The effects of flow on growth, fin, and otolith development in young of year lake sturgeon, Acipenser fulvescens
Date
2022-01-06
Authors
Merks, Kassandra
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Early rearing environment is critical for development of phenotypes, which will ultimately influence the fitness of the individual. In conservation aquaculture it is even more important to ensure the development of appropriate phenotypes upon release from the hatchery. A natural part of the Lake sturgeon (Acipenser fulvescens) habitat is water flow; therefore understanding its role in development is important for our conservation aquaculture programs. This thesis set out to examine the effects of flow on growth, fin, and otolith development in two cohorts of larval lake sturgeon. Larvae were reared in three treatments designed to increase the complexity of flow. A simple treatment with no flow, a moderate treatment with the addition of flow, and a complex treatment with both flow and substrate. Measurements of mass, total length, body depth, fin length, and finspan were taken for chapter 2 to investigate growth and fin differences across rearing environments. In chapter 3, measurements of otolith surface area, perimeter, and maximum diameter were taken from otolith imagery for differences in size across rearing environments. Additionally, otolith polymorph composition was quantified and difference between left and right otoliths were taken. This research demonstrated that growth was affected by flow and substrate use as fish were largest in the simple treatment. This was likely the result of a combination between poor foraging in substrate and above optimum flow. Further, the differences in growth were no longer seen by the last sampling point indicating fish grew larger and could forage efficiently or they perished. Fin metrics did show some differences with treatment; however, it was determined to be highly correlated with fish length. Otolith polymorph composition was not influenced by the rearing environment, and the ratio of aragonite and vaterite appeared similar in both years and across studies suggesting otolith development may be a fixed phenotype. However, otolith size was influenced by rearing environment where the simple treatment had the largest otoliths in the 2019 while the moderate treatment had the largest otoliths in the 2020 cohort. Further research into differences in swimming abilities and balance related to otolith size, as well as behavioural benefits such as foraging efficiency and predator evasion in this environment is indicated before hatcheries should widely adopt rearing with flow.
Description
Keywords
Otolith, Growth, Lake sturgeon, Flow