RIGA, Nov. 15 (Xinhua) -- Environmental experts are investigating the death of several tons of fish that have been washed onto a beach in Latvia's southwestern seaside city of Liepaja this week, local media reported on Wednesday.
About three tons of fish washed ashore on a 1.3 km long stretch of the Liepaja beach, authorities said.
Andris Junkurs, head of resource control at the Latvian State Environmental Service, said that although initially it was thought that the fish had been dumped into the Baltic Sea by some fishermen, this hypothesis had to be ruled out eventually.
The environmental authority's fish control department analyzed satellite images in an attempt to detect the fishing boat that might have dumped an unwanted catch of round goby at sea.
"The examination of the images revealed no unusual maneuvering of deep-sea fishing boats that would be worth paying attention to. So, this hypothesis had to be ruled out," Junkurs explained.
Fishermen catching fish closer to the shore have also been cleared of suspicions, as part of the dead fish washed ashore in Liepaja were too small to be caught in fishing nets.
"We therefore have no reason to believe that a catch has been dumped at sea in this case," Junkurs concluded.
An ichthyologist who was consulted about the unusual find said the fish might have perished in stormy waters as waves smashed them against a rocky surface like breakwater, for instance.
"We are inclined to believe that this has been a natural process," Junkurs said.
Poisoning has been excluded as a possible cause of the mass death of gobies due to the absence of visual signs of poisoning.
Besides, a toxic substance would have killed fish of various species, but there were almost only gobies except for some plaice and cod.