Statement of Problem
: New management tools are needed to control the highly invasive asian carps that are rapidily populating the Mississippi River watershed. Studies will be conducted to determine if bighead and silver carp respond to the alarm substance in skin extracts, to characterize the response and determine when during development it occurs. Studies will also be initiated to determine the presence of an attractant from hormone injected adult females. Chemical control measures have been successfully applied in the past to control invasive organisms such as the lamprey in the Great Lakes. But such measures may also affect non-target indigenous species. The use of species-specific repellants and lures, based on natural pheromones may be more effective. Numerous species of fish including cyprinids such as bighead and silver carp have an alarm pheromone that is produced by cells in the outermost epidermal layer of fish skin (Pfeiffer 1977). The substance is released into the water upon damage to the layer of skin overlying the scales as would occur during attack by a predator. This substance, initially described 60 years ago (Von Frisch 1941), induces a fright reaction in conspecifics (same species) which may include freezing, heightened swimming, or rapid escape from the area. Some other species will also avoid areas where the alarm substance is present. In minnows the alarm substance persists for hours in water, it is not affected by freezing and apparently is unaffected by digestion after a predator consumes fish containing alarm substance. In such cases the alarm substances scent the predator and its feces (Mathis and Smith, 1993). Because of the effectiveness of alarm substances as a repellant, the use of alarm substance extracts has been proposed as a chemical barrier to prevent movement of the Eurasian ruffe (gymnocephalus cernuus) between the Great Lakes to the Mississippi River (Maniak et al. 2000). Such methods may also be useful in protecting stream tributaries on the Missouri, Mississippi, and Ohio Rivers, or repelling Asian carps from areas identified as critical habitats for endemic fish such as paddlefish (Polyodon spathula). Sex pheromones are olfactory signals that pass between conspecifics and mediate reproductive interactions (Sorenson and Wyatt 2000). The Asian carps probably also release sex pheromones as described in other common carp and goldfish as unspecialized hormonal products that are released in ratios that vary with sexual status (Poling et al. 2001). These include "primer" pheromones that stimulate gonadal development in other adult conspecifics and synchronize sexual readiness within the population as well as "releaser" pheromones that cause specific behaviors such as attraction, nest preparation and defense, and spawning behaviors (Wilson and Bossert 1963).
: Conduct research and develop methods and technologies to prevent the introduction of invasive species. Specifically, this investigation will determine the existence of alarm and sex pheromones and characterize the fishes response to them in order to develop repellants and lures that can used to control invasive bighead carp and silver carp.
Invasive Carp IPM USGS Demonstration Project on the Illinois River: