Evolutionary impact of size-selective harvesting on shoaling behavior: Individual-level mechanisms and possible consequences for natural and fishing mortality

Harvesting forage fish can prevent fishing-induced population collapses of large piscivorous fish

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1917079118 ◽

2021 ◽

Vol 118 (6) ◽

pp. e1917079118 ◽

Cited By ~ 2

Author(s):

Floor H. Soudijn ◽

P. Daniël van Denderen ◽

Mikko Heino ◽

Ulf Dieckmann ◽

André M. de Roos

Keyword(s):

Community Dynamics ◽

Size Structure ◽

Stock Assessment ◽

Fish Stock ◽

Forage Fish ◽

Fishing Mortality ◽

Positive Interaction ◽

Individual Level ◽

Piscivorous Fish ◽

The Baltic

Fisheries have reduced the abundances of large piscivores—such as gadids (cod, pollock, etc.) and tunas—in ecosystems around the world. Fisheries also target smaller species—such as herring, capelin, and sprat—that are important parts of the piscivores’ diets. It has been suggested that harvesting of these so-called forage fish will harm piscivores. Multispecies models used for fisheries assessments typically ignore important facets of fish community dynamics, such as individual-level bioenergetics and/or size structure. We test the effects of fishing for both forage fish and piscivores using a dynamic, multitrophic, size-structured, bioenergetics model of the Baltic Sea. In addition, we analyze historical patterns in piscivore-biomass declines and fishing mortalities of piscivores and forage fish using global fish-stock assessment data. Our community-dynamics model shows that piscivores benefit from harvesting of their forage fish when piscivore fishing mortality is high. With substantial harvesting of forage fish, the piscivores can withstand higher fishing mortality. On the other hand, when piscivore fishing mortality is low, piscivore biomass decreases with more fishing of the forage fish. In accordance with these predictions, our statistical analysis of global fisheries data shows a positive interaction between the fishing mortalities of forage-fish stocks and piscivore stocks on the strength of piscivore-biomass declines. While overfishing of forage fish must be prevented, our study shows that reducing fishing pressures on forage fish may have unwanted negative side effects on piscivores. In some cases, decreasing forage-fish exploitation could cause declines, or even collapses, of piscivore stocks.

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Size-selective harvesting and individual personality in a social fish

10.32942/osf.io/ze9nv ◽

2019 ◽

Author(s):

Valerio Sbragaglia ◽

Josep Alós ◽

Kim Fromm ◽

Christopher T. Monk ◽

Carlos Díaz-Gil ◽

...

Keyword(s):

Personality Traits ◽

Risk Taking ◽

Fishing Mortality ◽

Behavioral Differences ◽

Behavioral Traits ◽

Selective Harvesting ◽

Individual Personality ◽

Selective Harvest ◽

The Mean ◽

Induced Changes

In fisheries worldwide, larger fish are subjected to substantially greater fishing mortality than smaller fish. Body length and behavioral traits are often correlated, such that fisheries-induced changes in either behaviour or morphology can also alter other traits as result of direct or indirect selection. Consistent behavioral differences among individuals, known as personality traits, provide the proximate framework by which selection can act; however, empirical evidence regarding how size-selective harvesting alters mean personality traits in exploited stocks is scarce. We examined three experimental lines of zebrafish (Danio rerio) that were exposed to positive, negative or random size-selective harvest over five generations to investigate whether simulated fishing changed the mean personality of the survivors five generations after harvesting was halted. We found that females mean boldness (defined as risk-taking tendency), activity and sociability were significantly altered relative to a randomly harvested line; however, harvest-induced changes in personality were only detected in the negatively size-selected line, in which 75% of the smallest fishes were harvested. By contrast, we did not find evidence for harvest-induced evolution of personality in the positively size-selected line, in which 75% of the largest fishes were harvested. We conclude that size-selective harvesting alters individual fish personality in a social fish.

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The shoaling behavior of two cyprinid species in conspecific and heterospecific groups

PeerJ ◽

10.7717/peerj.3397 ◽

2017 ◽

Vol 5 ◽

pp. e3397 ◽

Cited By ~ 13

Author(s):

Zhong-Hua Tang ◽

Hui Wu ◽

Qing Huang ◽

Lu Kuang ◽

Shi-Jian Fu

Keyword(s):

