Quote:
Originally Posted by MathGeek
The weir management plan is reasonable and based on sound science. Since they took over management of the weirs in 2012, CPRA has done a very good job managing the weirs according to the management plan. CPRA has been kind enough to share detailed weir opening data with us that has allowed us to compute correlations between the condition of finfish in the lake (specks, redfish, drum, and gafftops) with the weir openings.
The most consistent and strongest correlations between our data on fish condition and any environmental factor we've considered are the NEGATIVE correlations between weir openings and fish condition. In other words, the more the weirs are opened, the thinner the fish are. The attached graph completely disproves the hypothesis that weir closures somehow negatively impact fish condition. The asterisks denote statistical significance at the p < 0.05 level.
Our working hypothesis to explain the NEGATIVE correlations between weir openings and fish condition is based on an analogy with rotating pastures to maximize the forage available for cattle. If the gates between pastures are open all the time, cattle graze all the pastures continuously which results in less production than limiting the pastures that can be grazed and opening the gates occasionally. As applied to the weirs, the idea is that the marsh behind the weirs produces more forage if more separation is allowed to reduce feeding pressure from the finfish until the crop of forage has achieved a larger biomass.
In any event, there is no scientific basis to complain about CPRA's management of the weirs. The biggest issue relating to Big Lake that is within regulatory control is the overharvesting of oysters.
|
MG,
Thanks for posting the information from your study. Is it possible, and has consideration been given to the idea that the difference in condition of the fish during open and closed periods may be due to a change in WHAT they are feeding on? If for example open weirs provided easy pickings on shrimp so the fish avail themselve of it, but when the weirs are closed they feed more on menhaden and finfish, it could be a matter of the fish being thinner when the weirs are open becasue they are taking advantage of easy prey that is lower in nutrients verses eating more nutrient dense food.