Darren Dennis

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.

Modelling climate-change effects on Australian and Pacific aquatic ecosystems: a review of analytical tools and management implications

Climate change presents significant challenges to modelling and managing aquatic resources. Equilibrium assumptions common in many modelling approaches need to be replaced by formulations that allow for changing baselines and integration of ongoing changes and adaptations by species, ecosystems and humans. As ecosystems change, so will the ways humans use, monitor and manage them. Consequently, adaptive management loops and supporting tools deserve more prominence in the management toolbox. Models are critical tools for providing an early understanding of the challenges to be faced by integrating observations and examining possible solutions. We review modelling tools currently available to incorporate the effect of climate change on marine and freshwater ecosystems, and the implications for management of natural resources. System non-linearity can confound interpretations and hence adaptive management responses are needed that are robust to unexpected outcomes. An improvement in the ability to model the effects of climate change from a social and economic perspective is necessary. The outputs from ‘end-to-end’ and socio-ecological models can potentially inform planning, in both Australia and the Pacific region, about how best to build resilience to climate change. In this context, the importance of well directed data-collection programs is also emphasised. Lessons from this region, which is advanced with regard to modelling approaches, can guide increased use of models to test options for managing aquatic resources worldwide.

Distribution and transport pathways of Panulirus ornatus (Fabricius, 1776) and Panulirus spp. larvae in the Coral Sea, Australia

Distribution of phyllosoma larvae and pueruli of the rock lobster Panulirus ornatus and other Panulirus species was surveyed in the north-west Coral Sea in May 1997 and compared to ocean currents. Distribution of P. ornatus larvae revealed the sources of recruits to the Torres Strait lobster fishery. Phyllosomas and pueruli of P. ornatus dominated the Panulirus spp. plankton-trawl catch. Surviving pueruli were transferred to an aquarium to await confirmation of their identity. Pregilled P. ornatus phyllosomas were most abundant approximately 300 km east of the northern Great Barrier Reef (GBR) and near the confluence of the South Equatorial Current and Coral Sea Gyre. Gilled phyllosomas were also common there but most numerous adjacent to the GBR. Pueruli were most abundant adjacent to the GBR well south of Torres Strait. The distribution of P. ornatus phyllosomas and pueruli in relation to the ocean currents supported the hypothesis that phyllosomas are transported from the Gulf of Papua breeding grounds by the Hiri boundary current into the Coral Sea Gyre and then by surface onshore currents onto the Queensland coast and into Torres Strait. Distributions of larvae of other Panulirus species and the synaxid Palinurellus wieneckii differed from those of P. ornatus.

DEA-based predictors for estimating fleet size changes when modelling the introduction of rights-based management

The introduction of individual transferable quotas (ITQs) into a fishery is going to change not only the amount of catch a fleet can take, but often also changes the fleet structure, particularly if total allowable catches are decreased. This can have an impact on the economic, social and environmental outcomes of fisheries management. Management Strategy Evaluation (MSE) modelling approaches are recognised as the most appropriate method for assessing impacts of management, but these require information as to how fleets may change under different management systems. In this study, we test the applicability of data envelopment analysis (DEA) based performance measures as predictors of how a fishing fleet might change under the introduction of ITQs and also at different levels of quota. In particular, we test the assumption that technical efficiency and capacity utilisation are suitable predictors of which boats are likely to exit the fishery. We also consider scale efficiency as an alternative predictor. We apply the analysis to the Torres Strait tropical rock lobster fishery that is transitioning to an ITQ-based management system for one sector of the fishery. The results indicate that capacity utilisation, technical efficiency and scale efficiency are reasonable indicators of who may remain in the fishery post ITQs. We find that the use of these measures to estimate the impacts of lower quota levels provides consistent fleet size estimates at the aggregate level, but which individual vessels are predicted to exit is dependent on the measure used.

Assessing the impacts of trawling breeding lobsters (Panulirus ornatus) on the catch of the Torres Strait lobster fishery shared between Australia and Papua New Guinea

Abstract The shared Torres Strait rock lobster (Panulirus ornatus) fishery provides important income for commercial and traditional fishers in Australia and Papua New Guinea. The lobster stock is first fished in Torres Strait by divers from both countries and then becomes vulnerable to Australian prawn trawlers, followed by Papua New Guinea trawlers during its annual breeding migration. Lobster catch sharing arrangements are governed by the Torres Strait Treaty ratified in 1985, but the sequential trawling of breeding lobsters has been controlled by bilateral agreements. A trawl ban was implemented in 1984 in both countries to conserve the breeding stock, but some trawling has been conducted in the Gulf of Papua since then and there is renewed interest in Papua New Guinea to resume trawling. To evaluate the impact of trawling migratory breeding lobsters on the lobster fishery, a model that combines a cohort depletion model with a stock recruitment relationship was developed in this study. The model showed that when the fishery is fully or over‐exploited by the dive fishery, trawling breeding lobsters would reduce both the spawning stock and the total catch of the fishery. The reduction in catch would increase with increasing fishing mortality. If trawling occurred on the Papua New Guinea side only, a redistribution of catch between Australia and Papua New Guinea would result in a small gain in catch for Papua New Guinea at the expense of the Australian dive fishery. But when fishing mortality reaches a certain level, any trawling in any country will incur catch loss to both countries. For the long‐term sustainability and maximum production of the fishery, regulations should be implemented in both countries under a co‐management scheme of a shared fish stock.

The Ecological Impacts of Submarine Tailings Placement

Tidal range is a master factor governing the differences in physico-chemical and biological characteristics between microtidal ( 2 m) estuaries, which, for convenience, thus include mesotidal estuaries (2–4 m). Microtidal estuaries differ from macrotidal estuaries in geomorphology, tidal water movements, salinity regimes, residence times, turbidity, sedimentology and intertidal area. Consequently, their phytoplankton, microphytobenthos and macrophytes communities differ in biomass and production, areal extent, distribution patterns and composition. Mesozooplankton comprise predominantly autochthonous species in microtidal estuaries and allochthonous species in macrotidal estuaries. Meiobenthos in microtidal estuaries have greater densities in subtidal than intertidal areas and species persist along the estuary. Macrobenthos is dominated by small deposit-feeding species in microtidal estuaries, whereas macrotidal estuaries contain some larger species and suspension feeders. Species richness and abundance of estuarine-resident fish species and the contributions of diving piscivorous birds and wading invertebrate-feeding birds are greater in microtidal estuaries. As paradigms regarding estuarine ecology have been based mainly on northern hemisphere macrotidal systems, this review has redressed this imbalance by detailing the extent of differences between microtidal and macrotidal estuaries. In particular, it uses data and case studies for southern hemisphere microtidal systems to demonstrate that the physico-chemical characteristics and ecology of the main flora and fauna of microtidal estuaries are frequently not consistent with those paradigms.