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Patterns of cohort decline are key demographic traits that provide a unique temporal perspective vital to understanding population dynamics. The discovery of multidecadal lifespans in tropical surgeonfishes in the 1990s created a paradigm shift to the notion that they are highly vulnerable species with low population recovery rates; however, research into the mortality patterns of surgeonfishes (Acanthuridae) has been sparse until recently. Recent studies on this family have demonstrated an unusual (possibly unique), two‐phase pattern of adult catch‐at‐age, whereby there is a population‐level shift from higher‐than‐expected rates of decline early in life to lower‐than‐expected decline rates for the remainder of the lifespan. To examine the geographic and phylogenetic ubiquity of this pattern, we compiled age‐based information from demographic samples of 70 populations of 25 tropical species spanning the Indo‐Central Pacific and Central‐Western Atlantic. Overall, we found that 79% of populations exhibited strong biphasic patterns, including 88% of populations across the Indo‐Central Pacific. By accounting for empirical relationships instead of using linear catch curves or classical assumptions of natural population decay based on lifespan, we demonstrate that surgeonfishes have turnover times that are two to four times faster than previously believed. Faster turnover times may suggest a higher level of sustainability for surgeonfish fisheries throughout the global tropics than previously estimated. [ABSTRACT FROM AUTHOR]

Less variable than life history parameters (LHPs), it is life history ratios (LHRs) that define how taxa allocate energy between growth, maintenance and reproduction, and respond to fishing pressure. Limited by small samples, variable data quality, and a focus on LHP estimation, previous meta-analyses have failed to settle debate about the extent to which LHRs are relatively invariant across all taxa or characteristic of specific taxa. We collected de novo 1335 published studies and applying rigorous standardization and quality control procedures developed, and make available, a database of high-quality M / K and L m/ L ∞ estimates. We describe two parallel but independent meta-analyses: a cross-validation study of the predictability of M / K by taxonomic category and an evaluation of alternative relationships between the LHRs using Akaike information criteria. These analyses demonstrate that the LHRs are correlated and vary predictably by taxa, with aggregation to the level of family and genera having the most predictive power in our database. We postulate that the LHRs of taxa may relate to their stoichiometric niches, which could open up interesting lines for ecological research and provide new tools for predicting the LHRs of poorly studied taxa. [ABSTRACT FROM AUTHOR]

Selectivity in fish is often size-dependent, which results in differential fishing mortality rates across fish of the same age, an effect known as 'Lee's Phenomenon'. We extend previous work on using length composition to estimate the spawning potential ratio (SPR) for data-limited stocks by developing a computationally efficient length-structured per- recruit model that splits the population into a number of subcohorts, or growth-type-groups, to account for size- dependent fishing mortality rates. Two simple recursive equations, using the life history ratio of the natural mortality rate to the von Bertalanffy growth parameter (M/K), were developed to generate length composition data, reducing the complexity of the previous approach. Using simulated and empirical data, we demonstrate that ignoring Lee's Phenomenon results in overestimates of fishing mortality and negatively biased estimates of SPR. We also explored the behaviour of the model under various scenarios, including alternative life history strategies and the presence of size-dependent natural mortality. The model developed in this paper may be a useful tool to estimate the SPR for data- limited stock where it is not possible to apply more conventional methods. La selectivite des poissons depend souvent de la taille, ce qui se traduit par differents taux de mortalite par peche pour des poissons du meme age, un effet appele << phenomene de Lee >>. Nous elargissons des travaux anterieurs sur l'utilisation de la distribution des longueurs pour estimer le rapport du potentiel de reproduction (RPR) de stocks pour lesquels les donnees sont limitees, en developpant un modele par recrue structure par la longueur efficace sur le plan informatique qui divise la population en un certain nombre de sous-cohortes, ou groupes de type de croissance, pour tenir compte des taux de mortalite par peche dependant de la taille. Deux equations recursives simples, qui utilisent le rapport associe au cycle biologique du taux de mortalite naturelle et du parametre de croissance de von Bertalanffy (M/K), ont ete etablies pour generer des donnees de distribution des longueurs, reduisant du coup la complexite de l'approche anterieure. En utilisant des donnees simulees et empiriques, nous demontrons que le fait de ne pas tenir compte du phenomene de Lee entraine une surestimation de la mortalite par peche et des estimations du RPR caracterisees par des erreurs systematiques negatives. Nous avons egalement explore le comportement du modele pour differents scenarios, dont differentes strategies de cycle biologiques et la presence d'une mortalite naturelle dependant de la taille. Le modele pourrait constituer un outil utile pour estimer le rapport du RPR pour des stocks pour lesquels les donnees sont limitees auxquels l'application de methodes plus traditionnelles n'est pas possible. [Traduit par la Redaction], Introduction To maintain the long-term stability of yield from capture fisheries, the dynamics of fish populations and the impact of harvesting these populations must be understood. While there have been [...]

