010. The improvement has been seen no more so than in 2014; many new coral colonies are forming on a number of Similan dive sites.

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Healthier corals could mean healthier fish life in the Similan Islands

Whilst recently on board the MV Hallelujah I spoke to Julian, a Phuket freelancer. He thinks that the increase in Whale Sharks is linked with healthier corals and more fish life in general.

Jo Healy, who runs Hidden Depths Diving on Koh Lanta, has gone to greater lengths to explain and document her observations in the South Andaman Sea:

Manta and Whale Shark Sightings 2013-2014

“This season, diving in the Andaman Sea has been absolutely stunning. In the five years we have been diving the sites situated close to Koh Lanta, we have never before seen such a profusion of megafauna. At Hidden Depths Diving, we have our own speedboat that makes daily trips to the dive sites of Koh Haa, Koh Bida and Hin Daeng and Hin Muang, so we have a good idea of what marine life is present.

The dive sites at Hin Daeng and Hin Muang are famously great places to spot Manta Rays and Whale Sharks. Last season, we did see Manta Rays for a two week period around January 2013, but there were only a few days of really close encounters with them. This season, the first sightings of mantas occurred in October 2013 and continue up to this day [in March]. On some dives, there have been six or seven mantas, including an unusual all black manta.

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We saw whale sharks for each of the first three seasons we were here but did not have one sighting at all last season. We have not seen any at Hin Daeng & Hin Muang this season, but for the last six weeks, there has been a 3.5 metre juvenile Whale Shark at Koh Haa that seems to really enjoy the interaction with both divers and snorkellers.

Many have speculated about the reason behind the increase in large marine animals, and mantas in particular. There have certainly been large quantities of zooplankton in the water around Hin Daeng, so it may be related to feeding habits. It is unusual for the mantas to remain here for as long as they have. For the Whale Shark to appear at Koh Haa, and in such shallow waters, is rare but not unheard of. There was a sighting there in 2011, but only for a few days, not for six weeks. There have been no noticeable increases in zooplankton levels around Koh Haa that would explain such a prolonged visit.

It is hard to give an estimation of the total number of Manta Rays seen this season, although we always try to take a photo of the underside of the ray for identification purposes, accurate identification is not always possible. There could be as many as 50 different mantas observed over the last six months. Whatever the reason for the increase in sightings here, we certainly aren’t complaining!” – Jo Heally

Like Jo said, whatever the reason for the increase, there is certainly an air of optimism within the local dive industry.

Joe Blasy, a 13 year Thailand resident and dive instructor involved in marine conservation in Phuket, states:“This year almost every trip returning from the Similans is reporting whale sharks. This huge amount of sightings of this endangered species could just be part of a random or natural pattern. My guess, and my hope, is that the increase we have seen recently in both awareness and legal protections may have something to do with it.”

Joe is administrator for the Facebook Group Phuket Marine Conservation which is steadily growing in numbers and influence. There is certainly a blooming and more positive movement within the dive industry these days, especially with organisations such as Shark Guardian and the See & Sea Organisation who are fighting hard for shark conservation and a greater public awareness.

It would be a fantastic success if Joe’s hopes were indeed true, but with other shark species sightings at an all time low in the Similan Islands it still feels like there is a lot more hard work is to be done. Illegal fishing activities continue to be blatantly obvious within the National Park boundaries.

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Megafauna species need proper protection if we hope to continue to see them in the Similan Islands

A great concern with Megafauna species like Whale Sharks and Manta Rays is they migrate huge distances. If Thailand does begin to offer these animals greater protection, it will be to little avail if other neighbouring countries do not follow suit. Evidence shows that Thailand’s Manta Ray populations are also aggregating in Myanmar, and possibly even in Indian waters. Manta fisheries are on the increase in India, which will have a huge negative affect on this gentle giant already listed as vulnerable to extinction.

What is definitely the case for local dive instructors, and more importantly divers visiting the region, is that they have been dazzled by the quality of diving this season, and especially at Koh Tachai. The knock on effects could be a major boost to diving tourism for years to come. We can certainly hope that these trends continue and surely there must now be clear evidence that Whale Shark and Manta Ray tourism has a huge benefit for Thailand?

It is time to enforce the fishing sanctions that have been put in place to help conserve the environment and marine life in the Similan Marine National Parks.

It is time to protect these animals for good.by Ric Parker