Growth and post-spawning survival in capelin (Mallotus villosus) on the Northeast coast of Newfoundland

• Main Author: Magnaye, Muriel
• Other Authors: Davoren, Gail (Biological Science), Gillis, Darren (Biological Science), Rideout, Rick (Department of Fisheries and Oceans Canada)
• Format: Master Thesis
• Language: English
• Published: 2018
• Subjects: Capelin; Mallotus villosus; Post-spawning survival; Otolith; Histology; Growth; Newfoundland
• Online Access: http://hdl.handle.net/1993/33375

Capelin (Mallotus villosus) is a small, short-lived forage fish species, which is a key prey for many top predators. Newfoundland capelin spawn during the summer, after which most are thought to die. I evaluated the reliability of a spawning zone in the otolith in female capelin by comparing direct (histological) and indirect (otolith-based) indicators of spawning. 50% of individuals with a spawn check identified in the otolith had residual oocytes. This suggests that otolith-based determination may not be a reliable method of identifying previous spawning. I also examined inter-annual variation in growth and links with environmental conditions. Age-specific annual growth was quantified using otolith-based techniques. Generalized Additive Models revealed that higher growth occurred during 2010-2012 and a Principal Components Analysis on environmental factors indicated that these years were characterized by warmer conditions, with earlier and higher magnitude spring blooms, but the abundance of capelin prey varied widely. This suggests that temperature and bloom dynamics may have a larger influence on capelin growth. We highlight the importance of understanding environmental conditions influencing population dynamics, as well as the importance of further characterizing the life history of capelin. October 2018