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Diets of Deepwater Sculpin collected from fall forage (2003-05 and 2010-14) in Lake Huron

February 6, 2017

Diet contents of Deepwater Sculpin (Myoxocephalus thompsonii) were identified, enumerated, and measured to monitor the changes in the offshore benthic fish community within Lake Huron. Collections were made using a 21-m headrope with a 4.76mm square mesh cod-end with 10 minute contour trawl tows.. Deepwater Sculpin collected from the USGS fall forage (2003-2005 and 2010-2014) were counted and weighed en masse on board research vessel. Individual weights (nearest 0.001g) and measurements (0.1mm) were conducted in laboratory setting. Stomachs were extracted in laboratory setting (from esophogus to pyloric ceaca). Stomachs were stored in ethanol for later dissection. Stomach contents were removed in petri dish. All stomach contents were identified (to lowest possible taxonomic level), enumerated, and measured using ocular micrometer or Image Pro Plus 7.0. Previous O'Brien study did not count Bythotrephes longimanus (only presence/absence). Length-weight regressions were used for comparing diets by biomass (Johnson and Brinkhurst 1971, Grossnickle and Beeton 1979, Winnell and White 1984, Shea and Makarewicz 1989). Partially digested items were counted using pairs of eye stalks and measuring the antennal scale for Mysis, head capsules for Chironomidae, and eye to the telson for Diporeia (Mychek-Londer and Bunnell 2013).

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