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The greater argentine is a benthopelagic fish with a northern amphi-Atlantic and southern Arctic distribution. Landings of this species have been steadily increasing since the early 2000s, mainly for ultra-processed fish food. The rising economic importance of this species begs for an accurate delineation of the management units needed to ensure the sustainability of the fishery. The alignment between management and biological units was investigated on three of the ICES stocks in the NE Atlantic (123a4, 5a14, and 5b6a) by genotyping 88 ad hoc- developed SNPs on 1299 individuals sampled along the Norwegian coast, north of Shetland, around the Faroe Islands, and in the Denmark Strait within Icelandic waters. Candidate loci to positive selection were particularly crucial for units' delineation and supported the current ICES 5b6a and 5a14 stocks around the Faroe Islands and Iceland, respectively. However, within the third stock investigated, 123a4, which corresponded mainly to the Norwegian coast, the sample from area 3a (Skagerrak) was significantly different from all the remaining in the same stock. This differentiation advocates for reconsideration of the present policy and suggests considering ICES Area 3a (Skagerrak) as an independent management unit. The environmental conditions in the Skagerrak area have left a genetic print on other marine taxa, which could putatively be the case in the greater argentine. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Applied Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aquaculture of Atlantic salmon Salmo salar is in transition to precision fish farming and digitalization. As it is easier, cheaper and safer to study a digital replica than the system itself, a model of the fish can potentially improve monitoring and prediction of facilities and operations and replace live fish in many what‐if experiments. Regulators, consumers and voters also want insight into how it is like to be a salmon in aquaculture. However, such information is credible only if natural physiology and behaviour of the living fish is adequately represented. To be able to predict salmon behaviour in unfamiliar, confusing and stressful situations, the modeller must aim for a sufficiently realistic behavioural model based on the animal's proximate robustness mechanisms. We review the knowledge status and algorithms for how evolution has formed fish to control decisions and set priorities for behaviour and ontogeny. Teleost body control is through genes, hormones, nerves, muscles, sensing, cognition and behaviour, the latter being agentic, predictive and subjective, also in a man‐made environment. These are the challenges when constructing the digital salmon. This perspective is also useful for modelling other domesticated and wild animals in Anthropocene environments.Modern digitized aquaculture requires a digital twin of the Atlantic salmon Salmo salar: a realistic simulation replica of the fish physiology, life history and behaviour. It will be able to predict fish behavior in unfamiliar, confusing, and stressful situations based on proximate robustness mechanisms. We review the current knowledge on how evolution has shaped fish to set priorities and control decisions for adaptive behavior and ontogeny, and survey models and component algorithms for a biology‐based digital twin of the salmon. [ABSTRACT FROM AUTHOR]

This case study explores educational practices and processes in an interdisciplinary summer course addressing SDG14 (Life below water), SDG13 (Climate action), SDG4 (Education), SDG3 (Good health and wellbeing), and SDG17 (Partnerships). From May to August in 2022, students from 12 countries participated in an undergraduate summer course (SDG 200 Ocean–Climate–Society) on the sailship Statsraad Lehmkuhl as part of the One Ocean Expedition. Sustainability, marine biology, behavioral science, and sail training were core aspects of the daily assignments for the 86 students during the Pacific crossing from Chile to Tahiti. The students took part in watch duties 24–7 and were assigned to 18 working groups in their academic studies. Active learning approaches such as team-based learning and storytelling proved essential to engage students in interdisciplinary exchange on sustainability issues. A major challenge was to strike a balance between the academic work and the requirements from sea duties and life on board a sailship. Student feedback and assessment contribute to contextualize the learning experiences and personal development during the first five weeks on board. This case study provides an example of how life on a sailship can present a formative learning experience and an interdisciplinary laboratory to study and live in alignment with SDGs and with the overall mandate of the Global Agenda for Sustainable Development. [ABSTRACT FROM AUTHOR]

