The possible roles of culture, gender, and age-related factors as mediators of decision making about socioscientific issues (SSIs) have been underexplored, particularly the impact of distinct cultural groups’ perspectives. This comparative study explored culturally influenced decision-making using a mixed methods approach. To study the impact of culture and cross-cultural understanding on students’ decision-making, and how these impacts are possibly mediated by age and gender-related variables, 106 11-13 year old students and 60 15-17 year old students from three Hong Kong schools and four UK schools were engaged indecision-making about shark fishing, framed as an SSI. Data were collected on how students make decisions about the issue before and after interacting with their own peers and considering the views of their international counterparts, using discussion records, supplemented with focus group interviews. The findings show that students associated with the culture of shark eating do not necessarily identify with shark fishing. Three dimensions characterize students’ decisions: the human activities to be controlled, the ways to address issues arising from shark fishing, and the concerns underlying students’ decisions. Although students showed support for conserving sharks, there were nuanced differences between the two cultural groups in the three decision dimensions, which were possibly mediated by gender and age factors. The findings provide support to the impact of cultural exchange through cross-cultural presentations, post-activity discussion and reflections on their own and others’ views on broadening students’ perspectives and stimulating their critical reasoning. The study raises some important questions relating to group decision-making about shark conservation.