by kamp cook[/h]
An amazing rainbow from Lake Mary Ronan. FWP started planting triploid Arlee rainbows in 2008 when the natural run failed due to perch competition and predation. Triploids in general haven’t done much but in some cases triploids – and Arlees – make a breakthrough.
Here is the photo of the 19# and 34 inch long rainbow trout caught this summer in Lake Mary Ronan.
UPDATE: The angler has been identified as 72 year old, Jim Lowe, of Grey Cliff, MT. According to Mark at Camp Tuffiit, who took the picture, Jim caught the trout in 30 ft of water, while fishing for kokanee on Wednesday August 5th. Mark wasn’t confident with his old scale reading only 19lbs, so when Jim returned to Grey Cliff, he took the fish to a grocery store and had it weighed on a certified scale. It weighed 21.5 lbs. Montana Outdoor Radio Show Facebook fans have reported the fish was taken to Northern Anglers Taxidermy in Billings.
Jim’s family has been fishing Lake Mary Ronan since the 1930’s. For information on Camp Tuffit call Mark at 406-849-5220
Sorta makes you wonder how far the stocking of triploid fish might go.
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And a follow up:
Many of our viewers asked, “What the heck is a Triploid Arlee Rainbow Trout??” after the post about the21 lb Rainbow caught out of Lake Mary Ronan. We did some research and received the following information from retired fisheries manager, Jim Vashro.
To sum up the process, fish eggs in hatcheries are treated after fertilization with precise heat and pressure at precise intervals so the resulting fish have three strands of chromosomes (triploid) instead of the normal two (diploid) strands in their DNA. Triploid fish appear normal but can’t reproduce so it is hoped they will grow longer/larger, their numbers can be controlled and they won’t interbreed with other reproducing fish.When a normal egg is fertilized it receives a set of chromosomes from each parent that combine into that classic helix pattern of DNA– e. g., diploid. Cells multiply by splitting those strands of DNA, copying each strand and combining back into additional DNA/cells. That process happens in an orderly manner in early cell development.
If you really want to dive into this process further, here is a more detailed summary of the process. Geneticists and fish culturists discovered that by subjecting the eggs to precise heat and temperature at a certain time (about 20 minutes after fertilization which is about the 5th cell division, I’m not sure on sequence/timing) the cells would produce and combine a third set of DNA – e.g, the cell now has DNA with triple (triploid) strands instead of double (diploid). The fish appears normal but cannot reproduce because the DNA strands don’t match.
The initial thought was that triploid fish would not reproduce so they wouldn’t divert energy into eggs and sperm and go through the rigors of spawning. The energy freed up would let the fish grow bigger. Also, some fish like salmon might not be timed to die. That has happened in some cases, triploid fish can grow much larger than their diploid brethren. The world record rainbow from Diefenbaker Lake, Saskatchewan as well as rainbows in the Columbia River are triploids.
However, triploids are not the silver bullet as hoped. Montana has found that many triploids still go through the motions of spawning, even producing sterile eggs. The process of heat/pressure produces higher egg loss (30-40% or more) so there is an upfront cost to produce more eggs. And it seems like triploids might not be able to withstand stress (high water temperature, poor water quality, competition) with poorer survival in the wild. And triploiding is not always 100%, some of a batch of eggs may still develop into diploid fish. It’s a work in progress.
Montana is still experimenting. One obvious benefit would be to produce larger fish, particularly in a water where you don’t expect them to successfully reproduce anyway. The other benefit would be where you are trying to protect the genetics of existing fish stocks. Montana is planting triploid Gerrards/Kamloops into Lake Koocanusa because BC doesn’t want rainbows interbreeding with their westslope cutthroat. Good plan but few seem to survive beyond 24”. You could plant triploid rainbows or cutthroat in a lake or reservoir knowing they won’t interbreed with stream stocks above or below. There are attempts to produce triploid walleye so that fish could be stocked but numbers could be controlled to minimize impacts on other species.
If you would like more information on what Montana Hatcheries are working on, contact Hatchery Section Manager Eileen Ryce @ 444-2448.
