Season- and size-dependent risk taking in juvenile coho salmon: experimental evaluation of asset protection

Reinhardt, Ulrich G.; Healey, M. C.

doi:10.1006/anbe.1998.1051

Cited by 40 publications

(29 citation statements)

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“…It should be noted that the fish were not stimulated by any predator models during trials, and thus the conclusion that state-dependent safety is of large importance for the trout fry behavior may be less valid when individuals perceive direct predation risk. Other studies have shown that salmonid juveniles (slightly larger than our trout, and thus with more energy reserves) rely on asset protection, i.e., larger fish take fewer risks, when directly attacked by model predators (Reinhardt and Healey 1999). …”

Section: Discussionmentioning

confidence: 90%

State-dependent behavior and alternative behavioral strategies in brown trout (Salmo trutta L.) fry

Näslund

Johnsson

2016

Behav Ecol Sociobiol

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Animals generally adjust their behavior in response to bodily state (e.g., size and energy reserves) to optimize energy intake in relation to mortality risk, weighing predation probability against the risk of starvation. Here, we investigated whether brown trout Salmo trutta adjust their behavior in relation to energetic status and body size during a major early-life selection bottleneck, when fast growth is important. Over two consecutive time periods (P1 and P2; 12 and 23 days, respectively), food availability was manipulated, using four different combinations of high (H) and low (L) rations (i.e., HH, HL, LH, and LL; first and second letter denoting ration during P1 and P2, respectively). Social effects were excluded through individual isolation. Following the treatment periods, fish in the HL treatment were on average 15–21 % more active than the other groups in a forced open-field test, but large within-treatment variation provided only weak statistical support for this effect. Furthermore, fish on L-ration during P2 tended to be more actively aggressive towards their mirror image than fish on H-ration. Body size was related to behavioral expression, with larger fish being more active and aggressive. Swimming activity and active aggression were positively correlated, forming a behavioral syndrome in the studied population. Based on these behavioral traits, we could also distinguish two behavioral clusters: one consisting of more active and aggressive individuals and the other consisting of less active and aggressive individuals. This indicates that brown trout fry adopt distinct behavioral strategies early in life.Significance statementThis paper provides information on the state-dependence of behavior in animals, in particular young brown trout. On the one hand, our data suggest a weak energetic state feedback where activity and aggression is increased as a response to short term food restriction. This suggests a limited scope for behavioral alterations in the face of starvation. On the other hand, body size is linked to higher activity and aggression, likely as a positive feedback between size and dominance.The experiment was carried out during the main population survival bottleneck, and the results indicate that growth is important during this stage, as 1) behavioral compensation to increase growth is limited, and 2) growth likely increases the competitive ability. However, our data also suggests that the population separates into two clusters, based on combined scores of activity and aggression (which are positively linked within individuals). Thus, apart from an active and aggressive strategy, there seems to be another more passive behavioral strategy.Electronic supplementary materialThe online version of this article (doi:10.1007/s00265-016-2215-y) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 90%

State-dependent behavior and alternative behavioral strategies in brown trout (Salmo trutta L.) fry

Näslund

Johnsson

2016

Behav Ecol Sociobiol

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“…Actively feeding and satiated individuals may North American Journal of Fisheries Management 28: [1529][1530][1531][1532][1533][1534][1535][1536][1537][1538][1539][1540]2008 Ó Copyright by the American Fisheries Society 2008 DOI: 10.1577/M07-120.1 [Article] have a higher risk of predation (Lankford et al 2001). Large individuals may self-limit future growth potential through adoption of low-risk feeding behaviors (Reinhardt and Healey 1999). In some circumstances, there may be no single ''best'' size.…”

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confidence: 99%

Length Variation in Age‐0 Westslope Cutthroat Trout at Multiple Spatial Scales

McGrath

Scott

Rieman

2008

N American J Fish Manag

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Phenotypic diversity provides ecological and evolutionary functions, stabilizing populations in variable environments. Although benefits of larger body size in juvenile fishes are well documented, size variation may have value as well. We explored the distribution of length and length variation in age-0 westslope cutthroat trout Oncorhynchus clarkii lewisi at three spatial scales: area (10 2 km 2 ), stream (10 1 km 2 ), and site (10 0 km 2 ). In addition, we examined relationships between length variables (mean length and interquartile range of length) and instream (temperature and conductivity) and landscape (aspect, elevation, headwater distance, and valley width) variables that were expected to be associated with fish size. Conductivity was included as a surrogate for productivity. Most variation in mean length and interquartile range of fish length was found among areas (62.2% and 62.6%, respectively). Mean length also varied among streams and sites (21.9% and 15.8%, respectively). Similarly, interquartile range of fish length varied among streams and sites (19.1% and 18.3%, respectively). Both length variables were associated with temperature and elevation. Mean fish length was also associated with conductivity, but the association between interquartile length range and conductivity was weak. We conclude that the conservation of variation in phenotypic attributes, such as length, in westslope cutthroat trout may require conservation of viable populations across broad areas and across environmental gradients that are associated with growth.

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“…This principle occurs in many animal systems. For example, in juvenile salmon (Oncorhynchus kisutch) the negative correlation between body size and risk taking is an example of asset protection, whereby larger animals assume less predation risk to protect their greater accumulated fitness value (Reinhardt and Healey, 1999). Also, future fitness has important consequences for variation in a risky behaviour such as helping effort in eusocial wasps (Field and Cant, 2009).…”

Section: Discussionmentioning

confidence: 98%

Reproductive state affects hiding behaviour under risk of predation but not exploratory activity of female Spanish terrapins

Ibáñez

Marzal

López

et al. 2015

Behavioural Processes

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Female investment during reproduction may reduce survivorship due to increased predation risk. During pregnancy, the locomotor performance of gravid females might be diminished due to the additional weight acquired. In addition, egg production may also increase thermoregulatory, metabolic and physiological costs. Also, pregnant females have greater potential fitness and should take fewer risks. Thus, females should ponder their reproductive state when considering their behavioural responses under risky situations. Here, we examine how reproductive state influence risk-taking behaviour in different contexts in female Spanish terrapins (Mauremys leprosa). We simulated predator attacks of different risk levels and measured the time that the turtles spent hiding entirely inside their own shells (i.e. appearance times). We also assessed the subsequent time after emergence from the shell that the turtles spent immobile monitoring for predators before starting to escape actively (i.e. waiting times). Likewise, we performed a novel-environment test and measured the exploratory activity of turtles. We found no correlations between appearance time, waiting time or exploratory activity, but appearance times were correlated across different risk levels. Only appearance time was affected by the reproductive state, where gravid females reappeared relatively later from their shells after a predator attack than non-gravid ones. Moreover, among gravid females, those carrying greater clutches tended to have longer appearance times. This suggests that only larger clutches could affect hiding behaviour in risky contexts. In contrast, waiting time spent scanning for predators and exploratory activity were not affected by the reproductive state. These differences between gravid and non-gravid females might be explained by the metabolic-physiological costs associated with egg production and embryo maintenance, as well as by the relatively higher potential fitness of gravid females.

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Season- and size-dependent risk taking in juvenile coho salmon: experimental evaluation of asset protection

Cited by 40 publications

References 0 publications

State-dependent behavior and alternative behavioral strategies in brown trout (Salmo trutta L.) fry

State-dependent behavior and alternative behavioral strategies in brown trout (Salmo trutta L.) fry

Length Variation in Age‐0 Westslope Cutthroat Trout at Multiple Spatial Scales

Reproductive state affects hiding behaviour under risk of predation but not exploratory activity of female Spanish terrapins

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