Assessing Evolutionary Consequences of Size-selective Recreational Fishing on Multiple Life-history Traits, with an Application To Northern Pike (Esox lucius)

Despite mounting recognition of the importance of fishing-induced evolution, methods for quantifying selection pressures on multiple adaptive traits affected by size-selective harvesting are still scarce. We study selection differentials on three life-history traits - reproductive investment, size at maturation, and growth capacity - under size-selective exploitation of northern pike (Esox lucius L.) with recreational-fishing gear. An age-structured population model is presented that accounts for the eco-evolutionary feedback arising from density-dependent and frequency-dependent selection. By introducing minimum-length limits, maximum-length limits, and combinations of such limits (resulting in harvestable-slot length limits) into the model, we examine the potential of simple management tools for mitigating selection pressures induced by recreational fishing. With regard to annual reproductive investment, we find that size-selective fishing mortality exerts relatively small positive selection differentials. By contrast, selection differentials on size at maturation are large and consistently negative. Selection differentials in growth capacity are often large and positive, but become negative when a certain range of minimum-length limits are applied. In general, the strength of selection is reduced by implementing more stringent management policies, but each life-history trait responds differently to the introduction of specific harvest regulations. Based on a simple genetic inheritance model, we examine mid- and long-term evolutionary changes of the three life-history traits and their impacts on the size spectrum and yield of pike. In general, fishing-induced evolution reduces sizes and yields, but details depend on a variety of factors such as the specific regulation in place. We find no regulation that is successful in reducing to zero all selection pressures on life-history traits induced by recreational fishing. Accordingly, we must expect that inducing some degree of evolution through recreational fishing is inevitable

Explaining participation rates in recreational fishing across industrialised countries

On average, 10.52% of the total population was found to fish for recreation across the industrialised world (N = 27 countries), amounting to an estimated 118 million (95% confidence interval 81–154 million) people in North America, Europe and Oceania. Participation rates declined with population density and gross domestic product, indicating a negative effect of urbanisation and post-modernisation on fishing interest. Participation rates also declined with increasing median age, average household size and unemployment rate, suggesting resource limitation to constrain participation in fishing. By contrast, two indicators of the cultural importance of fish (fish landings and per capita fish consumption) and an indicator of perceived need for leisure (weekly working hours) were positively correlated with fishing participation. Based on these findings, which explained 60% of the variance in fishing participation across the industrialised world, reduced fishing interest is to be expected with post-industrialisation. Dedicated management and marketing intervention is needed to reverse the track of diminishing fishing interest in industrialised countries

Diversity and complexity of angler behavior drive socially optimal input and output regulations in a bioeconomic recreational-fisheries model

In many areas of the world, recreational fisheries are not managed sustainably. This might be related to the omission or oversimplification of angler behaviour and angler heterogeneity in fisheries-management models. We present an integrated bioeconomic modelling approach to examine how differing assumptions about angler behaviour, angler preferences, and composition of the angler population altered predictions about optimal recreational-fisheries management, where optimal regulations were determined by maximizing aggregated angler utility. We report four main results derived for a prototypical northern pike (Esox lucius) fishery. First, accounting for dynamic angler behaviour changed predictions about optimal angling regulations. Second, optimal input and output regulations varied substantially among different angler types. Third, the composition of the angler population in terms of angler types was important for determining optimal regulations. Fourth, the welfare measure used to quantify aggregated utility altered the predicted optimal regulations, highlighting the importance of choosing welfare measures that closely reflect management objectives. A further key finding was that socially optimal angling regulations resulted in biological sustainability of the fish population. Managers can use the novel integrated modelling framework introduced here to account, quantitatively and transparently, for the diversity and complexity of angler behaviour when determining regulations that maximize social welfare and ensure biological sustainability

Fish life history, angler behaviour, and optimal management of recreational fisheries

