Just last week I was at anchor, fishing at Unicorn wreck for mackerel. This wreck lies a couple of kilometers north of Koh Tao which makes it almost 60 kilometers from the mainland and any estuary system. Water is nearly 50 meters deep. Another local boat was jigging bait flies on a heavy handline. He wasn’t getting many bites, but in betwen the tiny scad that he was catching were a few 2 kilo tarpon(megalops cyprinoides). The indopacific tarpon is very closely related to the giants of America and the Caribbean. Very surprising to see them out there.
Rainbow runner(Elagatis bipinulata) turn up occasionally, often arriving at the same time as the whale sharks that visit the island. I have only seen these at SW pinnacle and Chumpon pinnacle. Usually large size over 5 kilos. The last one we hooked was eaten by a bull shark a few meters under the boat. The head made a nice soup.
This week trolling daisy chain in the shallow channel between Nangyuan island and Koh Tao we have caught 3 of these small mackerel. Very similar shape to a king mackerel but only tiny teeth and very nice blue and green stripes on their backs. Almost as striking blue as a bluefin trevally. Appears to be doublelined mackerel (Grammatorcynus bilineatus). Average 40cm long.
Calecale trevally(Ulua mentalis) are a rare catch. I have seen this caught twice. Once at Lighthouse pinnacle and the other time at Green rock near Nangyuan island. The Green rock specimen was well over 5 kilos and looked to be a very strong fighter.
Threadfin salmon(Eleuteronema tetradactylum) occasionally make a visit to Koh Tao. I have seen them caught at Chumpon pinnacle and Green rock. Reliable reports also that they have been taken at Taatoh pinnacle. Usually around the 3 kilo mark, nice fighting and good looking fish. Only seen this fish caught in late December and January after the NE monsoon has just finished.
Lionfish(Pterois volitans) are a very unwelcome catch when using bait flies inshore. Not much fun getting them off the hook! Far more amusing to watch Leslie Nielsen handle one on Naked Gun. Lighthouse pinnacle seems a popular hangout for lionfish.
Another irritating species that sometimes eats a bait is the shark sucker(Echeneis naucrates). These like to stick under the boat and do their best to eat the entire berley trail, as well as attacking newly launched livebaits. Poor mans’ cobia or not? Crap fight, not enough meat on it to try cooking one, and sticking to the deck but not to my hand or belly make this species a three time loser. Any implied similarity is an insult to cobia.
One evening, out night fishing at Kong Mai pinnacle, nothing was biting. The Canadian customer getting bored by his live squid bait being ignored decided to try a chunk of his salami dinner on the hook. Apparently it works well in Canadian lakes even better when sprayed with WD40. The sausage didn’t last long on the bottom before a large dark brown catfish ate it. Never seen one before or since and no idea what species of cat. Tasted good on the BBQ I hear.
The Giant trevally(Caranx ignobilis) makes a rare appearance here at times. I have caught juveniles under 2 kilos at Chumpon pinnacle while bottom fishing. In mid 2009 a local fish trapper caught two much larger fish from Lighthouse pinnacle. They looked to be around the 10 kilo mark.