The monogamous mating habits of Kerala’s state fish ‘Karimeen,’ along with habitat disruption, is posing a serious threat to its population in Kuttanad. A study, conducted by Dr K G Padmakumar, former Associate Director of the Regional Agricultural Research Station, Kumarakom, has revealed some interesting facts about Pearl Spot (etroplus suratensis), a delicacy for tourists and locals.
The Pearl Spot leads a strictly monogamous life, according to Dr Padmakumar. Male and female Pearl Spots form exclusive spawning pairs and mate only with each other during the mating period of seven to eight months.
“After the eggs are laid by the female, they are stuck to the substratum one by one, and the male fish fertilises them immediately”, he explains. “The process of egg-laying and fertilisation is repeated several times about an hour and the eggs are cemented closely without touching each other. The eggs hatch in another 70 to 72 hours, and the hatchlings are transferred by the parents to a breeding pit, which is prepared on the shallow pond bottom. The female closely guards the pit and continues the parental care till the young one attains a size of 30-40 mm,” he said. This could be one reason contributing to the dwindling population of Pearl Spot in the Vembanad lake.
Breeding and mating are carried out only in clear water. Pollution in the lake, strong underwater currents and any such disturbances negatively affect the mating and breeding of the rare species, the research found. Indiscriminate dredging of the lake bottom for lime shell deposits has turned catastrophic for the natural breeding of the fish.
Padmakumar also said the Pearl Spot lays only 1,000 to 1,200 eggs in a breeding period, which is very low compared to other species laying nearly one lakh eggs. In 1969, the annual production of the pearl spot was about 1,252 tonnes. It decreased to 200 tonnes in 2002.