To predict recreational-fishing impacts on freshwater fish species, it is important to understand the interplay among fish populations, anglers, and management actions. We use an integrated bioeconomic model to study the importance of fish life-history type (LHT) for determining (i) vulnerability to overexploitation by diverse angler types (generic, consumptive, and trophy anglers), who respond dynamically to fishing-quality changes; (ii) regulations (i.e., minimum-size limits and license densities) that maximize the social welfare of angler populations; and (iii) biological and social conditions resulting under such socially optimal regulations. We examine five prototypical freshwater species: European perch (Perca fluviatilis), brown trout (Salmo trutta), pikeperch (Sander lucioperca), pike (Esox lucius), and bull trout (Salvelinus confluentus). We find that LHT is important for determining the vulnerability of fish populations to overfishing, with pike, pikeperch, and bull trout being more vulnerable than perch and brown trout. Angler type influences the magnitude of fishing impacts, due to differences in fishing practices and angler-type-specific effects of LHT on angling effort. Our results indicate that angler types are systematically attracted to particular LHTs. Socially optimal minimum-size limits generally increase with LHT vulnerability, whereas optimal license densities are similar across LHTs. Yet, both regulations vary among angler types. Despite this variation, we find that biological sustainability occurs under socially optimal regulations, with one exception. Our results highlight the importance of jointly considering fish diversity, angler diversity, and regulations when predicting sustainable management strategies for recreational fisheries. Failure to do so could result in socially suboptimal management, fishery collapse, or both

Standardizing selection strengths to study selection in the wild: A critical comparison and suggestions for the future

We critically review the main approaches for standardizing and comparing selection differentials and gradients among traits, populations, and species and assess their differential merits. In particular, we explain why the most widespread approach to standardizing selection, which measures selection differentials in units of a trait's phenotypic standard deviation, is less appropriate for characterizing strengths of natural selection in wild populations. In contrast, an alternative standardization approach, which uses a trait's phenotypic mean in addition to its standard deviation, results in another dimensionless measure - the mean-standardized selection gradient. This measure offers some key benefits over alternative approaches - such as ease of interpretation, independence of a trait's variance, and the natural interfacing of ecological and evolutionary dynamics - and yet remains rarely used by evolutionary biologists. We explain how the more routine application of this measure will facilitate comparisons of selection strengths in the wild among traits, populations, and species

Food Insecurity as a Predictor of Hurricane Exposure among Underserved Adolescents

Low-income populations are at increased risk for experiencing negative hurricane exposures and food insecurity. However, little is known regarding how pre-hurricane food insecurity experiences are related to youth hurricane exposure. This study examined the types of hurricane disaster exposures low-income, ethnic minority adolescents experienced during Hurricane Harvey and examined the association between food insecurity and hurricane exposure. Low-income adolescents (n = 185) were recruited from a Houston-area school district. Two days before the hurricane, food insecurity was assessed. Adolescents with at least one affirmative answer on the 9-item USDA Child Food Security Survey Module were classified as food insecure. Adolescents self-reported hurricane exposure three weeks post-hurricane using both the National Child Traumatic Stress Network Hurricane and Assessment Referral Tool and Survey of Hurricane Katrina Evacuees. Affirmative answers to lacking access to food, water, or medicine, being rescued, home damage, and displacement were each given a score of one and summed to create an overall hurricane exposure score. A covariate-adjusted linear regression model regressed overall hurricane exposure onto food insecurity. Separate covariate-adjusted logistic regression models were performed where each individual hurricane exposure was regressed onto food insecurity. Prior to the hurricane, 46% of adolescents experienced food insecurity and 43% experienced hurricane exposure. Pre-hurricane food insecurity (p = 0.004) and being foreign born (p = 0.033) were associated with increased hurricane exposure. Adolescents who experienced food insecurity had 132% higher odds of lacking access to fresh water (p = 0.047) and 105% higher odds of lacking access to food (p = 0.034) during the hurricane. Food insecurity and immigrant status appear to be at-risk indicators for hurricane exposure. Schools serving underserved adolescents could consider assessing food security and immigration status as part of disaster preparedness programs

Body length rather than routine metabolic rate and body condition correlates with activity and risk-taking in juvenile zebrafish Danio rerio

In this study, the following hypotheses were explored using zebrafish Danio rerio: (1) individuals from the same cohort differ consistently in activity and risk-taking and (2) variation in activity and risk-taking is linked to individual differences in metabolic rate, body length and body condition. To examine these hypotheses, juvenile D. rerio were tested for routine metabolic rate and subsequently exposed to an open field test. Strong evidence was found for consistent among-individual differences in activity and risk-taking, which were overall negatively correlated with body length, i.e. larger D. rerio were found to be less active in a potentially dangerous open field and a similar trend was found with respect to a more direct measure of their risk-taking tendency. In contrast, routine metabolic rate and body condition were uncorrelated with both activity and risk-taking of juvenile D. rerio. These findings suggest that body length is associated with risk-related behaviours in juvenile D. rerio for which larger, rather than smaller, individuals may have a higher risk of predation, while the role for routine metabolic rate is relatively limited or non-existent, at least under the conditions of the present study