WLF commission meeting

[MathGeek]

The weir management plan is reasonable and based on sound science. Since they took over management of the weirs in 2012, CPRA has done a very good job managing the weirs according to the management plan. CPRA has been kind enough to share detailed weir opening data with us that has allowed us to compute correlations between the condition of finfish in the lake (specks, redfish, drum, and gafftops) with the weir openings.

The most consistent and strongest correlations between our data on fish condition and any environmental factor we've considered are the NEGATIVE correlations between weir openings and fish condition. In other words, the more the weirs are opened, the thinner the fish are. The attached graph completely disproves the hypothesis that weir closures somehow negatively impact fish condition. The asterisks denote statistical significance at the p < 0.05 level.

Our working hypothesis to explain the NEGATIVE correlations between weir openings and fish condition is based on an analogy with rotating pastures to maximize the forage available for cattle. If the gates between pastures are open all the time, cattle graze all the pastures continuously which results in less production than limiting the pastures that can be grazed and opening the gates occasionally. As applied to the weirs, the idea is that the marsh behind the weirs produces more forage if more separation is allowed to reduce feeding pressure from the finfish until the crop of forage has achieved a larger biomass.

In any event, there is no scientific basis to complain about CPRA's management of the weirs. The biggest issue relating to Big Lake that is within regulatory control is the overharvesting of oysters.

[Duck Butter]

Originally Posted by MathGeek

The most consistent and strongest correlations between our data on fish condition and any environmental factor we've considered are the NEGATIVE correlations between weir openings and fish condition. In other words, the more the weirs are opened, the thinner the fish are..

This makes zero sense. You can't sit at calcasieu point and do a creel survey from fishermen and assume that all fish are affected by the weirs Those "thin" fish may have been caught miles away from the weirs at black lake or prien lake. They may have not even swam within miles of the weirs.

Overanalyzing it

[MathGeek]

Originally Posted by Duck Butter

This makes zero sense. You can't sit at calcasieu point and do a creel survey from fishermen and assume that all fish are affected by the weirs Those "thin" fish may have been caught miles away from the weirs at black lake or prien lake. They may have not even swam within miles of the weirs.

Overanalyzing it

The average body condition of fish in the lake is most probably impacted by the total forage availability in the lake. Fish and forage both move throughout the system in any 90 day span that most strongly impacts the body condition. Further, our study samples fish from multiple locations and includes as many or more fish from the southern end of the estuary as from the northern end, so it either ignorant or dishonest (or both) to characterize our creel surveys as limited to Calcasieu Point. However, as expected, the fish condition does not depend on where in the estuary they are sampled from.

Does increased oil production in the mid-east impact oil prices and availability in the US? Sure it does.

[Duck Butter]

Originally Posted by MathGeek

The average body condition of fish in the lake is most probably impacted by the total forage availability in the lake. Fish and forage both move throughout the system in any 90 day span that most strongly impacts the body condition. Further, our study samples fish from multiple locations and includes as many or more fish from the southern end of the estuary as from the northern end, so it either ignorant or dishonest (or both) to characterize our creel surveys as limited to Calcasieu Point. However, as expected, the fish condition does not depend on where in the estuary they are sampled from.

Does increased oil production in the mid-east impact oil prices and availability in the US? Sure it does.

Get out of statistics and numbers mode and go into common sense mode. I have never fished the weirs but I would bet that the majority of fish that are caught there are fat. That's why they are there to fatten up on the abundance of baitfish.


In what way possible would weirs being open (which provides an abundance of forage) cause fish to be thinner?

[Smalls]

Originally Posted by biggun

Guys.. If U can NOT make it?? Not a problem... Every commission member has a contact email.. U can email everyone of them ur thoughts and opinions.. Just go to WL&F home page.

EVERY OPINION COUNTS. Get INVOLVED....

Don't know that I agree there. Plenty of people e-mailed their thoughts and opinions to the commission, and plenty more spoke out through the surveys. Yet, a vocal minority that showed up at the meeting was able to sway the commissioners to change the season dates proposed by Mr. Reynolds.

