The Louisiana Department of Wildlife and Fisheries is alerting the public to the potential for statewide fish kills due to a combination of environmental factors. According to their recent publication, high-water temperatures, coupled with extended periods of cloudy weather, and ensuing storms may contribute to freshwater and nearshore marine fish kills in Louisiana’s waterways. The LDWF has issued a reminder for individuals to report such occurrences on their fish kill webpage.
As the warmer weather increases, the capacity of water to hold oxygen decreases, causing a precarious balance of oxygen levels needed for fish survival. Conditions, such as stagnant water, hot weather, and runoff containing decaying debris and nutrients, can exacerbate the situation, creating hypoxic water zones, also known as areas with depleted oxygen. In particular, Louisiana’s marshes, ponds, and bayous are at extreme risk for hypoxia.
The LDWF notes that different fish species and sizes vary in their tolerance for low oxygen levels. Consequently, not all fish are equally affected by these hypoxic events, for instance, shad may be more susceptible while others manage to survive. The department also emphasizes the natural role of decomposers and scavengers, such as microbes and crawfish which help to clear up the aftermath of fish kills. As fall approaches and temperatures decline, the risk of these oxygen-related die-offs reduces.
While fish kills are a part of Louisiana’s natural ecology, the ecosystems have the resilience to recover from such setbacks. The aquatic organisms often disperse from unaffected areas to repopulate the impacted habitats. Therefore, maintaining aquatic connectivity is essential to this recovery process, LDWF says. Additionally, after fish kills the aquatic environment may actually support higher survival rates for young fish due to fewer predators and more available resources, that is if conditions remain favorable.
Although immediate negative impacts on commercial and recreational fishing might occur post fish kill, patience is warranted as young fish populations in recovery grow to catchable sizes. Fish kills caused by other factors such as chemical spills, should still be promptly reported to the LDWF.
