Redfish and Specks Benefit from Limited Weir Closings

[MathGeek]

Originally Posted by dmtfish

Which is why I believe the oyster dredging has more of a detrimental effect on the health and quality of the lake than wier management.

I believe the data. Fish condition correlates positively with oyster stock assessments for benthic feeding fish. Fish condition correlates negatively with weir openings.

We were certainly open to the idea of the weirs being the dominant effect on fish condition in the lake, which is why we did so much work acquiring and analyzing the weir data.

Other than the effects of oyster reefs on fish condition, most of what we are seeing relates fish condition negatively to factors that increase metabolic costs (salinity, temperature, etc.) rather than positively to factors that increase food supply. Slowing down currents and providing fish places to rest out of the current may be a more important factor for increasing fish condition than increasing the food supply. We may not need to feed them more so much as work them less.

[BuckingFastard]

Originally Posted by "W"

Weirs should never be closed 4 days before full moon and 4 days after
Same with new moon

So they should be open at least 16 days a month at bare minimum...

The should also operate on tide changes of the marsh if salty with low water and readings are higher in marsh than in lake like last year , you need fill it back with lower salinity water even if it's over the 5ppt or what ever it is


They do it all for duck grass

bounce da hen 2030 will not exist!! cant wait!!

[BassYakR]

I havent fished the lake for near as long as some ppl on here. But from i think their are many many factors that effect the fish. IMO one of the biggest factors is Pressure/ IE boat traffic! SOOO much easier to find fish on a monday than a saturday..... ppl dont realize how many fish they run over on the way to the "hot" spot...

[Smalls]

Originally Posted by "W"

I have my own science !! It's called years and years of fishing this lake and when the weirs are closed for a long period of time , it effects the lake !

It effects everything , the natural flow of water , shrimp migration etc

If I'm reading MG's statements correctly, then you obviously aren't. He clearly states that when the weirs are between 40-80% open over a particular period of time there is a NEGATIVE correlation between body condition and weir openings.

This clearly contradicts your hypothesis.

MG, feel free to correct me if I'm reading that wrong, but I definitely see a chart that shows at 80%, the Condition is below 100, whereas around 40%, the Condition is above 100.

["W"]

Originally Posted by Smalls

If I'm reading MG's statements correctly, then you obviously aren't. He clearly states that when the weirs are between 40-80% open over a particular period of time there is a NEGATIVE correlation between body condition and weir openings.

This clearly contradicts your hypothesis.

MG, feel free to correct me if I'm reading that wrong, but I definitely see a chart that shows at 80%, the Condition is below 100, whereas around 40%, the Condition is above 100.

1st off let me make this statement

Trout weight diffrent every month ... So you can not go by body weight or fatness

Here is why , when fish are schooling and gorging on shrimp and pogy they burn as much as they eat !! Have you ever followed a school of fish ? They can move over 12 Miles a day !!

Colder month fish are not as mobile and eat slower and bigger meals and do not burn the enegry

Also fish sitting closer to the weirs over a givin time will likely be fatter depending on there movement compared to a trou up north ?


So saying fish are fatter or better health with weirs open or closed is not telling me anything

Unless you sit and catch every fish at weir !!


Trout move miles everyday

I can show you this summer when I caught 45 trout all soild 2-4lb trout and next day 45 dinks non over 3lbs on same spot same tide ?

[T-TOP]

Originally Posted by "W"

1st off let me make this statement

Trout weight diffrent every month ... So you can not go by body weight or fatness

Here is why , when fish are schooling and gorging on shrimp and pogy they burn as much as they eat !! Have you ever followed a school of fish ? They can move over 12 Miles a day !!

Colder month fish are not as mobile and eat slower and bigger meals and do not burn the enegry

Also fish sitting closer to the weirs over a givin time will likely be fatter depending on there movement compared to a trou up north ?


So saying fish are fatter or better health with weirs open or closed is not telling me anything

Unless you sit and catch every fish at weir !!


