Positive outcomes and insights for scaling from a randomized pilot of a gear exchange program to reduce bycatch in small-scale fisheries
Abstract
Incentive-based conservation programs offer a promising approach for reducing fishing pressure on threatened species while supporting coastal livelihoods, yet causal evidence remains scarce. Modest budgets and small samples are a persistent challenge to evaluating pilots of novel conservation programs. We conducted a 12-month pre-registered randomized pilot of a gear exchange program in Aceh Province, Indonesia, allocating 11 vessels to treatment (N = 4) or control (N = 7) after 26 months of baseline (pre-treatment) monitoring. Treatment vessels were offered fish traps in exchange for gillnets — associated with bycatch of Critically Endangered elasmobranchs. After comparable pre-treatment bycatch rates, treatment vessels recorded zero bycatch across 306 pilot trips while control vessel bycatch declined but persisted (64 individuals, 890 trips), yielding a 95% reduction in bycatch odds (difference-in-differences odds ratio 0.050 [0.002–0.420]). Net income was also $48.62 higher per trip (95% CI: 37.90–59.35). Bycatch also declined in controls due to opportunistic shifts towards handlining, meaning effects would have been overstated without a counterfactual-based design. Survey data revealed high acceptability and dual conservation-livelihood motivations. Through our randomized mixed-methods pilot we generated credible causal estimates and mechanistic insights that an uncontrolled pilot could not, demonstrating the value of randomized piloting before scaling.
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BibTeX
@misc{booth2026positive,
title = {{Positive outcomes and insights for scaling from a randomized pilot of a gear exchange program to reduce bycatch in small-scale fisheries}},
author = {Hollie Booth and Ilham Fajri and Rusdiansyah R and Kusuma Banda Naira and Muhammad Rizal and Luky Adrianto and Julia P. G. Jones},
howpublished = {EcoEvoRxiv},
year = {2026},
month = sep,
doi = {10.32942/x2c40d},
url = {https://ecoevorxiv.org/repository/view/15106/},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Positive outcomes and insights for scaling from a randomized pilot of a gear exchange program to reduce bycatch in small-scale fisheries
AU - Hollie Booth
AU - Ilham Fajri
AU - Rusdiansyah R
AU - Kusuma Banda Naira
AU - Muhammad Rizal
AU - Luky Adrianto
AU - Julia P. G. Jones
PY - 2026
DA - 2026/09/22
PB - EcoEvoRxiv
DO - 10.32942/x2c40d
UR - https://ecoevorxiv.org/repository/view/15106/
AB - Incentive-based conservation programs offer a promising approach for reducing fishing pressure on threatened species while supporting coastal livelihoods, yet causal evidence remains scarce. Modest budgets and small samples are a persistent challenge to evaluating pilots of novel conservation programs. We conducted a 12-month pre-registered randomized pilot of a gear exchange program in Aceh Province, Indonesia, allocating 11 vessels to treatment (N = 4) or control (N = 7) after 26 months of baseline (pre-treatment) monitoring. Treatment vessels were offered fish traps in exchange for gillnets — associated with bycatch of Critically Endangered elasmobranchs. After comparable pre-treatment bycatch rates, treatment vessels recorded zero bycatch across 306 pilot trips while control vessel bycatch declined but persisted (64 individuals, 890 trips), yielding a 95% reduction in bycatch odds (difference-in-differences odds ratio 0.050 [0.002–0.420]). Net income was also $48.62 higher per trip (95% CI: 37.90–59.35). Bycatch also declined in controls due to opportunistic shifts towards handlining, meaning effects would have been overstated without a counterfactual-based design. Survey data revealed high acceptability and dual conservation-livelihood motivations. Through our randomized mixed-methods pilot we generated credible causal estimates and mechanistic insights that an uncontrolled pilot could not, demonstrating the value of randomized piloting before scaling.
ER -