Kamloops fisherman Dave Shaw was on Pass Lake, north of Batchelor Heights, on Thursday, April 26, when he witnessed at least 66 trout floating on the water’s surface at the south end of the lake, victims of a winter kill. On a more positive note, Shaw’s fishfinder showed some fish near the lake bottom, where there remains oxygen for them. Pass Lake also suffered fish kills in 2008 and 2009. According to the Freshwater Fisheries Society of B.C., fish kill occurs when ice covers a lake’s surface and water can no longer obtain oxygen with air mixing. The combination of ice and snow on a lake result in limited sunlight penetration. Vegetation in lakes produces oxygen through photosynthesis during the ice-free portion of the year. With light unable to penetrate the lake surface, photosynthesis stops and vegetation can begin to decompose. Decomposition results in oxygen consumption. Winter kill occurs when the result of these conditions deplete dissolved oxygen levels below threshold levels able to support fish.