Bottom-up and top-down control of small pelagic forage fish: factors affecting age-0 herring in the Strait of Georgia, British Columbia

Marine ecology progress series

Christopher N. Rooper^2¹  Jennifer L. Boldt^1²  Douglas E. Hay^3³  Matthew Thompson^1⁴ 

[1] Emeritus, Fisheries and Oceans Canada, Nanaimo, BC V9T 6N7, Canada^3;Fisheries and Oceans Canada (DFO), Nanaimo, BC V9T 6N7, Canada^1;Juneau Center, School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, AK 99801, USA^4;National Marine Fisheries Service, Alaska Fisheries Science Center, Seattle, WA 98115, USA^2

关键词: Age-0 herring;    Abundance;    Condition;    Bottom-up;    Top-down;    Forage fish;    Strait of Georgia;    Density dependence;   

DOI  :  10.3354/meps12485

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

Small pelagic fish are key planktivores and prey in marine ecosystems, and their population abundances undergo strong temporal and spatial variability. Top-down (predator controlled) and bottom-up (prey-driven) processes during early life history are important for determining forage fish survival and recruitment. We examined biological and environmental factors hypothesized to influence age-0 Pacific herring Clupea pallasi in the Strait of Georgia (SOG), British Columbia, Canada. Primarily bottom-up processes affected interannual variability in age-0 herring abundance and condition, with some evidence of top-down effects on condition. Age-0 herring abundance increased with increasing adult spawning biomass and peaked when most adults spawned about 20 d prior to the peak spring primary production bloom. This timeline would temporally align first-feeding herring larvae with their prey, such as small copepods. Age-0 herring abundance also increased with increasing juvenile salmon abundance, indicating that conditions favourable for herring were also favourable for their predators and competitors. Age-0 herring condition decreased with increasing spawning biomass, increased when most adults spawned closer to the peak spring bloom, increased with increasing temperatures above 8.2°C, and increased then stabilized with increasing prey zooplankton density. Age-0 herring condition had a dome-shaped relationship with predator abundance, indicating that high predator abundances negatively affected fish condition. Study results suggest that density-dependent processes, such as intraspecific competition, may be important in the SOG. A positive correlation between age-0 herring abundance and subsequent age-3 recruit abundance may provide a leading indicator of low recruitment years.

【 授权许可】

Unknown