Growth of Hatchery‐Reared Chinook Salmon in Lakes Michigan and Huron Exhibits Limited Spatial Variation but Is Temporally Linked to Alewife Abundance

Kornis, Matthew S.; Simpkins, Darin G.; Lane, Allen A.; Warner, David M.; Bronte, Charles R.

doi:10.1002/nafm.10349

Cited by 6 publications

(1 citation statement)

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“…In some regions, introduced megafish populations are managed to provide socio‐economic benefits for people. For example, chinook salmon and brown trout were introduced to the Great Lakes to control the invasive alewife ( Alosa pseudoharengus ) and have since become valuable species for recreational fishing (Kornis et al., 2019; Simpson et al., 2016). Nevertheless, they also compete with the reintroduced Atlantic salmon, possibly impeding the recovery of this native species in the Great Lakes (Grant & Weir, 2022; Scott et al., 2003).…”

Section: Discussionmentioning

confidence: 99%

Global introductions and environmental impacts of freshwater megafish

Chen,

Evans,

Jeschke

et al. 2024

Global Change Biology

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Freshwater megafish species, such as sturgeons, salmonids, carps, and catfishes, have a maximum reported weight ≥30 kg. Due to their charisma and economic value, they have been widely introduced outside of their native ranges. Here, we provide a comprehensive overview of the introduction of freshwater megafish and an assessment of their environmental impacts. Of the 134 extant freshwater megafish species, 46% have been introduced to new environments, and of these, 69% have established self‐sustaining alien populations. These introductions affect 59% of the world's main basins, with the USA and western Europe being particular hotspots of megafish introductions. The common carp (Cyprinus carpio) is the most widely introduced species. Using the Environmental Impact Classification for Alien Taxa (EICAT and EICAT+) frameworks, we assessed the severity and type of negative and positive impacts posed by alien megafish on native species. Alien megafish caused negative impacts through nine different mechanisms, with predation being the most frequently reported mechanism, followed by herbivory and competition. Moreover, 58% of the alien megafish species with sufficient data to evaluate the severity of their impacts caused declining populations of native species, or worse, extirpations of native species populations. The positive environmental impacts of alien megafish were far less frequently documented. They include biotic interactions that benefit native species, and the provision of trophic resources or habitats. Widely introduced or extensively studied species are more likely to have documented severe impacts on native species. There is a clear trade‐off between the economic benefits associated with megafish introductions and the severe adverse impacts they have on native biodiversity. Our study highlights the need for comprehensive risk assessments to evaluate the potential environmental impacts of megafish. More research and long‐term monitoring schemes are required to inform management actions to protect biodiversity, particularly in the Global South.

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Section: Discussionmentioning

confidence: 99%

Global introductions and environmental impacts of freshwater megafish

Chen,

Evans,

Jeschke

et al. 2024

Global Change Biology

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Testing food web theory in a large lake: The role of body size in habitat coupling in Lake Michigan

Maitland,

Bootsma,

Bronte

et al. 2024

Ecology

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The landscape theory of food web architecture (LTFWA) describes relationships among body size, trophic position, mobility, and energy channels that serve to couple heterogenous habitats, which in turn promotes long‐term system stability. However, empirical tests of the LTFWA are rare and support differs among terrestrial, freshwater, and marine systems. Further, it is unclear whether the theory applies in highly altered ecosystems dominated by introduced species such as the Laurentian Great Lakes. Here, we provide an empirical test of the LTFWA by relating body size, trophic position, and the coupling of different energy channels using stable isotope data from species throughout the Lake Michigan food web. We found that body size was positively related to trophic position, but for a given trophic position, organisms predominately supported by pelagic energy had smaller body sizes than organisms predominately supported by nearshore benthic energy. We also found a hump‐shaped trophic relationship in the food web where there is a gradual increase in the coupling of pelagic and nearshore energy channels with larger body sizes as well as higher trophic positions. This highlights the important role of body size and connectivity among habitats in structuring food webs. However, important deviations from expectations are suggestive of how species introductions and other anthropogenic impacts can affect food web structure in large lakes. First, native top predators appear to be flexible couplers that may provide food web resilience, whereas introduced top predators may confer less stability when they specialize on a single energy pathway. Second, some smaller bodied prey fish and invertebrates, in addition to mobile predators, coupled energy from pelagic and nearshore energy channels, which suggests that some prey species may also be important integrators of energy pathways in the system. We conclude that patterns predicted by the LTFWA are present in the face of species introductions and other anthropogenic stressors to a degree, but time‐series evaluations are needed to fully understand the mechanisms that promote stability.

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