Sexual size dimorphism (SSD) is caused by differences in selection pressures and life‐history trade‐offs faced by males and females. Proximate causes of SSD may involve sex‐specific mortality, energy acquisition, and energy expenditure for maintenance, reproductive tissues, and reproductive behavior. Using a quantitative, individual‐based, eco‐genetic model parameterized for North Sea plaice, we explore the importance of these mechanisms for female‐biased SSD, under which males are smaller and reach sexual maturity earlier than females (common among fish, but also arising in arthropods and mammals). We consider two mechanisms potentially serving as ultimate causes: (a) Male investments in male reproductive behavior might evolve to detract energy resources that would otherwise be available for somatic growth, and (b) diminishing returns on male reproductive investments might evolve to reduce energy acquisition. In general, both of these can bring about smaller male body sizes. We report the following findings. First, higher investments in male reproductive behavior alone cannot explain the North Sea plaice SSD. This is because such higher reproductive investments require increased energy acquisition, which would cause a delay in maturation, leading to male‐biased SSD contrary to observations. When accounting for the observed differential (lower) male mortality, maturation is postponed even further, leading to even larger males. Second, diminishing returns on male reproductive investments alone can qualitatively account for the North Sea plaice SSD, even though the quantitative match is imperfect. Third, both mechanisms can be reconciled with, and thus provide a mechanistic basis for, the previously advanced Ghiselin–Reiss hypothesis, according to which smaller males will evolve if their reproductive success is dominated by scramble competition for fertilizing females, as males would consequently invest more in reproduction than growth, potentially implying lower survival rates, and thus relaxing male–male competition. Fourth, a good quantitative fit with the North Sea plaice SSD is achieved by combining both mechanisms while accounting for sex‐specific costs males incur during their spawning season. Fifth, evolution caused by fishing is likely to have modified the North Sea plaice SSD. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Density-dependent growth, which might influence the effects of fisheries on a population, is often ignored when management strategies are evaluated, mainly due to a lack of appropriate models readily available to be implemented. To improve on this, we investigated if somatic growth in Norwegian spring-spawning herring (Clupea harengus) depends on cohort density using a formulation of the von Bertalanffy growth function on cohorts from 1921 to 2014 and found a significant negative correlation between estimated asymptotic length and density. This clearly indicates density-dependent effects on growth, and we propose a model that can be used to predict the size-at-age of Norwegian spring-spawning herring as a function of herring density (the abundance of two successive cohorts) in short-term predictions of catch advice, and in Management strategy evaluations, including estimation of their reference points such as F MSY. [ABSTRACT FROM AUTHOR]

Unaccounted mortality caused by discarding or pre-catch losses is a major challenge for fisheries management. In pelagic fisheries, a considerable proportion of catches may be lost due to intentional release of unwanted catch (slipping) or net bursts (fishing net tears due to the weight of the catch). Here we review and estimate ranges of discard and pre-catch mortality for two important pelagic fisheries, the Northeast Atlantic (NEA) mackerel and Norwegian spring spawning (NSS) herring, and explore the effects on stock estimates and catch advice. We show that mortality caused by discarding, slipping, and net bursts is unknown but probably corresponds to a considerable percentage of total registered catches. Including estimated unaccounted mortality into assessment models leads to underestimation of the stock levels by 3.7–19.5% and 2.8–6.8% for NEA mackerel and NSS herring, respectively, corresponding to up to several million tonnes of fish that die annually due to fishing without being landed. If discard and pre-catch mortality were eliminated, allowed catches could increase by 10–20%. We demonstrate that unaccounted mortality in pelagic fisheries may be substantial, affecting stock estimates and catch advice. This may undermine the sustainable management and efficient use of pelagic resources. [ABSTRACT FROM AUTHOR]

