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Knowledge of population structure is particularly important for long-term fisheries management and conservation. Lesser-spotted leatherjacketThamnaconus hypargyreusis an economically important fish species in the South China Sea. Fish specimens (totally 158 individuals) used in this study were collected from five geographical locations in the north of the South China Sea and the southwestern Nansha Islands. The results were as follows: a total of 636 nucleotides of the mitochondrial DNA (mtDNA) control region (CR) ofT. hypargyreuswere amplified by polymerase chain reaction (PCR) technology. Both 103 mutations of nucleotide acids without inserting or deleting one and 91 haplotypes were found among the examined CR fragment. High haplotype diversity (0.9419 ± 0.0151) and nucleotide diversity (0.0095 ± 0.00506) relatively together with a recent and sudden population expansion which characterizes the genetic population structure of this species. Analysis of molecular variance (AMOVA) and the fixation indices (Fst) of five groups showed that the genetic variance mainly came from individuals within groups, and there was no genetic differentiation between groups. The phylogenetic trees including maximum likelihood (ML) and Bayesian inference (BI) proved no phylogeographic differentiation structure in five groups. The mtDNA marker suggested the five groups should be genetic homogeneity, which impliedT. hypargyreusin the north and southwest continental shelf of the South China Sea belongs to one population. [ABSTRACT FROM AUTHOR]

We measured the target strength (TS) of three commercial fish species: whitespotted spinefoot ( Siganus canaliculatus), black porgy ( Acanthopagrus schlegelii), and creek red bream ( Lutjanus argentimaculatus), in the South China Sea. The TS of caged or tethered fish ( n=76 total) was measured using a Simrad EY60 portable scientific echosounder at 120 kHz. We evaluated the relationship between TS and total length (TL, cm) for the three species. This is the first attempt to use split-beam acoustics to measure single-fish TS in the South China Sea by Chinese researchers. Our results will improve the accuracy and precision of acoustic abundance estimates of commercially important species and further the development of underwater acoustic survey techniques in fisheries in the South China Sea. [ABSTRACT FROM AUTHOR]

Abstract: A fish monitoring program was conducted in the northern region of the South China Sea from March 2009 to December 2010. During this period, two typhoons, GONI and Koppu, hit this region consecutively in August and September 2009. The fish and satellite data were analyzed to understand the influence of the typhoons on fish activities. The results showed that the fish species number (FSN) increased by approximately 14.29% and 14.81% after the two typhoons, GONI and Koppu, respectively. The five increased fish species included three estuarine species and two shallow sea species. However, one shallow sea species was also absent. In the nearshore (near the Pearl River Estuary) and offshore (along the typhoon’s track) regions after GONI, the FSN increased by approximately 24% (nearshore) and 52.63% (offshore), with estuarine species accounting for 42.86% (nearshore) and 33.33% (offshore) of the fish species; after Koppu, the FSN increased by approximately 15.38% (nearshore) and 163.64% (offshore), with estuarine species accounting for 60% (nearshore) and 26.32% (offshore) of the fish species. In the increased records, small and medium-sized fish species were dominant nearshore, and small fish species were dominant offshore. The FSN increased to a maximum value between the 5th and the 10th days after the typhoon nearshore and between the 3rd and 8th days after the typhoon offshore. The results indicated that river discharge, triggered by the typhoon’s nearshore rainfall, as well as offshore upwelling nutrients, also triggered by the typhoons, and may have played important roles in the variability of fish species. This research found that the increase in the FSN was associated with the typhoons in the northern South China Sea. [Copyright &y& Elsevier]

Due to the logistical difficulties associated with fish data sampling after typhoons, short-term effects of typhoons on fishery in the South China Sea (SCS) have not been well-understood. The present study is to evaluate the impacts on the fish catch per unit effort (CPUE) owing to the three typhoons Chanthu, Vicente, and Kai-tak in the northwestern SCS, using long-term fish catch data and satellite data. The results show that the CPUE of total catch and some sorted catches have been changing because of the typhoons. On total catch, firstly, the CPUE has increased approximately 0.32kgh−1kw−1, 0.20kgh−1kw−1, and 0.25kgh−1kw−1 during the three typhoon periods. Then, the CPUEs decreased to the pre-typhoon level in about three weeks. Thirdly, among the three typhoons, the slow-moving Chanthu has caused a larger increase in CPUE. The typhoons impact was two-pronged, depending on fish species. One is the positive effects on meso-demersal fishes, cephalopoda and pelagic fishes. The other is the increase in CPUE of low trophic level carnivorous fishes after the three typhoons. This research provided the first evidence of CPUE increase after typhoons in the open sea. [ABSTRACT FROM AUTHOR]