The paper discusses the integration of traditional ecological knowledge (TEK) and scientific methods for monitoring populations to support sustainable customary wildlife harvests by indigenous peoples. It highlights the value of TEK, which is based on long-term observations, large sample sizes, and low costs, and suggests that it can be complemented by scientific methods to enhance accuracy and reliability. The authors analyze two specific TEK methods: catch per unit effort (CPUE) and body condition, and discuss their limitations and potential biases. They argue that combining these methods can build community consensus and allow indigenous users to critically evaluate scientific predictions and adapt their practices accordingly. The paper also presents case studies from Canada and New Zealand, emphasizing the importance of co-management and the need for scientific research to support sustainable customary use. The authors conclude that a holistic approach, integrating both TEK and science, is essential for effective population monitoring and sustainable resource management.The paper discusses the integration of traditional ecological knowledge (TEK) and scientific methods for monitoring populations to support sustainable customary wildlife harvests by indigenous peoples. It highlights the value of TEK, which is based on long-term observations, large sample sizes, and low costs, and suggests that it can be complemented by scientific methods to enhance accuracy and reliability. The authors analyze two specific TEK methods: catch per unit effort (CPUE) and body condition, and discuss their limitations and potential biases. They argue that combining these methods can build community consensus and allow indigenous users to critically evaluate scientific predictions and adapt their practices accordingly. The paper also presents case studies from Canada and New Zealand, emphasizing the importance of co-management and the need for scientific research to support sustainable customary use. The authors conclude that a holistic approach, integrating both TEK and science, is essential for effective population monitoring and sustainable resource management.