The following information is from the Louisiana Department of Wildlife and Fisheries:
As an arctic blast continues to move across the state, the Louisiana Department of Wildlife and Fisheries would like to warn the public of potential fish kills throughout coastal Louisiana as a result of freezing water temperatures.
It is still too early to determine what, if any, impact the cooler temperatures may have on fish populations. Many fish that may have been killed by the freeze would still be on the bottom of water bodies, and may not be visible for a week or more.
Coastal species commonly impacted by low water temperatures are sand seatrout, (a.k.a. "white trout"), red drum, black drum, and spotted seatrout.
"Typically water temperatures below 40 degrees Fahrenheit for any more than a day begin to cause problems for spotted seatrout, whereas red drum are slightly more tolerant and will begin to experience problems in the mid-30s," explained LDWF fisheries biologist Jason Adriance. "The rate at which the water cools is also important. If fish have a chance to acclimate and move, the potential for survival is better."
More definitive estimates of the effects of the freeze on fish population sizes and distribution within the coastal areas will be available as information is collected through the department's fishery-independent monitoring programs. Later, success rates from fishery-dependent monitoring, including both recreational and commercial sampling, will provide an indication of how the changes in population sizes affected the harvest.
Should you come across significant numbers of dead or dying fish, LDWF encourages you to contact the department. Contact information along with requested reporting specifics, is available here: http://www.wlf.louisiana.gov/fish-kills. Important information to include in your report are your name and phone number in case additional information is needed, along with the location including good directions to the fish kill site, the approximate numbers and species that you saw, and their condition (still dying, all dead, decomposing, etc.).
People should also be aware that legal creel and size limits are in effect, and harvest of fish beyond those limits is illegal.