Wireless Multimedia Sensor Networks (WMSNs) consist of a large number of sensor nodes that have multiple sensing units. Unlike traditional wireless sensor networks, WMSNs are used to collect multimedia data such as video or image. As WMSNs are employed by military or civil surveillance/tracking applications security of these Networks must be ensured. As in traditional wireless sensor networks, sensor nodes in WMSNs are resource limited. Hence, data collection in WMSNs must be performed in an energy efficient way. In this study, a watermarking based protocol that ensures secure and energy efficient data collection in WMSNs is proposed. In the proposed protocol, sensor nodes embed the secret data into image data using an attack resilient watermarking algorithm and data aggregators aggregate the image data. Performance analysis and simulations show that the proposed protocol ensures secure data aggregation and reduces the amount of data transmission.