Geology topics

Anjanette Bowen

Publications and source records attributed to Anjanette Bowen.

3 recordsLinked to original sources

USGS2023

Assessing potential spawning locations of Silver Chub in Lake Erie

Objective Silver Chub Macrhybopsis storeriana , a predominately riverine species throughout its native range, exists within Lake Erie as the only known lake population. Its population declined in the 1950s and never fully recovered. Canada has listed Silver Chub in the Great Lakes–St. Lawrence River as endangered and has initiated a recovery plan that recognized the identification of spawning areas as a critical component to inform Silver Chub's recovery potential. Methods We investigated potential spawning locations of Silver Chub using capture records, otolith microchemistry, and daily age analysis. Lapillus otolith Sr:Ca ratios from 27 age-0 Silver Chub were used to identify potential spawning areas. Daily ages estimated from lapilli were used to calculate hatch dates, which then were compared with capture data of adults and river flows to further inform potential spawning areas. Result The Detroit River (and its nearshore area) was all but ruled out as a potential spawning location. The Maumee, Portage, and Sandusky rivers or their nearshore areas were all possible spawning locations. Projected hatch dates spanned the end of May through the end of June and occurred across a wide range of flows, although some peaks in hatch dates corresponded to flow peaks, indicating recruitment is potentially enhanced by high flows. Conclusion Silver Chub spawning period and hypothesized spawning rivers or lacustuaries overlap those of invasive Grass Carp Ctenopharyngodon idella , creating a need to jointly consider Grass Carp control efforts with conservation of Silver Chub when assessing management alternatives. Further research on spawning guild and the use of rivers themselves or nearshore areas influenced by rivers as spawning areas are required to maximize potential for conservation and recovery of Silver Chub.

Lake Erie↗

USGS2011

Long-term trends in the St. Marys River open water fish community

We examined trends in species composition and abundance of the St. Marys River fish community. Abundance data were available approximately once every six years from 1975 through 2006, and size and age data were available from 1995 through 2006. We also compared survey data in 2006 with results of a concurrent creel survey that year, as well as data from prior surveys spanning a 69 year time frame. The St. Marys River fish community was best characterized as a coolwater fish community with apparent little variation in species composition, and only slight variation in overall fish abundance since 1975. However, we did find recent trends in abundance among target species sought by anglers: centrarchids increased, percids appeared stable, and both northern pike Esox lucius and cisco Coregonus artedii declined. Survey results suggested that walleye ( Sander vitreus ) and yellow perch ( Perca flavescens ) experienced moderate exploitation but benefited from recent strong recruitment and faster growth. Mechanisms underlying declines of northern pike and cisco were not clear; reduced abundance could have resulted from high exploitation, variation in recruitment, or a combination of both factors. Despite these challenges, the St. Marys River fish community appears remarkably stable. We suggest that managers insure that creel surveys occur simultaneously with assessments, but periodic gill net surveys may no longer provide adequate data in support of recent, more complex management objectives. While additional surveys would add costs, more frequent data might ensure sustainability of a unique fish community that supports a large proportion of angler effort on Lake Huron.

Michigan;Ontario↗

USGS2005

Invasion history, proliferation, and offshore diet of the round goby Neogobius melanostomus in western Lake Huron, USA

We used data from three trawl surveys during 1996–2003 to document range expansion, population trends, and use of offshore habitats by round gobies in the U.S. waters of Lake Huron. Round gobies ( Neogobius melanostomus ) were not detected in any survey until 1997, but by 2003 they had been recorded at 18 of the 28 sites sampled. The only areas not colonized were offshore habitats in northern Lake Huron. Round goby abundance increased during 1997–2001, thereafter overall abundance either increased (offshore) or became variable (near shore and Saginaw Bay). Mean lengths varied among surveys primarily due to high abundance of age-0 gobies in Saginaw Bay samples. Round gobies were found up to 34 km offshore at depths of 73 m. Round gobies consumed a wide range of invertebrate prey, but focused on dreissenids in shallow water (27–46 m), and native invertebrates at greater depths. The pattern of round goby dispersal was consistent with a pattern of simultaneous initial introductions at shipping ports followed by natural dispersal, and lake wide population size has probably not stabilized.

western Lake Huron↗