An Assessment of Gear Efficiency, Size Selectivity, and Detection Probability for Asian Carp: Designing Sampling Programs to Monitor Invasion Fronts

Bighead carp (Hypophthalmichthys nobilis) and silver carp (H. molitrix), together known as Asian carp, have invaded large portions of the Mississippi River basin and continue to spread into new watersheds.  Various agencies are employing a variety of sampling gears to monitor Asian carp populations, but these gears may vary widely in their ability to capture Asian carp relative to their abundance and may select for different sizes of fish.  We are evaluating the efficiency of multiple sampling gears, their size selectivity, and their ability to detect Asian carp in areas of low abundance in order to strengthen monitoring and control efforts.  Hoop nets and trammel nets appear to be the most effective gears for targeting bighead carp, although these gears captured different sizes of fish, whereas electrofishing was most effective for silver carp of all sizes.  Entanglement gears vary in their ability to capture Asian carp depending on the configuration and mesh sizes used.  Detection probability modeling indicates that the ability of different gears to detect Asian carp varies widely among gear types and among sampling locations, and suggests that large sampling efforts are required to detect Asian carp near the edges of their invasion fronts.