The Yellow River estuary is located at the intersection between Bohai Bay and Laizhou Bay, and is an im-portant spawning, feeding, and rearing ground for marine organisms because of the abundant food supply. Water and sediment discharge regulations (WSDR) were implemented in 2002 and the period between June 16, 2012 and July 9, 2012 was the 14th time the regulations had been invoked. However, it is unclear whether the WSDR affects fish com-munity structure and distribution. We used survey data collected before, during, and after the WSDR were implemented in the Yellow River estuary in 2012 to compare the fish community structure and determine the ecological impact of the WSDR. Fifteen sample sites were established between 37°40′-38°10′N, 118°55′-119°35′E. We calculated the index of relative importance (IRI), the Margalef richness index (D), the Shannon’s diversity index (H′), and the Pielou’s even-ness index (J′) as measures of fish community structure. A total number of 39 species were captured during the three surveys, belonging to 8 orders, 23 families, and 37 genera, of which 27, 33, and 30 species were captured before, during, and after implementation of the WSDR, respectively. The dominant order was Perciformes. The assemblage was domi-nated by demersal fishes (percent of biomass=95.7%) before implementation of the WSDR and the dominant species was Chaeturichthys stigmatias. Conversely, the community was dominated by pelagic fishes during and after the WSDR were implemented (percent of biomass =72%and 67.1%, respectively). The dominant species were Chaetu-richthys stigmatias, Konosirus punctatus, Sardinella zunasi, and Engraulis japonicas. The community was dominated by warm water species in all three surveys. The average relative biomass was (6.4±1.9) kg/h and there was little differ-ence in biomass between sites prior to implementation of the WSDR. During implementation of the WSDR, the bio-mass was (62.1±29.1) kg/h and fish were primarily distributed offshore, particularly in the northwest of the estuary. Af-ter implementation of the WSDR, the biomass was (48.2±17.2) kg/h and fish primarily distributed in the estuary and the southeast of survy area. The Margalef richness index (D) was 1.24±0.10, 1.27±0.08, and 1.35±0.08 for the three surveys and was not different among the three surveys (P>0.05). Shannon’s diversity index (H′) was 0.63±0.04, 0.36±0.04, and 0.50±0.04 and Pielou’s evenness index (J′) was 1.44±0.09, 0.93±0.11, and 1.24±0.09 during the three surveys. H′and J′were highest before the WSDR was implemented and lowest during implementation of the WSDR, and were signifi-cantly different (P<0.01) among the three surveys. We conclude that sediment deposition altered the distribution of demersal fishes in the Yellow River estuary. However, the addition of large volumes of fresh water and nutrients into the Yellow River estuary had a positive effect on pelagic fishes, especially those that preyed on plankton. To more accu-rately determine the influence of WSDR on fish community structure, future analyses should account for environmental changes during implementation of the WSDR in the Yellow River estuary.%为了解黄河调水调沙期间黄河口海域鱼类群落结构变化,根据2012年调水调沙前、中、后3航次底拖网调查数据,研究分析了该海域鱼类群落组成、优势种、空间分布及多样性特征。结果表明,3次调查共捕获鱼类39种,隶属8目23科37属。鱼类栖息水层类型组成变化较大,前调查优势类群以底层鱼类为主,中调查和后调查以中上层鱼类为主,而适温类型组成则较稳定。生物量及其空间分布变化明显,前调查平均生物量(6.4±1.9) kg/h,各站位分布较均匀；中调查平均生物量(62.1±29.1) kg/h,高值主要分布在近岸海域；后调查平均生物量(48.2±17.2) kg/h,高值主要分布在近河口及东南调查海域。3次调查丰富度指数(D)依次升高,但各航次间差异不显著(P>0.05)；多样性指数(H′)以前调查最高,中调查最低,各航次间差异极显著(P<0.01)；均匀度指数(J′)变化趋势和多样性指数一致。研究认为黄河调水调沙导致的泥沙沉降对底层鱼类产生了不利影响,而淡水和营养盐的注入,对中上层鱼类特别是浮游生物食性鱼类则产生了有利影响。
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