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Developing spatially explicit assessment and management techniques that engage stakeholder behaviour has been an enduring priority for fisheries targeting benthic marine invertebrates like abalone. This study describes the basis of 'Shellogy'; a concept with the potential to empower reef-scaled management by using shell morphology to qualitatively evaluate abalone populations and their variability. The premise of shellogy is that a range of shell characteristics, previously established as distinguishing between populations with differing life history parameters, are also indicative of relative age and stage of maturation. Using the analysis of existing data, literature synthesis and illustrations, together with simulation of length frequency histograms, this study establishes from first principles that the morphometric ratios of abalone shells, along with superficial internal and external shell characteristics, change predictably with age and maturation. This study explains how recognising the connection between shell shape, and relative age and maturity, enables the appearance of shells in populations and catches, to be used to inform qualitative reef-scale assessment and facilitate stakeholder engagement with reef-scale management initiatives. [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 [...]

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]

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]