Evidence of market‐driven size‐selective fishing and the mediating effects of biological and institutional factors

Abstract

Market demand is often ignored or assumed to lead uniformly to the decline of resources. Yet little is known about how market demand influences natural resources in particular contexts, or the mediating effects of biological or institutional factors. Here, we investigate this problem by examining the Pacific red snapper (Lutjanus peru) fishery around La Paz, Mexico, where medium or “plate-sized” fish are sold to restaurants at a premium price. If higher demand for plate-sized fish increases the relative abundance of the smallest (recruit size class) and largest (most fecund) fish, this may be a market mechanism to increase stocks and fishermen’s revenues. We tested this hypothesis by estimating the effect of prices on the distribution of catch across size classes using daily records of prices and catch. We linked predictions from this economic choice model to a staged-based model of the fishery to estimate the effects on the stock and revenues from harvest. We found that the supply of plate-sized fish increased by 6%, while the supply of large fish decreased by 4% as a result of a 13% price premium for plate-sized fish. This market-driven size selection increased revenues (14%) but decreased total fish biomass (−3%). However, when market-driven size selection was combined with limited institutional constraints, both fish biomass (28%) and fishermen’s revenue (22%) increased. These results show that the direction and magnitude of the effects of market demand on biological populations and human behavior can depend on both biological attributes and institutional constraints. Fisheries management may capitalize on these conditional effects by implementing size-based regulations when economic and institutional incentives will enhance compliance, as in the case we describe here, or by creating compliance enhancing conditions for existing regulations.

How do small-scale fishers adapt to environmental variability? Lessons from Baja California, Sur, Mexico

“…There is a perception that the state would like fishers to move into tourism, however many feel that there are not enough jobs in tourism for everyone to be gainfully employed. They also associate this drop in tourists with a decreased demand (presumably by restaurants) for particular fish like grouper (see Reddy et al 2013 for an example of how fisheries-related ecological and economic outcomes in this area are mediated by tourist demand).…”

“…Most fishing cooperatives on the gulf coast are not involved in fisheries comanagement. A few cooperatives in the La Paz area are able to influence the fishing practices of their members, especially related to size selection and the use of specific fishing gear in particular habitats (Reddy et al 2013). However, as they lack rights to particular species or areas, none actively patrol fishing areas.…”

Fish market prices drive overfishing of the ‘big ones’

“…Thus, fish species attaining higher market price (i.e., those with higher potential profit) are targeted first (Sethi, Branch & Watson, 2010). The direction and magnitude of the effects of market demand on biological populations and human behavior can depend on both biological attributes and institutional constraints (Reddy et al, 2013). …”

Subsistence fishing in a 21st century capitalist society: From commodity to gift

“…Operating within a modernized profit-oriented industry, the assumption then is that profit motivation drives the behaviors and decisions of commercial fishermen, including influencing decisions about species selection. For example, commercial fishermen are driven to select more profitable "big fish" (within and across taxa), which in turn puts pressure on biological trophic levels (Sethi et al, 2010;Tsikliras and Polymeros, 2014; although, see Reddy et al (2013) for a discussion on the institutional and biological contexts that mediate this fish size-profit maximization effects).…”