Smeltcam: Underwater Video Camera Codend for Trawled Nets

Studying rare and sensitive species is a challenge in conservation biology.  This problem is exemplified by the case of the imperiled delta smelt Hypomesus transpacificus, a small delicate fish species endemic to the San Francisco Estuary, California.  Persistent record-low levels of abundance and relatively high sensitivity to handling stress pose considerable challenges to studying delta smelt in the wild.  In an attempt to overcome these and other challenges we have developed the SmeltCam, an underwater video camera codend for trawled nets. The SmeltCam functions as an open-ended codend that automatically collects information on the number and species of fishes that pass freely through a trawled net without handling.  In the course of development, the SmeltCam has been applied to studies of distribution and habitat of delta smelt and other fishes.  Results to date suggest that application of the SmeltCam has increased survival of individual delta smelt by 72-100% compared to using a traditional codend. The SmeltCam improves upon similar previously-developed silhouette photography or video recording devices and demonstrates how new technology can be developed to address important questions in conservation biology, as well as lessen the negative effects associated with traditional sampling methods on imperiled species.