Basin-scale sampling for high frequency oceanic primary production (PP) is available from satellites and must achieve a strong match-up with in situ observations. This study evaluated a regionally high-resolution satellite-derived PP using a vertically generalized production model (VGPM) with in situ PP. The aim was to compare the root mean square difference (RMSD) and relative percent bias (Bias) in different water masses around Taiwan. Determined using light–dark bottle methods, the spatial distribution of VGPM derived from different Chl-a data of MODIS Aqua (PPA), MODIS Terra (PPT), and averaged MODIS Aqua and Terra (PPA&T) exhibited similar seasonal patterns with in situ PP. The three types of satellite-derived PPs were linearly correlated with in situ PPs, the coefficients of which were higher throughout the year in PPA&T (r2 = 0.61) than in PPA (r2 = 0.42) and PPT (r2 = 0.38), respectively. The seasonal RMSR and bias for the satellite-derived PPs were in the range of 0.03 to 0.09 and −0.14 to −0.39, respectively, which suggests the PPA&T produces slightly more accurate PP measurements than PPA and PPT. On the basis of environmental conditions, the subareas were further divided into China Coast water, Taiwan Strait water, Northeastern upwelling water, and Kuroshio water. The VPGM PP in the four subareas displayed similar features to Chl-a variations, with the highest PP in the China Coast water and lowest PP in the Kuroshio water. The RMSD was higher in the Kuroshio water with an almost negative bias. The PPA exhibited significant correlations with in situ PP in the subareas; however, the sampling locations were insufficient to yield significant results in the China Coast water.

This study estimated the impact of fishing exploitation and climate change on the stock of Grey Mullet (known as Striped Mullet in North America) Mugil cephalus in the Taiwan Strait. Cohort analysis was employed to estimate the population abundance and instantaneous rate of fishing mortality by age of Grey Mullet in the Taiwan Strait. The instantaneous rate of natural mortality (M) was varied to 0.50, 0.75, 1.00, 1.25, and 1.50 times the estimated M to conduct a sensitivity analysis of varying M on correlation coefficients on other factors. Since 1986, the annual catches have sharply dropped and remained at a very low level despite high fishing intensity, indicating that overfishing has occurred since the 1980s. The population of the age‐group 4 years and older has decreased since 1986, reaching 20,000 individuals in 2004, which is only 1% of what the population was in 1981. The overexploitation of Grey Mullet reduced its biomass, and environmental changes during the past two decades are likely to have driven the stock to consecutive years of poor recruitment, causing its current low level in the Taiwan Strait. We also observed that the recruitment population of Grey Mullet was influenced by the Pacific Decadal Oscillation, with the lag in its influence changing from 2–3 years from the time period of 1958–1985 to 0–2 years after 1986. In addition, sea surface temperature anomalies have shown a significant time lag of a 0–2‐year effect since 1986. Overexploitation of the Grey Mullet population after the 1980s suggested an increased sensitivity to short‐term environmental changes.