Geology topics

Ben S Breaker

Publications and source records attributed to Ben S Breaker.

3 recordsLinked to original sources

USGS2025

Stable C and N isotope analyses redefine cisco as pelagic piscivores in Lake Michigan

Lake Michigan’s cisco ( Coregonus artedi ) population is in the midst of an expansion (2011-present) recovering from near extirpation levels observed in the 1970 s. Strong evidence of piscivory derived from observed diet analyses suggests the population may occupy a unique trophic position relative to typical expectations for the species. To verify these observations, cisco and their prey were collected from 2017 to 2020 for stable C and N isotope analyses. Leveraging existing stable isotope datasets for Lake Michigan, the trophic position of cisco was assessed by quantifying the isotopic niche space occupied relative to common salmonine piscivores and prey fish species. Diet mixing models were constructed to estimate the relative importance of potential prey sources to cisco diets. Results suggested that cisco occupied an isotopic niche similar to Pacific salmonines ( Oncorhynchus spp.) and brown trout ( Salmo trutta ) that are mainly piscivorous. Conversely, there was low isotopic niche overlap with prey fish species that are mainly planktivorous. Mixing models suggest greater reliance on pelagic prey sources (including alewife Alosa pseudoharengus and Bythotrephes longimanus ) in cisco diets when compared with observations of stomach contents. Under the present ecological conditions in Lake Michigan, it appears that adult cisco in this population occupy the trophic role of a pelagic piscivore.

Lake Michigan↗

USGS2025

Sunburned after a day at the beach? Investigation of ultraviolet radiation tissue damage on larval Lake Whitefish and Alewife across lake Michigan nursery habitats of varying water clarities

No abstract available.

Illinois, Indiana, Michigan, Wisconsin↗

USGS2020

Piscivory in recovering Lake Michigan Cisco (Coregonus artedi): The role of invasive species

Contemporary conditions in Lake Michigan where cisco ( Coregonus artedi ) populations are expanding are vastly different from those encountered by the historic fish community. Invasive species introductions have substantially altered the Lake Michigan ecosystem in the last half century. Successful management efforts for cisco in Lake Michigan hinge on our ability to understand their contemporary ecology, especially diet. We collected 725 cisco stomachs opportunistically from commercial fisheries (2%) and in agency surveys (98%) over six years (2014–2019). The majority (70%) of stomachs were from East Grand Traverse Bay and 96% of these were collected at Elk Rapids. Additional samples were collected from Charlevoix (8%), Little Traverse Bay (11%), other sites in northern Lake Michigan (4%), Central Lake Michigan (6%), and Green Bay (1%). Our results indicated a high degree of piscivory, in contrast to historical and contemporary accounts of planktivory for cisco in the other Laurentian Great Lakes. The top three prey items by mass were not native to the Great Lakes and these accounted for 87% of all observed prey mass consumed: round goby ( Neogobius melanostomus) (58%), Bythotrephes longimanus (15%), and alewife ( Alosa pseudoharengus) (14%). Round goby dominated the prey in the spring and summer, while B. longimanus and alewife occurred more in summer and fall diets. The contemporary population of cisco in Lake Michigan has been able to uniquely capitalize on abundant invasive prey resources, which may be less limiting and more energy-rich than a more typical planktivorous cisco diet.

Lake Michigan↗