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Kokanee Salmon in Kathleen Lake ( DOC ) |
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| Source: | Wolf Riedl, YFGA director | Date: | April 1, 2006 | |
| No more Kokanee! ……….“You mean I can’t get any more?” At 2 in the morning in the Gold Rush bar, it just means it’s over for the evening – come back tomorrow. In Haines Junction, headquarters of Kluane National Park and Reserve, it may be signaling a much longer ‘closing time’ - the end for a very special fish. The only naturally occurring population of kokanee salmon in a Canadian national park is disappearing! When I first arrived in Haines Junction in 1977, long time residents spoke of the abundance of these landlocked salmon in Kathleen Lake and how they could be caught in the spring by the sackful. Creation of a park reserve, a desire for better understanding of this unique population, and a concern for their conservation led to several years of research and better regulation. Baseline studies of weather, stream flow, water quality, and water chemistry were conducted in the kokanee spawning area for several years at that time, and salmon returns have been regularly monitored since. Over the intervening 30 years, spawning run counts have averaged about 2800 fish, but recently these numbers have dropped dramatically. Only 700 were counted in 2002, followed by 160 in 2003, 53 in 2004 and 66 in 2005. Given these numbers it only made sense to close the sport fishery for kokanee and ask that anglers not target the few that remain, even if they are to be released. Kokanee is the name given to land-locked sockeye salmon. Typically these salmon live as adults in the ocean and return to fresh water to spawn and die. Kluane Park’s kokanee probably evolved from sockeye salmon that once migrated from the Gulf of Alaska up the Alsek River into the Kathleen Lake system, but then became land-locked when a surge in the Lowell Glacier created an ice dam across their return route. The kokanee now complete their entire life cycle in the fresh water of the Kathleen Lake system. Adults are silver coloured and normally weigh less than a kilogram. At about four years, the male turns bright red and develops a slightly humped back and elongated jaw, while females turn a darker shade of red. Both males and females stop feeding and begin to migrate upstream in July, swimming from Kathleen Lake into Louise Lake and then to the spawning stream between Louise and Sockeye Lakes. By mid-August females are digging spawning redds and not long after the eggs have been laid, fertilized by the male, and covered, both fish are dead. An ageless cycle is once again complete. If all goes well, the eggs remain in the gravel of the spawning stream, hatching out in January or February as alevins nourished by egg sacs attached to their bodies, but still remaining in the gravel. In a few months alevins develop into kokanee fry which emerge from the gravel and ride the currents downstream to begin the cycle again. So what’s the problem? The park environment does not appear to be affected by significant pollution, introduced species or water diversion, all of which contribute to kokanee declines elsewhere in North America; and past studies have shown the kokanee here to be virtually disease and parasite free. No one knows yet, but park wardens have shared information and asked for input from the local community, and are consulting limnologists and aquatic specialists. They are continuing to conduct studies to gain information which will allow comparison to the 1970’s information and lead to better understanding of this puzzle. Some of this research includes: - Measuring stream flow, depth and temperature changes in the spawning stream. - Collecting air temperature and precipitation data. - Doing plankton hauls to examine the relative abundance or scarcity of the kokanee’s main food source. - Measuring water clarity in the three lakes and analysing water chemistry in the spawning area. - Conducting creel surveys and checking stomach contents of lake trout. - Conducting a hydro-acoustic survey to learn more about kokanee population dynamics in the Kathleen Lake system. - Reviewing studies of the causes of declines in kokanee populations elsewhere in North America. It’s too early for certainty, but initial work has highlighted potential suspects. Over-fishing is unlikely, but climate change could be making its appearance known. Warmer air temperatures may be raising water temperatures to lethal levels, or causing kokanee fry to emerge before enough plankton is available as food. Changing snowmelt may be more erratic, affecting abrupt changes in stream flow, depth, and ice protection for eggs. Are beetle-killed spruce and their fallen needles acidifying the waters they overhang? Are unidentified environmental conditions driving the kokanee into different areas where they are more vulnerable to predators, secretly spawning, or just more difficult to find? It’s also possible that an unknown parasite has been introduced, or that changing conditions have made the kokanee more vulnerable. Who knows whether this unique kokanee salmon population survives current events? If these wonderful fish return to their previous abundance it will likely be as a result of their ability to adapt rather than much of what we attempt on their behalf. However, it confirms again the complexity of the wild, and our frustrating inability to just ‘set it right’. In baseball lingo ….. “Mother Nature always bats last.” Wolf Riedl, YFGA director Haines Junction |
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