LE3 .A278 2022

2022

Avery, Trevor
Easy, Russell
Gibson, Glenys

Acadia University

Master of Science

Masters

Biology

Biology

Striped Bass Morone saxatilis is a native species in Nova Scotia and New Brunswick, but its northern range expanded into southern Labrador in 2017. Thus, understanding reproduction and Striped Bass diets will help us better understand potential effects of its expansion. The current study conducted and compared traditional gut content analyses to molecular diet analyses to characterize the interactions between Striped Bass and target prey species including Arctic Char Salvelinus alpinus, Atlantic Cod Gadus morhua, Atlantic Salmon Salmo salar, Capelin Mallotus villosus, gaspereau Alewife Alosa pseudoharengus and Blueback Herring Alosa aestivalis, American lobster Homarus americanus, and Rainbow Smelt Osmerus mordax in Minas Basin and southern Labrador. Further, we also explored the Striped Bass reproductive biology through the gonadosomatic index (GSI), hepatosomatic index (HSI) and histological sectioning with Striped Bass gonads to describe stages of gonad development. Striped Bass showed spatial preference for targeting prey items. The traditional diets show that Striped Bass primarily feed on Sand Shrimp (28.2 %) in Minas Basin and on Capelin (59.1 %) in Labrador. The molecular results showed no Atlantic Salmon in Striped Bass stomachs in either site, and Arctic Char were only found in Labrador Striped Bass diets. Atlantic Cod, a commercially important and at-risk species, was detected in Minas Basin (52.9 %) and Labrador (71 %) samples. For gonad development, female GSI started to decline in early May and in males declined in late May. The highest GSI was 16.68 % for females and 14.05 % for males. Female and male GSI remained at a low level throughout summer. Gonads of both sexes increased in size and GSI during the fall until mid-November with female GSI showing a faster increasing rate of GSI than males. Gonadal sectioning showed six stages of oogenesis and four spermatogenesis stages in Striped Bass collected from Minas Basin. Stage V and Stage VI oocytes were found in abundance in mid-May, Stage-II cells were found in high proportions from post-spawning to July, and Stage-IV cells were first observed in summer. The spawning period is outlined by a drop in GSI and a high proportion of Stage II oocytes. Striped Bass spawning period in the current study was about from 17 May to 17 June. Pre-spawning samples had the highest HSI. HSI and GSI showed similar patterns over the sampling period. The current study was the first to explore Striped Bass diets in Labrador and Minas Basin and the first to identify Striped Bass gametogenesis seasonal changes in Minas Basin.

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https://scholar.acadiau.ca/islandora/object/theses:3891