An Agent-based Model of the South African Offshore Hake Trawl Industry: Part I Model Description and Validation

- Complex interactions of drivers and industry structure are important for fisheries.
- Drivers include fuel price, exchange rate, environmental stochasticity, and others.
- The development of a novel agent-based model, HakeSim, is described.
- Model demonstrates which & how drivers are important for South African hake fishery.
- Understanding drivers and economic-ecological system links is relevant to managers.

The most valuable component in South Africa's fishing industry is its hake fishery, which targets two species, the shallow-water (Merluccius capensis) and deep-water (M. paradoxus) Cape hakes. Modelling provides a means to assist in understanding the dynamics of the economic system of this fishery and identify potential links to the ecological system in future, which can inform management. This study develops and describes a novel agent-based model of the South African offshore hake trawl industry, HakeSim, which captures drivers such as fuel price, catch per unit effort, export markets, exchange rate, industrial organization and uncertainty in catches as a proxy for environmental uncertainty. It allows identification of key drivers and their relative importance to the industry to be assessed. It has desirable and realistic sensitivities and it can successfully reproduce profitability scenarios for the industry under different fuel prices. Fuel prices above ZAR18.783 per litre, which could result from increased prices or reduced subsidies, are demonstrated to push the modelled fishing companies to making losses, which could potentially reduce employment. This model represents a strategic tool for management and significant advancements over existing bio-economic and agent-based models of fisheries.