Intense pressure on small and juvenile coral reef fishes threatens fishery production in Madagascar.

Size‐based indicators are appropriate for monitoring status and guiding management of multi‐species, multi‐gear fisheries, such as coral reef fisheries. From May 2018 to April 2019, size distribution and composition of coral reef fish catches were monitored through a participatory landing survey in southwestern Madagascar. Fishers targeted a large diversity of fish taxa (75 families) and range of sizes (1.6–86 cm). Five predominant gears accounted for most of the catch (1360 [±39] t), including mosquito net trawl (27.7%), beach seine (26.8%), speargun (7.2%), gillnet (30.6%), and handline (7.1%). Due to widespread use of gears made from mosquito nets, 75% of fishes smaller than 9 cm and 47% of juvenile fishes were represented in the total catch number. Large‐size taxa (Scaridae, Lethrinidae, Siganidae, Acanthuridae, Synodontidae, Mullidae, and Labridae) were mostly harvested as juveniles. Catches varied by 8%–70% throughout the year. Size of coral reef fish, annual catches, and catch rates all declined since the 1990s. [ABSTRACT FROM AUTHOR]