Management plans for marine benthic resources : a new governance institution for Chilean coastal benthic fisheries.
Creators: name: Tascheri Oyaneder, RM
Publisher: name: University Of Tasmania
Year: 2023

description: The growing recognition of the importance of Small-Scale Fisheries (SSF) for the achievement of global fisheries sustainability has led to a steady increase in the research on these fisheries, particularly in the fields of institutional analysis and governance. this emphasis understands environmental management institutions as mediators of the relations between society and the ecological or biophysical system and therefore as major factors in determining the prospects for sustainability. The unsustainable state in which many of the worlds SSF are found has therefore led researchers to conclude that a transformation is needed to systems of governance that can improve their viability. Adaptive governance (AG) is an emergent form of environmental governance. It features prominently in the research on SSF governance and is considered a viable alternative to coordinate resource management regimes in the face of the complexity and uncertainty associated with rapid environmental change. Much of the current management practice is, however, concerned with balancing the value derived from fishing with the long-term sustainability of populations. To this end, it measures human impacts on populations of fishing resources by estimating fishing rate and population abundance. these quantities are then used to determine trends in biomass and to assess stock status relative to reference points. this requires a population model, with data on fishery removals and relative abundance. This thesis investigates these concepts and issues using a case study from Chile. the new \Management Plans for Benthic Resources\" (MPBR) policy created by the Chilean government in 2013 for the management of the many small-scale coastal benthic fisheries that target shellfish along the countries extensive coastline. The first half of this thesis examines the recent changes in Chilean coastal benthic fisheries governance arrangements from the perspective of AG and polycentrism Chapter 2 investigates AG and polycentric governance theory viability of delivering sustainable coastal benthic fisheries. Chapter 3 shows that insight can be gained by understanding coastal benthic fisheries governance dynamics as learning processes. It is concluded that AG and polycentrism can contribute coherence to ecosystem-based fisheries management by structuring the different policies around its concepts and principles. However these theories seem over optimistic about power asymmetries casting doubt on their ability to deliver on sustainability goals. Understanding the governance dynamics in coastal benthic fisheries as a learning process highlighted the importance of informal networks and made it plain that the direction of institutional change has been towards more flexible regulations increasingly allowing for context specific adaptations In Chapters 4 and 5 the problem of model uncertainty in fish stock assessment is explored by using two alternative population model structures to assess the status of two bivalve stocks managed under the MPBR policy the clam Ameghinomya antiqua and the razor shell Ensis macha targeted in the small-scale diving fishery of the Los Lagos Region in Southern Chile. Chapter 4 introduces the fishery system its management framework and the data available to estimate the fishing rate and population abundance and develops the assessments for these two bivalve populations using an integrated catch-at-age model (ASM) and an integrated catch-at-size model (SSM). Chapter 5 explores the problem of model uncertainty in these stock assessments using simulation and investigates how well can management quantities of these two bivalve stocks be estimated. It was shown that the use of a valid alternative population model can have a significant impact on our conclusions about the status of the resource. However, the extent of the impact of the use of different model structures can be difficult to discern from data conflict arising from model misspecification. The performance of the ASM and SSM was conditioned on data quality and the estimation model structure and settings. Otherwise the SSM exhibited the same or better performance than the ASM. Estimation ability differed among quantities of interest to management. Pre-exploitation biomass and the fishing mortality at which spawning biomass per recruit is reduced to 40% of its unfished level exhibited less bias and higher precision. This variation should be routinely presented to managers together with the usual measures of within model variation to convey a more accurate representation of uncertainty."