Belize maintains the largest proportion of the Endangered Antillean manatee Trichechus manatus manatus population in its range, but tourism and boat traffic have increased substantially over the past 3 decades. We utilized 25 yr of Belize Antillean manatee stranding data (1995-2019), 6 aerial surveys (1997, 1999, 2000, 2001, 2002, 2014), and 2 decades of boat registration data to examine: (1) spatial patterns in stranding incidence and risk of watercraft collision; (2) temporal patterns in strandings and registered watercraft; and (3) the relationship between manatee strandings attributed to watercraft collision and watercraft numbers. The number of watercraft collision strandings increased significantly over time, from 1-4 yr-1 in the late 1990s and early 2000s to 10-17 yr-1 in the late 2010s. The per manatee risk of watercraft collision stranding increased across space and time with the number of registered boats. Strandings were greater in areas of high boat traffic, high human population density, and mangrove habitats, particularly in Belize City and Placencia. These results highlight the need to reduce the threat of watercraft collisions to conserve this Endangered subspecies in Belize. Conservation efforts should focus on reducing the number of boats and their speed within zones of high manatee use to reduce mortality due to boat collisions, including establishing additional non-motorized vessel areas, restricted access, and reduced speed zones.

SUMMARYThe aim of this study was to evaluate the effect of culture medium supplementation with conjugated linoleic acid (CLA) on embryo cleavage, embryo production, sex ratio and embry o quality in in vitro produced bovine embryos at day 7 of culture. 308 COCs were used for the group supplemented with 100 µM of the CLA isomer Cis-9 trans-11 and Cis-10-Trans-12 and 257 COCs for the untreated control group; the embryo production was 25.32% vs 35.40%, respectively, with significant difference between them (P < 0.05). The embryos were classified according to the IETS in Mo, Bt, Bl and Bx stages for morphological and molecular analysis. PCR was used for sex determination; embryo quality was assessed as grade 1 (excellent or good) and Grade 2 (regular). The results showed no significant difference in the proportion of embryos male:female for any of the stages in the CLA supplemented group achieving the expected natural ratio (50:50), while the control maintained a greater number of males. The CLA improved quality in Bl and Bt stages for both females and males (P < 0.05) having a greater number of grade 1 embryos in supplemented group, while control embryos were more in grade 2. In conclusion, CLA adversely affects the production of bovine embryos in vitro, but the sex ratio equals the natural one in all stages and improves embryo quality in some stages of early development.Palabras clave: bovino, CLA, calidad embrionaria, proporción de sexo.

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