Trout move miles everyday

I can show you this summer when I caught 45 trout all soild 2-4lb trout and next day 45 dinks non over 3lbs on same spot same tide ?

The numbers are from 3 week periods of may-june over a 4 yr time frame.

["W"]

Originally Posted by T-TOP

The numbers are from 3 week periods of may-june over a 4 yr time frame.

Exacty you can not tell the health of the estuary with that data


Now don't get me wrong MG you are an asset to this fisheries I wish they would find you to do all our research

[MathGeek]

Originally Posted by Smalls

If I'm reading MG's statements correctly, then you obviously aren't. He clearly states that when the weirs are between 40-80% open over a particular period of time there is a NEGATIVE correlation between body condition and weir openings.

This clearly contradicts your hypothesis.

MG, feel free to correct me if I'm reading that wrong, but I definitely see a chart that shows at 80%, the Condition is below 100, whereas around 40%, the Condition is above 100.

That's right. One should be careful not to extrapolate the line below 40% where there is no available data. Shutting the weirs up to a 10% opening may well negatively impact the fish. But once they are open 40%, opening them up more DOES NOT FATTEN the fish.

[MathGeek]

Originally Posted by "W"

Trout weight diffrent every month ... So you can not go by body weight or fatness

Sure you can. The "expected weight" is determined from state wide data from the same time window. We are not comparing our data from a three week window to data from throughout the year. We are comparing our data with statewide data from the same time of year. Seasonal variations are thus accounted for.

[MathGeek]

Originally Posted by "W"

Exacty you can not tell the health of the estuary with that data


Now don't get me wrong MG you are an asset to this fisheries I wish they would find you to do all our research

The data are from a three week window each year, so they indicate the health of the estuary during that time window and things that impact fish condition when assessed at that time of year.

It is possible that fish condition is somehow negatively correlated with weir openings when assessed in late May and early June, but that there is some mysterious factor that makes the relationship so strongly opposite the rest of the year that the data we are missing the rest of the year would overwhelm our seasonal snapshot?

Yes, it is possible. But it isn't likely.

By what mechanism would fish condition be negatively correlated with weir openings in May and June, and then suddenly switch to a strong positive correlation the rest of the year?

But it is a point worthy of some consideration and debate.

["W"]

So Could it be that when the weirs are open fish are more active and gorging ( regurgitating) due to the amout of bait and tidle flow?

When weirs are open we have move tide and bait on east side as to none when close ? So could it just change there feeding habits as when you have affective tides and bait trout on east side gorge more ?

Let's take last summer for prime example , weirs were closed all summer long and trout fishing was horrible. East side and south end were not very productive as it has been this year due to them being open all summer long

[The shop in Broussard]

Who decides when to open or close the weirs?


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[MathGeek]

Originally Posted by "W"

So Could it be that when the weirs are open fish are more active and gorging ( regurgitating) due to the amout of bait and tidle flow?

When weirs are open we have move tide and bait on east side as to none when close ? So could it just change there feeding habits as when you have affective tides and bait trout on east side gorge more ?

You have some interesting ideas here, to be sure. Regurgitating would likely decrease feed efficiency and increase energy costs.

Question: specks are well known for their rapid gorging and regurgitating under certain conditions. This may account for their negative correlation with weir openings in the spring months. What do you know about redfish gorging and regurgitating? Sure, any fish can vomit in the boat or in the ice chests, but do you know of redfish gorging and regurgitating like specks do? Or is this a unique behavior to specks and more closely related species?

Originally Posted by "W"

Let's take last summer for prime example , weirs were closed all summer long and trout fishing was horrible. East side and south end were not very productive as it has been this year due to them being open all summer long

The weirs concentrate the fish in a predictable location so they are easy to catch. The fish may be responding more to the moving water than actual feeding efficiency. "Productive" from an angling viewpoint means hungry (easy to catch) and concentrated fish. "Productive" from a fish condition viewpoint means well fed and spread evenly through areas of the estuary with sufficient forage.

In 2013, the weirs were mostly open through May and June, and the mostly closed situation began July 10, 2013 and persisted until early October when fresher water allowed switching to a mostly open operational scheme. In 2014, the weirs were mostly closed (30% or so open) from April 15, closed even tighter in early May, and remained closed tightly (10% or so open) until mid July when heavy rains dropped the salinity and allowed going back to a mostly open condition.

There were similar length weir "closings" in both 2013 and 2014, but it occurred earlier in 2014. The greater productivity of the estuary in 2014 was not due to the weir openings after mid-July. The productivity was obvious back in May when we were doing our measurements. Lots of anglers were complaining that the fish were hard to find, but the fish were fat and happy and chasing abundant bait fish (menhaden, croaker, mullet) in schools scattered throughout the estuary rather than stacking up at the weirs sharing a meager influx of shrimp (came on stronger later in the summer).

[MathGeek]

Originally Posted by Smalls

So you mean that opening the weirs actually makes for SMALLER FISH?!?!

GASP!!

And all this time we've been led by some to believe that the weirs should be open all the time!

More specifically keeping the weirs open more than 40% of the total gates is correlated with THINNER fish.

In the long run, protecting the marsh is in the best interests of the entire fishery.

[BloodKnot]

MG,
I am a pro-weir big lake guy. So I appreciate your thoughts and research.

Do you or anyone have an knowledge if the weirs affect the oysters any? Not sure if weirs being closed for a long period hurt the oysters, which would indirectly negatively affect the fish.

Just wanted to get your 2 cents on that.

[T-TOP]

Originally Posted by BloodKnot

MG,
I am a pro-weir big lake guy. So I appreciate your thoughts and research.

Do you or anyone have an knowledge if the weirs affect the oysters any? Not sure if weirs being closed for a long period hurt the oysters, which would indirectly negatively affect the fish.

Just wanted to get your 2 cents on that.

I have been looking into the whole oyster issue for a while now. It appears that the main problem with the oysters is that the salinity levels in the lake are too high. There is data to back this up. The upcoming salinity control projects would be good for the oysters and hopefully would possibly allow the weirs to be open almost all the time.


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[MarshRat89]

Originally Posted by T-TOP

I have been looking into the whole oyster issue for a while now. It appears that the main problem with the oysters is that the salinity levels in the lake are too high. There is data to back this up. The upcoming salinity control projects would be good for the oysters and hopefully would possibly allow the weirs to be open almost all the time.


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What are they planning to do that would lower the salinity?



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["W"]

Originally Posted by The shop in Broussard

Who decides when to open or close the weirs?


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Miami corp duck hunters

["W"]

Originally Posted by MarshRat89

What are they planning to do that would lower the salinity?



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There is a group I have been in contact with That is planing to install a rock or levee system along ship channel to lower salinity by 6-8 ppt

[MathGeek]

Originally Posted by BloodKnot

MG,
I am a pro-weir big lake guy. So I appreciate your thoughts and research.

Do you or anyone have an knowledge if the weirs affect the oysters any? Not sure if weirs being closed for a long period hurt the oysters, which would indirectly negatively affect the fish.

Just wanted to get your 2 cents on that.

That's a great idea worthy of consideration.

Other than overharvesting and dredging, the biggest enemies of oysters are the oyster drill, the black drum, and overly low and high salinities.

Is it possible that opening or closing the weirs somehow impacts (for better or worse) one of the key predators so that predation pressure is increased or decreased? Sure, but this is likely a second order effect that may vary depending on the time scale. For example, suppose opening the weirs pulls a lot of the drum off of the oyster reefs to feed at the weirs, thus reducing predation pressure. This is good in the short term, but could also have the effect of increasing the drum population in the longer term.

One big issue for the oysters at the S end of Big Lake (east side) is the additional stress from high salinities. The weirs may have a small effect here, but in the long run, improvement requires smaller coupling between the lake and the Gulf.