The Cost of Co-viability in the Australian Northern Prawn Fishery

Abstract

Fisheries management must address multiple, often conflicting objectives in a highly uncertain context. In particular, while the bio-economic performance of trawl fisheries is subject to high levels of biological and economic uncertainty, the impact of trawling on broader biodiversity is also a major concern for their management. The purpose of this study is to propose an analytical framework to formally assess the trade-offs associated with balancing biological, economic and non-target species conservation objectives. We use the Australian Northern Prawn Fishery (NPF), which is one of the most valuable federally managed commercial fisheries in Australia, as a case study. We develop a stochastic co-viability assessment of the fishery under multiple management objectives. Results show that, due to the variability in the interactions between the fishery and the ecosystem, current management strategies are characterized by biological and economic risks. Results highlight the trade-offs between respecting biological, economic and non-target species conservation constraints at each point in time with a high probability and maximizing the net present value of the fishery.

Ecoviability for ecosystem‐based fisheries management

“…The viability models, scenarios and performances of these examples are detailed in ; Gourguet et al (2013Gourguet et al ( , 2014Gourguet et al ( , 2015; Cissé et al (2013Cissé et al ( , 2015; Hardy et al (2013). The viability models, scenarios and performances of these examples are detailed in ; Gourguet et al (2013Gourguet et al ( , 2014Gourguet et al ( , 2015; Cissé et al (2013Cissé et al ( , 2015; Hardy et al (2013).…”

“…The paper also highlights some important differences of ecoviability scenarios between more heavily regulated and less regulated fisheries in terms of economic risk as well as effort reallocation. The viability models, scenarios and performances of these examples are detailed in ; Gourguet et al (2013Gourguet et al ( , 2014Gourguet et al ( , 2015; Cissé et al (2013Cissé et al ( , 2015; Hardy et al (2013).…”

“…As described in Gourguet et al (2014Gourguet et al ( , 2015, three species of prawns were modelled using a size-structured population model that operates on a weekly time step. The parameters of this multispecies population model were estimated using data on catches and effort, catch rates, as well as length frequency data from both surveys and commercial landings (Punt et al, 2010).…”

“…Results differ according to the case-studies and constraints. The efforts associated with the ecoviability scenarios for the four casestudies are detailed in ; Gourguet et al (2013Gourguet et al ( , 2014Gourguet et al ( , 2015; Cissé et al (2013Cissé et al ( , 2015; Hardy et al (2013) and summarized in Table 4. It turns out that, in the Bay of Biscay and the Australian cases, ecoviability was achieved by decreasing the capac- (11) and ecoviability probability (X-axis) ℙ(Constraints (3),(5),(4) are fulfilled for t = t 0 , … ,T) as in Equation (10) under the three scenarios SQS (grey disc striped), NPVS (red empty circle), EVS (full disc degraded blue).…”

Operationalizing Sustainability as a Safe Policy Space

“…The second challenge is the methodology to relate the performance of the system relative to the boundaries, and how the position of the system can be adjusted by policies. Co-Viability Analysis (CVA), based on the mathematical framework called viable control theory or viability theory [22,23], meets this objective, as an extension of Population Viability Analysis [24] to bio-economic contexts [20,[25][26][27][28][29]. If we have only quantifiable standards, CVA is a formal route to define the safe policy space able to maintain ecosystems or socio-ecosystems within a safe operating space.…”