Catastrophic overfishing of small‐scale coastal fisheries through the Pacific poses a major threat to regional food security and biodiversity. Globally, approaches to fisheries assessment and management that were developed for industrial fisheries, are failing small‐scale data‐poor fisheries. The Pacific Community has called for a complete rethink of fisheries methodologies for the region; a "new song" of change for small‐scale coastal fisheries. This article describes the application in Fiji of a new approach to facilitating coastal fisheries management reform. Spawning Potential Surveys (SPS) is a pragmatic multi‐disciplinary blend of sciences, that combines a new form of length‐based assessment and communication strategies informed by theories of behavior change, nudge and diffusion, that is initiated with programs of citizen science to inform policy development and catalyze broader societal change. Our project successfully coordinated Fiji‐based NGOs to work with the Ministry of Fisheries, communities, provincial government and supply chains, to collect the data needed to assess ~90% of the Fijian reef fish catch, conduct the analyses needed to develop new management policies, and build a broad consensus in society to support the ongoing reform process that has now been initiated by the Ministry. This project demonstrates the feasibility and effectiveness of the SPS methodology for informing and motivating coastal fisheries reform in the Pacific, as well as the necessity of a long term and multi‐disciplinary approach to achieve the societal change needed. [ABSTRACT FROM AUTHOR]

The cost, complexity and the lack of technical capacity in many countries have made the scientific assessment and sustainable management of data‐poor fisheries a persistent problem. New and innovative approaches are needed to stop the ongoing decline of data‐poor fisheries and loss of coastal biodiversity they are driving. In recent decades, marine protected areas have become the most preferred form of management for study and have been widely implemented as broadly applicable powerful management tools for data‐poor fisheries, but although clearly capable of building biomass within sanctuaries, their effectiveness for sustaining fisheries is proving more difficult to substantiate. This study suggests the new approach needed is actually a return to the established basics of managing size selectivity. Previous studies have established the wisdom of managing size selectivity and fishing pressure to catch fish above the size or age of maturity, but their prescriptions are difficult to implement without age studies, or the capacity for controlling catches and fishing pressure. This study develops an easily implementable rule of thumb based simply on multiples of size of maturity and quantifies its benefit where controlling fishing pressure is not yet possible. Our study provides a timely reminder that even if used alone, size selectivity, the oldest form of management, still produces pretty good sustainable yields. We suggest our rule of thumb can be used to prevent data‐poor fisheries declining while capacity for more complex forms of assessment and management are developed. [ABSTRACT FROM AUTHOR]

The complexity and cost of assessment techniques prohibits their application to 90% of fisheries. Simple generic approaches are needed for the world's small-scale and data-poor fisheries. This meta-analysis of the relationship between spawning potential and the normalized size and age of 123 marine species suggests that the so-called Beverton–Holt life-history invariants (BH-LHI; Lm/L∞, M/k, M × Agem) actually vary together in relation to life-history strategy, determining the relationship between size, age, and reproductive potential for each species. Although little realized, the common assumption of unique values for the BH-LHI also implies that all species share the same relationship between size, age, and reproductive potential. This implicit assumption is not supported by this meta-analysis, which suggests that there is considerable but predictable natural variation in the BH-LHI ratios and the relationships between size, age, and reproductive potential that they determine. We believe that this reconceptualization of the BH-LHI has potential to provide a theoretical framework for “borrowing” knowledge from well-studied species to apply to related, unstudied species and populations, and when applied together with the assessment technique described by Hordyk et al. (2015b), could make simple forms of size-based assessment possible for many currently unassessable fish stocks. [ABSTRACT FROM PUBLISHER]

Evaluating the status of data-poor fish stocks is often limited by incomplete knowledge of the basic life history parameters: the natural mortality rate (M), the von Bertalanffy growth parameters (L∞ and k), and the length at maturity (Lm). A common approach to estimate these individual parameters has been to use the Beverton–Holt life history invariants, the ratios M/k and Lm/L∞, especially for estimating M. In this study, we assumed no knowledge of the individual parameters, and explored how the information on life history strategy contained in these ratios can be applied to assessing data-poor stocks. We developed analytical models to develop a relationship between M/k and the von Bertalanffy growth curve, and demonstrate the link between the life history ratios and yield- and spawning-per-recruit. We further developed the previously recognized relationship between M/k and yield- and spawning-per-recruit by using information on Lm/L∞, knife-edge selectivity (Lc/L∞), and the ratio of fishing to natural mortality (F/M), to demonstrate the link between an exploited stock's expected length composition, and its spawning potential ratio (SPR), an internationally recognized measurement of stock status. Variation in length-at-age and logistic selectivity patterns were incorporated in the model to demonstrate how SPR can be calculated from the observed size composition of the catch; an advance which has potential as a cost-effective method for assessing data-poor stocks. A companion paper investigates the effects of deviations in the main assumptions of the model on the application of the analytical models developed in this study as a cost-effective method for stock assessment [Hordyk, A. R., Ono, K., Valencia, S., Loneragan, N. R., and Prince, J. D. 2015. A novel length based empirical estimation method of spawning potential ratio (SPR), and tests of its performance, for small-scale, data-poor fisheries. ICES Journal of Marine Science, 72: 217–231]. [ABSTRACT FROM PUBLISHER]

