Bet-hedging strategies determine daily choices in effort allocation for Nile perch fishers of Lake Victoria
Small scale fishers experience high variability in daily catches within a resource space limited in extent by operational constraints, and biophysical factors affect daily choices in spatial effort allocation. We focus on the management consequences of the extent of the individual fisher's resource space and his options to handle risk arising from daily catch variability through a portfolio of sizes and species from within that resource space. Gillnet and longline Nile perch fishers in south-eastern Lake Victoria, Tanzania were provided with a GPS and recorded their position together with their daily catch and operations. Three different gillnet and longline fishing strategies could be discerned. All had bet-hedging characteristics, differing in the size of their resource space of on average 120 – 141 km2, distance from the shore fished and emphasis on the mix of sizes of Nile perch and other species caught. Daily choice of fishing locations did not relate to previous days’ catch success. Still, fishers used the general inshore to offshore distributional patterns of small and large Nile perch in their daily choices of mesh and hook sizes. The mix of sizes and species reduced day-to-day catch variability due to a portfolio effect. Current mesh and landing size regulations based on classical arguments around growth-overfishing interfere with these strategies and force individual fishers to specialise in size, species, and area. They must accept higher uncertainties by either choosing their fishing locations further offshore or accepting a more variable lower catch, leading to higher personal and occupational risk or ongoing management conflicts when disregarding regulations. Portfolio management of fished resources by compromising on mesh size regulations would make sense by allowing fishers to utilise a certain proportion of smaller mesh or hook sizes that are now illegal as part of their fishing strategies.
| Main Authors: | , |
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| Format: | Article/Letter to editor biblioteca |
| Language: | English |
| Subjects: | Bet-hedging, Catch portfolio, Effort allocation, Lake Victoria, Resource space, Uncertainty and risk, |
| Online Access: | https://research.wur.nl/en/publications/bet-hedging-strategies-determine-daily-choices-in-effort-allocati |
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