Beverton and Holt's (1957. On the dynamics of exploited fish populations. UK Ministry of Agriculture, Fisheries and Food. Fisheries Investigations, 2: 533 pp.) monograph contributed a widely used stock–recruitment relationship (BH-SRR) to fisheries science. However, because of variation around a presumed relationship between spawning biomass and recruits, the BH-SRR is often considered inadequate and approached merely as a curve-fitting exercise. The commonly used and simplified version of the BH-SRR has eclipsed the fact that in their classic monograph, the derivation accounted for mechanistic recruitment processes, including multi-stage recruitment with explicit cohort-dependent and -independent mortality terms that represent competition between recruits and extrinsic, cohort-independent factors such as the environment or predation as two independent sources of mortality. The original BH-SRR allows one to recreate recruitment patterns that correspond to observed ones. Doing so shows that variation in density-independent mortality increases the probability of overlooking an underlying stock–recruitment relationship. Intermediate coefficients of variation in mortality (75–100%) are sufficient to mask stock–recruitment relationships and recreate recruitment time series most similar to empirical data. This underlines the importance of variation in survival for recruitment and that Beverton and Holt's work still provides a fundamental and useful tool to model the dynamics of populations. [ABSTRACT FROM AUTHOR]

Reproductive investment is a central trait for population dynamics and productivity. Fishing and environmental variations are major drivers affecting population structure, dynamics, and adaptation of life-history and behavioural traits. However, those factors are often considered independently, and few studies take into account their joint effect. In this study, we investigate the contribution of environment, fishing pressure, and intra-specific competition to variation in the reproductive investment of the Norwegian spring-spawning herring (Clupea harengus), a stock that has been fished for centuries, and monitored for decades. Reproductive investment and post-spawning weight were affected differently by growth rate (measured as mean age-at-length), sea surface temperature, North Atlantic Oscillation, and spawning stock biomass in periods with no fishing, unselective fishing, and low but size-selective fishing. We hypothesize that those changes can be explained by direct effects of exploitation such as age truncation and changes in migration patterns. Our results highlight how fishing, by affecting population-level dynamics, can modify the impact of environmental variations on life-history traits. [ABSTRACT FROM AUTHOR]

The effect of size-selective predation on prey communities and their traits is well documented, but the relative roles of genetic adaptation and phenotypic plasticity continue to be debated. We looked for evidence of genetic adaption in a population of the water flea Daphnia pulex that faced a novel, introduced predator, Eurasian perch (Perca fluviatilis), selectively preying upon large zooplankton. Theory predicts adaptive changes towards a faster life history. We compared growth, age and length at maturation, egg size, and fecundity of two groups of clones kept in common-garden conditions, 13 clones isolated at around the time of the perch introduction and 14 isolated 3 years after. All animals were photographed daily and observed every third hour to detect maturation and measure the clutch size. Post-introduction clones matured earlier, but this was an indirect response triggered by genetic change in growth: post-introduction clones had faster growth prior to maturation than pre-introduction ones, reaching earlier the size threshold for maturation, but the threshold itself remained unchanged. Post-introduction clones showed also higher clutch size for 2nd and 3rd clutch, and slower growth from maturation (first appearance of eggs) to the moult after the release of the first clutch. Egg size did not differ between the periods. The experiment shows how life-history responses to predation involve multiple interlinked traits and both direct and indirect genetic responses. [ABSTRACT FROM AUTHOR]

Recruitment dynamics are challenging to assess or predict because of the many underlying drivers that vary in their relevance over time and space. Stock size, demographic and trait composition, condition and distribution of spawning fish and the spatio‐temporal dynamics of trophic and environmental interactions all influence recruitment processes. Exploring common patterns among stocks and linking them to potential drivers may therefore provide insights into key mechanisms of recruitment dynamics. Here, we analysed stock‐recruitment data of 64 stocks from the north‐east Atlantic Ocean for common trends in variation and synchrony among stocks using correlation, cluster and dynamic factor analyses. We tested common trends in recruitment success for relationships with large‐scale environmental processes as well as stock state indicators, and we explored links between recruitment success and demographic, environmental and ecological variables for a subset of individual stocks. The results revealed few statistically significant correlations between stocks but showed that underlying common trends in recruitment success are linked to environmental indices and management indicators. Statistical analyses confirmed previously suggested relationships of environmental–ecological factors such as the subpolar gyre and Norwegian coastal current with specific stocks, and indicated a large relevance of spawning stock biomass and demographics, as well as predation, whereas other suggested relationships were not supported by the data. Our study shows that despite persistent challenges in determining drivers of recruitment due to poor data quality and unclear mechanisms, combining different data analysis techniques can improve our understanding of recruitment dynamics in fish stocks. [ABSTRACT FROM AUTHOR]