The spawning potential ratio (SPR) is a well-established biological reference point, and estimates of SPR could be used to inform management decisions for data-poor fisheries. Simulations were used to investigate the utility of the length-based model (LB-SPR) developed in Hordyk et al. (2015). Some explorations of the life history ratios to describe length composition, spawning-per-recruit, and the spawning potential ratio. ICES Journal of Marine Science, 72: 204–216.) to estimate the SPR of a stock directly from the size composition of the catch. This was done by (i) testing some of the main assumptions of the LB-SPR model, including recruitment variability and dome-shaped selectivity, (ii) examining the sensitivity of the model to error in the input parameters, and (iii) completing an initial empirical test for the LB-SPR model by applying it to data from a well-studied species. The method uses maximum likelihood methods to find the values of relative fishing mortality (F/M) and selectivity-at-length that minimize the difference between the observed and the expected length composition of the catch, and calculates the resulting SPR. When parameterized with the correct input parameters, the LB-SPR model returned accurate estimates of F/M and SPR. With high variability in annual recruitment, the estimates of SPR became increasingly unreliable. The usefulness of the LB-SPR method was tested empirically by comparing the results predicted by the method with those for a well-described species with known length and age composition data. The results from this comparison suggest that the LB-SPR method has potential to provide a tool for the cost-effective assessment of data-poor fisheries. However, the model is sensitive to non-equilibrium dynamics, and requires accurate estimates of the three parameters (M/k, L∞, and CVL∞). Care must be taken to evaluate the validity of the assumptions and the biological parameters when the model is applied to data-poor fisheries. [ABSTRACT FROM PUBLISHER]

The article discusses fisheries assessment and management. It presents an analysis of the International Center for Living Aquatic Resources Management and the Institute of Fisheries Management's Fisheries Co-Management Research Project. It discusses how to manage fine-scale spatially complex fisheries with a focus on resources users, governance and management systems, and the use of a generic approach. It relates a case study of the Australian abalone fisheries reef scale assessment.

When the biomass and area occupied by a stock decline together, catch rates can remain high (hyperstability) and management with effort controls may be ineffectual. Banana prawn (Penaeus merguiensis) catches declined from 2000 until 2005 in the Albatross Bay area in the Gulf of Carpentaria (GOC), Australia. Data from commercial logbooks were used to investigate historical changes in the banana prawn fishery in this and other regions of the Northern Prawn Fishery to infer the potential causes of this decline. Data since 1970 were analysed using: (1) the mapping of catch and effort; and (2) normalised rank order catch curves, to determine the distribution of catches across fishing areas. These analyses show that there has been a marked contraction of the Albatross Bay fishery over 33 years of fishing into the centre of a stable ?hotspot', suggesting a potential mechanism for the observed negative relationship between catchability and biomass. We believe this is the first observation of a Peneaus prawn fishing ground contracting as biomass declines, supporting the view that the contraction of an area occupied by a stock as biomass declines, is a generalised phenomena observed widely across fisheries resources and not a dynamic confined to certain finfish and molluscs. [ABSTRACT FROM AUTHOR]

Discusses the facets of abalone biology for the sustainable management of fisheries. Details on the decline in global abalone production; Implications for the management of wild stocks of abalone; Accounts on the scale of functional units of abalone stocks.

Haliotid (abalone) fisheries are comprised of small-scale (<5 km2) stocks and serve as a model for many such fisheries. Extremely valuable to local fishing communities in aggregate, these micro-stocks are myriad and complex to study, monitor, assess and manage. Micro-stocks need assessment and management at local scales to prevent small components from suffering the tragedy of commons. This paper asks how can we ever hope to address the research and management needs of so many small resources? Community-based and territorial rights-based systems may help in sustaining these resources, but servicing the technical needs of many small communities of stakeholders raises problems. A new generation of ‘barefoot ecologists’ is envisaged to perform this task. [ABSTRACT FROM AUTHOR]