Redfish and Specks Benefit from Limited Weir Closings

[capt coonassty]

Originally Posted by dmtfish

Someone educate me here... Since when do oysters die in high salinities? Are the oysters in BL different from other gulf oysters?? The best oysters I have eaten came from old project areas where we collected data and the salinity was 25 ppt +. Its been my experience that high temps and low salinities are the cause for poor oyster production

"Crassostrea virginica appears to have a higher tolerance of salinity fluctuation than other oyster species (Berquist et al. 2006). The optimal salinity for growth and reproduction is 10 - 28 ppt (Wilson et al. 2005). Larvae will not settle and metamorphose into spat when salinity is less than 6 ppt (Wilson et al. 2005). Adult C. virginica can live in salinities up to 35 ppt (Buroker 1983)".

But one of the problems with higher salinity waters is predation. When salinity is higher oyster drills become more numerous and predation rates are higher.

[slickfish]

Originally Posted by "W"

Name
Date
Time

$1000 you will not show are your mom punished you or your dog died

Better yet I'll pay $1000 just to smash your aZZ flat in the mud !!!

I'm looking forward to introducing myself to you.

[BloodKnot]

Anger management class list: Ray Rice, Adrian Peterson, W,...

[T-TOP]

Originally Posted by capt coonassty

"Crassostrea virginica appears to have a higher tolerance of salinity fluctuation than other oyster species (Berquist et al. 2006). The optimal salinity for growth and reproduction is 10 - 28 ppt (Wilson et al. 2005). Larvae will not settle and metamorphose into spat when salinity is less than 6 ppt (Wilson et al. 2005). Adult C. virginica can live in salinities up to 35 ppt (Buroker 1983)".

But one of the problems with higher salinity waters is predation. When salinity is higher oyster drills become more numerous and predation rates are higher.

I will add to this about high salinity levels.

Perkinsus marinus a parasite that causes Dermocystidium Marinum (also known as Derma)= this parasite kills oysters.

The critical environmental factors which favor the proliferation of the parasite are high
water temperatures and high salinities. Thus infections are more intense in the late summer, on
the seaward side of estuaries and during droughts.

Also when you control the salinity going in the lake the sediment will also be controlled it goes hand and hand really.

Most of this info that I post is in the oyster assessments that are on the LDWF website. Very informative for a person that is interested in these issues.

[Bobbynofish]

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[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??

[dmtfish]

Originally Posted by T-TOP

I will add to this about high salinity levels.

Perkinsus marinus a parasite that causes Dermocystidium Marinum (also known as Derma)= this parasite kills oysters.

The critical environmental factors which favor the proliferation of the parasite are high
water temperatures and high salinities. Thus infections are more intense in the late summer, on
the seaward side of estuaries and during droughts.

Also when you control the salinity going in the lake the sediment will also be controlled it goes hand and hand really.

Most of this info that I post is in the oyster assessments that are on the LDWF website. Very informative for a person that is interested in these issues.

Thanks TTOP

["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

[Duck Butter]

Originally Posted by T-TOP

I will add to this about high salinity levels.

Perkinsus marinus a parasite that causes Dermocystidium Marinum (also known as Derma)= this parasite kills oysters.

The critical environmental factors which favor the proliferation of the parasite are high
water temperatures and high salinities. Thus infections are more intense in the late summer, on
the seaward side of estuaries and during droughts.

Also when you control the salinity going in the lake the sediment will also be controlled it goes hand and hand really.

Most of this info that I post is in the oyster assessments that are on the LDWF website. Very informative for a person that is interested in these issues.

add to this and what capt coonassty said, there are a few oyster reef restoration projects (several miles of them) around the state that are showing the same thing. One at Vermilion Bay SW Pass are not growing oysters due to too much freshwater. At Grand Isle the water is too saline too long and they are getting hammered by drill snails. The project in St Bernard Parish though seems to be the perfect mix as they are growing oysters 'like gangbusters' per the manager

add: some of the reefs are enclosed so there is no predation from black drum to account for either

[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.

[dmtfish]

Originally Posted by MathGeek

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.

"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."

AMEN!!

[MathGeek]

Originally Posted by T-TOP

I will add to this about high salinity levels.

Perkinsus marinus a parasite that causes Dermocystidium Marinum (also known as Derma)= this parasite kills oysters.

The critical environmental factors which favor the proliferation of the parasite are high
water temperatures and high salinities. Thus infections are more intense in the late summer, on
the seaward side of estuaries and during droughts.

Also when you control the salinity going in the lake the sediment will also be controlled it goes hand and hand really.

Most of this info that I post is in the oyster assessments that are on the LDWF website. Very informative for a person that is interested in these issues.

Right. It is not the high salinity that directly kills the oysters. It is this parasite and the oyster drills. But in practice, these issues are making it difficult to reestablish oyster reefs in higher salinity waters in Louisiana right now. Moving further inland (lower salinity) gives a higher probability of successful reef establishment

[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.


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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...