Escape response in elongated fish under two temperature scenarios

Abstract

Escaping from predators is a crucial behavior for organism survival and represents a key target of natural selection. Temperature is one of the most influential environmental factors in individual development by influencing physiological performance and, consequently, overall fitness. This study aimed to describe the escape response of a flexible fish species to a simulated predator attack and to evaluate the effect of increasing temperature—associated with climate change—on escape velocity, using Galaxias maculatus as a model species. We hypothesized that G. maculatus exhibits a higher turning rate compared to less flexible fish, and that individuals exposed to warmer experimental temperatures perform faster escape responses due to enhanced neurophysiological processes. Specimens were collected from Tierra del Fuego National Park (55° S) and maintained at 10°C (current average summer temperature) and 16°C (projected average temperature for the year 2100). Their escape responses to a mechano‐acoustic stimulus were recorded at 480 fps. Galaxias maculatus displayed a two‐stage “C‐start” escape response, with an average duration of 70 ms and a high turning rate. Individuals tested at 16°C exhibited higher velocity and turning rates, and shorter stage 1 durations compared to those at 10°C. Our results indicate that G. maculatus changes its behavior with increasing ambient temperature in response to simulated attacks, producing faster escape responses at higher temperatures. Moreover, the findings suggest that this species tends to prioritize directional control—often swimming toward the predator—over maximizing escape speed.