Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Natural life expectancy of LMB

What is the experience of forum PBs on life of LMB?

I have a quarter acre pond, stocked with 20 LMB females - as sexed by supplier. They were one year old at stocking this spring.

I'm supplementing with high-protein feed, good aeration system, with plenty of natural forage, so I was just wondering about how long LMB live if everything goes ok...

I'm not sure how similar your climate is to mine, but we commonly see LMB live to eight years, and probably have some individuals that make 10-12.

From Fishbase " max. reported age: 23 years " . TPW did a study on LMB that followed some through 16 years. I will have to check to see if any lived that long but IIRC some lived 10 years. As a general rule LMB live longer and grow slower the farther north you go within their normal geographic range .


I checked the TPW study and they did have LMB live to 16.

I've heard of tournaments in Minnesota where black bass were aged at 20+ years, but I've never sampled any here older than 12. I'll bet it mostly depends on average water temperature, and how many stresses the fish has to withstand on a regular basis, such as low oxygen, starvation, extremely hot water, etc.

NE Mason - Since you live in NH, expect at least some of your northern female bass to live 15-20 yrs. However, expect some to die before the 15 yr mark similar to other animals in various populations including humans. Not everyone lives the full life expectancy for various reasons. It all depends.

It will be very interesting to watch these female bass grow over the next 10 yrs. Please keep good notes for us and occassionally report to us about how they are doing as far as growth rate (fastest and slowest), body condition Rw, tendency to become hook smart, deaths, etc. If your bass are fed pellets their growth may slow down quite a bit when they reach 3-4 lbs. You have the ability to give us some good information about LMB. We will also see how well or accurately the hatchery was able to sex your fish. I assume the females are the only bass in the pond. It won't take very long to find out about the sexing accuracy.

Just a pet theory of mine, but expect the life expectancy to be slightly shorter for every time the fish is caught. Even good quick releases are probably somewhat stressful, depending on how warm the water was, and how much the fish was handled.

Excellent information. Thanks, Bruce, Ewest, Bill C, for your time & effort in support of this forum.

I've had little prior experience with LMB, but am now finding them a delight for a small pond experience. Put them in at 8 inches, and they are now aggressively attacking the larger shiners that nibble on surface pellets. There is a horizontal 'pursuit' on the surface that is quite a different attack pattern than that of trout. I joke with my friends that it is the first time I've openly rooted for the bully, the attacker, the dominator. "Go, crush/eat/devour on them defenseless little shiners..." Like rooting for the Lion instead of the Gazelle.

Yes, Bill C, they are the only bass in the pond. I am also interested in whether the sexing was accurate... As you suggest, I will report back on growth and any unexpected reproduction. The pond sides are steep and rock-lined to 9 feet except for one wading/beach area of about 2-3 feet in depth. So I would expect to see nests if there are males?

Bill C, can you explain why growth should slow at 3-4 lbs on pellet feed? I don't doubt your expertise, but would like to know why natural forage would induce a different growth pattern than that of pellets (I assume this point). Maybe I can develop sufficient natural forage base.

NE - Now that you tell us that the "female" LMB were stocked at 8" long, I have major doubts that you did not get at least one male in the 20 bass that you purchased. LMB at 8" long are in my opinion VERY difficult to accurately sex. I have high regard for the hatchery man if he was 100% accurate in his selection of those 20 female LMB at just 8" long. Time will tell the rest of this story. If he accurately sexed all your bass at 8" long, I would really like to have his name.

I predict that the LMB will top out at 3-4 lbs in your 1/4 acre pond based on several things. This is especially true if all 20 or even 18 bass live past 3-4 yrs.

1. If they are eating primarily high protein pellets, then this is often the size or weight where traditionally the LMB will seem to hit a growth plateau. If you can get the bass to feed on the NEW large Aquamax bass pellet when the bass get 3-4 lbs, then you might be able to get them beyond the 4 pound mark. More experience of feeding LMB this large pellet will provide more results about growing bass larger than 4 lbs on pellets.

2. Your pond is only 1/4 acre. Ponds typically support around 50 lbs and at the high range 100 lbs of bass per acre. Extrapolating - 20 LMB at 5 lbs is 100 lbs and this equates to 400 lbs of bass per acre. If you can maintain 20, 5 lb+ healthy, plump bass in a 1/4 acre pond, then please educate us as to how it is being done. We want to know. To to achieve this amount of trophy bass biomass in 1/4 acre for any length of time (2-4yrs) you are defying the laws of nature. Try it and keep us informed about your results. It could be possible if done very correctly.

3. When bass hit the 3-4-5 lbs mark they need a progressively different type and size class of food items. See Bob Lusk's book Raising Trophy Bass. I doubt that you can provide this type of quality and quantity of food items for 20 big bass in a 1/4 acre pond. Doing this will test your education, creativity, and resources. Doing it for 1 to 4 trophy bass in 1/4 acre is one thing, but doing it for 20 big trophy bass in 1/4 acre is another thing altogether.

