Effects of physical parameters on fish migration between a reservoir and its tributaries

Abstract

Reservoirs interrupt natural riverine continuity, reduce the overall diversity of the environment, and enhance the spread of non-native fish species through suitable environments. Under favourable conditions, invasive species migrate to tributaries to benefit from local resource supplies. However, the changes in physical conditions in reservoirs that motivate fish species to migrate remain poorly understood. We analysed migration between a reservoir and its tributary in three non-native (asp Leuciscus aspius, ide Leuciscus idus, and bream Abramis brama) and two native (chub Squalius cephalus and pike Esox lucius) species equipped with radio tags. This 5-year study revealed that an increasing day length was the most general predictor of migration into the tributary in all observed species except E. lucius. Only L. aspius responded to the substantially increasing water level in the reservoir, while the migration of L. idus and S. cephalus was attenuated. Abramis brama and S. cephalus occurred more frequently in tributaries with an increase in temperature in the reservoir and vice versa, but if the difference in temperature between the reservoir and its tributary was small, then A. brama did not migrate. Our results showed that migration from the reservoir mainly followed the alterations of daylight, while responses to other parameters were species specific. The interindividual heterogeneity within the species was significant and was not caused by differences in length or sex. Our results contribute to the knowledge of how reservoirs can affect the spread of non-native species that adapt to rapid human-induced environmental changes.

Living on the edge: Reservoirs facilitate enhanced interactions among generalist and rheophilic fish species in tributaries

“…As tributary temperatures drop, food resources become scarcer in the tributary, while predation risks increase (Harvey and Nakamoto, 2013). For this reason, most generalist species occupy tributaries in productive period of the year and return to reservoirs for overwintering (Pfauserová et al, 2021;Pfauserová et al, 2022). Although the mechanisms driving fish migrations from reservoirs to tributaries are not completely understood, it appears that the motivations may be similar to fish migrations from lakes to tributaries, where reproduction plays an important role (Kristiansen and Dølving, 1996;Baril and Magnan, 2002), as well as the predator-prey relationships (Skov et al, 2011).…”

The effect of temperature on the dynamics of common bream Abramis brama migrations between the reservoir and its tributary

“…The results suggested that temperature was not the primary reason for the common bream occurrence in the tributary of the reservoir, as was indicated by observations showing the initiation of species migration into the tributary when the temperature in the reservoir was higher than that in the tributary (Pfauserová et al, 2022). Other behavioural patterns considered in response to specific environmental conditions, for example, the avoidance of predators, did not seem to be the reason for initiating movement during our study.…”

“…According to our 5-year field observations, a prolonged photoperiod seems to be the key factor influencing common bream migrations from the reservoir to the tributary, supported by flow conditions in the tributary (Pfauserová et al, 2021(Pfauserová et al, , 2022. The common bream migrated from the reservoir into the tributary during the period when the temperature in the reservoir was higher than in its tributary (Pfauserová et al, 2022); hence, its effect appears to be overshadowed by the search for seasonal resources.…”

“…Data on fish positions in the longitudinal profile of the reservoir and its tributary, differences between individual fish positions within a time interval, status of movement activity of fish (yes/no) and fish body temperature were available for the statistical analyses. Detailed information on the site and methodology has been provided in previous publications (Pfauserová et al, 2021, 2022). Data were collected in accordance with the Guide for the Care and Use of Animals from the Czech University of Life Sciences Prague, and all experimental protocols were approved by the Faculty of Agrobiology, Food and Natural Resources Licensing Committee (Expert Commission Ensuring Welfare of Experimental Animals).…”

“…Migrations of freshwater fish and their intensity are influenced by environmental factors such as water flow, photoperiod, turbidity and/or temperature (Cunjak & Power, 1986; Lucas & Baras, 2001; Parkinson et al, 1999; Pfauserová et al, 2021, 2022; Tracey et al, 2020) An active preference for higher temperatures within the physiological optimum is beneficial for ectothermic animals, including fish, allowing them to achieve higher fitness, faster growth and better movement (Angilletta, 2009; Angilletta et al, 2002; Benjamin et al, 2020). As migrations are energetically consuming (Lennox et al, 2018) and reflect the correlation between increasing metabolism and temperature (Beamish, 1978; Magnuson et al, 1979), the temperature ascent within an optimal range corresponds with an increase in fish migration (Bizzotto et al, 2009; LovellFord et al, 2020; Tracey et al, 2020).…”