Japanese seahorses in Goa - tourists or old settlers?

Paul Fernandes
Monday, 25 May 2020

In 2017, a specimen found at Chapora followed by another in June 2018 at Dhaddo backwaters of Carambolim – a bird and crocodile paradise – stirred excitement among scientists and others to search for clinching evidence.

Panaji: Four tiny, unusual-shaped fishes that were found nearly two years back in stake fishing nets in Mandovi estuarine system at Britona have been confirmed as the first records of Japanese seahorses (Hippocampus mohnikei) in Goan waters.
A study by National Institute of Oceanography (NIO) scientists, supported  by both morphological and molecular analysis, has helped establish that the sighted specimens of H. mohnikei indicate significant dispersal from its native and reported range within Southeast Asia to the far west, a few thousands away.
In 2017, a specimen found at Chapora followed by another in June 2018 at Dhaddo backwaters of Carambolim – a bird and crocodile paradise – stirred excitement among scientists and others to search for clinching evidence.
The netting of four at Britona in July 2018 was a lucky catch.
The highly prized fish, belonging to the single genus, Hippocampus is found in many parts of the world, but has been overfished to an endangered status for its value in traditional medicine, souvenir industries or as an aquarium attraction.
The four similar looking seahorse specimens – ranging from 47.3mm to 60.1mm in length – inspired the paper co-authored and published by Sushant Sanaye, Rakhee Khandeparkar, Mamatha SS Jayu Narvekar and other NIO scientists in PLOS ONE, a scientific journal.
Considering that the tiny fish are not quick swimmers, their long journey baffles scientists.  “This new sighting of H. mohnikei could indicate a long-distance dispersal facilitated by the prevailing oceanic circulation in Indo-Pacific region or increased habitat suitability in bay-estuarine systems of Goa,” the paper states.
Scientists say the young seahorses used rafting – latching on to debris and seaweeds floating in sea for their long distance travel.
Japanese seahorses, being natives of the far eastern country, have migrated to China, Vietnam and other countries.
The study pinpointed the genetic closeness of Goan populations to Thai or Vietnamese populations of H mohnikei rather than those inhabiting Japanese and Chinese waters.
“The first Indian record of H. mohnikei was found along Tamil Nadu coast in 2007. But it was based only on a morphological study,” R A Sreepada, a seahorse researcher and a corresponding author said.
The Japanese seahorse was compared with two out of ten species found in India, H kuda and H trimaculatus and found to be shorter than them.
 “H mohnikei are much darker, but being experts in camouflage, they are known to change colours. Whether they arrived here as vagrants or had previously established needs further study,” Sreepada said.

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