Temporal Changes and Sexual Differences in Spatial Distribution of Burbot in Lake Erie

Abstract

We used GIS mapping techniques to examine capture data for Burbot Lota lota from annual gill-net surveys in Canadian waters of Lake Erie during late August and September 1994-2011. Adult males were captured over a larger area (3-17% for ≥20% maximum yearly catch [MYC]) than adult females. More males than females were caught in the gill nets in 14 of the 15 study years. Collectively, these results support a hypothesis of greater activity by adult males during summer, when Burbot are actively feeding. The area of capture contracted by more than 60% (for ≥20% MYC) for both sexes during the time period, which is consistent with the documented decrease of the Burbot population in the lake. The sex ratio (females : males) varied over the time series but declined steadily from 0.97 in 2001 to 0.59 in 2011. The overlap in the capture areas of adult males and females was scale dependent. The depth distribution at which adult Burbot were caught did not change over the time series, and there was no difference in the median depths (about 30 m) at which adult male and female Burbot were caught. The last results are consistent with the Burbot's reliance on coldwater habitats. Additional research is recommended, including telemetry to describe daily and seasonal movements and assessment of gender bias in active and passive capture gear.

Polychlorinated biphenyl congener distributions in burbot: Evidence for a latitude effect

“…Burbot were captured in gill net surveys conducted in Canadian waters of the eastern basin of Lake Erie ( Figure 1) during August 2012 and September 2012. Complete descriptions of the capture gear and procedures are provided elsewhere [30][31][32][33]. Following capture, sagittal otoliths were removed, sex was determined, stomach contents were removed Figure 1.…”

Ecology, culture, and management of Burbot: an introduction

“…However, nearly extirpated Burbot populations have recovered in some systems without stocking, following improved water quality and decreased predation from invasive species (Stapanian & Madenjian, 2007;Stapanian et al, 2006Stapanian et al, , 2010. Although external sexual dimorphism is subtle and seasonal, the testes of Burbot are very large compared with most other fishes and Burbot exhibit sexual differences in range (Stapanian et al, 2013a) and uptake of contaminants (Madenjian et al, 2013Stapanian et al, 2013b). Burbot have been shown to be ideal organisms for studies of contaminants in freshwater systems, revealing, for example that latitudinal trends in polychlorinated biphenyl congener distributions are more complex than previously thought , and like in ''higher'' vertebrates, androgen levels may enhance mercury elimination in teleost fish (Madenjian et al, 2015).…”