Pond Boss Forums INTRO Questions & Observations Maybe RW is a poor indicator of LMB sex?

Well, I "used to think" that female LMB tend to have higher RW than male LMB.

This chart was derived from data supplied by this 17 year study of LMB sibling growth.

ls there some "spawning correction" in a survey like that?

Immediately pre-spawn, lady LMB should be at their highest RW. Shortly after the spawn they have ejected a significant portion of their weight, and "wasted" a lot of energy to create those eggs rather than sustainable body mass. Changing the sampling date by only a few weeks would give widely variant results.

Also, the biggest difference on the chart appears to be right near the end of life. Perhaps old females are more physically handicapped to hunt than males at the end of life, or have some biochemical senescence that makes it more difficult for them sustain body weight.

OTOH, perhaps just a few fat males survive past age 15? The steepness of the final slope for males might be partly due to a very small sample size.

Good questions FishingRod.

Those are all Fall metrics. There are no Spring pre-spawn metrics in their report.

Good observation on the early going being essentially equal. RW was a coin flip as an indicator of sex during the first 5 years (really throughout the study there is no statistical support of RW as an indicator of sex). The reason for the divergence of males late in the study deals with the benefit of being smaller than females. IOWs it takes less forage for a smaller male to put on excess weight (weight above 100 RW) than it does a larger female.


I don't think this is necessarily true. For the RW to be higher, the lady LMB must gain weight and this means she must consume enough forage to support her current fall weight and additional to forage for gain. There will be, of course, cases where this takes place but there will also be cases where she is only maintained or even cases where she loses weight through that period. It depends soley on how much she consumes. She may gain length which would be a headwind against RW. In any of the above cases she will grow eggs and the eggs in the spring will be a greater proportion of her body weight than they were in the Fall. In cases where she doesn't gain weight, there will be a transformation of muscle and fat into egg mass. So the pre-spawn ladies have more distended bellies but not necessarily higher RW.

But for sake of discussion. Let's consider the cases where female LMB are of higher RW prior to spawning. In these cases we know the females consumed a surplus of forage over maintenance. But if this is true and conditions prevail that support additional weight gain from Fall to Spawn, wouldn't the conditions also help male LMB gain and improve their RW? Should we presume that it is easier for Females to gain RW than males? For example, is the larger proportionate mass of eggs less energy dense than the male's smaller (by proportion) mass of male gametes? It is really hard to argue that males are at a disadvantage for over winter increase of RW. There is no spring data in their report so it is an unknown for their study.

So one thing I had always previously thought. "Males and Females may have separate Standard Weight Functions". But this seems to be completely debunked by their data. For the first five years there was little difference of RW between the sexes using the same standard weight function. It seems hardly worth the effort to model different standard weight functions for each sex.

jpsdad has determined all of this from extensive studies on LMB in his pond(s).

Right?

That Year 1-5 is very interesting to me.

First off is the steady decline from a high RW to a sub 100RW at year 1.
Continued, but lower RW into year 2.
Back to 100 RW for year 3
Back to below RW for year 4
Then at year 5 above RW that they maintain for the rest of the study at varrying RW's.

Is this due to lack something early in the way of forage?
I guess I would have assumed that if all LMB went through this that RW for year 1 would be more similar and dropped below 100.

Haven't read the study yet, but will this evening when I get a little quite time around here. Thanks for posting.

Who here has extensively studied an LMB population where the RW of the entirety of the population of positively identified sexes can be determined over their lifespans? Anyone? If so, please reach out to me by PM because I would LOVE to see your data. I use to dream of this place as being a great source of good data.

Not sure what Theo is trying to say but it seems to be this. Do not trust facts but rather rely on impressions that people have from their personal experience of pond ownership. Don't trust the facts if sourced to a scientific paper. To be sure, I rarely start a thread that doesn't challenge conventional thoughts. Theo is always there to shoot the messenger. Sometimes people I guess don't want factual information when they disagree with it.

The primary reason that I post this is help you all. I get nothing out of it but crap from Theo and occasionally some great conversation and a new friendship. Anyways if one is going to try to sex his LMB as he culls it may behoove him to use a more reliable method of sexing LMB.

