Redfish and Specks Benefit from Limited Weir Closings

[Duck Butter]

many things to point out, but a couple are:

1. angler creel surveys (fish caught by rod and reel) do not always show the true picture of what is happening as a whole in the population. These are only fish that are susceptible to being caught (it can be argued that these fish were hungry, therefore that is why they are 'thin'). To get a true picture of the ENTIRE population, seines, nets, and electrocshocking are used. They are all equally susceptible of being captured. Angler creel surveys are good for a general picture of what is going on such as success rates, but for actual population data you need to sample all the fish not just fish that were caught by rod and reel

2. the assumption is being made that the weirs have something to do with all the fish in the lake. These fish may not have even been within a mile of a weir ever in their lives, for all we know they came straight in from the gulf and went to Prien Lake. Possibly if the fish that were measured were all caught in front of the weirs, maybe, but these fish were caught all over the lake and possibly in Prien or Lake Charles

3. no distinction between males and females, it does matter

[dmtfish]

Originally Posted by Duck Butter

many things to point out, but a couple are:

1. angler creel surveys (fish caught by rod and reel) do not always show the true picture of what is happening as a whole in the population. These are only fish that are susceptible to being caught (it can be argued that these fish were hungry, therefore that is why they are 'thin'). To get a true picture of the ENTIRE population, seines, nets, and electrocshocking are used. They are all equally susceptible of being captured. Angler creel surveys are good for a general picture of what is going on such as success rates, but for actual population data you need to sample all the fish not just fish that were caught by rod and reel

2. the assumption is being made that the weirs have something to do with all the fish in the lake. These fish may not have even been within a mile of a weir ever in their lives, for all we know they came straight in from the gulf and went to Prien Lake. Possibly if the fish that were measured were all caught in front of the weirs, maybe, but these fish were caught all over the lake and possibly in Prien or Lake Charles

3. no distinction between males and females, it does matter

Point #2 was why I originally responded to MGs thread. Also, forgive me for not going back and reading your points MG, but did you say that the 90 days prior to sampling are key to body mass??? If such is the case, you mentioned lower body mass in May and June, which would correspond to Feb-Apr feeding. Are not the wiers typically closed during these months??

[Duck Butter]

Originally Posted by dmtfish

Point #2 was why I originally responded to MGs thread. Also, forgive me for not going back and reading your points MG, but did you say that the 90 days prior to sampling are key to body mass??? If such is the case, you mentioned lower body mass in May and June, which would correspond to Feb-Apr feeding. Are not the wiers typically closed during these months??

also if the weirs are not really' closed' and bait can get through per MGs post#18 also kinda makes me take the study with a bigger grain of salt:

You need to realize that the weirs are never completely closed. Even when all of the mechanical gates and flaps are closed, over 10% of the total area coupling the marsh and lake remain open. And the operating procedures for opening the mechanical gates are such that, over most 90 day operating periods, the average coupling between the marsh and lake is at least 40% of the possible total.

So, you may be right that extended closures (90+ days) of all the gates so that only 10% remained open might negatively impact the fish. However, the historical operating data shows that the gates are never all closed for more than a couple weeks at a stretch, and that this only occurs during high salinity periods.

You cannot judge the openings from the boat bay or from the surface gates. There are numerous gates and flaps and slats below water level that allow bait to move back and forth even when the boat bay and surface gates are closed.

[dmtfish]

Originally Posted by Duck Butter

also if the weirs are not really' closed' and bait can get through per MGs post#18 also kinda makes me take the study with a bigger grain of salt:

You need to realize that the weirs are never completely closed. Even when all of the mechanical gates and flaps are closed, over 10% of the total area coupling the marsh and lake remain open. And the operating procedures for opening the mechanical gates are such that, over most 90 day operating periods, the average coupling between the marsh and lake is at least 40% of the possible total.

So, you may be right that extended closures (90+ days) of all the gates so that only 10% remained open might negatively impact the fish. However, the historical operating data shows that the gates are never all closed for more than a couple weeks at a stretch, and that this only occurs during high salinity periods.

You cannot judge the openings from the boat bay or from the surface gates. There are numerous gates and flaps and slats below water level that allow bait to move back and forth even when the boat bay and surface gates are closed.

Bingo... Really appreciate your efforts MG, and keep it up. Just no way to develop your hypothesis

[MathGeek]

Originally Posted by dmtfish

Bingo... Really appreciate your efforts MG, and keep it up. Just no way to develop your hypothesis

I don't think I'd say there is no way to develop the hypothesis, just that we have not yet thought of a simple way.

A lot of feed efficiency issues have been worked out in great detail in freshwater trout, and a lot of ways of untangling food webs have been used in large freshwater lakes and the open oceans.

