Science Advisory Report  2011/071

Binational ecological risk assessment of the bigheaded carps (Hypophthalmichthys spp.) for the Great Lakes basin

Summary

• The most likely entry point into the Great Lakes basin is the Chicago Area Waterway System (CAWS) into Lake Michigan. The effectiveness of the electrical barrier in the Chicago Sanitary and Ship Canal (CSSC) was not evaluated. Nevertheless, the complex nature of the CAWS and proximity of bigheaded carp populations led to the conclusion this is the most likely entry point.
• Once bigheaded carps have gained entry into the basin, they are expected to spread to other lakes within 20 years. The spread will be more rapid for lakes Michigan, Huron, and Erie, and potentially Lake Superior; longer for Lake Ontario.
• Bigheaded carps would find suitable food, and thermal and spawning habitats in the Great Lakes basin that would allow them to survive and become established. The areas that would be attractive and favorable are Lake Erie, including Lake St. Clair, and high productivity embayments of lakes Superior, Michigan, Huron and Ontario.
• There is a greater than 50% probability of successful mating each year with very few (< 10) adult females (and a similar number of adult males) within the basin of a Great Lake.
• Population growth is most sensitive to the survivorship of juveniles.
• The consequences of an established bigheaded carp population are expected to include changes in planktonic communities, reduction in planktivore biomass, reduced recruitment of fishes with early pelagic life stages, and reduced stocks of piscivores.
• To reduce the probability of introduction (either at the arrival, survival, establishment or spread stage), and delay or reduce subsequent ecological consequences, immediate prevention activities would be most effective, especially in conjunction with population management activities at the invasion front.

This Science Advisory Report is from the Fisheries and Oceans Canada, Canadian Science Advisory Secretariat, national advisory meeting of November 8-10, 2011 on the Binational Risk Assessment for Asian Carps in the Great Lakes. Additional publications from this process will be posted as they become available on the DFO Science Advisory Schedule.

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