Evaluation of multi-scale climate effects on annual recruitment levels of the Japanese eel, Anguilla japonica, to Taiwan
Journal
PLoS ONE
Journal Volume
7
Journal Issue
2
Date Issued
2012
Author(s)
Tzeng, Wann-Nian
Hsu, Chih-Chieh
Chang, Chih-Wei
Di Lorenzo, Emanuele
Abstract
Long-term (1967-2008) glass eel catches were used to investigate climatic effects on the annual recruitment of Japanese eel to Taiwan. Specifically, three prevailing hypotheses that potentially explain the annual recruitment were evaluated. Hypothesis 1: high precipitation shifts the salinity front northward, resulting in favorable spawning locations. Hypothesis 2: a southward shift of the position of the North Equatorial Current (NEC) bifurcation provides a favorable larval transport route. Hypothesis 3: ocean conditions (eddy activities and productivity) along the larval migration route influence larval survival. Results of time series regression and wavelet analyses suggest that Hypothesis 1 is not supported, as the glass eel catches exhibited a negative relationship with precipitation. Hypothesis 2 is plausible. However, the catches are correlated with the NEC bifurcation with a one-year lag. Considering the time needed for larval transport (only four to six months), the one-year lag correlation does not support the direct transport hypothesis. Hypothesis 3 is supported indirectly by the results. Significant correlations were found between catches and climate indices that affect ocean productivity and eddy activities, such as the Quasi Biennial Oscillation (QBO), North Pacific Gyre Oscillation (NPGO), Pacific Decadal Oscillation (PDO), and Western Pacific Oscillation (WPO). Wavelet analysis reveals three periodicities of eel catches: 2.7, 5.4, and 10.3 years. The interannual coherence with QBO and the Niño 3.4 region suggests that the shorter-term climate variability is modulated zonally by equatorial dynamics. The low-frequency coherence with WPO, PDO, and NPGO demonstrates the decadal modulation of meridional teleconnection via ocean-atmosphere interactions. Furthermore, WPO and QBO are linked to solar activities. These results imply that the Japanese eel recruitment may be influenced by multi-timescale climate variability. Our findings call for investigation of extra-tropical ocean dynamics that affect survival of eels during transport, in addition to the existing efforts to study the equatorial system. © 2012 Tzeng et al.
SDGs
Other Subjects
anguilla japonica; article; climate; climate change; controlled study; eel; environmental aspects and related phenomena; fishing; larval stage; nonhuman; North Equatorial Current; North Pacific Gyre Oscillation; ocean atmospheric interaction; ocean current; Pacific Decadal Oscillation; periodicity; population movement pattern; precipitation; Quasi Biennial Oscillation; salinity; spawning; Taiwan; time series analysis; wavelet analysis; Western Pacific Oscillation; Anguilla (fish); animal; climate; climate change; computer simulation; oscillometry; physiology; population migration; regression analysis; sea; statistical model; water flow; Anguilla japonica; sea water; Anguilla; Animal Migration; Animals; Climate; Climate Change; Computer Simulation; Models, Statistical; Oceans and Seas; Oscillometry; Regression Analysis; Seawater; Taiwan; Water Movements
Type
journal article