And even if the available data never becomes available to describe all the biological and life history causes behind the observations, the observations themselves (condition of the fish) and the resulting correlations are pretty solid.

["W"]

Originally Posted by Duck Butter

many things to point out, but a couple are:

1. angler creel surveys (fish caught by rod and reel) do not always show the true picture of what is happening as a whole in the population. These are only fish that are susceptible to being caught (it can be argued that these fish were hungry, therefore that is why they are 'thin'). To get a true picture of the ENTIRE population, seines, nets, and electrocshocking are used. They are all equally susceptible of being captured. Angler creel surveys are good for a general picture of what is going on such as success rates, but for actual population data you need to sample all the fish not just fish that were caught by rod and reel

2. the assumption is being made that the weirs have something to do with all the fish in the lake. These fish may not have even been within a mile of a weir ever in their lives, for all we know they came straight in from the gulf and went to Prien Lake. Possibly if the fish that were measured were all caught in front of the weirs, maybe, but these fish were caught all over the lake and possibly in Prien or Lake Charles

3. no distinction between males and females, it does matter

A lot of fish to come in and out of the gulf and our tagging shows that but we do have thousands of trout to spawn in the marshes behind the weirs which is safer and more protection of eggs than spawning on the beach or lake

Marsh is a nursery

[Duck Butter]

Originally Posted by "W"

A lot of fish to come in and out of the gulf and our tagging shows that but we do have thousands of trout to spawn in the marshes behind the weirs which is safer and more protection of eggs than spawning on the beach or lake

Marsh is a nursery

absolutely

marsh is a nursery for a number of things all the way up the food chain, and one of the most productive ecosystems in the world which is why every means necessary is needed to protect the marsh from saltwater intrusion

[BuckingFastard]

its funny we all fight back and forth over the weirs. truth of the matter is, the lake would be a lot better if the channel was never made/dredged in the start. so much salt is allowed in now and the billionaires are completely benefiting from our loss. maybe one day something will be done about all of this... probably around the same time its safe enough to build a new i10 bridge.

[T-TOP]

Originally Posted by BuckingFastard

its funny we all fight back and forth over the weirs. truth of the matter is, the lake would be a lot better if the channel was never made/dredged in the start. so much salt is allowed in now and the billionaires are completely benefiting from our loss. maybe one day something will be done about all of this... probably around the same time its safe enough to build a new i10 bridge.

You are correct, we would be bass fishing in prien lake today instead of trout.


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[BuckingFastard]

Originally Posted by T-TOP

You are correct, we would be bass fishing in prien lake today instead of trout.


Sent from my iPhone using Tapatalk

yep, had my pops old paintings of the area and it was way different. said they used to duck hunt near where memorial was haha

[BassYakR]

If it werent for big business bringing in all of the jobs tho... most of us wouldnt live here. bc there would be no jobs.... GIVE AND TAKE...

[MathGeek]

I don't mind the ship channel itself. It is responsible for most of the economic productivity of the Lake Charles, etc. The response was slow and ineffective to much of the early land loss. Too few policy makers take the long view and make policy choices based on what is best for Louisiana citizens in a generation or two.

[MathGeek]

I should note that the data shows that the weir operation since 2012 has been very scientific and driven by salinity data, fishery considerations, moon, tide, fronts, and water flow needs in accordance with the principles that have been propounded.

The single weir operating event that seemed more selfish or politically motivated (rather than scientific) was the closing of the boat bay coinciding with the Federal government shutdown on 1 October 2013.

Other than that, every opening and closing is well justified by salinity conditions, flood conditions, an approaching front, full moons, new moons, the need to let fish and shrimp through, etc.

On every occasion where the weirs were closed to the fullest extent possible (about 10% remaining open in the non-closeable slats), salinity data shows measurements of 19 ppt or greater both inside and outside of every weir at the time of closing.

[Duck Butter]

Originally Posted by MathGeek

I should note that the data shows that the weir operation since 2012 has been very scientific and driven by salinity data, fishery considerations, moon, tide, fronts, and water flow needs in accordance with the principles that have been propounded.

The single weir operating event that seemed more selfish or politically motivated (rather than scientific) was the closing of the boat bay coinciding with the Federal government shutdown on 1 October 2013.

Other than that, every opening and closing is well justified by salinity conditions, flood conditions, an approaching front, full moons, new moons, the need to let fish and shrimp through, etc.

On every occasion where the weirs were closed to the fullest extent possible (about 10% remaining open in the non-closeable slats), salinity data shows measurements of 19 ppt or greater both inside and outside of every weir at the time of closing.

