Impacts of invasive fish removal through angling on population characteristics and juvenile growth rate

Abstract

Exploitation can modify the characteristics of fish populations through the selective harvesting of individuals, with this potentially leading to rapid ecological and evolutionary changes. Despite the well-known effects of invasive fishes on aquatic ecosystems generally, the potential effects of their selective removal through angling, a strategy commonly used to manage invasive fish, are poorly understood. The aim of this field-based study was to use the North American pumpkinseed Lepomis gibbosus as the model species to investigate the consequences of selective removal on their population characteristics and juvenile growth rates across 10 populations in artificial lakes in southern France. We found that the maximal individual mass in populations decreased as removal pressure through angling increased, whereas we did not observed any changes in the maximal individual length in populations as removal pressure increased. Total population abundance did not decrease as removal pressure increased; instead, here was a U-shaped relationship between removal pressure and the abundance of medium-bodied individuals. In addition, population biomass had a U-shaped curve response to removal pressure, implying that invasive fish populations can modulate their characteristics to compensate for the negative effects of selective removals. In addition, individual lengths at age 2 and juvenile growth rates decreased as removal pressure through angling increased, suggesting a shift toward an earlier size at maturity and an overall slower growing phenotype. Therefore, these outputs challenge the efficiency of selective management methods, suggesting the use of more proactive strategies to control invasive populations, and the need to investigate the potential ecological and evolutionary repercussions of nonrandom removal.

Angling selects against active and stress-resilient phenotypes in rainbow trout

“…Therefore, our study shall not be misread to suggest that angling alone will be an efficient removal method of invasive phenotypes or species (e.g. Paul et al 2003;Evangelista et al 2015).…”

Passive gear‐induced timidity syndrome in wild fish populations and its potential ecological and managerial implications

“…downsizing, Jørgensen et al 2007;Al os et al 2014). In addition, passive gears tend to remove the fastest growing segment of the population (Biro and Post 2008;Saura et al 2010;Al os et al 2014;Crane et al 2015;Evangelista et al 2015;Pieterek et al 2016). Hence, a timidity syndrome suggests an even stronger downsizing than expected from life-history evolution alone, which can ultimately affect population growth rate and biomass at carrying capacity (Fig.…”

Resource composition mediates the effects of intraspecific variability in nutrient recycling on ecosystem processes

“…This highlights the importance of integrating body size variation in assessments of the effects of intraspecific variability on ecosystem functioning (Rudolf and Rasmussen ). In addition, since human activities can affect body size distribution in wild population (Evangelista et al ), it would be of interest to assess how they affect the relative importance of consumer‐driven nutrient recycling along a gradient of perturbation, such as anthropogenic eutrophication.…”

“…To assess inter‐individual variability in the trophic niches of Lepomis gibbosus , populations were sampled from 11 lakes that were former gravel pits in the flood plain of the Garonne River, France (Zhao et al ). Sampling was completed in similar weather conditions (21 to 24°C, mixed cloud cover) between mid‐September and mid‐October 2012 by electrofishing along the littoral shoreline (Evangelista et al ). To reduce biases between lakes in SCA related to the feeding period of consumers, one lake was sampled per day and electrofishing was conducted during the same period of time in each lake (between 1:00 to 3:30 p.m.).…”