Small fish recover faster after workouts

U. ILLINOIS (US) — After exercise, small fish bounce back faster than large fish, a finding that suggests anglers may want to adjust their catch-and-release methods based on fish size.

For the study, published in Fish Physiology and Biochemistry, largemouth bass were caught in nets, put into dark tanks, and allowed to rest. Later they were chased for 60 seconds to simulate angling and the amount of energy they might expend during a catch-and-release episode. They were allowed to recover for 0, 1, 2, or 4 hours before being sampled for plasma and white muscle.

Large largemouth bass exhibited elevated concentrations of plasma glucose and sodium relative to small fish following the exercise challenge. Large fish required additional time to clear metabolic disturbances in plasma and failed to restore potassium to basal levels even following 4 hours of recovery, indicating an improved ability of the smaller fish to recover from disturbances.

Both big fish and small fish don’t experience major hardships during exercise and all survive easily, but small fish recover faster than big fish. (Credit: U. Illinois)

“The point of the study was to replicate an angling situation where anglers catch and release fish,” says Cory Suski, assistant professor of natural resources and environmental sciences at the University of Illinois.

“We wanted to know if large fish and small fish had similar physiological responses to being exercised and released, particularly regarding the time it takes the fish to recover from exercise.

“What we found is that the large fish take longer to recover from exercise than the small fish do. None of the fish really experienced any major hardships, and they all survived easily, but the small fish recovered faster than the big fish.

“Big fish are reproductively valuable as they tend to have more babies than small fish,” Suski says. “Big fish are also rarer than small fish, and they are more often targeted by anglers.

“If anglers are planning to release a large fish after catching it, the results from this study emphasize the importance of angling the fish for a short duration, handling the fish gently, and getting it back into the water quickly so that excessive disturbances are minimized and the fish can recover quickly, begin feeding, and get back to normal,” Suski says.

“Before we began the research, we predicted that the larger fish would respond and recover from exercise more quickly, providing another size-based advantage for larger fish, but we found the opposite to be true.”

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