Marine mammal bycatch poses a particular challenge in developing countries, where data to document bycatch and its effects are often lacking. Using the Bycatch Risk Assessment (ByRA) toolkit, based on InVEST open-source models, we chose 4 field sites in Southeast Asia with varying amounts of data on marine mammals and fishing occurrence: Trat province in the eastern Gulf of Thailand, the Sibu-Tinggi Islands and Kuching Bay, Malaysia, and Kien Giang Biosphere Reserve in southwestern Vietnam. These field sites have similar species of coastal marine mammals, small-scale and commercial fisheries, and support for research from universities and/or management. In Thailand and Kuching, results showed changing patterns of fishing and Irrawaddy dolphin Orcaella brevirostris habitat use across seasons, showing how bycatch risk could change throughout the year. Risk maps for dugongs Dugong dugon in peninsular Malaysia highlighted patterns of bycatch risk concentrated around a mainland fishing pier, and revealed high risk in a northern subregion. In Vietnam, first maps of bycatch risk for the Irrawaddy dolphin showed the highest risk driven by intensive use of gillnets and trawling gear. ByRA pinpointed areas of spatial and seasonal bycatch exposure, and estimated the consequence of bycatch on local species, providing managers with critical information on where to focus bycatch mitigation and meet new global standards for US Marine Mammal Protection Act and other international regulation (e.g. Official Journal of the European Union 2019; Regulation 2019/1241) compliance. The toolbox, a transferable open-source tool, can be used to guide fisheries management, marine mammal conservation, spatial planning, and further research.

Agrochemical-free rice farming has attracted interest for restoring paddy field biodiversity and producing safe food. Odonata are commonly used as a biodiversity indicator in these low-input farms. However, the effect of agrochemical-free rice farming on odonate diversity has rarely been assessed over the entire emergence period of these insects. We investigated whether different farming practices, such as conventional or natural (agrochemical-and fertilizer-free) cultivation, and associated water management strategies affect the emergence rates of Odonata in paddy field landscapes in central Japan. Weekly exuviae sampling in 2017 and 2019 suggested that odonate assemblages differed between conventional and natural paddy fields, with a higher number of taxa emerging from natural paddy fields. Contrary to expectations, conventional paddy fields had equivalent or higher emergence rates of all Odonata and two numerically dominant Sympetrum species. Peak emergence periods for numerically dominant taxa differed between the farming types, with the emergence of three Sympetrum species peaking in late June in conventional paddy fields and that of S. frequens peaking in early to mid-July in natural paddy fields. Our findings suggest that both conventional and natural paddy fields are important habitats for Odonata in Japan.

Background In light of the dramatic expansion of Japan’s bamboo forests, it is necessary to develop a strategy for the effective use of bamboo biomass resources. In this study, we tested the effects of ground bamboo as an organic mulching material or soil conditioner during a 3-year, agrochemical-free rice cultivation period. Methods We performed field experiments in 16 experimental paddy fields and established five treatments with three or four replicates each: control, manual weeding, low-volume ground bamboo application (0.5 kg m−2), medium-volume ground bamboo application (1.0 kg m−2), and high-volume ground bamboo application (2.0 kg m−2). Results We observed no suppression of aquatic weeds with the ground bamboo treatments. Nevertheless, in the first year, rice yields were 1.7–1.8 times greater in the medium- and high-volume ground bamboo treatments than in the controls. In the second and third years, rice yields did not differ among treatments. During the 3-year period, mean rice yields dropped dramatically to around 20%. Simple linear regression analyses indicated that rice yields were positively associated with available phosphate, and negatively associated with the silicic acid content of post-experiment paddy soils after the second and third years of cultivation. Multiple linear regression analyses indicated that available phosphate and silicic acid were important variables explaining rice yields. Application of ground bamboo did not appear to reduce external rice grain quality. Conclusions Application of ground bamboo may enhance the production of high-quality rice, particularly when soil phosphorus is not deficient.