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Reducingby-catchofseaturtlesinpelagiclonglinefisheries,inconcertwithactivitiesto reduce other anthropogenic sources of mortality, may contribute to the recovery of marine turtle populations. Here, we review research on strategies to reduce sea turtle by-catch. Due to the state of management regimes in most longline fisheries, strategies to reduce turtle interactions must not only be effective but also must be commercially viable. Becausemostresearchhasbeeninitiatedonlyrecently,manyresultsarenotyet peer-reviewed, publishedor readily accessible. Moreover, mostexperiments havesmall sample sizes and have been conducted over only a few seasons in a small number of fisheries; many study designs preclude drawing conclusions about the independent effectofsinglefactorsonturtleby-catchandtargetcatchrates;andfewstudiesconsider effects on other by-catch species. In the US North Atlantic longline swordfish fishery, 4.9-cm wide circle hooks with fish bait significantly reduced sea turtle by-catch rates and the proportion of hard-shell turtles that swallowed hooks vs. being hooked in the mouth compared to 4.0-cm wide J hooks with squid bait without compromising commercial viability for some target species. But these large circle hooks might not be effective or economically viable in other longline fisheries. The effectiveness and commercialviabilityofaturtleavoidancestrategymaybefishery-specific,dependingon thesizeandspeciesofturtlesandtargetfishandotherdifferencesbetweenfleets. Testing of turtle avoidance methods in individual fleets may therefore be necessary. It is a priority to conduct trials in longline fleets that set gear shallow, those overlapping the most threatened turtle populations and fleets overlapping high densities of turtles such as those fishing near breeding colonies. In addition to trials using large 4.9-cm wide circlehooksinplaceofsmallerJandJapantunahooks,otherfishingstrategiesareunder assessment. These include: (i) using small circle hooks (£ 4.6-cm narrowest width) in place of smaller J and Japan tuna hooks; (ii) setting gear below turtle-abundant depths; (iii) single hooking fish bait vs. multiple hook threading; (iv) reducing gear soak time and retrieval during daytime; and (v) avoiding by-catch hotspots through fleet communication programmes and area and seasonal closures.