With at least a few more weeks of potential cold weather, wildlife experts with the South Carolina Department of Natural Resources are urging everyone to be aware of water temperatures that could potentially kill coastal marine fish.
The urgency comes on the heels of extreme mid-January cold weather that saw low temperatures hover between 15 to 23 degrees, even colder when factoring in wind chill — leaving a number of spotted seatrouts dead along the IOP coast.
“Winter cold weather and periodic impacts to coastal fish is a natural part of our coastal ecosystems,” said Dr. Joseph Ballenger, associate marine scientist with SCDNR’s Marine Resources Research Institute. “For spotted seatrout, one of the more vulnerable species, our research has shown that mortality occurs if they are exposed to five or more days at temperatures at or below 40 to 42 degrees fahrenheit.”
Ballenger added that the most susceptible areas are shallow tidal areas, intertidal creeks, saltmarsh flats and saltwater impoundments, which experience lower temperatures that fluctuate more rapidly unlike larger bodies of water such as harbors or bays.
“Estuarine organisms present in these shallow water habitats are the most susceptible to rapid temperature drops unless they move to warmer, deeper waters,” Ballenger said. “White shrimp, another vulnerable species, can begin to be affected when exposed to water temperatures below 48 degrees fahrenheit for extended periods of seven or more days.”
Since 1993, SCDNR has recorded four cold weather fish kills that depleted fisheries. The last one came during the winter storm in January 2018.
“But by 2019, population numbers were at or above -event levels, with a further increase in 2020,” Ballenger said. “Clearly the ability of a population to recover is dependent on its health prior to the event, with stressed populations taking longer to rebound. Additionally, recovery will be lengthened if other stressors, such as high fishing pressures, remain after the event.”
Ballenger suggested that people, especially anglers, can do their part during these periodic times by releasing captured fish, employing the best handling techniques and considering reducing pressure on sensitive species.
“Such approaches are important because decreasing the mortality experienced by those remaining fish, particularly adults who are getting ready to spawn in the spring, can hopefully accelerate the potential population recovery,” Ballenger said.
Other actions anglers can always take to benefit local fish populations, especially in times of environmental stress, are participating in Release Over 20 – a nonprofit that stresses setting your own fish limits and protecting the spawning fish that are most valuable in maintaining a sustainable fishery or Keep Fish Wet – which promotes the use of science-based best practices to catch, handle and release fish.
By L. C. Leach III
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