Originally Posted by Duck Butter

This makes zero sense. You can't sit at calcasieu point and do a creel survey from fishermen and assume that all fish are affected by the weirs. Those "thin" fish may have been caught miles away from the weirs at black lake or prien lake. They may have not even swam within miles of the weirs.

Overanalyzing it

Sure you can. People here do it all the time.

So, the marsh can be the lifeblood of the estuary, but it can't affect fish all over the estuary? Isn't the marsh a foundation of the estuary? A nursery ground for the nekton that live in the entire estuary?

Come on, DB. You want to call MG out for not using common sense. Well, you need to do it yourself. Go read up on estuary ecology again. Pretty sure there is a good read on this website somewhere that talks about the trout move throughout the estuary.

[Duck Butter]

Originally Posted by Smalls

Don't know that I agree there. Plenty of people e-mailed their thoughts and opinions to the commission, and plenty more spoke out through the surveys. Yet, a vocal minority that showed up at the meeting was able to sway the commissioners to change the season dates proposed by Mr. Reynolds.



Sure you can. People here do it all the time.

So, the marsh can be the lifeblood of the estuary, but it can't affect fish all over the estuary? Isn't the marsh a foundation of the estuary? A nursery ground for the nekton that live in the entire estuary?

Come on, DB. You want to call MG out for not using common sense. Well, you need to do it yourself. Go read up on estuary ecology again. Pretty sure there is a good read on this website somewhere that talks about the trout move throughout the estuary.

On what planet does it make sense that a weir being open ("lifeblood of the estuary") make fish skinnier? It deoesnt. I would bet the fish that are caught at the weirs are significantly fatter than fish caught elsewhere in the estuary Those weirs affect one very small portion of the entire estuary that is Big Lake. There is a large portion of marsh on the west side as well

[Smalls]

Originally Posted by Duck Butter

On what planet does it make sense that a weir being open ("lifeblood of the estuary") make fish skinnier? It deoesnt. I would bet the fish that are caught at the weirs are significantly fatter than fish caught elsewhere in the estuary Those weirs affect one very small portion of the entire estuary that is Big Lake. There is a large portion of marsh on the west side as well

That is not the point I was making, try to keep up. You said:

"Those "thin" fish may have been caught miles away from the weirs at black lake or prien lake. They may have not even swam within miles of the weirs."

I'm not arguing whether the weirs make the fish skinnier or not. Hell, there is only one person in this thread that has anything to back up that argument, so you argue that until you are blue in the face and it won't make a difference. No data equals no foundation.


So do you believe that the west side of the lake affects a majority of the lake, considering the east marsh only affects "one very small portion of the entire estuary that is Big Lake"? What is your basis? That whole marsh on the west side is not feeding into Calcasieu Lake, mind you, considering Sabine Lake is to the west.

For what its worth, I will agree with you on the effect of the weirs on the entire lake. You are doing a fantastic job of arguing a point I've long made here--that those weirs don't have near the effect on the lake as some on this forum would lead people to believe. Hell, even the negative correlation in MG's study does that. I could look at that opposite of the way you are. To me it says those weirs being open doesn't do a damn thing for the fish.

[redchaserron]

Originally Posted by MathGeek

The weir management plan is reasonable and based on sound science. Since they took over management of the weirs in 2012, CPRA has done a very good job managing the weirs according to the management plan. CPRA has been kind enough to share detailed weir opening data with us that has allowed us to compute correlations between the condition of finfish in the lake (specks, redfish, drum, and gafftops) with the weir openings.

The most consistent and strongest correlations between our data on fish condition and any environmental factor we've considered are the NEGATIVE correlations between weir openings and fish condition. In other words, the more the weirs are opened, the thinner the fish are. The attached graph completely disproves the hypothesis that weir closures somehow negatively impact fish condition. The asterisks denote statistical significance at the p < 0.05 level.