Yes, Boondoggle. Good take away. The bass in this study did not grow at maximum potential due to forage limitations. RW wasn't constant either. So in years it improves, these are years where the weight gain is best. Mortality is highest also in years with the steepest declines of RW. The density of LMB was in most years too high for sufficient in-situ production of forage. Forage was supplemented.

Bump. Just wanted to add that the data isn't real time. It was taken once a year in autumn. It is a snap shot of average values of the population at those sampling times.

jpsdad - what method did the study participants use to determine male vs female? That technique may be useful to pond owners.

I love it! A little back and forth on pond boss forum! Livens it up a little bit !

Disclaimer............... I have no clue what you guys are talking about - I just like the banter

Bill,

I am confident that the methods were not the field techniques that I have referenced here but by the laboratory technique of observing gametes by catheterization. They are fisheries biologists and I don't think they would leave that aspect to chance. I could be wrong about that but I just don't see them eyeballing the fish and slapping a sex ID on them. The fish were PIT tagged in 1988 but were not sexed until 1991. But since they were PIT tagged in 1988 I have confidence in their Male-Female data from 1988 onward is reliable.

They did provide data for individual fish from before they were PIT tagged. But clearly this earlier data is averaged and I suspect they did apply some type of assumption assign individual fish to a sex group. They noted that the data was bimodal and I think it is likely that they used a statistical approach to allocate individual measurements to sex groups. Males grow slower and so the lower mode was probably considered to be consistent with males. To be sure, the data remained bimodal after PIT tagging and sex ID. As it turns out the males are associated with the mode with lower values of length and weight .... so it wouldn't be a bad approach when attributing weight and lengths to male and females before the PIT tagging in 1988 (age 3.5 years).

This data among others has helped me to build what I think is good model for average RW for females at various annual weight increments. Males are more problematic because I don't have good data on maximum weight increments for males and the RWs associated with those annual gains. Further I don't know maximum observed limits of male RW or male weight increment. For females, 2.2 lbs gain per year and RW 180 are practical limits. For females, can only explain less than 50% of the variation of RW from weight increment. All of the remaining variation is apparently explained by variation of length among the fish making the same weight increment. For example the regression estimates a RW for a weight increment but there will be distribution of RW for that weight increment where some individuals will have higher RW (shorter fish) and some will have lower RW (longer fish). High annual weight gains push annual length increment and RW to their limits.

One of the things I have learned is that females do not have to grow really fast to maintain 100 RW. Females growing around 1/2 lb annually will average a little higher than 100 RW (my model estimates 102). Those with higher RW are shorter than peers of the same weight ... those with lower RW are longer than peers of the same weight. Males require less weight increment to maintain 100 RW. I know this from the study above where males having an average weight increment of 0.3 lbs per annum were consistently above 100 RW. They just make smaller length increments and I think that is why they are able to maintain higher RW than females on a smaller weight increment.

jpsdad wrote: "Not sure what Theo is trying to say but it seems to be this. Do not trust facts but rather rely on impressions that people have from their personal experience of pond ownership. Don't trust the facts if sourced to a scientific paper. To be sure, I rarely start a thread that doesn't challenge conventional thoughts. Theo is always there to shoot the messenger. Sometimes people I guess don't want factual information when they disagree with it."

Unfortunately, this is not accurate. Those with long years of active pond ownership don't have 'impressions.' They have actual experience. The only thing that is certain in ponds is that no two bodies of water are the same. As such, it's laughable to state anything as 'facts' when it comes to pond management, especially when dispensing advice. Scientific studies are valuable as reference points, or loose guidelines, but are based on sets of assumptions that simply do not fully convey to any other bodies of water (location, climate, vegetation, depth, water source & chemistry, aeration or lack thereof, benign and non-benign tampering by other humans as well as wildlife, etc.)

Personally, after close to (3) decades of pond ownership and management over several bodies of water, I am constantly and consistently surprised, and guided, by hands-on observations of my own pond(s) as well as observations and experiences of other pond owners and professionals.

Also, there have been a few developments in Pond Management since the days of Homer Swingle.

Looked like there was some growth rate data in there for year one that I also found helpful in trying to set up brackets for fish in my personal BoW. Granted it's a different region, different species with pure FL but RW's and lengths between the FL, Northern and F1's bear no separation in any of the charts I've seen. Found it helpful to see a bracket of slow and fast growers as I estimate future growth to be used in milestone data.

There was nothing in the study you found useful, or reinforcing of current knowledge?

