The impacts of these changes on the hydrodynamic features of YS in turn influence the productivity of plankton prey for the anchovy.
Climate variability seems to indirectly influence the anchovy stock through bottom-up control via a cascading effect from the changes in the North Pacific Gyre Oscillation (NPGO) or the Pacific North American pattern (PNAP).
#Bottom up control driver#
This was possibly due to overfishing becoming a major driver after 1980, thereby altering the cascading of the marine ecosystem towards a different structure. However, the bottom-up processes became unclear under excessive fishing. In addition, we found positive relationships between the anchovy abundance and plankton productivity in proxies before the period of intense fishing (1860–1980 AD), indicating bottom-up processes affecting the anchovy stock. Principal component analysis (PCA) identified negative effects of strong stratification (higher δ 15N) and high abundance of haptophytes (higher alkenone content) on the anchovy stock through our analytical period (~1860–2005 AD). We discussed the linkages of the anchovy abundance to ecosystem structure and sea surface temperatures (SSTs). Here, we used 150-year sediment records of the abundance of Japanese anchovy ( Engraulis japonicus) scales, phytoplankton, and zooplankton biomarkers, and δ 15N data previously reported from the central Yellow Sea (YS). Fortunately, marine sedimentary archives of fish abundance and environmental changes in the past, may provide new insights into long-term fish population fluctuations. However, limited data combined with climate variability and fishing further constrain our understanding of fish population dynamics. Elucidating the mechanisms of fluctuations in fish populations are key to sustainable fisheries management.
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