For years anglers have believed that catfish innately understand winter is coming and they feed heavily to pack on weight to tide them over the lean times on the horizon. But new research suggests that may not be the case.
A recent study out of the University of Arkansas at Pine Bluff shows that even though cold-water temps make catfish lethargic and uninterested in feeding, they do not completely shut down their metabolisms. Instead, the fish eat small amounts of food frequently to maintain their body temperatures and keep their metabolic rates up to prevent a major crash that would trigger a decline in their immune systems and potentially lead to disease.
The researchers tracked the movements of more than 300 individual channel catfish across four winters in a reservoir located in northeast Arkansas. They found that the fish formed long-lasting aggregations in a moderately deep area of the lake, which they defined as the “aggregation zone.” The formation and stability of the aggregation was closely linked to low water temperatures. The aggregation behavior could be a way to conserve energy by reducing travel costs and the need for predator detection. The fish also tended to stay in their aggregation zone throughout the day, but moved out at dusk and night when they went to hunt or spawn.
In the study, the researchers manipulated both air and water temperatures to more accurately mimic the changes in temperature and salinity that occur in natural lakes on longer time scales. They found that while both temperature and salinity impacted the behavior of the fish, the effect of the temperature was much greater. They also found that the aggregation zone was influenced by a number of other factors including water movement and dissolved oxygen concentrations.
While the aggregation zones did not change in size over the study, they did shift location on the lake. The location of the aggregation was also influenced by weather conditions such as rainfall and wind. In the warmer 2019 winter, the aggregation zone was positioned slightly further south than in previous years. However, the overall size of the aggregation zone was comparable to that of other winters.
Interestingly, the study also found that snow triggered a feeding response in both flathead and blue catfish. They tend to be the most lethargic of all catfish in winter but snow triggers them to rise out of their winter holes and seek out food. They also feed more aggressively in cloudy weather. This is because clouds reduce visibility making it easier for the fish to find their prey.
As an angler I have seen this same behavior on many days in the winter. If the conditions are right I will often go fishing before a snow storm. I believe it is a natural tendency for the fish to want to stock up on food before they are trapped in their holes by a heavy snow. I have also seen this same action occur during rain showers that cause the water temperature to rapidly rise.