Our working hypothesis to explain the NEGATIVE correlations between weir openings and fish condition is based on an analogy with rotating pastures to maximize the forage available for cattle. If the gates between pastures are open all the time, cattle graze all the pastures continuously which results in less production than limiting the pastures that can be grazed and opening the gates occasionally. As applied to the weirs, the idea is that the marsh behind the weirs produces more forage if more separation is allowed to reduce feeding pressure from the finfish until the crop of forage has achieved a larger biomass.

In any event, there is no scientific basis to complain about CPRA's management of the weirs. The biggest issue relating to Big Lake that is within regulatory control is the overharvesting of oysters.

MG,

Thanks for posting the information from your study. Is it possible, and has consideration been given to the idea that the difference in condition of the fish during open and closed periods may be due to a change in WHAT they are feeding on? If for example open weirs provided easy pickings on shrimp so the fish avail themselve of it, but when the weirs are closed they feed more on menhaden and finfish, it could be a matter of the fish being thinner when the weirs are open becasue they are taking advantage of easy prey that is lower in nutrients verses eating more nutrient dense food.

[MathGeek]

Originally Posted by redchaserron

MG,

Thanks for posting the information from your study. Is it possible, and has consideration been given to the idea that the difference in condition of the fish during open and closed periods may be due to a change in WHAT they are feeding on? If for example open weirs provided easy pickings on shrimp so the fish avail themselve of it, but when the weirs are closed they feed more on menhaden and finfish, it could be a matter of the fish being thinner when the weirs are open becasue they are taking advantage of easy prey that is lower in nutrients verses eating more nutrient dense food.

That could be. But note that our correlations are not between fish condition and whether the weirs were open the day a fish was caught, but rather our correlations are between fish condition and the average weir openings over the 90 day period immediately before each fish was caught.

But thanks for the idea, we need to give more consideration to whether weir closures forces the fish to feed on more nutritional forage.

[redchaserron]

Originally Posted by MathGeek

That could be. But note that our correlations are not between fish condition and whether the weirs were open the day a fish was caught, but rather our correlations are between fish condition and the average weir openings over the 90 day period immediately before each fish was caught.

But thanks for the idea, we need to give more consideration to whether weir closures forces the fish to feed on more nutritional forage.

[QUOTE=MathGeek;780718]That could be. But note that our correlations

How much influence do you think the seasonality of the opening/closing of the weirs have to do with it. For example, the weirs are more likely to be closed in July - August than in April/May. Obviously there are some seasons where fish will weigh more or less Did you compare same season openings/closures?

[MathGeek]

[quote=redchaserron;780724]

Originally Posted by MathGeek

How much influence do you think the seasonality of the opening/closing of the weirs have to do with it. For example, the weirs are more likely to be closed in July - August than in April/May. Obviously there are some seasons where fish will weigh more or less Did you compare same season openings/closures?

All of our studies are in the same period each year (late May/early June). Seasonality can affect fish body weight, but we are comparing with the long term Louisiana average weights from the same time of year for each species.

The weir openings are more governed by salinity than season. For example, the average 30 day weir openings over our study period (same time each year) has varied from a low of the weirs only being open 15% of their maximum possible to a high of about 70%.

Weir openings and closures in July-Aug do not impact our study at all, because all our fish are measured in late May/early June and we only consider the weir openings in 30, 60, and 90 day windows before each fish was weighed and measured.

[redchaserron]

[quote=MathGeek;780737]

Originally Posted by redchaserron

All of our studies are in the same period each year (late May/early June). Seasonality can affect fish body weight, but we are comparing with the long term Louisiana average weights from the same time of year for each species.

The weir openings are more governed by salinity than season. For example, the average 30 day weir openings over our study period (same time each year) has varied from a low of the weirs only being open 15% of their maximum possible to a high of about 70%.

Weir openings and closures in July-Aug do not impact our study at all, because all our fish are measured in late May/early June and we only consider the weir openings in 30, 60, and 90 day windows before each fish was weighed and measured.

Ah, I see now, I thought it was an "all year" study. My saying the weirs are more likely to be open in spring than August July, is simply an observation that we tend to get a lot more rain/lower salinity in spring than mid/late summer.