Huanzhang Liu

Mitochondrial capture and incomplete lineage sorting in the diversification of balitorine loaches (Cypriniformes, Balitoridae) revealed by mitochondrial and nuclear genes

Tang, Q.‐Y., Liu, S.‐Q., Yu, D., Liu, H.‐Z. & Danley, P.D. (2012) Mitochondrial capture and incomplete lineage sorting in the diversification of balitorine loaches (Cypriniformes, Balitoridae) revealed by mitochondrial and nuclear genes. —Zoologica Scripta, 41, 233–247.

Seasonal Variation in Drifting Eggs and Larvae in the Upper Yangtze, China

From 5 March to 25 July 2008, ichthyoplankton drifting into the Three Gorges Reservoir from the upper reaches of the Yangtze River were sampled daily to investigate the species composition, abundance, and seasonal variation in early-stage fishes in this area. Twenty-eight species belonging to five orders and 17 families or subfamilies were identified by analyzing fish eggs and larvae, and a total of 14.16 billion individuals were estimated drifting through the sampling section during the investigation. Among the ichthyoplankton sampled, species in Cultrinae, Cobitidae, Gobioninae and Gobiidae, along with the common carp (Cyprinus carpio Linnaeus), comprised 89.6% of the total amount. Six peaks of drift density were identified during the sampling period, and a significant correlation was found between drift density with water discharge. The dominant species were different in each drift peak, indicating different spawning times for the major species. The total amount of the four major Chinese carps that drifted through the sampling section was estimated as 0.88 billion, indicating an increase in the population sizes of these species in the upper reaches of the Yangtze River after construction of the Three Gorges Dam. Actually, these reaches have become the largest spawning area for the four major Chinese carps in the Yangtze River. The large total amount of eggs and larvae drifting through this section demonstrated that the upper reaches of the Yangtze River provided important spawning sites for many fish species, and that conservation of this area should be of great concern.

Impact of the Three Gorges Dam on the spawning stock and natural reproduction of Chinese sturgeon in the Changjiang River, China

Chinese sturgeon (Acipenser sinensis) is the flagship species of the Changjiang River. The migration route of this species is blocked by the first dam, the Gezhou Dam, and its reproduction is affected by the Three Gorges Dam (TGD), one of the largest dams in the world. We studied the impact of the impoundment of the Three Gorges Reservoir (TGR) since 2003 on the spawning stock and the natural reproduction of the Chinese sturgeon by using our monitoring data from 1997 to 2013. Results indicate that TGR impoundment has delayed the first spawning dates of the fish from middle-late October to late November, decreased the amount of spawning activities from twice to only once each year, and significantly reduced egg production. In particular, the fish did not demonstrate any spawning activities in 2013. Therefore, TGR impoundment significantly affects the natural reproduction of the fish downstream of the TGD. The spawning stock size of the fish is also predicted to further decrease in the future, which will lead to a risk of population extinction. Ecological regulations must be imposed on decreasing the water temperature to 20°C before mid-October and increasing water discharge downstream of the TGD in October to induce spawning of the Chinese sturgeon.

Analysis of fish eggs and larvae flowing into the Three Gorges Reservoir on the Yangtze River, China

Studies on fish eggs and larvae are important for understanding the recruitment dynamics of fish assemblages and their relationships with environmental conditions. Located in the upper reaches of the Yangtze River, China, the Three Gorges Reservoir (TGR) is one of the largest reservoirs in the world, where the fish resource ecology has drawn great attention. With the purpose of evaluating fish recruitment in the TGR, in the present study, samples of fish eggs and larvae were collected at Luoqi County, the upper end of the TGR, from April 15th to July 29th 2011. From the samples collected, we identified 46 fish species belonging to nine families and five orders. The most abundant species were in the Cultrinae, Gobiidae, and Gobioninae. An estimated 12.4 billion fish eggs and larvae drifted into the TGR. There were approximately 2.6 billion Pseudolaubuca sinensis, 1.9 billion Hemiculter leucisculus, and 1.8 billion Gobiidae. The spawning grounds of fishes that release pelagic eggs are in the reaches 13–162xa0km upstream from our sampling site. More attention should be paid to protecting the habitat in large free stretches upstream of the reservoir, since these areas are important spawning grounds for many fishes. Also, an ample natural flooding regime should be retained in this region.

