Feeding ecology of a common benthic fish, shorthorn sculpin (Myoxocephalus scorpius) in the high arctic

• Published in: Polar Biology
• Main Authors: Landry, Justin J., Fisk, Aaron T., Yurkowski, David J., Hussey, Nigel E., Dick, Terry, Crawford, Richard E., Kessel, Steven T.
• Format: Text
• Language: unknown
• Published: Scholarship at UWindsor 2018
• Subjects: Arctic food webs; Dietary specialization; Shorthorn sculpin; Trophic position; Arctic; Boreogadus saida; polar cod
• Online Access: https://scholar.uwindsor.ca/glierpub/317; https://doi.org/10.1007/s00300-018-2348-8

Shorthorn sculpin (Myoxocephalus scorpius) commonly occur in nearshore areas during open water periods in the Arctic, yet little is known about their feeding strategies or trophic roles. This study used carbon (δ13C) and nitrogen (δ15N) stable isotopes (SIs) and stomach content analysis (SCA) to assess shorthorn sculpin trophic position (TP), carbon sources, dietary specialization and prey selection, and the significance of polar cod (Boreogadus saida) in their diet across body size and multiple years. Sculpin TP increased with body size [range = 4.0 ± 0.1 (< 20 cm) to 4.6 ± 0.2 (> 25 cm)] and was consistent with SCA; smaller individuals fed predominantly on invertebrates while larger fed more on fishes. Shorthorn sculpin had high % reliance on pelagic resources (α) for a benthic fish, from 0.62 ± 0.05 to 0.63 ± 0.06, thus coupling benthic and pelagic sources. Dietary specialization based on SIs in liver and muscle occurred in all size groups, and along with TP and niche width varied between years, generally increasing with fish found in SCA. The presence of polar cod, absent two of the four study years, did not significantly affect any dietary metrics measured in shorthorn sculpin, and cannibalism appears to have had a greater impact on shorthorn sculpin trophic ecology. This study demonstrates that shorthorn sculpin are an important secondary to tertiary consumer in nearshore Arctic marine habitats due to coupling multiple trophic pathways, demonstrating plasticity in diet between years, and exploiting an array of prey across size ranges.