Why Rainbows?

[JackM]

E're body knows brookies and even gemmies are push-overs. Quit exaggerating.

 

[pete41]

Same way cattle ranching works [similar anyway].The bulls that sell for large sums ? They're the ones that carefully kept records show sire offspring that gain weight the fastest.Less time the ranchers have to hold them the more profit.

 

[JackM]

I have been secretly working on a strain of brown trout that ONLY rise to duns and grow rapidly anywhere there is a hatch. I am having trouble, however, keeping them away from the emergers.

 

[FarmerDave]

jifigz wrote:
When evaluating the number and types of trout stocked throughout the Commonwealth, it is astounding the number of Rainbow Trout that are stocked in comparison to Brook and Brown Trout. Why is this? The state stocks as many Rainbows as it does Brooks and Browns combined. Are Rainbow trout easier to raise in a hatchery setting than the other two? I can understand why Brook Trout are stocked the least as their habitat requirements are a little more picky and less common in the state than those that are suitable habitats for Browns and Rainbows,

Not true. Everywhere that wild browns and rainbows exist, brown trout could also exist if not for the browns and rainbows. the same cannot be said the other way around.

The brook trout are just out-competed by the larger invasive fish and decades of stocking same.

but why not stock more Browns and less Rainbows? Given that by the large number of Class A Brown Trout streams in the state and the very few streams recognized as Class A Rainbow Trout waters, it seems that Browns are much more likely to colonize and create a self-sustaining and reproducing fishery. So why not stock Browns instead with the hopes to create a reproducing population of fish? I know that Rainbows do colonize and reproduce in a higher number of streams than they are given credit for, but Browns are still more likely to do so. Do they stock Rainbows to keep the wild Brown Trout genes separate and uncontaminated with hatchery brood? I doubt this as Browns and Rainbows are often stocked in the same waters...so I'm stumped. What is the reason?

To me, that is a good reason to NOT stock more brown trout instead of Rainbow.

The purpose of stocking is NOT to colonize, but to provide fish for people to catch and eat.

If a stream has a wild population of trout, leave it alone. Most stocked trout are stocked over some wild trout. there are tons of class B, C, and D populations that get stocked over. Many times the predominant wild species is browns trout. many times it is brook trout (as you said).

The current stocked trout are fairly far removed from most wild populations in the state and that includes all three species. It's because the stocked trout are bred for hatchery survival. Granted Hatchery raised Browns and rainbows are likely closer genetically to the wild populations than the stocked brook trout are to wild brook trout, but still fairly different.

So, if you must stock a stream that has wild trout, why not stock something that is less likely to colonize and replace them, or inadvertently skew the gene pool for lower survival rate.

Besides, rainbow trout taste better.

I hadn't read the other point of views, so if somebody already said this, I apologize. It is just another point of view.

The biggest reason is they are likely cheaper to raise.

 

[FarmerDave]

jifigz wrote:
A couple of degrees can make a huge difference, but I believe that the 3 species' temperature preferences are within a couple of degrees, not what they can tolerate. Brookies can't tolerate water much warmer than the mid sixties while Brown Trout can tolerate water approaching the 80° mark. That is a staggering difference and can make all the difference in the world. Rainbows can tolerate water just a few degrees cooler than the maximum for Brown Trout.

It actually has to do with the dissolved oxygen content more so than temperature. Brook trout require a little bit more dissolved Oxygen. Warmer water cannot hold as much dissolved Oxygen. It works out that the temperature tolerance is only a couple degrees different.

In any case, brook trout can "survive" in any "stream" where browns and rainbows survive. It may require a little bit more migration, but it is a true statement.

On the other hand, brook trout can handle considerably lower PH content than the other 2. Some strains of brook trout can actually survive for a time at PH below 4.0. Brown trout can handle down to about 5.0, and rainbows have the narrowest tolerance range down to about 5.5.

PH for reproduction is a little different, but brook trout likely have the advantage in that, too.

where they don't have the advantage is in larger streams with more optimal PH against larger species of trout that prey on them such as large limestone streams.

 

[FarmerDave]

JackM wrote:

pabrookie94 wrote:
They grow faster=less food=cheaper..

Whenever I painted for my Dad for extra money, he would always remind me that "paint is cheaper than labor." Rainbows grow quicker, but they only do this by consuming and processing food. The cost of food is the same, to grow to the same size, or closely similar, but it is spent quicker. Meanwhile, the other fixed and variable cost of raising a certain sized fish decreases.

