MEPS 357:207-212 (2008)  -  DOI: https://doi.org/10.3354/meps07303

Indirect predator effects on age-0 northern rock sole Lepidopsetta polyxystra: growth suppression and temporal reallocation of feeding

Clifford H. Ryer*, Thomas P. Hurst

Fisheries Behavioral Ecology Program, Alaska Fisheries Science Center, National Marine Fisheries Service/ National Oceanic & Atmospheric Association (NMFS/NOAA), Hatfield Marine Science Center, 2030 SE Marine Science Dr., Newport, Oregon 97365, USA

ABSTRACT: Field observations reveal that age-0 northern rock sole avoid feeding during daylight hours, instead, concentrating their feeding at dusk. Laboratory studies demonstrate these fish to be extremely risk averse in their behavior relative to predators. We hypothesized that dusk feeding may be an adaptation to mitigate the conflict between feeding and predator avoidance, which if unresolved, could negatively affect not only short term survival, but growth as well. We designed experiments to examine firstly, whether growth of juvenile northern rock sole is suppressed by the perception of chronic predation risk, and secondly, whether growth suppression is alleviated by allowing fish to feed at dusk. Replicate groups of 15 fish were grown in the presence or absence of predators (2 walleye pollock) and given access to food under either daylight or dusk conditions over a 6 wk period. Flatfish growth was independently and negatively influenced by both predator presence and daylight conditions; fish fed in daylight in the presence of predators lost weight, while those fed under dusk conditions in the absence of predators grew faster. These results are consistent with our hypothesis that dusk feeding is a behavior that mitigates effects of predation, not only upon survival, but also upon growth. Further, if predator abundance influences growth, as suggested by our data, indirect predator effects such as growth suppression may significantly influence the quality of nursery habitats that differ in predator abundance.


KEY WORDS: Juvenile flatfish · Growth rate · Behavioral inhibition · Habitat quality · Non-lethal effects


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Cite this article as: Ryer CH, Hurst TP (2008) Indirect predator effects on age-0 northern rock sole Lepidopsetta polyxystra: growth suppression and temporal reallocation of feeding. Mar Ecol Prog Ser 357:207-212. https://doi.org/10.3354/meps07303

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