Swimming Speed ◽

Collective Motion ◽

Species Group ◽

Activity Level ◽

Mixed Species ◽

Individual Level ◽

Cyprinid Species ◽

Percent Time ◽

Significant Difference ◽

Shoaling Behavior

Mixed-species shoals of fish are frequently found in the field; however, little is known about individual-level interactions within these groups. We examined the collective motion of two cyprinid species (Chinese bream, Parabramis pekinensis, and qingbo, Spinibarbus sinensis) that occupy partially overlapping habitats but differ in social behavior (high vs low aggressiveness) and preferred flow regime (slow vs fast water velocity). We extracted measures of collective motion from video recordings of eight replicate groups of four individuals of either Chinese bream or qingbo (conspecific group) or two Chinese bream plus two qingbo (heterospecific group). Chinese bream in conspecific groups showed lower percent time moving and mean swimming speed but a similar speed while moving as compared to the qingbo conspecific groups. However, the difference in mean swimming speed and percent time moving vanished in the heterospecific group as Chinese bream elevated their swimming activity to coordinate with qingbo. This finding suggests that the two species may share similar interaction rules regarding shoaling behavior. The conspecific groups of qingbo exhibited a greater distance between group members than Chinese bream, suggesting a difference in cohesion. However, the inter-individual distances of all fish were similar in the heterospecific group. Qingbo in the heterospecific group swam more frequently at the front compared to Chinese bream, possibly due to their higher activity level. We also measured the startle response to an artificial stimulus and found that there was no significant difference among groups. In conclusion, the present study demonstrated that in the heterospecific groups, Chinese bream elevated their percent time moving while qingbo decreased their inter-individual distance to achieve consistent collective movement; thus, the two species showed similar behavior in the mixed-species group.

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Proportion of Individuals With Past-Year Suicidal Ideation Who Attempted Suicide Over the Past 10 Years in the United States, and the Influence of Age and Sex

Crisis ◽

10.1027/0227-5910/a000690 ◽

2020 ◽

pp. 1-5

Author(s):

Shannon Lange ◽

Courtney Bagge ◽

Charlotte Probst ◽

Jürgen Rehm

Keyword(s):

United States ◽

Suicidal Ideation ◽

Random Effects ◽

Attempted Suicide ◽

Suicide Attempts ◽

The United States ◽

Individual Level ◽

The Past ◽

Meta Analyses ◽

Age Category

Abstract. Background: In recent years, the rate of death by suicide has been increasing disproportionately among females and young adults in the United States. Presumably this trend has been mirrored by the proportion of individuals with suicidal ideation who attempted suicide. Aim: We aimed to investigate whether the proportion of individuals in the United States with suicidal ideation who attempted suicide differed by age and/or sex, and whether this proportion has increased over time. Method: Individual-level data from the National Survey on Drug Use and Health (NSDUH), 2008–2017, were used to estimate the year-, age category-, and sex-specific proportion of individuals with past-year suicidal ideation who attempted suicide. We then determined whether this proportion differed by age category, sex, and across years using random-effects meta-regression. Overall, age category- and sex-specific proportions across survey years were estimated using random-effects meta-analyses. Results: Although the proportion was found to be significantly higher among females and those aged 18–25 years, it had not significantly increased over the past 10 years. Limitations: Data were self-reported and restricted to past-year suicidal ideation and suicide attempts. Conclusion: The increase in the death by suicide rate in the United States over the past 10 years was not mirrored by the proportion of individuals with past-year suicidal ideation who attempted suicide during this period.

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Development and Validation of a German Language Unit-Level Organizational Citizenship Behavior (OCB) Scale

European Journal of Psychological Assessment ◽

10.1027/1015-5759/a000558 ◽

2020 ◽

Vol 36 (5) ◽

pp. 852-863 ◽

Cited By ~ 1

Author(s):

George Gunnesch-Luca ◽

Klaus Moser

Keyword(s):

Factor Analysis ◽

Organizational Citizenship ◽

Organizational Citizenship Behavior ◽

Helping Behavior ◽

Citizenship Behavior ◽

German Language ◽

Individual Level ◽

Unit Level ◽

Confirmatory Factor ◽

Development And Validation

Abstract. The current paper presents the development and validation of a unit-level Organizational Citizenship Behavior (OCB) scale based on the Referent-Shift Consensus Model (RSCM). In Study 1, with 124 individuals measured twice, both an Exploratory Factor Analysis (EFA) and a Confirmatory Factor Analysis (CFA) established and confirmed a five-factor solution (helping behavior, sportsmanship, loyalty, civic virtue, and conscientiousness). Test–retest reliabilities at a 2-month interval were high (between .59 and .79 for the subscales, .83 for the total scale). In Study 2, unit-level OCB was analyzed in a sample of 129 work teams. Both Interrater Reliability (IRR) measures and Interrater Agreement (IRA) values provided support for RSCM requirements. Finally, unit-level OCB was associated with group task interdependence and was more predictable (by job satisfaction and integrity of the supervisor) than individual-level OCB in previous research.

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Differential Effects of Competence and Morality on Self-Esteem at the Individual and the Collective Level

Social Psychology ◽

10.1027/1864-9335/a000410 ◽

2020 ◽

Vol 51 (3) ◽

pp. 183-198

Author(s):

Wiktor Soral ◽

Mirosław Kofta

Keyword(s):

Self Esteem ◽

Differential Effects ◽

Individual Level ◽

The Subject ◽

The Individual

Abstract. The importance of various trait dimensions explaining positive global self-esteem has been the subject of numerous studies. While some have provided support for the importance of agency, others have highlighted the importance of communion. This discrepancy can be explained, if one takes into account that people define and value their self both in individual and in collective terms. Two studies ( N = 367 and N = 263) examined the extent to which competence (an aspect of agency), morality, and sociability (the aspects of communion) promote high self-esteem at the individual and the collective level. In both studies, competence was the strongest predictor of self-esteem at the individual level, whereas morality was the strongest predictor of self-esteem at the collective level.

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