While regurgitating data that is found in reference books and other sources is fine, (people should always cite their source material. If not, other people that read the data will think that it was generated by the person that posted the information - I see this in FB posts more than I see it here.) there is absolutely no substitution for real world, personal hands on data and in multiple ponds over multiple locations and climates. What is seen on a daily basis cannot be transmitted to digital or paper pages in a way that gives a person "hands on knowledge". This doesn't just apply to ponds, it applies to other things in life too.

Just like a book smart mechanical engineer telling me that a vertical down weld isn't as strong as a vertical up weld. O.K., that may be true, but in this particular application where FMVSS testing was being performed and the attachment point had to withstand a 60,000psi pull. I got up, went to hand him the welder and helmet and asked him to show me how it was done. His reply? "I have never welded before." O.K., then don't tell me how to do my job if you have only had book learning or minimal hands on experience. Maybe the vertical down weld was ultimately weaker, but it was still more than strong enough. Book learning in my experience is NOT a substitute for real world, hands on experience.

FWIW, the weld and the test passed with flying colors.

Female fish are supposed to be larger than male fish, right? Everybody "knows" that. O.K., then why was a "female" 14" YP that I pulled from my pond to eat this Spring post spawn filled with milt? Because it wasn't a female, that's why.

Like Sunil said " The only thing that is certain in ponds is that no two bodies of water are the same. As such, it's laughable to state anything as 'facts' when it comes to pond management, especially when dispensing advice. Scientific studies are valuable as reference points, or loose guidelines, but are based on sets of assumptions that simply do not fully convey to any other bodies of water (location, climate, vegetation, depth, water source & chemistry, aeration or lack thereof, benign and non-benign tampering by other humans as well as wildlife, etc.) "

Two ponds, not 10 feet apart, that are the same depth, filled with the same water, dug in the same soil, can be two completely different BOW's. That has been proven to me and even with a water test, I cannot determine why the two ponds are so different water quality wise.

On the Male vs Female topic and RW.
In the last 2 weeks, on 2 separate occasions, we have caught 2 LMB within 15 minutes of each other.
The body shape and size was almost identical. You couldn't tell them apart other than one was a little darker or more olive looking in color.
Sample A was 13" and 1.43# (darker and more colorful)
Sample B was 13" and 1.08# before even weighing this one just felt empty but was thick and fat.

A week later something very similar happened. One heavy fish, one light fish but their body composition was very similar

Any idea why or how this could be ?

I could understand if one was long and lean and the other was short and fat but this was not the case

Bass are basically hunters for their meals.

Whoever is the "better" hunter will get more food.

Any chance you caught the heavier fish first on both occasions? Being the most aggressive is only a benefit when you are at the top of the food chain. However, once humans are fishing in a pond, the bass are no longer at the top - so now aggression does have a penalty.

I totally understand what you are saying

I guess my question was , How can 2 fish have the same body composition (look the same) and be the same length but weigh so much different ?
Also I caught the lighter fish first last night, Do not remember which one was first on the previous occasion

Jason, because fish are neutral buoyancy with water, I think the heavier fish of the same length displaced more water. It's volume was larger. So try this. Going forward ... in addition to the length measurement ... also take a girth measurement. Do this at the same relative location and see if this can explain the difference in weight. The fish with the greatest girth should be the heavier fish.

Sorry Jason, I did not understand your question correctly.

I didn't realize you meant the fish looked EXACTLY the same, but weighed different amounts.

I suspect if you held them up side-by-side you would have noticed the difference. jpsdad's advice to take an actual girth measurement should give you a definitive answer.

So is this a RW chart you made from the raw data in the study. I did not see this chart or a discussion of RW. The study through out states caveats about the sample size and changing conditions and other reservations and was intended to compare fast growing vs slow growing LMB over long time periods.

FWIW standard RW includes whole populations not males vs females. Under the same conditions I would expect RW by design would be similar for both as it is an average of all populations.

Indeed I know the standard weight tables include both sexes. But for quite some I was influenced by others who suggested that males would tend to be of lower RW. The arguments on the face seem plausible, cull skinny males but this study is the only data available to me with both sexes documented. The RW findings were not what I expected and not what I have been taught here and everywhere else for that matter and I thought I should share this with the community. Obviously not appreciated but the intent to share the information was genuine.