The role of social network behavior, swimming performance, and fish size in the determination of angling vulnerability in bluegill

An individual’s behavioral and physiological characteristics can have important impacts on fitness, including during interactions with humans. For example, certain traits (metabolic rate, boldness, etc.) have been shown to impact angling vulnerability in fish targeted by recreational anglers. While prior work has focused on boldness behavior and several metrics of metabolic performance, the role of two critical traits, social behavior and swimming performance, have rarely been directly examined. To address this gap, we conducted a study utilizing bluegill Lepomis macrochirus, a highly popular sportfish species found throughout much of North America, to determine the relationship between social behavior, swimming performance, fish size, and angling vulnerability. One hundred and seven bluegill were assessed for social behavior in a laboratory setting, using scoring methods derived from social network analysis. Bluegill were then assessed for swimming performance (critical swimming speed, Ucrit) before being angled in a naturalistic pond setting over nine daily angling sessions. Following angling, a subset of fish were left uncaptured (N = 28), were captured only once (N = 68), or were captured twice (N = 11). Both fish total length and swimming performance were positively linked with vulnerability to initial capture, with fish length also being linked to vulnerability to recapture. In addition to length, social behavior (higher sociability and lower aggression) was positively linked to vulnerability to recapture. Collectively, these results indicate that the drivers of angling vulnerability shift as angled fish populations gain more experience with lures, and that for bluegill, the most vulnerable individuals are likely to be larger and highly social.