Geology topics

James A. Hoyle

Publications and source records attributed to James A. Hoyle.

4 recordsLinked to original sources

USGS2021

Lake Ontario cisco population dynamics based on long-term surveys

Prior to European settlement, cisco (Coregonus artedi) were likely one of Lake Ontario’s most abundant fishes but currently represent a small portion of the fish community. To understand how the population has changed over the past 70 years we compared trends in annual catch rates from gillnet and bottom trawl surveys and commercial fishery landings. In surveys, cisco were generally rare, and represented 0.2, 0.4, and 0.001% of all fish caught in two gillnet surveys and bottom trawl surveys. Cisco catch rates in gillnets and trawls were positively correlated and correlations increased when gillnet catches two years later were compared to trawls since trawls tended to capture smaller, juvenile-sized cisco relative to gillnets. Survey catch rates suggest recruitment is generally low, but discrete periods of relatively greater recruitment in the 1980s and mid-2010s suggest reproductive conditions for cisco vary temporally. Trawl surveys were the most spatially extensive survey and illustrated catch rates were highest in northeastern Lake Ontario. Greater cisco abundance in this region may be related to more-abundant embayment spawning habitat, greater distance from winter aggregations of nonnative planktivores, or more appropriate environmental conditions during spawing. At the basin scale, Lake Ontario bottom trawl catch per unit effort (CPUE) was positively correlated to Lake Superior trawl CPUE suggesting a regional driver, such as climate, may be similarly impacting both populations. Concurrent patterns across Lake Ontario surveys support the idea that cisco are currently a small portion of the fish community, recruitment remains inconsistent, and habitats in northeastern Lake Ontario appear critical to the remnant populations.

Lake Ontario↗

USGS2017

Deepwater sculpin status and recovery in Lake Ontario

Deepwater sculpin are important in oligotrophic lakes as one of the few fishes that use deep profundal habitats and link invertebrates in those habitats to piscivores. In Lake Ontario the species was once abundant, however drastic declines in the mid-1900s led some to suggest the species had been extirpated and ultimately led Canadian and U.S. agencies to elevate the species' conservation status. Following two decades of surveys with no captures, deepwater sculpin were first caught in low numbers in 1996 and by the early 2000s there were indications of population recovery. We updated the status of Lake Ontario deepwater sculpin through 2016 to inform resource management and conservation. Our data set was comprised of 8431 bottom trawls sampled from 1996 to 2016, in U.S. and Canadian waters spanning depths from 5 to 225 m. Annual density estimates generally increased from 1996 through 2016, and an exponential model estimated the rate of population increase was ~ 59% per year. The mean total length and the proportion of fish greater than the estimated length at maturation (~ 116 mm) generally increased until a peak in 2013. In addition, the mean length of all deepwater sculpin captured in a trawl significantly increased with depth. Across all years examined, deepwater sculpin densities generally increased with depth, increasing sharply at depths > 150 m. Bottom trawl observations suggest the Lake Ontario deepwater sculpin population has recovered and current densities and biomass densities may now be similar to the other Great Lakes.

Journal of Great Lakes Research↗

USGS2017

Nearshore fish community

Lake Ontario’s nearshore fish community consists of a diverse assemblage of warm- and cool-water species. The “nearshore zone,” loosely separated from the “offshore zones” by the 15-m depth contour, consists of complex habitats spanning a gamut from vast open-coastal areas to sheltered embayments and wetlands. Lake Ontario’s nearshore habitat has been affected to varying degrees by human activities. Although many areas are relatively unimpaired, some are severely degraded and have been designated as Areas of Concern (AOCs) (http://www.ec.gc.ca/raps-pas/; http://www2.epa.gov/great-lakes-aocs).

Report↗

USGS2014

The offshore benthic fish community

Lake Ontario’s offshore benthic fish community includes primarily slimy sculpin, lake whitefish, rainbow smelt, lake trout, burbot, and sea lamprey. Of these, lake trout have been the focus of an international restoration effort for more than three decades (Elrod et al. 1995; Lantry and Lantry 2008). The deepwater sculpin and three species of deepwater ciscoes (Coregonus spp.) that were historically important in the offshore benthic zone became rare or were extirpated by the 1960s (Christie 1973; Owens et al. 2003; Lantry et al. 2007b; Roth et al. 2013). Ecosystem changes continue to influence the offshore benthic fish community, including the effects of dreissenid mussels, the near disappearance of burrowing amphipods (Diporeia spp.) (Dermott et al. 2005; Watkins et al. 2007), and the increased abundance and expanded geographic distribution of round goby (see Nearshore Fish Community chapter) (Lantry et al. 2007b). The fish-community objectives for the offshore benthic fish community, as described by Stewart et al. (1999), are: The offshore benthic fish community will be composed of self-sustaining native fishes characterized by lake trout as the top predator, a population expansion of lake whitefish from northeastern waters to other areas of the lake, and rehabilitated native prey fishes.

New York↗