Jack, I'm going to say that last part is likely true, but not necessarily.

It could be that some species are better at converting food to fat or body mass much better. It's true in cattle and I would assume some variation in metabolism between trout species.

I just don't know.

But time is money, so the other part is true and would probably outweigh any difference in feed conversion.

 

[Mike]

Rainbows have been the darlings of the the hatchery system for many if not all of the reasons presented above. There is, however, a chink in the armor, and that is the susceptibility to disease, which has now led to repeated shortages of RT in some hatcheries over at least the past two years. As a result, substantially more browns are being stocked in substitution for rainbows from some hatcheries. As a theoretical example a 90%RT/10%BT load now may be 50%/50%. I would expect that in some streams under cold water temp conditions of the early season this may lead to poorer catches temporarily for those used to a quick 5 fish limit on opening day. What I have observed in the past on some creel surveys is that the RT are quickly caught and anglers seem to think that the stream is fished out only to find that during the first warming trend the browns come to life and fishing gets very good again.

Thank you to JackM for the temperature chart. I don't have time to get into it fully so I will only say for now that anglers need to pay much closer attention to temperatures that fall between those that are the upper optimum and those that are the maximum (upper limit on Jack's chart). The impact of chronic temperatures in that range are cumulative, deadly, and largely overlooked in my experience by the angling public, which is generally fixated on the maximums. I don't blame this on the anglers as I don't think this info has been generally publicized, but I do know of a situation where a group has either not understood it or chosen to ignore it after having been repeatedly exposed to that info for decades.

Somewhat recent research on RT indicates that the number of 15 minute periods in a month that the fish are exposed to stream temps that are over 68 deg F determines the monthly mortality. You could have 50-70% of the stocked RT dying in a month in a given creek and never come close to the thermal maximum. Water temperature caused mortality slam-dunks the impact of fishing mortality in these situations.

 

[troutbert]

Mike, the general rule most flyfishermen have used for decades is to quit fishing when the water temps hit 70F.

Should it be lower?

At what specific water temp should C&R fishermen quit fishing?

 

[Mike]

You will note that the upper limit of the optimum range for RT from the chart that JackM provided is 64 deg while 68 deg has been used in two research papers relatively recently in which the researchers simply stated that 68 was above the optimum and preferred range. I think you would find some limited variability in the optimum range depending which studies were referenced and that would also be true for thermal maximums. I assume 68 was used because it is a temp which is definitely above the optimum and preferred ranges for all studies that the researchers referenced.

As for angling, I think 70 is a little high for C&R, but not for harvest, although browns may be a bit more tolerant than rainbows. When fishing in warm water anglers should consider what they intend to do with the fish that they catch. If successful C&R is the objective, then 70 could result in varying degrees of delayed mortality, especially if the stream is going to warm further as the day progresses. Anglers should remember that now they are adding a second stressor to the already existing temperature stressor, and that stress increases with time spent playing/handling the fish. Anglers should also ask themselves how likely it is that the stream is going to repeatedly cross the water temperature stress threshold in the rest of the week or month, as temperature stress is cumulative.

I would be much more comfortable using 68 deg as a maximum for C&R fishing for RT and BT (browns). I would certainly avoid removing caught fish from the water at 70 deg (that should be avoided as much as possible always for best survival chances) and I would suggest terminating the selfie camera antics at those temps. None of this should be taken as being official guidance, but I think anglers who have not previously been exposed to such info should consider this as new info to ponder in making personal decisions about their trout fishing.

 

[troutwilleatflies]

Mike,why would they stock browns in the Jorden creek and RT in the LL?There is next to no hold over capacity in the Jordon and 100% capacity on the LL,and also as you know there is natural reproduction on the LL!In the past the stocked fish on the LL were almost all browns.

 

[LetortAngler]

90%RT/10%BT load now may be 50%/50%
I'm not complaining 🙂

 

[Mike]

Jordan has only a minor wild brown trout population in one extremely short stretch in Allentown. The Little Lehigh has substantial wild brown trout populations in a few sections. Those sections that are Class A, like the other Class A sections on other streams that were recently approved, are being stocked with 100% RT, which will provide the least competition for the wild browns and which will be harvested fairly quickly.