Redesigning harvest strategies for sustainable fishery management in the face of extreme environmental variability.

Short-lived, fast-growing species that contribute greatly to global capture fisheries are sensitive to fluctuations in the environment. Uncertainties in exact stock-environment relationships have meant that environmental variability and extremes have been difficult to integrate directly into fisheries management. We applied a management strategy evaluation approach for one of Australia's large prawn stocks to test the robustness of harvest control rules to environmental variability. The model ensemble included coupled environmental-population models and an alternative catchability scenario fitted to historical catch per unit effort data. We compared the efficacy of alternative management actions to conserve marine resources under a variable environment while accounting for fisher livelihoods. Model fits to catch per unit effort were reasonably good and similar across operating models (OMs). For models that were coupled to the environment, environmental parameters for El Niño years were estimated with good associated precision, and OM3 had a lower AIC score (77.61)  than the base model (OM1, 80.39), whereas OM2 (AIC 82.41) had a similar AIC score, suggesting the OMs were all plausible model alternatives. Our model testing resulted in a plausible subset of management options, and stakeholders selected a permanent closure of the first fishing season based on overall performance of this option; ability to reduce the risk of fishery closure and stock collapse; robustness to uncertainties; and ease of implementation. Our simulation approach enabled the selection of an optimal yet pragmatic solution for addressing economic and conservation objectives under a variable environment with extreme events.

Rediseño de las Estrategias de Captura para el Manejo de Pesquerías Sustentables de Caraa una Variabilidad Ambiental Extrema Resumen Las especies de vida corta y rápido crecimiento que contribuyen enormemente a la captura mundial de las pesquerías son sensibles a las fluctuaciones en el ambiente. La incertidumbre en torno a las relaciones exactas entre el ambiente y el stock ha representado una dificultad para integrar directamente la variabilidad y los extremos ambientales a la gestión de las pesquerías. Aplicamos un enfoque de evaluación de estrategia de manejo (EEM) para uno de los stocks de camarones de Australia y así analizar la solidez de las reglas de control de captura para la variabilidad ambiental. El ensamblado modelo incluyó modelos ambientales-poblacionales emparejados y un escenario alternativo de capturabilidad ajustado a los datos históricos de esfuerzo de captura por unidad. Comparamos la eficiencia de acciones alternativas de manejo para conservar los recursos marinos bajo un ambiente variable teniendo en cuenta el sustento de los pescadores. Los ajustes del modelo para el esfuerzo de captura por unidad fueron razonablemente buenos y similares en los modelos operantes (MO). Para los modelos que estuvieron emparejados con el ambiente, los parámetros ambientales para los años de El Niño estuvieron estimados con una buena precisión asociada, y el MO3 tuvo un puntaje AIC menor (77.61) que el modelo base (MO1, 80.39), mientras que el MO2 (AIC 82.41) tuvo un puntaje AIC similar, lo que sugiere que los MO eran todos modelos plausibles alternativos. Nuestro análisis de los modelos resultó en un subconjunto plausible de opciones de manejo, y los actores seleccionaron un cierre permanente de la primera temporada de pesca con base en el desempeño general de esta opción, la habilidad para reducir el riesgo del cierre de la pesquería y el colapso del stock, la solidez ante las incertidumbres y la facilidad de implementación. Nuestra estrategia de simulación permitió la selección de una solución óptima pero pragmática para abordar los objetivos económicos y de conservación bajo un ambiente variable con eventos extremos.

Spatially structured relationships between white banana prawn (Penaeus merguiensis) catch and riverine flow in the Northern Prawn Fishery, Australia.

Water resource development can lead to the significant alteration of natural flow regimes, which can have impacts on the many aquatic species that rely on both freshwater and estuarine environments to successfully complete their lifecycles. In tropical northern Australia, annual catches of commercially harvested white banana prawns (WBP) are highly variable in response to environmental conditions, namely rainfall and subsequent riverine flow. However, little is known about the spatial extent to which flow from individual rivers influences offshore WBP catch. In this study, we quantify how the relationship between WBP catch in the Gulf of Carpentaria is influenced by flow from the Mitchell River, Queensland Australia. We used a Bayesian framework to model both prawn presence and catch per unit effort, and found evidence that multiple components of the flow regime contribute to fishery catch. We also found evidence to suggest that the relationships between prawn presence and flow were spatially structured across the fishing ground. Our results suggest that attributing fishery catch to a single river remains challenging, though highlights the importance of maintaining natural flow regimes to support a highly valuable commercial fishery species in the face of potential water resource development.

Integrating indigenous livelihood and lifestyle objectives in managing a natural resource.

Evaluating the success of natural resource management approaches requires methods to measure performance against biological, economic, social, and governance objectives. In fisheries, most research has focused on industrial sectors, with the contributions to global resource use by small-scale and indigenous hunters and fishers undervalued. Globally, the small-scale fisheries sector alone employs some 38 million people who share common challenges in balancing livelihood and lifestyle choices. We used as a case study a fishery with both traditional indigenous and commercial sectors to develop a framework to bridge the gap between quantitative bio-economic models and more qualitative social analyses. For many indigenous communities, communalism rather than capitalism underlies fishers' perspectives and aspirations, and we find there are complicated and often unanticipated trade-offs between economic and social objectives. Our results highlight that market-based management options might score highly in a capitalistic society, but have negative repercussions on community coherence and equity in societies with a strong communal ethic. There are complex trade-offs between economic indicators, such as profit, and social indicators, such as lifestyle preferences. Our approach makes explicit the "triple bottom line" sustainability objectives involving trade-offs between economic, social, and biological performance, and is thus directly applicable to most natural resource management decision-making situations.