Vaskar Nepal KC

Product Proposal: “What Controls the Establishment and Spread of an Introduced Fish?”

Blue Catfish Ictalurus furcatus was introduced into the tidal freshwater regions of the James, York and Rappahannock rivers during the 1970s and 1980s to enhance recreational fishery in these rivers. In addition, Blue Catfish have expanded in range not only downriver in brackish waters of these river systems, but also into other tributaries of the Chesapeake Bay. Owing to the large population size, high trophic status and substantial range expansion, this species may now be negatively impacting the ecosystem structure and function of the Chesapeake Bay region and is thus, considered an invasive species. Yet, we currently do not know the ecological constraints to reproduction, growth, and survival of this species in estuarine habitats, nor do we have the ability to accurately assess the potential for future range expansion of blue catfish in Chesapeake Bay subestuaries. In particular, the effect of salinity on the movement, survival, and reproduction of blue catfish is unknown. However, this knowledge is required to address management concerns about the spread of blue catfish populations in Virginia and Maryland. My research attempts to assess the potential of this species to expand in range and negatively affect native species of commercial and recreational value.

I will create an infographic/poster showing some of the most crucial factors that determine the establishment and spread of an introduced species: how different factors come into play; what the potential outcomes are, and what the potential effects can be. This poster will be geared towards general public. I might be tempted to create a more animated version of the poster (may be a short video or a slideshow presentation) for younger audiences.

I will start with an example of a generalized animal, probably a fish. First of all, if the animal has broad environmental tolerance, the animal can survive in the new environment better. E.g. If the animal can survive in cold water as well as warm water, then this animal can establish in most environments. Also, if the fish can tolerate freshwater as well as brackish water, then this fish can potentially establish in estuarine habitats.

Second, the number and the survival of offspring is an important factor. If the animal produces a lot of offspring (and/or frequently), and the offspring survive well, then the population will increase rapidly, otherwise, not.

Third, if the fish grows fast and lives long, then its population will have a better chance of establishment and spread. This is because even if the conditions are bad on particular years and the fish can barely survive, the fish gets another chance at reproduction next year (or the year after).

Fourth, if the fish has little competition for food or space in the new environment, or if few other animals feed of this fish, then the fish has a better chance at establishment and spread. In other words, if this fish is a better competitor than other native fishes in the new environment, then it can outcompete the native fishes.

In all of these scenarios, the introduced animal “wins.” It would be interesting to modify this outline to show what to take into account when screening for potential invasive species. E.g. Does this fish have a long lifespan? Does it reproduce a lot? Does it eat everything? Does it have high salinity tolerance?