So you are saying that the weirs are being operated as per the agreement put in place? Not per Miami Corps duckhunters? .....but the wigeongrass bruh

:mindblown

[MathGeek]

Another important point in the science centers on the attraction vs. production debate in fisheries. One viewpoint stresses that conditions that attract a lot of fish (reefs usually) must provide a net benefit to the fish through increased forage production, because the fish are drawn to food sources. The counter point stresses that this may not always be true and should be empirically demonstrated in each case, because a number of negative effects are possible when fish congregate in high densities.

This debate has raged for decades with respect to red snapper and artificial reefs/oil platforms. The empirical data has just emerged in the past few years showing that artificial reefs actually increase production of red snapper, they do not simply attract red snapper that were fed by the Gulf food web that would be present without the artificial reefs/oil platforms.

We've found some surprising results when correlating oyster stocks to fish condition factors. As we had expected, the more benthic and demersal species (redfish, drum, gafftops) show significant positive correlations with oyster stocks, suggesting that healthy oyster reefs contribute significantly to the benthic food web in ways that benefit these species.

However, fish condition in spotted sea trout is negatively correlated with oyster stock assessments. This suggests the propensity for sea trout to congregate at reefs may not be benefiting them. Their design makes them less able to utilize benthic food resources compared with the other species, and there is likely strong competition for available resources near the reefs, since the fish density seems to be much higher there. When stocks are low, specks are forced to spread out over the entire estuary and may thrive better when chasing bait higher in the water column throughout the estuary than when competing with dense populations of fish near oyster reefs.

Natural selection in specks probably drives them toward oyster reefs for protection from predators rather than increased forage that they can utilize. But specks in Big Lake today probably face far fewer natural predators than Gulf inshore and near shore specks have faced over the past few thousand years.

[MathGeek]

Sending a recent weir discussion back to the top!

[wishin i was fishin]

Interesting topic MG, you make SC a better place. If only we could get you over to VB and get those coastal projects prioritized. We would have some kind of chance to restore this fishery back to what it was.

You definitely have your hands full with BL.

[Smalls]

Originally Posted by wishin i was fishin

Interesting topic MG, you make SC a better place. If only we could get you over to VB and get those coastal projects prioritized. We would have some kind of chance to restore this fishery back to what it was.

You definitely have your hands full with BL.

Unfortunately, beaurocracy defines which projects are important. No amount of campaigning or science will do otherwise. These "priority" areas have already been defined. Vermilion Bay was practically given up on when the Master Plan was released. You don't plan to spend millions of dollars on levee systems if you intend on working to restore a particular area. They will turn everything into a New Orleans or Houma, and condemn anything south of those areas to their inevitable fate.

[wishin i was fishin]

Originally Posted by Smalls

Unfortunately, beaurocracy defines which projects are important. No amount of campaigning or science will do otherwise. These "priority" areas have already been defined. Vermilion Bay was practically given up on when the Master Plan was released. You don't plan to spend millions of dollars on levee systems if you intend on working to restore a particular area. They will turn everything into a New Orleans or Houma, and condemn anything south of those areas to their inevitable fate.

True dat Smalls, true dat. The increase in diversion projects there is a finite amount of water and sediment to feed them. our only hope is that will reduce the water flowing through the Atchafalaya diversion. i could go on for a while but don't want to hijack the thread.

So, back to the weirs...Has anything changed from last year?

[MathGeek]

Originally Posted by wishin i was fishin

True dat Smalls, true dat. The increase in diversion projects there is a finite amount of water and sediment to feed them. our only hope is that will reduce the water flowing through the Atchafalaya diversion. i could go on for a while but don't want to hijack the thread.

So, back to the weirs...Has anything changed from last year?

Not really. The evidence is convincing that the weirs are being operated according to the management plan which incorporates some pretty good science.

The available evidence also suggests that since the gates in the weirs are at least 40% open most of the time and never less than 10% open, there is ample flow of forage between the marsh and lake that weir closures are not having any negative impact on the lake.

Seasonal variations in what anglers see is more dependent on where the fish are chasing forage than an actual dearth or abundance of fish. The weirs concentrate the fish were they are easy to catch. Last year, when there was a dry spell and the weirs were closed, the fish were eating very well, but they were eating pogies and bait fish spread throughout the lake rather than stacking up at the weirs.

The closing of the Omega protein plant lead to a very healthy age zero class of pogies last summer. This changed the speck pattern and frustrated anglers, but the specks were well fed and began to be caught with regularity again by fall. The moving of that pogie harvest has probably done more for the fishery for the next few years than leaving the weirs open 100% of the time ever could have.

As far as I can tell, oyster dredging, salinity, erosion, and loss of marsh are the biggest issues threatening the fishery.