Response of Native Fish and Plankton to the Arrival and Subsequent Reduction of Asian Carp

Session: 02a. - Status and Management of Invasive Carps in the Great Lakes

Andrew Casper, Shedd Aquarium, [email protected]
Jason DeBoer, Illinois natural History Survey, [email protected]
Kristopher Maxson, Illinois Natural History Survey, [email protected]
Alison Anderson, USACE-St. Louis District, [email protected]

Abstract

While much is speculated about the potential effects of the rapid spread and large population sizes of the Asian carp species, information on the array and intensity of their primary ecological impacts is not yet well understood. What is currently clear is that the Asian carp’s primary influence will be through their roles as pelagic planktivores. We will present analyses from field studies and multi-decadal datasets that span the proliferation of one species, the Silver carp (Hypophthalmichthys molitrix). These include significant shifts in the plankton abundance and composition and, subsequently, the native fish assemblage and planktivores. We will also show the plankton’s  response to the intensive control efforts instituted since 2010, especially targeted removal of carp through commercial fishing. In general, the ecological response to removal has been positive: rotifer abundance increases more quickly the copepods and cladocerans and the condition of some planktivores like Gizzard shad (Dorosoma cepedianum) has rebounded to pre-carp levels. While invaded ecosystems and its aquatic assemblages have clearly been degraded by the arrival of the carp, there is also clear evidence that accelerating management and control efforts can have a measurably positive effect.

1. Keyword
invasive species

2. Keyword
plankton

3. Keyword
fish management

4. Additional Keyword
ecosystem response