Report Available Relating Fish Condition and Primary Production to Calcasieu Oysters

[MathGeek]

We've been studying fish condition in Calcasieu for the past four years, having weighed and measured over 1000 fish. Work is ongoing, but the a draft report for 2011-2014 is now available. Please PM me with an email address and I'll send you a copy.

Main findings are:

*Fish condition is significantly correlated with oyster stock assessments for black drum, gafftop catfish, and longer length classes of red drum. Spotted sea trout condition is not positively correlated with oyster stock assessments.

*Available data does not support the hypothesis that limited weir closures needed to protect the marsh from saltwater intrusion reduce fish condition.

*Oyster stock assessments are significantly correlated with primary production in nearshore Gulf waters. This suggests that oysters not only increase production in Calcasieu Estuary itself, but that filtering effects and exchange of water between the Estuary and nearshore Gulf result in oysters benefitting production in nearshore waters up to 100 km from the Estuary.

Correlation coefficients between oyster stocks and primary production for regions studied are shown in the attached map.

[Nietzsche]

Originally Posted by MathGeek

We've been studying fish condition in Calcasieu for the past four years, having weighed and measured over 1000 fish.

Not criticizing this important work you are doing but isn't measuring just 250 fish a year from such a large body of water a very small sample size to be statistically valid?

[MathGeek]

Originally Posted by Nietzsche

Not criticizing this important work you are doing but isn't measuring just 250 fish a year from such a large body of water a very small sample size to be statistically valid?

The sample sizes used were adequate to determine mean relative condition factors with an accuracy of 1-2% for each species studied. This was sufficient to test the hypothesis that oyster overharvesting had lead to reduced fish condition. Our annual sample sizes were also much larger than a USGS study that also yielded statistically significant results using a very similar method.

In most cases the small uncertainties in relative condition factors yielded p-values below 0.001, indicating good statistical significance. (See table 2 in the paper.)

[juicegoose]

So what next?

[MathGeek]

Originally Posted by juicegoose

So what next?

We've sent the report to LDWF and other Gulf region scientists for their review and consideration. We believe the results strengthen the case to protect oysters due to their valuable ecosystem services that enhance primary production and fish condition. Hopefully, conservation groups like CCA will take notice and begin working harder to protect existing oyster reefs and restore oyster reefs in Louisiana.

We're limited in our manpower, but a few ideas we are considering as far as moving the science forward are:

* Study correlations of oyster stocks and primary production in other areas of the Louisiana coast.
* Use annual otolith deposition widths as a historical record to determine high-growth years and low-growth years and see how this correlates with oyster stock assessments and other factors that may impact growth and condition of finfish.
* Extend the study to a 5th and possibly a 6th year. Each additional year of data increases confidence in discerning causal factors from confounding factors.
* Look for correlations between oyster stock assessments and other water quality metrics like fecal coliform. Does anyone know of good contacts at LA DEQ or DHH who might share their water quality data? Showing that oysters improve water quality would provide an fishery independent line of reasoning to more carefully protect oyster reefs.

[juicegoose]

Best of luck to ya bud. I'd love to see the dredging stop.

[marshrunner757]

MG, you do a lot of good work to help protect our resources. Thanks

[Smalls]

Originally Posted by MathGeek

*Available data does not support the hypothesis that limited weir closures needed to protect the marsh from saltwater intrusion reduce fish condition.

Good luck convincing most fishermen of that.

Originally Posted by marshrunner757

MG, you do a lot of good work to help protect our resources. Thanks

Research is only part of it. Guys like MG are valuable to the protection of our resources, but they can't do it all. MG is a great advocate for the resource as well, and does more than just research, but he can't do it alone.

Anyone that has an interest in protecting the resource should step up and do something.

[MathGeek]

Originally Posted by Smalls

Research is only part of it. Guys like MG are valuable to the protection of our resources, but they can't do it all. MG is a great advocate for the resource as well, and does more than just research, but he can't do it alone.

Anyone that has an interest in protecting the resource should step up and do something.

Thanks Smalls. For CCA members, the most valuable thing you could do is most likely getting CCA on board working for conservation and restoration of oyster reefs in Big Lake. Getting behind efforts to reduce the coupling of salt water between the channel and main lake would also aid efforts at restoring oysters in the southern end of the lake. Currently, salinity levels stress the oysters and make them more susceptible to predation and disease. CCA bought some goodwill with LDWF by supporting the license fee increase. It would be great to see them use that goodwill to benefit the ecosystem rather than pushing for lower limits on trout, redfish, or flounder.

If one happens to be on good terms with legislators, this is an issue that can be broached with them as well. I also expect there will be a meeting late in 2015 where the LWC sets the 2016 rules and restrictions for oyster harvest in Big Lake. This is not a meeting to pound your fist and demand dredging be stopped, but a calm an informed voice explaining your concerns for the long term health of the estuary would help balance the voices of those who profit from overuse of the oyster resource. The oyster lobby has a lot of clout and momentum, but a steady voice over time should change the LWC's view of oysters from a resource to be exploited to a keystone species for estuary health and fisheries production.

