Oct. 15 Linwood Bay closure

[Downrigger]

Does anyone know why Linwood Bay closes between sunset and sunrise starting on October 15th?

Is this to protect spawning lake trout? If so, doesn't that conflict with the 8 lake trout limit which was set for the express purpose of reducing the number of lake trout in the lake?

Is the thinking that there is less impact to the fishery by taking a bunch of pups than to pound on the big ones that are trying to do their thing?

Does this rule conflict with the general desire to increase kokanee populations?

 

[jacksonlaker]

I beleive the rule is to keep the snaggers from ripping big macs at night. The smaller lake trout are mainly plankton eaters, just like the kokanee. They dont switch over to a fish diet until they get around 24", some not at all. So go ahead and bonk all the little macs. There are a lot of them. And I'm sure Ryno can explain this much better than I can !!!

 

[Ryno]

The nightime closure was issued to reduce the lake trout snagging efforts that were taking place while lake trout are spawning in Linwood Bay. In case you weren't aware, it's a popular area for lake trout anglers as there are large gravel humps that attract large numbers of spawning fish, many of which are trophy sizes. By no means does this rid the area of those unethical practices, but it does reduce the opportunity and reduce the issues for law enforcement.

Downrigger, your question is valid, "If so, doesn't that conflict with the 8 lake trout limit which was set for the express purpose of reducing the number of lake trout in the lake?". Lake trout abundance increased dramatically about a decade ago, mostly for smaller fish less than 20-inches. Based on netting results it peaked in 2006, and has started to decline, likely a result of angler exploitation. The goal of the current reg on lake trout, "8 fish, 1 over 28-inches" is to reduce the overall abundance of lake trout while maintaining the trophy lake trout component which is also popular with Flaming Gorge anglers. Like Jacksonlaker stated, most of your smaller lake trout (pups) feed on invertebrates like zooplankton and crayfish. They are extremely opportunistic though and will utilize smaller kokanee when available. This is observed in the annual netting and you may also see this yourself if you harvest lake trout. The thought is to reduce the more abundant pups which have more impact on small kokanee and consequently kokanee recruitment to catchable/harvestable and reproductive size classes. Pups are also the size class that is most commonly caught and the better table fare, and the reg simply allows anglers to keep more of those fish when they're already "in-hand".

In closing, the harvest reg is designed to maintain a trophy lake trout component all the while maintaining adequate forage (kokanee) for that component and still providing a highly-sought quality kokanee fishery for anglers utilizing the Gorge.

Hope that helps some, Ryno

 

[SuperD]

Has Utah or Wyoming considered the Lake trout / Brookie hybrid that grows to trophy size but is sterile? Also, within the large trophy Lake trout, has it been studied to find out if they are already sterile? I know some species are real reproducers in their mid size range.

 

[Ryno]

Utah stocks "splake" into several waters including Fish Lake in central Utah. Fish Lake also has a lake trout population. I've never heard that those hybrids limit reproductive success of lake trout, but they do grow rapidly being all their energy goes into growth and provide some quality fish there.

I've also never heard of sterility being a concern in wild lake trout stocks, although I suspect it is possible. With the abundance of lake trout in the Gorge, I think they are pretty prolific and the water quality and habitat conditions provide good egg to fry survivorship. The text books state that on average a female lake trout produces about 750 eggs per pound of weight. If it's a big fish, that's a lot of eggs. A 30 lber could produce about 22,500 eggs.

Good questions, Ryno

 

[Downrigger]

Ryno,

Thanks for your great insight. It seems like it is as I thought - catching a bunch of pups has less impact on the lake trout than catching the big ones. I think this is an excellent management tool to keep a good number of kokanees while maintaining the large lake trout stocks.

You mentioned that the abundance of lake trout in the lake peaked in 2006 and has start to come down since then. Do you see the excellent 2009 year class of kokanees as a result of the downward trend in lake trout abundance?

How was the 2010 spawning year for kokanees? Did it follow the same trend as 2009?

I've read that already 100 kokanees have entered Sheep Creek as of Sept. 1 and that is a promising sign for another good crop of kokanees for this year. Is that what you expected based on this years' survey of lake trout abundance?

What impact is the catch and kill regulation having on the burbot? Are we making any headway?

Thanks!

 

[Downrigger]

Has Utah or Wyoming considered the Lake trout / Brookie hybrid that grows to trophy size but is sterile? Also, within the large trophy Lake trout, has it been studied to find out if they are already sterile? I know some species are real reproducers in their mid size range.

Several years ago (2008, I think) Utah stocked the Gorge with ~60,000 Brook trout/Brown trout hybrid (Tiger Trout) to eat Burbot fry that live in shallow water. The Utah record for tigers is only 10 pounds but I bet in the Gorge they could get pretty big. My brother caught one a year or two ago.

 

[Ryno]

Kokanee are an interesting species. We used to have a pretty consistent cycle in the Gorge, but it's been unpredictable the last several years. I think the 2009 year class was a result of a good spawning run (lots of Age-4 fish) in the fall of 2008, hatchery production (collective stocking of 1.4 million fingerlings) in 2009, and like you suggest, possibly the result of reduced predation (burbot and lake trout).

Kokanee recruitment in 2009 was the highest ever recorded for Flaming Gorge since hydroacoustics surveys have been used as a monitoring tool (1988). An estimated 922K young-of-the-year kokanee were surveyed in August 2009, almost double that of the previous high measured in 1998. Surveys conducted in 2010, showed a good representation of Age-1 fish (that 2009 year class) but poor recruitment with only 172K young-of-the-year.

The run in Sheep Creek started with a "bang". Oddly, it started about 2-weeks early with a couple hundred fish. Those fish are in there, doing there thing, but as of late last week not many new spawners have shown-up. I suspect more fish will come but based on previous experience with kokanee, I won't hold my breath. Hopefully the reservoir spawning kokanee are successful this year as they are the major component of the total kokanee population in the Gorge. In previous studies, it was identified that about 90-95% of the kokanee production is a result of in-reservoir spawning kokanee. Burbot now play a part in that though being they are prone to eating kokanee eggs once they've spawned. The gillnetting data hasn't been summarized completely yet, so I'm unsure what lake trout abundance was for 2011.

As far as the trammel netting data shows for burbot, relative abundance peaked in 2007 and has declined gradually ever since. Trammel net catch rates dropped about 30% (reservoir-wide) in the fall 2010 sample. I suspect that has much to do with angler exploitation and we're always happy to see declines when it comes to burbot.

Tiger trout were stocked in 2008, but zero have been sampled or creeled since. There have been some angler reports, but so far they are unconfirmed.

As you suggest, anglers can help by harvesting abundant predators like lake trout and burbot, in turn reducing pressure on kokanee, and hopefully allowing the Gorge to maintain a healthy kokanee fishery into the future.

Hope it helps, Ryan

 

[Downrigger]

Ryno,

Thanks for the very interesting information. There's a lot there to think about but the future of the Gorge looks very bright, especially in your very capable hands.