Executive Summary
Global change drivers, such as population growth, increasing consumption, inequity in resource distribution, overfishing, climate change and pollution, are challenging the sustainability of global coupled human-natural seafood production system. Modelling the linkages between the biophysical and socio-economic components of the seafood production systems is a useful way to explore the interactions between these drivers and policy responses. Moreover, combining the use of models and scenarios can then provide quantitative projections for pathways of changes in ocean human-natural systems.
This report documents a newly developed model, herein called Dynamic Integrated Marine Climate, Biodiversity, Fisheries, Aquaculture and Seafood Market Model (DIVERSE) to project future pathways to seafood sustainability under global change. DIVERSE is supported by a system of linked and harmonised infrastructure of environmental, biodiversity, fisheries and socio-economic databases (Appendix). In parallel, scenarios of direct and indirect drivers of changes in the marine human-natural systems are developed based on the Representative Concentration Pathway (RCP) and the Shared Socioeconomic Pathway (SSP) frameworks.
DIVERSE is grounded in the framework of coupled human-natural systems for the ocean. Chapter 1 describes the basic structure of DIVERSE and its potential applications. Specifically, the different sub-components of DIVERSE and their main interconnections are introduced. Some of the overarching research questions in the context of exploring scenarios and pathways for ocean futures under climate change that can be addressed by DIVERSE are also highlighted.
DIVERSE includes five interconnected sub-components: climate-living marine resources, fishing effort dynamics, mariculture, and global seafood markets. These model sub-components are described in separate chapters. Specifically, Chapter 2 describes the structure of the climate-living marine resources component of DIVERSE. This component includes models and scenarios for changes in ocean conditions and abundance of fish stocks. Ocean conditions are projected by Earth system models while fish stock abundance is projected by the Dynamic Bioclimate Envelope Model (DBEM). The projections of abundance forcing under scenarios of greenhouse gas emissions and marine protected areas are illustrated using four fish stocks as examples.
The projected abundance forcing is subsequently linked to a newly developed fishing effort dynamic model (EDM). The EDM, described in Chapter 3, is a bio-economic model that simulates changes in fishing fleets dynamics based on scenarios of changes in abundance of fish stocks projected from DBEM and fisheries economic variables such as the price of fish and cost of fishing. The main outputs of the EDM are projected changes in fishing efforts, catches, fisheries revenues and profits by countries and fishing fleets (demersal and pelagic). The EDM reproduces historical trends of global fisheries catches and fishing effort, demonstrating its potential utility to make projections for the future.
In addition to capture fisheries, DIVERSE also includes a model for mariculture (marine aquaculture) production. The mariculture production model, described in Chapter 4, accounts for inputs of mariculture production in modelling procedure such as price, suitable marine area for farming, total world fishmeal and fish oil production, and farm species trophic level. These inputs can also be affected directly or indirectly by climate change. The model then simulates changes in mariculture production potential by countries for the main farmed marine species. The outputs from the EDM and mariculture production model provide inputs into the global seafood market model (GFish).
The GFish model, described in Chapter 5, is a partial equilibrium model of global fish supply and demand. It aims to facilitate the analysis of the supply, demand and trade consequences, associated with different scenarios subject to changing market forces, policy, demographics and environments. The GFish model can be used to assess the impacts of market and non-market forces have on the marine resources and the effects of changing seafood supply from capture fisheries and mariculture on the global seafood markets.
In addition to commercial fishing and aquaculture that are connected to seafood markets, DIVERSE also accounts for fishing for subsistence purposes. Subsistence catches are predicted using an empirical model established based on historical subsistence catches. The model predicted expected subsistence catch for each country based on the average income level of the country, its rural population size, per capita seafood consumption and fisheries resources abundance. The model is able to significantly explain variations in subsistence catches in the world over the last few decades. In DIVERSE, the subsistence model is used to project subsistence catches based on projections of social-economic drivers (income classes and human population) and changes in fisheries resources abundance under SSPs and RCPs.
The last two chapters of this report describe and discuss scenarios of direct and indirect drivers for capture fisheries and mariculture. These scenarios are based on the Shared Socioeconomic Pathways (SSPs) framework to examine the challenges and limits to climate mitigation and adaptation. Three sets of fisheries- and mariculture- focused storylines are developed based on three SSPs (SSP1, SSP3, and SSP5) that describe alternative futures engaged in ‘sustainability’, ‘regional rivalry’ and ‘fossil-fuel based development’ pathways, respectively. Specific quantitative drivers such as population and per capita income under each scenario are provided. These drivers are applied to model future changes in seafood sustainability using DIVERSE.
Overall, this report describes the structure, parameterization and testing of DIVERSE. The report also highlights the strengths, weaknesses and future opportunities for the potential extension of DIVERSE. This report provides the main documentation of DIVERSE that will be useful for future applications of the model and analyses of its outputs
Tags: Andrés Cisneros-Montemayor, Colette Wabnitz, CORU, faculty, FCRR, Gabriel Reygondeau, IOF postdoctoral fellows, IOF Research Associates, IOF students, Lydia Teh, Muhammed Oyinlola, Nereus Program, Oa Li Chen, Publications, Research, Vicky Lam, William Cheung
