Marine reserve creation and interactions between fisheries and capture‐based aquaculture: A bio‐economic model analysis

Abstract

The rapid growth of aquaculture world-wide affects capture fisheries in several ways. We present a bio-economic model to clarify interactions between these two activities, including the effect of a marine protected area (MPA). The aquaculture production is assumed to reduce the intrinsic growth rate of fish, and hence stock size and harvest, while the dispersal from the MPA may limit these effects. This is considered applying both open access and economically optimal management outside the MPA. The results of a numerical simulation show that the wild fish stock in an open access fishery is independent of the aquaculture development, while the wild catch significantly declines. Introducing an MPA, the wild fish stock increases, while the wild catch varies depending on the aquaculture development and the MPA size. With optimal management, the stock size declines for small MPA sizes, but increases for larger sizes, while aquaculture production declines for large MPA size. The harvest and the total profits increase with increasing MPA size. These results show that an MPA may not only compensate for negative effects of aquaculture upon a wild fishery, but may be biologically and economically enhancing under both open access and optimal management regimes as well. JEL Codes: Q22, Q28

Biological life‐history and farming scenarios of marine aquaculture to help reduce wild marine fishing pressure

“…Alternatively, if only the 35 countries practicing CBA replaced their fishing of these species with mariculture, then results would be more modest, but still positive (64,000 tonnes, Q 25 = 29,000 Q 75 = 91,000). Importantly, however, increasing extraction of seed for CBA without reducing wild capture fisheries simply increases fishing pressure on wild stocks, meaning that aligning aquaculture–fisheries policy and management is key to realizing the potential ecological benefits explored here, and, perhaps more importantly, accounting for the socioeconomic trade‐offs that may result, for example, Xuan & Armstrong, 2017.…”

“…Alternatively, if only the 35 countries practicing CBA replaced their fishing of these species with mariculture, then results would be more modest, but still positive (64,000 tonnes, Q 25 = 29,000 Q 75 = 91,000). Importantly, however, increasing extraction of for CBA without reducing wild capture fisheries simply increases fishing pressure on wild stocks, meaning that aligning aquaculture-fisheries policy and management is key to realizing the potential ecological benefits explored here, and, perhaps more importantly, accounting for the socioeconomic tradeoffs that may result, for example, Xuan & Armstrong, 2017. Biomass savings were strongly dependent on earlier life-stage (discrete) natural mortality of the farmed CBA species: in aggregate, savings were projected to occur in all species with earlier life-stage natural mortality greater than 0.30, and peaking in those with mortalities of approximately 0.78 (Figure 4; df 2 = 769, p < .001, R 2 adj = 0.98). Similar thresholds were found in the later-stage natural mortality CBA sensitivity test (Figure S3; 0.30-0.65).…”

Allocation of harvest between user groups in a fishery with habitat effect

“…Recent studies incorporating such multi‐sector interactions include Sala et al. () and Xuan and Armstrong ().…”

Interactions and management for the future of marine aquaculture and capture fisheries

“…To further support such analyses, improved models of the potential interactions between mariculture and wild fisheries, as described in this paper, are necessary, particularly pertaining to FAD and MPA effects. For example, Xuan and Armstrong () developed a bioeconomic model to examine when capture‐based mariculture has a negative effect on wild fish stocks (e.g. lower intrinsic growth rate due to the stocking of wild juveniles).…”