Life tables and elasticity analyses of Yangtze River fish species with implications for conservation and management

In conservation biology, knowing the life history strategy of a species is crucial for deciding which stage needs the greatest protection: reproduction, juveniles, or adults. Here, we compiled biological data for 83 Yangtze River fish species, constructed their life tables and conducted elasticity analyses, which calculates the proportional contribution of each vital rate (age-specific survival and fecundity) to the annual population multiplication rate. Life tables showed that, for our analyzed species, the survival rate of age 0 fish was extremely low, ranging from 1.25xa0×xa010−6 to 1.74xa0×xa010−2xa0year−1. All species showed a type III survivorship curve. Elasticity analysis revealed slow–fast continuum life histories ranging from species with a high contribution of fertility elasticity to the population growth rate, but lower juvenile and adult survival elasticity, as well as early maturation and short generation time to species that mature late, possess a long generation time, exhibit low fertility elasticity, and a high adult or juvenile survival elasticity. In addition, the analysis of all the species showed that fertility elasticity was significantly smaller than the sum of juvenile and adult survival elasticity, indicating the need to increase the juvenile and adult survival rates of Yangtze fish rather than focusing only on protecting reproduction and age 0 survival via a breeding season fishing ban which is the current conservation practice. Since overfishing has been proposed as the major factor responsible for the decline of Yangtze fish populations, we further suggest that controlling fishing pressure on juvenile and adult fish is another key conservation requirement.

Impact of the Three Gorges Dam on reproduction of four major Chinese carps species in the middle reaches of the Changjiang River

Silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), grass carp (Ctenopharyngodon idella), and black carp (Mylopharyngodon piceus) are the four major Chinese carps and are commercially important aquaculture species in China. Reproduction of these carp has declined since the construction of the Three Gorges Dam (TGD) due to an altered water flow and thermal regime in the Changjiang (Yangtze) River. However, details of the changes in reproduction of the four species are not well understood. To assess the impact of the TGD on reproduction of the four carp, we investigated their eggs and larvae at Yidu City, which is 80 km below the TGD, during 2005–2012. We examined diff erences in larval abundance of the four species in the Jianli section (350 km downstream of the TGD) before (1997–2002) and after (2003–2012) construction of the TGD. Based on these observations, the first spawning date of the four species was delayed a mean of about 25 days after the dam was constructed. Mean egg abundance in the Yidu section of the river was 249 million and mean larval abundance was 464 million, which were significant decreases since the 1980s. Moreover, larval abundance in the Jianli section after the dam was constructed was significantly lower than that before construction (ANCOVA, P<0.05). The observed larval abundance accounted for only 24.66% of the predicted value in 2003 when the dam was first inundated. The present spawning grounds between the TGD and Yidu section of the river are very similar to those described in the 1980s, and some spawning grounds exist upstream of the TGD. Large free-flowing stretches upstream of the TGD and the creation of artificially flooded downstream reaches are needed to stimulate spawning and eff ectively conserve these four major Chinese carps species.

The complete mitochondrial genome sequence of Jinshaia abbreviata (Cypriniformes, Balitoridae).

Abstract Jinshaia abbreviata, belonging to the family Balitoridae in Cypriniformes, is endemic to the Upper Yangtze River with most population distributed in the Jinsha River. In this study, the complete mitochondrial genome of J. abbreviata was sequenced with its structure analyzed. The mitochondrial genome of J. abbreviata is similar to those of the typical vertebrates, 16,567u2009bp in length, including 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and one non-coding control region (D-loop). The D-loop of J. abbreviata was characterized by one termination-associated sequence with two pair of motifs and six conserved sequence blocks (CSB-F, CSB-E, CSB-D, and CSB I-III). The mitogenome sequence of J. abbreviata could contribute to estimate the phylogenetic relationship of the Balitoridae. And further investigations with more Jinshaia species and individuals included need to be performed to better understand the speciation process and evolutionary history of the genus Jinshaia.

