Use of scenarios with multi-criteria evaluation to better inform the selection of aquaculture zones

Abstract

The allocation of zones for aquaculture development is a strategic problem as it involves long-term outcomes and many stakeholders with competing interests. Resource planners require tools to support such complex allocation decisions, but these are either lacking or with serious limitations. This paper presents an approach that improves the traditional method of developing aquaculture zoning model. Four scenario narratives describing potential development pathways for aquaculture in Nigeria were used to guide the model development, from selection of suitability factors to evaluation of alternatives. The modelling objective was to identify a suitable location for zoning small-to-medium scale commercial pond catfish production in Nigeria. So, a GIS-based multi-criteria evaluation (MCE) was used to produce a suitability map, from which five alternative zones were extracted. These zones were then compared using three sustainability criteria that were designed based on future uncertainties highlighted by the four scenarios. Results show that 4 of the 5 zones are concentrated in the north-eastern part of Nigeria, while the other one occurred in the north-west. Furthermore, this study found two top-ranking zones that can be selected in all the scenarios, meaning the two zones with the most potential to support the sustainable development of small-to-medium scale aquaculture in Nigeria. As these two were almost tied in ranking, sensitivity analyses across the scenarios revealed the most stable zone to changes in the criteria scores. These findings can be used to inform aquaculture expansion policy in Nigeria and integrate the activity into wider land use planning. Overall, the new approach advances the traditional method of developing GIS-based MCE models for aquaculture zoning, as it generates options and relevant information to facilitate strategic decision-making.