[Clampy]

Originally Posted by MathGeek

Anecdotal reports of catch rates usually reflect the anglers being in the same place at the same time as the fish, especially in Big Lake, where the fish have lots of places to be where the anglers either can't or don't bother to look. Absolute population densities (or biomass densities) are very hard to assess in places like Big Lake.



The situation is further complicated by the openness of the system. There's a much greater flux of fish through the Calcasieu pass (plus the intracoastal waterway) than most freshwater lakes see to and from feeder streams.



It is obvious to all that Louisiana inshore waters are among the most productive in the world in terms of seafood production per unit area. Very few freshwater lakes come anywhere close. Choices about commercial and recreational harvest limits and management are mostly about resource partitioning. If tons and tons of shrimp are harvested, there will be less for the specks and juvenile redfish to eat. At some point in crab harvest numbers, there is less for the redfish and drum to eat. Harvesting all the pogeys probably had an impact higher in the food chain. However, most of the time, seafood production is highest at lower trophic levels, so if it is marketable, it makes economic sense to harvest 1000 lbs of shrimp even if it means producing 100 lbs less of spotted seatrout.



Oysters are different, however. The oysters are not only consumed by one species (black drum), oyster reefs provide essential hard bottom habitat and vertical relief to a whole array of benthic organisms. These benthic organisms contribute to ecosystem production in many ways. Further, the living oysters provide a variety of ecosystem services including improving water quality by filtering, serving as nurseries for fish, and buffering anthropogenic inputs.



While it is hard to know the actual biomass of a species in an estuary, it is easy to infer how much of the species are present relative to their food supply. If (on average) the fish are fat, the food supply could support additional fish, or the fish are underpopulated relative to the available food. If the fish are thin (on average), there are too many fish for the available food supply, which could mean an over abundance of fish or an under abundance of their preferred forage species.



The attached graph shows the relative condition factor for redfish in Calcasieu, analyzed by length class from 2011 to 2013. The statewide average is 100% based on analysis of large statewide data set measured from 1995 to 1999. Clearly, the adult redfish are having trouble finding sufficient forage to maintain body condition. The juveniles (16"-20") are doing better, but 2013 was the first year since 2011 that they were above the statewide average. A 2000 study (Jenkins 2004) found most fish sampled in Calcasieu were above the statewide body condition at about 103%.

I think it's mainly from lack of menhaden and mullet. Once they get that big they mainly eat mullet poggie and crab. The little ones eat a lot of shrimp and small crab. 7-8 years ago I would see huge rafts of mullet in the lake. I don't see that too much any more. Occasionally but not like back in the day.


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