[MathGeek]

Smalls, I agree there are challenges when assigning importance to competing hypotheses when multiple factors are in play. We've developed new analysis techniques (based on multivariate analysis techniques in other fields) that are effective in unravelling food web dynamics of complex ecosystems given sufficient years of data. With a decade of data, inferences are possible with greater statistical confidence than possible now. If hypothetical causes are relatively uncorrelated, confident inferences may result from only 5-7 years of data. Empirical methods to estimate interaction matrix elements in the coupled Lotka-Volterra equations are something of a holy grail in population modeling. Our analysis approach shows promise toward accurately estimating species interaction coefficients (matrix elements) as well as making inferences regarding competing hypotheses in food web dynamics.

For example, suppose current trends hold for a decade (they might not). If the mean annual relative condition factors of a given length class of a given species (say bull redfish > 800 mm) have a strong correlation (r > 0.8; P < 0.05) with oyster stock assessments, but relatively weak correlations with other hypothetical factors (r < 0.5; P > 0.2), then there would be greater statistical confidence that oyster reef condition plays the strongest role in bull redfish condition. Likewise, suppose a different length class/species combination (say redfish 400-500 mm TL) is most strongly correlated with the exchange between the marsh and lake (r > 0.7; P < 0.05), but only weakly correlated with other factors (r < 0.5; P > 0.2); one could confidently infer that weir operation has a strong role. Finally, suppose that the shortest sampled length class of specks (290-400mm TL) is most strongly correlated with exchange between marsh and lake (r > 0.8; P < 0.05), weakly correlated with population of speckled trout (r > 0.5; P < 0.05), and uncorrelated with other factors. This would suggest a rank ordering of weir operation (lake-marsh exchange) then speck overpopulation (limits) above other hypotheses regarding the relative condition factor of specks 12-16" TL.

Right now, there are three years of data, and we'll have a fourth year by the end of June. More can be said than with one or two years of data, but less than possible with a decade of data. For example, if the speck limit were a dominant factor in the lake's food web impacting redfish and drum and gafftops as well as specks, one would expect that the condition factor of specks (especially the shorter length classes, since they have the highest populations) would be more strongly reduced than the relative condition factors of redfish. This is because the food competition is stronger within a given species than with other species. One would also expect Kn of different length classes and species to be highly correlated with each other, since the underlying cause would be the same. However, that is not what we see. The Kn of shorter specks has been between 0.95 and 1.05 in all sampling years (2011, 2012, and 2013); whereas, the Kn of redfish in the 500-650mm length class (that tend to stack up strongly at the weirs) has dipped below 0.95. Weir operation seems to be having a bigger impact on redfish between 20-26" long than the change in the speck limit. This seems more likely than not with available data , but cannot be inferred with a 90% or 95% confidence level. With a decade of data, this apparent inference might wash out in the noise or it might be established with greater confidence.

Another factor to consider is that Kn for all length classes and species (except for Gaftops 450-550 mm TL and bull redfish) rebounded strongly in 2013 over 2012. Only the shorter length classes of specks and redfish 400-500 mm TL topped 1.0 (returned to normal). Most length classes and years had Kn increase by about 5%, whereas specks (combined lengths) had a Kn increase of 9% (+/- 1.5%). This rebound cannot be explained by a recovery of the oyster reefs. However, the rebound does coincide with much lower salinity levels in the lake for the first six months of 2013 (compared with 2011 and 2012) that allowed the weirs to be opened and bait to flow back and forth from the marsh and lake. Based on available data, it seems more likely than not that the exchange with the marsh plays a significant role in relative condition factors in these cases. Once again, this inference might wash out in the noise with a decade of data, or it might be established with greater confidence.

Salinity levels have been a bit in 2014 than in the same period in 2013, but lower than 2011 and 2012; however the weirs have hardly been opened so exchange with the marsh has been small. If we had LDWF's 2014 oyster stock assessment data (not available yet), we could weight the different factors and make some Kn predictions for each length class and species based on past years and our current understanding of the relative importance of each factor. If the 2014 oyster stock assessments are still down, I expect Kn's closer to what was measured in 2012 than in 2013.

Louisiana law mandates wildlife resources be managed with the "best available" science. My issues with the speck and tripletail limits is that CCA pushed for more restrictive regulations with no data at all. Available data was not reviewed; there were no hints of stock assessments; existing data from trawl studies and LDWF's fishery independent surveys was not consulted. In contrast, oyster stock assessments and the best available fisheries dependent data for Big Lake both suggest that oyster dredging is doing real and lasting harm. Volumes of published scholarly papers document valuable ecosystem services provided by oyster reefs, additional annual fisheries production around restored reefs, and the negative consequences on estuaries from the destruction of oyster reefs.

It is sad to think that a humble relative condition factor study may constitute the "best available" data on the state of the fishery in Calcasieu Estuary, but until LDWF and CCA improve their scientific committment, this may be the situation. Air Force support for the project dried up about the time of the sequester and furlough, right before I left the Academy and moved back to Louisiana. The study moves forward on a bit of private funding, exiting equipment, many volunteer hours, and kindness of those who let us weigh and measure their fish. Will we manage to get hundreds of fish weighed and measured in a three week window every year from now until 2021? I don't know.