Fishing gears are designed to exploit the natural behaviors of fish, and the concern that fishing may cause evolution of behavioral traits has been receiving increasing attention. The first intuitive expectation is that fishing causes evolution toward reduced boldness because it selectively removes actively foraging individuals due to their higher encounter rate and vulnerability to typical gear. However, life‐history theory predicts that fishing, through shortened life span, favors accelerated life histories, potentially leading to increased foraging and its frequent correlate, boldness. Additionally, individuals with accelerated life histories mature younger and at a smaller size and therefore spend more of their life at a smaller size where mortality is higher. This life‐history evolution may prohibit increases in risk‐taking behavior and boldness, thus selecting for reduced risk‐taking and boldness. Here, we aim to clarify which of these three selective patterns ends up being dominant. We study how behavior‐selective fishing affects the optimal behavioral and life‐history traits using a state‐dependent dynamic programming model. Different gear types were modeled as being selective for foraging or hiding/resting individuals along a continuous axis, including unselective fishing. Compared with unselective harvesting, gears targeting hiding/resting individuals led toward evolution of increased foraging rates and elevated natural mortality rate, while targeting foraging individuals led to evolution of decreased foraging rates and lower natural mortality rate. Interestingly, changes were predicted for traits difficult to observe in the wild (natural mortality and behavior) whereas the more regularly observed traits (length‐at‐age, age at maturity, and reproductive investment) showed only little sensitivity to the behavioral selectivity. Using a state‐dependent dynamic programming model, we aimed at clarifying theoretical expectations about how behavior‐selective fishing can shape the evolution of risk‐taking behavior, life‐history traits, and emergent natural mortality. First, our results are in line with earlier findings that an increased fishing mortality leads to increased natural mortality, earlier maturation, reduced size at age, and increased reproductive investment. Second, we found that the intensity of changes in natural mortality, length, and risk‐taking behavior depends on whether fishing is targeting active, foraging ("bold") fish, or passive, sheltering ("timid") fish. [ABSTRACT FROM AUTHOR]

Uncertain and inaccurate estimates are a prevailing problem in stock assessment, despite increasingly sophisticated estimation methods and substantial usage of scientific and financial resources. Annual scientific surveys and assessment group meetings require frequent use of research vessels and skilled research staff and are, therefore, particularly costly. This data- and work-intensive approach is often considered paramount for reliable stock estimates and risk management. However, it remains an open question whether the benefits of increasing assessment effort outweigh its marginal costs, or whether the potential impacts of investing less in assessments could generate net benefits. In this study, we explore how different scenarios of reduced survey and assessment frequencies affect estimated stock biomass, predicted catch, and uncertainty. Data of two Northeast Atlantic stocks, blue whiting (Micromesistius poutassou) and Norwegian spring-spawning herring (Clupea harengus), and a widely applied stock assessment model are used to compare the impacts of removing surveys and/or annual assessments. The results show that lower survey and/or assessment frequencies tend to result in deviating estimates of spawning-stock biomass and catch and larger confidence intervals, the observed differences being, however, mostly small. While scenarios without a survey datapoint in the assessment year generally produced the largest deviations in estimates, biannual surveys in general did not affect assessment performance substantially. This indicates that a reduced frequency of surveys and assessments could be an acceptable measure to reduce assessment costs and increase the efficiency of fisheries management, particularly when accompanied by thorough management strategy evaluations and risk assessments. [ABSTRACT FROM AUTHOR]

