Graduation Date
Fall 2025
Document Type
Thesis
Program
Master of Science degree with a major in Biology
Committee Chair Name
Allison Bronson
Committee Chair Affiliation
Cal Poly Humboldt Faculty or Staff
Second Committee Member Name
John Reiss
Second Committee Member Affiliation
Cal Poly Humboldt Faculty or Staff
Third Committee Member Name
Darren Ward
Third Committee Member Affiliation
Cal Poly Humboldt Faculty or Staff
Fourth Committee Member Name
Melanie Stiassny
Fourth Committee Member Affiliation
Community Member or Outside Professional
Keywords
Olfaction, Morphology, Rod cells, Olfactory rosette
Subject Categories
Biology
Abstract
Rainbow trout (Oncorhynchus mykiss) are an ecologically and culturally important salmonid species that exhibits diverse life history strategies, including anadromous and resident freshwater life cycles. Though many studies have examined their olfactory morphology, none have directly compared possible olfactory microstructural differences between wild and hatchery-raised populations. Histology and scanning electron microscopy (SEM) were employed to compare the gross anatomy and ultrastructure of olfactory rosettes in three O. mykiss populations: wild residents from Jacoby Creek (JC), a resident lineage of hatchery fish from Mad River Hatchery (MRH), and an anadromous lineage from the Cal Poly Humboldt (CPH) Hatchery. The CPH population was also assessed after exposure to an anesthetic dose of buffered tricaine methanesulfonate (MS-222) following observations in 2022 of abnormal olfactory epithelia and rod cells. No morphological differences were observed between anesthetized and control CPH fish. All populations possessed olfactory receptor cells within the sensory epithelium. However, olfactory sensory regions between secondary lamellae were dominated by rod cells in CPH Hatchery fish, sporadically present in JC wild residents but absent in MRH residents. While rod cells have been documented in numerous fish species, their function remains unknown. Though olfaction is key in salmonid homing, foraging, and conspecific communication, without knowing the functional significance of rod cells and differences in rosette maturation, it is unclear whether their presence may impact the behavior or survival of hatchery trout.
Citation Style
APA
Recommended Citation
Rahman-Garnier, Nicole, "Comparative olfactory anatomy of wild and hatchery-raised rainbow trout (Oncorhynchus mykiss)" (2025). Cal Poly Humboldt theses and projects. 2514.
https://digitalcommons.humboldt.edu/etd/2514