[marshrunner757]

Originally Posted by Smalls

Good luck convincing most fishermen of that.



Research is only part of it. Guys like MG are valuable to the protection of our resources, but they can't do it all. MG is a great advocate for the resource as well, and does more than just research, but he can't do it alone.

Anyone that has an interest in protecting the resource should step up and do something.

Simply telling him thank you. Don't assume I do not do my part.

[Smalls]

Originally Posted by marshrunner757

Simply telling him thank you. Don't assume I do not do my part.

Did I make assumptions about you? Don't think so. I made a general statement.

[Nickt87]

Just finished reading my copy. Very interesting, and very informative. It was nice to read data backed info and analysis.

[marshrunner757]

Originally Posted by Nickt87

Just finished reading my copy. Very interesting, and very informative. It was nice to read data backed info and analysis.

X10. Very good read for sure. We need this kind of analysis to be ongoing.

[MathGeek]

I think I've completed the emails to the requesters so far. So if I missed you in error, please PM another request and include your email address. Thanks!

[Duck Butter]

Originally Posted by MathGeek

The sample sizes used were adequate to determine mean relative condition factors with an accuracy of 1-2% for each species studied. This was sufficient to test the hypothesis that oyster overharvesting had lead to reduced fish condition. Our annual sample sizes were also much larger than a USGS study that also yielded statistically significant results using a very similar method)

You got a link to the USGS study. Thanks

[Marque]

Math geek, I talked to a biologist doing a creel survey the other day that told me that LDWF has 7 gill nets placed through the estuary and that 5 of them are checked randomly each week. They fish retrieved are autopsied and documented. I had no idea they did that and didn't know if that buy was pulling my leg. Seems like a report generated from that kinda research would be a pretty useful to a lot of us. Was this guy messing with me? If not, is that something they publish or is it confidential?

[Duck Butter]

Originally Posted by Marque

Math geek, I talked to a biologist doing a creel survey the other day that told me that LDWF has 7 gill nets placed through the estuary and that 5 of them are checked randomly each week. They fish retrieved are autopsied and documented. I had no idea they did that and didn't know if that buy was pulling my leg. Seems like a report generated from that kinda research would be a pretty useful to a lot of us. Was this guy messing with me? If not, is that something they publish or is it confidential?

They do and they look at sex and age of the fish caught which is why I have been asking for the usgs study (even asked pretty please a couple times). Sex and age are very very important when looking at fish condition. MGs studies so not take into account this very important metric

Angler creel surveys have their place but a gillnet does not have any bias. It catches everything and gets a true representative sample and not just fish that are susceptible to being caught by rod and reel. That is why you don't see a biologist sitting at calcasieu point everyday checking what people caught. They sample by more efficient means

[B-Stealth]

Originally Posted by Marque

Math geek, I talked to a biologist doing a creel survey the other day that told me that LDWF has 7 gill nets placed through the estuary and that 5 of them are checked randomly each week. They fish retrieved are autopsied and documented. I had no idea they did that and didn't know if that buy was pulling my leg. Seems like a report generated from that kinda research would be a pretty useful to a lot of us. Was this guy messing with me? If not, is that something they publish or is it confidential?

I ran into a guy I went took Wildlife Management classes with a couple weeks ago and they were running some gill nets. I'm not sure exactly what they do with the data; but sometimes it takes several years of data collection to have anything worth publishing.

[Smalls]

Originally Posted by Marque

Math geek, I talked to a biologist doing a creel survey the other day that told me that LDWF has 7 gill nets placed through the estuary and that 5 of them are checked randomly each week. They fish retrieved are autopsied and documented. I had no idea they did that and didn't know if that buy was pulling my leg. Seems like a report generated from that kinda research would be a pretty useful to a lot of us. Was this guy messing with me? If not, is that something they publish or is it confidential?

As was previously mentioned, it may take several years to publish anything, if they do. They may gather that data with no intention of publishing it, especially if it gives them nothing worth publishing.

LDWF gathers harvest data on turkeys and deer, but they do no release a report every year with that information. For example, Jimmy Stafford told me they try to release a WMA turkey harvest report every 5 years.

[Marque]

The guy I talked to was at the launch at Prien Park on a day that no one in their right mind should have been fishing. It was 3 or so in the afternoon and I was the first person he questioned all day.I had only run up to the park to pick up a pack of cigarettes from the store across the street on my way to the casino. We had caught like 2 trout in turners that morning so he did his survey and thats when he told me about their study. He told me that the net in Prien had far more trout than any other one he checked for the last couple of weeks. Which surprised the hell out of me. the water temp was in the mid 50's and the river was at flood stage and fresh as hell. We ended up picking up a few off the ship channel after we left but I would have never thought to fish there on that day in those conditions. I guess the point I'm trying to make is that I think it would be great to have that kinda timely info available. Especially in a year like last year where the long cold winter screwed up the normal pattern.