Managing fisheries resources to maintain healthy ecosystems is one of the main goals of the ecosystem approach to fisheries ( EAF). While a number of international treaties call for the implementation of EAF, there are still gaps in the underlying methodology. One aspect that has received substantial scientific attention recently is fisheries-induced evolution ( FIE). Increasing evidence indicates that intensive fishing has the potential to exert strong directional selection on life-history traits, behaviour, physiology, and morphology of exploited fish. Of particular concern is that reversing evolutionary responses to fishing can be much more difficult than reversing demographic or phenotypically plastic responses. Furthermore, like climate change, multiple agents cause FIE, with effects accumulating over time. Consequently, FIE may alter the utility derived from fish stocks, which in turn can modify the monetary value living aquatic resources provide to society. Quantifying and predicting the evolutionary effects of fishing is therefore important for both ecological and economic reasons. An important reason this is not happening is the lack of an appropriate assessment framework. We therefore describe the evolutionary impact assessment ( Evo IA) as a structured approach for assessing the evolutionary consequences of fishing and evaluating the predicted evolutionary outcomes of alternative management options. Evo IA can contribute to EAF by clarifying how evolution may alter stock properties and ecological relations, support the precautionary approach to fisheries management by addressing a previously overlooked source of uncertainty and risk, and thus contribute to sustainable fisheries. [ABSTRACT FROM AUTHOR]

Heino, M., Baulier, L., Boukal, D. S., Ernande, B., Johnston, F. D., Mollet, F. M., Pardoe, H., Therkildsen, N. O., Uusi-Heikkilä, S., Vainikka, A., Arlinghaus, R., Dankel, D. J., Dunlop, E. S., Eikeset, A. M., Enberg, K., Engelhard G. H., Jørgensen, C., Laugen, A. T., Matsumura, S., Nusslé, S., Urbach, D., Whitlock, R., Rijnsdorp, A. D., and Dieckmann, U. 2013. Can fisheries-induced evolution shift reference points for fisheries management? – ICES Journal of Marine Science, 70: 707–721.Biological reference points are important tools for fisheries management. Reference points are not static, but may change when a population's environment or the population itself changes. Fisheries-induced evolution is one mechanism that can alter population characteristics, leading to “shifting” reference points by modifying the underlying biological processes or by changing the perception of a fishery system. The former causes changes in “true” reference points, whereas the latter is caused by changes in the yardsticks used to quantify a system's status. Unaccounted shifts of either kind imply that reference points gradually lose their intended meaning. This can lead to increased precaution, which is safe, but potentially costly. Shifts can also occur in more perilous directions, such that actual risks are greater than anticipated. Our qualitative analysis suggests that all commonly used reference points are susceptible to shifting through fisheries-induced evolution, including the limit and “precautionary” reference points for spawning-stock biomass, Blim and Bpa, and the target reference point for fishing mortality, F0.1. Our findings call for increased awareness of fisheries-induced changes and highlight the value of always basing reference points on adequately updated information, to capture all changes in the biological processes that drive fish population dynamics. [ABSTRACT FROM PUBLISHER]

Skagen, D. W., Skern-Mauritzen, M., Dankel, D., Enberg, K., Kjesbu, O. S., and Nash, R. D. M. 2013. A simulation framework for evaluating fisheries management decisions using environmental information. – ICES Journal of Marine Science, 70: 743–754.The population dynamics of marine fish stocks are influenced by both physical and biological conditions. Yet, such environmental impacts on stock dynamics, and hence stock production, are rarely included in applied fisheries management. To test the utility of taking ecosystem information into account in management decisions requires efficient tools. We propose a simulation framework for evaluating fisheries management schemes that use environmental information as part of the decision basis. A key feature is to link environmental signals to parameters in functions that define the population dynamics. This allows a direct incorporation of environmental drivers into models of population dynamic processes and emphasizes the need for a quantitative understanding of the influence of environmental drivers on such processes. The utility of the simulation framework is demonstrated through a worked example with different management scenarios, where decisions to increase or decrease the exploitation rely on environmental indicators only, or also on information on stock abundance. In this example, a management that was based on indicators only, without updated measures of the state of the stock itself, failed to respond adequately to changes in stock productivity. [ABSTRACT FROM PUBLISHER]

