Lake Michigan's suitability for bigheaded carp: The importance of diet flexibility and subsurface habitat

Abstract

As bighead (Hypophthalmichthys nobilis) and silver carp (Hypophthalmichthys molitrix)—collectively bigheaded carp (BHC)—arrive at Lake Michigan's doorstep, questions remain as to whether there is sufficient food to support these invasive filter‐feeding fishes in the upper Laurentian Great Lakes. Previous studies suggest that suitable BHC habitat is limited to a few productive, nearshore areas. However, those studies did not consider the influence of BHC's diet plasticity or the presence of spatially‐discrete subsurface prey resources. This study aimed to characterise Lake Michigan's suitability for BHC and evaluate the importance of these considerations in habitat suitability assessments. We used simulated outputs of prey biomass (phytoplankton, zooplankton, and detritus) and water temperature from a three‐dimensional biophysical model of Lake Michigan to evaluate growth rate potential (GRP, quantitative index of habitat suitability) of adult BHC throughout the entire volume of the lake. Our GRP model applied a foraging model and a bioenergetics model to translate prey concentrations and water temperatures into habitat quality indexed by individual fish growth rate. We defined suitable habitat as habitats that can support GRP ≥ 0 g g−1 day−1. We developed six feeding scenarios to evaluate the impact of diet flexibility and subsurface prey resources on suitable habitat quantity. Scenarios were defined by the number of prey types the fish could consume and the depths at which they could feed (surface or whole water column). Consistent with previous studies, we found that habitats with the highest quality were concentrated near river mouths and in eutrophic areas of Green Bay. However, in contrast to previous studies, we found suitable offshore habitat for bighead carp owing to our added considerations of diet plasticity and subsurface prey resources. For silver carp, these considerations extended suitable habitat within Green Bay and in some tributary‐influenced nearshore areas, but offshore areas remained predominantly unsuitable in all feeding scenarios. Differences in simulated habitat suitability between these two species probably reflect differences in energy density and mass of the specific fishes we used in our model. However, reports of these two species in environments where they coexist indicate that bighead carp grow at faster rates than silver carp, as our model simulated. Our vertical analysis at Muskegon, MI, U.S.A. indicates that subsurface temperature and prey biomass are not only sufficient to support bighead carp growth but provide maximum habitat quality during late summer stratification. Overall, our study demonstrates that BHC are capable of surviving and growing in much larger areas of Lake Michigan than predicted by previous studies, and thus suggests that the risk of establishment is not sufficiently reduced by low plankton concentrations. Maps generated by our model identified the potential for cross‐lake migration corridors that may facilitate and accelerate lake‐wide movements....

Asian carp: A threat to American lakes, a feast on Chinese tables

“…Asian carp are also found close to several hydrological connections to the Great Lakes, which include the Chicago sanitary and ship canal (Garvey et al., 2015). The hydrological conditions of the Great Lakes are ideal for Asian carp to thrive (Alsip et al., 2019; Anderson et al., 2015; Ivan et al., 2020; Nalepa et al., 2009). Even an accidental introduction of a few adult individuals into the Great Lakes has a high probability of producing established populations of Asian carp (Cuddington et al., 2014).…”

“…They and common carp ( Cyprinus carpio ) belong to the family Cyprinidae . Bighead carp and silver carp are the most abundant and widespread species and can be considered a threat to the Great Lakes (Alsip et al., 2019; Garvey et al., 2015; Ivan et al., 2020). Silver carp are notorious for being easily frightened by boats and personal watercraft, and the vibration from boat propellers causes silver carp to jump up to 3 m out of the water.…”

Potential establishment and ecological effects of bighead and silver carp in a productive embayment of the Laurentian Great Lakes

“…We used this wide range of seed populations specifically to generate a probability curve for establishment. The lower end of the range of seed population sizes (e.g., B 1000 individuals) is analogous to small numbers of fish being introduced accidentally, intentionally or through long range dispersal events from a distant site that has already been successfully invaded (e.g., Alsip et al 2019). The upper end of the range of seed population (sizes C 10,000 individuals) is, to a limited extent, analogous to a scenario where BHC have become established elsewhere in Lake Huron and that population's wave front is moving towards Saginaw Bay (e.g., Chuang and Peterson 2016).…”

Modeling the interactive effects of nutrient loads, meteorology, and invasive mussels on suitable habitat for Bighead and Silver Carp in Lake Michigan

“…Earlier skepticism regarding the plausibility of BHC to be able to survive and grow in the Great Lakes has been addressed through spatially-explicit models of BHC growth rate potential (GRP) (Cooke and Hill 2010;Anderson et al 2015Anderson et al , 2017Alsip et al 2019). In our previous study, Alsip et al (2019), we built on the work of Cooke & Hill (2010) and Anderson et al (2015Anderson et al ( , 2017 by demonstrating how bioenergeticallysuitable habitat for BHC is not only present in Lake Michigan, but more expansive than originally thought if the fish leveraged their characteristically-flexible diet and utilized subsurface habitat. High quality habitat for BHC growth was concentrated in a few highly productive areas, including Green Bay, whereas offshore areas were only capable of supporting weight maintenance for Bighead Carp.…”

“…The purpose of this paper is to investigate the mechanisms by which climate, nutrient loads, and invasive dreissenid mussels individually and interactively affect Lake Michigan's bioenergetic suitability for BHC. We build on our previous work in Alsip et al (2019) by applying a GRP model (Brandt et al 1992) to quantify habitat quality using scenario datasets from a 3-dimensional biophysical model of Lake Michigan developed by Rowe et al (2017). GRP provides a quantitative measure of fish habitat quality by translating measurements of environmental conditions (prey biomass and water temperature) into fish growth (g g -1 d -1 ) based on bioenergetics.…”