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Inshore Saltwater Fishing Reports Read and share fishing reports for your favorite inshore spots here |
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#1
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Calcasieu Croaker Science
If a predator gets fat when there are lots of croaker, it suggests that predator species is more heavily dependent on croaker than other forage species which show little correlation with the plumpness of the predator. Here is the CPUE for croaker from Jan-Jun for the past 5 years. OK, experts, which bioindicator species (specks, reds, drum, or gafftops) will have its plumpness most strongly correlated with the croaker stock assessments? |
#2
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Ok professor,
I don't pretend to be as smart as you but, I don't think you have given enough information to draw a conclusion to your question.... Plus your second paragraph does not make sense to me. Predators get fat when croaker abundant which is there main forage but shows no correlation with plumpness of predator. Am i the only one confused here???? |
#3
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Looks like the weirs were closed til month 3 in all those graphs but 2013 where they were closed til later. That keeps all the croakers behind the weirs
Or that the guides were all soaking croakers January through March and all the bait was in the bait tanks at Spicers. Once they start soaking shrimp in April, the croaker population goes back up |
#4
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what is cpue?
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#5
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#6
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Give us a little help here. I am confused but this is very interesting.
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#7
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Catch per unit effort.
LDWF catches fish in nets. CPUE is the number of fish caught divided by the total amount of time the net was out in a month. |
#8
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ok... was 2013 weather different from the rest? maybe the croaker were in a different area of the lake that year. Or do you already know why there weren't as many in 2013?
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#9
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In other words, I was challenging the experts regarding which predator species make the most use of abundant croaker. We'll be working on that part of the analysis starting today. Here's my prediction for the rank ordering of the four bioindicator predator species: 1. Gafftopsail Catfish 2. Spotted Seatrout 3. Redfish 4. Black Drum I think reds and specks may be close. But in recent years, we've caught more gafftops than anything else when hooking up croaker for bait. Gafftops also are showing much more piscivory in the esturary over the past 5 years than they are traditionally known for. |
#10
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There is a big difference |
#11
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We've had occasion to compare our original creel survey data with state agencies on a number of occasions. The trends are always similar, but our sample sizes, measurement care, and uniform sampling window yields higher accuracy. Only an idiot would suggest the 20 redfish LDWF measured from Jan-June 2015 would yield a condition factor estimate as accurate as the 86 redfish we weighed and measured in a 3 week window in May 2015. Similarly, their 15 gram weight measurement accuracy does not compare with our 2 gram uncertainty in weight measurements. The other challenge with a lot of the LDWF weight measurements for the sport species (specks, reds, etc.) is that they weigh groups of fish rather than individuals. Knowing that a group of ten specks they measured on May 6, 2015 weighed 185 ounces is not near as useful or accurate for assessing fish plumpness as having all 10 weights individually with an accuracy of 2 grams. LDWF measured 50 specks in May 2015, which yields an uncertainty in plumpness of over 3%. We weighed and measured 173 specks in May 2015 yielding an uncertainty in average plumpness of about 0.5%. |
#12
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mathgeek, I guess you take some kind of ratio between length and weight to figure out "plumpness"? Just curious to how you do it. This assessment gets fairly in depth and confusing for the ones who just want to skim over the sciency part and go straight to results. lol
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#13
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I can tell you 2013 was a cold winter and one of the better big trout fall/winter/springs I have had, since 2007.
Lot of 7lb. fish with numerous 8lb fish and a few 9's. Those big fish just have turned out like previous winters, last winter was the influx of fresh water and water temps not hardly getting into the 50's. Historically when the water temp holds consistently in the 50's for days or weeks is when those bid sows push up to eat. This is just strictly on the data I keep on the trips we make. This fall was a little irregular because the 5-6lb. fish were spread out and thin in areas they are holding in. There were a lot of 3-4lb. fish in these same areas we have fished since the late 90's |
#14
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Actually relative condition factor in fish is a bit simpler. For fish of a certain species caught at a certain time of year, there is a formula derived from measuring and weighing thousands of LA fish (same species and time of year) for what the fish of that length is expected to weigh. This is called the "standard weight". The relative condition factor is the actual weight divided by the standard weight for the length. A fish that should weigh 2.00 lbs (from the length) but actually weighs 2.10 lbs (measured) has a relative condition factor of 1.05 (5% over the expected weight). Another fish of the same species and length would also be expected to weigh 2.00 lbs, but if it only weighs 1.80 lbs, the relative condition factor is 0.90 (10% under the expected weight). If the fish of a given species are fat on average, they are eating well and not having high stress levels. If the fish are skinny, they are not eating so well (or may be stressed). In past publications, we've shown that this measure of plumpness can be used to study competition between species with the same forage base as well as to quantify forage overlap between different species. |
#15
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Only an idiot would suggest otherwise |
#16
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The peer-reviewers on our published papers also had no trouble accepting our results from several hook-and-line studies. Also, the USGS conducted a study in Big Lake using hook and line to catch fish to assess condition in the same way we are. Are they idiots too? Assessments of fish condition based on hook and line sampling are widely accepted in the fisheries science community. There is just no evidence to support your biased claim that fish caught by hook and line are not a representative sample, and there is a lot of evidence refuting it. |
#17
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Also, where have you published the other studies ? And did you figure in weir openings? Because you told us when weirs are open fish are skinnier |
#18
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There was a telemetry study out of LSU a few years back which studied movement. We also see loooong, older females caught every month of the year, but in the warmer months they are not usually as heavy, because fish have much higher energy requirements when the water is warm. |
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