The interest in fishing-induced life-history evolution has been growing in the last decade, in part because of the increasing number of studies suggesting evolutionary changes in life-history traits, and the potential ecological and economic consequences these changes may have. Among the traits that could evolve in response to fishing, growth has lately received attention. However, critical reading of the literature on growth evolution in fish reveals conceptual confusion about the nature of 'growth' itself as an evolving trait, and about the different ways fishing can affect growth and size-at-age of fish, both on ecological and on evolutionary time-scales. It is important to separate the advantages of being big and the costs of growing to a large size, particularly when studying life-history evolution. In this review, we explore the selection pressures on growth and the resultant evolution of growth from a mechanistic viewpoint. We define important concepts and outline the processes that must be accounted for before observed phenotypic changes can be ascribed to growth evolution. When listing traits that could be traded-off with growth rate, we group the mechanisms into those affecting resource acquisition and those governing resource allocation. We summarize potential effects of fishing on traits related to growth and discuss methods for detecting evolution of growth. We also challenge the prevailing expectation that fishing-induced evolution should always lead to slower growth. [ABSTRACT FROM AUTHOR]

Fisheries managers normally make decisions based on stock abundance estimates subject to process, observation, and model uncertainties. Considerable effort is invested in gathering information about stock size to decrease these uncertainties. However, few studies have evaluated benefits from collecting such information in terms of yield and stability of annual harvest. Here, we develop a strategic age-structured population model for a long-lived fish with stochastic recruitment, resembling the Norwegian spring-spawning herring (NSSH, Clupea harengus L.). We evaluate how uncertainties in population estimates influence annual yield, spawning stock biomass ( SSB), and variation in annual harvest, using both the proportional threshold harvesting (PTH) and the current harvest control rule for NSSH as harvest strategies. Results show that the consequences of a biased estimate are sensitive to the harvest strategy employed. If the harvest strategy is suitably chosen, the benefits of accurate information are low, and less information about the stock is necessary to maintain high average yield. Reduced harvest intensity effectively removes the need for accurate stock estimates. PTH (a variant of the constant escapement strategy) with low harvest ratio and the current NSSH harvest control rule both provide remarkable stability in yield and SSB. However, decreased uncertainty will often decrease year-to-year variation in harvest and the frequency of fishing moratoria. [ABSTRACT FROM AUTHOR]

Dickey-Collas, M., Nash, R. D. M., Brunel, T., van Damme, C. J. G., Marshall, C. T., Payne, M. R., Corten, A., Geffen, A. J., Peck, M. A., Hatfield, E. M. C., Hintzen, N. T., Enberg, K., Kell, L. T., and Simmonds, E. J. 2010. Lessons learned from stock collapse and recovery of North Sea herring: a review. – ICES Journal of Marine Science, 67: 1875–1886. The collapse and recovery of North Sea herring in the latter half of the 20th century had both ecological and economic consequences. We review the effect of the collapse and investigate whether the increased understanding about the biology, ecology, and stock dynamics gained in the past three decades can aid management to prevent further collapses and improve projections of recovery. Recruitment adds the most uncertainty to estimates of future yield and the potential to reach biomass reference points within a specified time-frame. Stock–recruitment relationships must be viewed as being fluid and dependent on ecosystem change. Likewise, predation mortality changes over time. Management aimed at maximum sustainable yield (MSY) fishing mortality targets implies interannual variation in TACs, and variability in supply is therefore unavoidable. Harvest control rules, when adhered to, aid management greatly. We advocate that well-founded science can substantially contribute to management through improved confidence and increased transparency. At present, we cannot predict the effects of collapse or recovery of a single stock on the ecosystem as a whole. Moreover, as managers try to reconcile commitments to single-species MSY targets with the ecosystem-based approach, they must consider the appropriate management objectives for the North Sea ecosystem as a whole. [ABSTRACT FROM PUBLISHER]

Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Worldwide depletion of fish stocks has led fisheries managers to become increasingly concerned about rebuilding and recovery planning. To succeed, factors affecting recovery dynamics need to be understood, including the role of fisheries-induced evolution. Here we investigate a stock’s response to fishing followed by a harvest moratorium by analyzing an individual-based evolutionary model parameterized for Atlantic cod Gadus morhua from its northern range, representative of long-lived, late-maturing species. The model allows evolution of life-history processes including maturation, reproduction, and growth. It also incorporates environmental variability, phenotypic plasticity, and density-dependent feedbacks. Fisheries-induced evolution affects recovery in several ways. The first decades of recovery were dominated by demographic and density-dependent processes. Biomass rebuilding was only lightly influenced by fisheries-induced evolution, whereas other stock characteristics such as maturation age, spawning stock biomass, and recruitment were substantially affected, recovering to new demographic equilibria below their preharvest levels. This is because genetic traits took thousands of years to evolve back to preharvest levels, indicating that natural selection driving recovery of these traits is weaker than fisheries-induced selection was. Our results strengthen the case for proactive management of fisheries-induced evolution, as the restoration of genetic traits altered by fishing is slow and may even be impractical. [ABSTRACT FROM AUTHOR]

Table of contents There is increasing evidence that fishing may cause rapid contemporary evolution in freshwater and marine fish populations. This has led to growing concern about the possible consequences such evolutionary change might have for aquatic ecosystems and the utility of those ecosystems to society. This special issue contains contributions from a symposium on fisheries-induced evolution held at the American Fisheries Society Annual Meeting in August 2008. Contributions include primary studies and reviews of field-based and experimental evidence, and several theoretical modeling studies advancing life-history theory and investigating potential management options. In this introduction we review the state of research in the field, discuss current controversies, and identify contributions made by the papers in this issue to the knowledge of fisheries-induced evolution. We end by suggesting directions for future research. [ABSTRACT FROM AUTHOR]

A key question of evolutionary importance is what factors influence who becomes dominant. Individual genetic variation has been found to be associated with several fitness traits, including behaviour. Could it also be a factor influencing social dominance? We investigated the association between social status and the amount of intra-individual genetic variation in juvenile brown trout ( Salmo trutta). Genetic variation was estimated using 12 microsatellite loci. Dominant individuals had higher mean heterozygosity than subordinates in populations with the longest hatchery background. Heterozygosity–heterozygosity correlations did not find any evidence of inbreeding; however, single-locus analysis revealed four loci that each individually differed significantly between dominant and subordinate fish, thus giving more support to local than general effect as the mechanism behind the observed association between genetic diversity and a fitness-associated trait. We did not find any significant relation between mean d 2 and social status, or internal relatedness and social status. Our results suggest that individual genetic variation can influence dominance relations, but manifestation of this phenomenon may depend on the genetic background of the population. [ABSTRACT FROM AUTHOR]

Heavy positively autocorrelated natural fluctuations in a fisheries stock level are problematic for fisheries management, and collapses in the stock dynamics are difficult to avoid. In this paper, we compare three different harvesting strategies (proportional harvesting, threshold harvesting, and proportional threshold harvesting) in an autocorrelated and heavily fluctuating fishery -- the Norwegian spring-spawning herring (Clupea harengus) -- in terms of risk of quasi-extinction, average annual yield, and coefficient of variation of the yield. Contrary to general expectations, we found that the three strategies produce comparable yields and risks of quasi-extinction. The only observable difference was slightly higher yield and variation in the proportional threshold strategy when the yield is optimized. Thus, it remains an open question as how to characterize the circumstances when it is particularly needful to apply threshold levels in harvest policies. [ABSTRACT FROM AUTHOR]