The metabolic cost of behavioural tradeoffs during the early life stages of three north-Atlantic marine fishes

• Main Author: Killen, Shaun S.
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2007
• Subjects: North Atlantic
• Online Access: https://research.library.mun.ca/10807/; https://research.library.mun.ca/10807/1/Killen_ShaunSteven.pdf

This thesis uses studies of physiology and behaviour to better understand the foraging and predator-avoidance tradeoffs experienced by young marine fishes. It has previously been speculated that, due to their small size and high growth rates, larval and juvenile fish may have a limited aerobic capacity compared to adult individuals. This could be an important constraint influencing the behavioural ecology of young fishes, but has been difficult to evaluate because there has been no single study to examine changes in metabolic rate or aerobic scope for any fish species over their entire life history. Thus, an important first step in this thesis was to examine the standard (minimal) metabolism, maximal metabolism, and aerobic scope for three species of north Atlantic marine fish (shorthorn sculpin Myoxocephalus scorpius, ocean pout Zoarces americanus, and lumpfish Cyclopterus lumpus) from the larval stage until adulthood. This research showed that young fish have a greatly increased mass-specific metabolic demand compared to adults, and that their aerobic scope is vastly diminished. The results also suggest that the relationship between aerobic scope and life history stage is greatly influenced by a species' developmental trajectory. -- A second group of projects then investigated the effects of increased mass-specific metabolic demand on anti-predator behaviour in young marine fishes. It is known that most animals will reduce foraging while in the presence of predatory threat, but that individuals are often more risky (i.e. they will continue to forage) during times when they are hungry or have increased energetic requirements. However, despite their high mass-specific energy demands, it was observed that young ocean pout and larval shorthorn sculpin both display large foraging reductions when exposed to predators. Due to the high energetic requirements of these fishes, these results suggest that these foraging interruptions could be very costly. To support this view, these studies also found that frequent, ...