I am not saying that you cannot do it, but I am saying it will be very difficult to achive your ultimate goal and do it consistantly for the long term over the life span of all 16-20 bass.

As I see it, your first major hurdle is to NOT have a bass spawn in 2008. That alone is very good success based on what you have done so far.
Keep us informed of your progress, We are very interested.
Good luck. Over the long term you will need at least a little luck.

Bill C - excellent elucidation.

I'm smiling as I (a greenie PBer) read your tactful observations about sexing accuracy, biomass, and laws of nature.

BTW for me, 20 LMB at even three pounds would be terrific. I'm mostly just curious about what was limiting growth. I may not even get them to three pounds, given that there also are/were about 70 trout. Although I don't know how many of my fish survive predation.

One last note. The feed I'm providing is silver cup high-protein Trout feed. The latest generation of which even provides the supplements by which the trout flesh is rosy colored like in wild populations. Don't know how that compares to Aquamax pellets.

My expectations are now more modest. I also understand the interest in record-keeping and reporting back results.

Thanks very much again.

NE - If you as a novice can raise in a 1/4 acre pond in NH, 16-20 female LMB to sizes of 2.5-3 lbs you are doing real good. This amounts to 160-240 lbs of bass per acre and it is very good by average standards. At 4 lbs each, it becomes 256 lbs/ac for 16 bass. As I see it your second biggest problem will be trying to keep them from getting hook smart by the time they reach 3-4 lbs. They could easily be hook smart to the point you will not be able to readily catch them by "normal" angling i.e. articicial lures. If you are not aware of the concept of hook smart fish do a search here using the words - hook smart.

Silver cup is a very good higher protein food for your LMB. Supposedly the extra high fat content (16%) of Silver Cup Trout feed can be harmful to some fish such as LMB, in that it produces too much fat and cholesterol in some of their organs. This may shorten their life span?.?.? Your record keeping and reporting will provide us some good information about this topic. Unless things are different in NH, I think that the 1/4 pellet will be the largest pellet that you can easily obtain for your bass/trout. As the bass grow to 15"-16" it would be advantagous to feed them a larger pellet (3/8"); not necessary but beneficial. The philosophy of the larger sized pellet is the fish expends less energy getting its food thus it puts on more weight per amount of expended effort. More weight gain usually means increased growth rate. Trout can be raised to quite large sizes on 1/4 pellets, so your bass may be able to grow past the 3-4 lb mark on the trout pellets. Another way to get your bass to grow beyond the 4 lb mark would be to regularly (spring and fall) feed them 8"-10" trout. Very do-able in the northeast, but maybe not practical for you.

Cecil Baird has for several years been regularly feeding pellets to LMB to produce bigger bass. He may be able to suppliment this information.

NEMASON,

If you're raising your bass in with your trout I can only assume your water temp is below optimum for largemouth bass for the trout to make it though the summer. Sounds to me like your bass may not grow especially fast in those water temps. At the same time slower growth will probably increase their lifespan. I have grown out largemouths to 3 or 4 pounds in 4 years but they seem to peak out at that size and some even show signs of senility with cataracts etc.

As far as the max amount of largemouth you can grow in a pond I have raised feed trained largemouths at 2000 lbs. per acre with no problems. But they were on pellets. I also had a good circulation of the pond with up to four diffusers (.62 acre pond).

Cecil brings up a good point about optimum water for LMB growth even for northern LMB that have been stocked into a pond capable of sustaining trout for 10-11-12 months of the year.

I think LMB grow best at water temps between mid 70's and low 80's. LMB will no doubt continue to eat at water temps even in the low 90's, although Mr. Mason will not get these temps. His highest water temps will probably be an occassional 76F-78F and most commonly the low 70's during July and August. The growing season for LMB at his location will be relatively short, thus growth of his LMB will be slow as Cecil mentions. NEM should consider his efforts quite good if, after the bass reach 14", he can get 1" of growth per year. Growth of his LMB in cool water habitat is more likely to be around 1/2" per yr.

See if this helps wrt LMB growth. I can get the temps if needed. I do think there is some difference in growth ranges based on genetics and adaptation north to south even in northern strain LMB. I know there is a big difference if Fla LMB are involved.

Eric - How do the growth values translate into length? Water temperatures are important and very relative to the data you present.

I will check. I posted the chart to show growth rate and time of year/temps generally. Note the difference between male and female.

Bits and pieces.

Growth
and energy storage commenced in both sexes
in early spring when water temperature rose
above 10 C and largemouth bass increased their
feeding rate.

When surface temperatures are
greater than 27 C (late July-mid-September),
largemouth bass seek their preferred temperature
of 25-27 C (Coutant 1975), which usually
is available in Watts Bar Reservoir during the
summer.

some
food consumption throughout the winter has
to be assumed at reservoir temperatures of 6-
10 C, even though the literature indicates that
largemouth bass generally do not feed at temperatures
below 10 C ...