Ontogenetic shifts in the diet of commander squid (Berryteuthis magister) in the Salish Sea revealed through stomach content and stable isotope analyses
| dc.contributor.author | Hummelbrunner, Elise | |
| dc.date.accessioned | 2026-02-19T23:49:43Z | |
| dc.date.available | 2026-02-19T23:49:43Z | |
| dc.date.issued | 2025 | |
| dc.description.abstract | Cephalopods play crucial roles in marine ecosystems, yet their dietary habits remain underexplored in many regions. This study examines ontogenetic shifts in the diet of Berryteuthis magister (commander squid) within the Salish Sea using stomach content and stable isotope analyses. Squid samples were obtained through Fisheries and Oceans Canada midwater trawl surveys, and their dietary composition was assessed across different size classes. Stomach content analysis revealed a dietary transition occurring at approximately 160 mm dorsal mantle length (DML), where individuals shift from a crustacean-dominated diet to increased piscivory. This shift was confirmed by stable isotope analysis, which demonstrated a sigmoidal increase in δ¹⁵N values, corresponding to an approximately one trophic level rise with growth. The study found no significant dietary differences between sexes or sampling locations. These findings indicate that B. magister is not merely an opportunistic feeder but a selective predator, actively adjusting its foraging strategy in response to prey availability, capture efficiency, and energetic demands. This research provides the first comprehensive analysis of ontogenetic dietary shifts in B. magister in the Salish Sea, highlighting its role as both competitor and predator in structuring marine food webs. Understanding these trophic interactions is essential for refining ecological models and assessing broader ecosystem dynamics in the region. | |
| dc.description.reviewstatus | Unreviewed | |
| dc.description.scholarlevel | Undergraduate | |
| dc.identifier.uri | https://hdl.handle.net/1828/23326 | |
| dc.language.iso | en | |
| dc.subject.department | Department of Biology | |
| dc.title | Ontogenetic shifts in the diet of commander squid (Berryteuthis magister) in the Salish Sea revealed through stomach content and stable isotope analyses | |
| dc.type | Honours thesis |