Life history traits and implications for conservation of rock carp Procypris rabaudi Tchang, an endemic fish in the upper Yangtze River, China

Rock carp is an endemic fish in the upper Yangtze River basin. Its populations have dramatically declined in the recent years due to human activities, such as overfishing and damming. In the present study, with the aim to give suggestions for better conservation, we investigated age, growth, and reproductive biology of the rock carp using samples collected between 2007 and 2013 from the Chishui River. The results indicate that there are no significant differences between the length–weight relationships of females and males (Wxa0=xa00.015SL3.155). The von Bertalanffy growth curves computed by the observed length-at-age data could be expressed as Ltxa0=xa064.9(1xa0−xa0e−0.101(t+0.217)). The estimated length at 50xa0% sexual maturity for males is 24.2xa0cm (approximately aged 4) and 37.0xa0cm for females. Female gonad analysis suggests that rock carp is a batch spawner, which can spawn at least twice during the reproductive season, from April to August. Standard length and age of 86.5xa0% individuals were below 25xa0cm and 4xa0years, respectively, indicating that the exploitation is too intensive and that populations are undergoing miniaturization. These data corroborate that a combination of natural and anthropogenic factors has caused a sharp decline in wild populations during recent years, calling for immediate design and implementation of conservation measures for this species.

Reproductive characteristics of Ancherythroculter nigrocauda, an endemic fish in the upper Yangtze River, China

Knowledge on the reproductive biology of fishes is critical for understanding a species’ life history and devising appropriate management strategies. Anthropogenic forces, such as damming and overfishing, threaten fishes endemic to the upper Yangtze River. We conducted a study on the reproductive biology of an endemic species, Ancherythroculter nigrocauda in order to provide information on the life history of this species and to assist in its conservation. From July 2011 to June 2012, a total of 417 fishes were captured via monthly sampling by fishermen in the Longxi River, a tributary in the upper Yangtze River. Although the female-male ratio was 1:1.03, females were predominantly larger in body size. Gonad somatic indices and oocyte diameter distribution showed that the spawning period of A. nigrocauda in the Longxi River ranged from April to August, with the peak in April. Body length at 50xa0% sexual maturity of A. nigrocauda was estimated to be 125 and 106xa0mm for females and males, respectively. Absolute fecundity of A. nigrocauda varied between 11,300 and 504,630 eggs, with the mean of 162,377 eggs. In conclusion, A. nigrocauda mature early, spawn once, and are highly fecund, all of which are consistent with an r-selected life history. It is recommended that a moratorium on fishing this species be enacted and the culture of this species be continued.

Evolutionary relationships of two balitorids (Cypriniformes, Balitoridae) revealed by comparative mitogenomics

Balitoridae, a family within the Cypriniformes, inhabit torrential mountain streams in Asia. Although they have long fascinated ichthyologists for their numerous adaptations to this tumultuous environment, the evolutionary history of this group remains poorly understood. In this study, we investigate the evolutionary relationships of the balitorids with particular attention to the phylogenetic placement of two balitorid species, Yaoshania pachychulis and Erromyzon kalotaenia. Both species have extremely limited distributions, they are limited to Mt. Dayaoshan of the Pearl River in China and require dedicated conservation plans. However, little is known about their evolutionary relationships to other balitorids. Here, we examined the evolutionary relationships of Y. pachychulis and E. kalotaenia to each other and other balitorids through sequencing the complete mitochondrial genomes of nine balitorid individuals. For the newly sequenced balitorids, the length of the whole mitogenome, gene arrangement and their base composition are similar to those of other bony fishes. Analyses based on these newly sequenced mitogenomes and an additional 50 previously published mitogenomes show that Y. pachychulis and E. kalotaenia cluster as different clade within the subfamily Gastromyzontinae. The genetic distance between these two species ranges from 0.127 ± 0.003 to 0.132 ± 0.004 which is slightly higher than that between some genera (e.g. the distance between Vanmanenia and Metahomaloptera is 0.127 ± 0.004). Therefore, it is reasonable to assign Y. pachychulis and E. kalotaenia to different genera. Phylogenetic signal assessment suggested that ND1, ND4 and ND5 genes as well as their concatenated subsets perform relatively well in reconstructing the Cobitoidea phylogeny. The divergence time estimation indicated that the balitorids distributed in Mt. Dayaoshan might have originated and evolved following the flattening and uplifting of the Yunnan–Guizhou Plateau during the late Miocene to late Pliocene.