Conservation Biology Of Spinibarbus Caldwelli(Nichols, 1925)

Spinibarbus caldwelli belonging to Spinibarbus, Barbinae, Cyprinidae, Cypriniformes, mainly distributes in Yuanjiang, Yangtze, Ninelongjiang, Minjiang, Pearl River and Hainan Island. In recent years, due to habitat fragmentation and shrinkage, overexploitation of resources, water pollution and invasions of exotic species, S. caldwelli suffered a serious collapsing for the population. It has been included in the IUCN Red List of Threatened Species since 2013. The age, growth, nutrient composition of different tissues and genetic diversity among 4 geographical populations of S. caldwelli were studied. The aim of the present study was to provide the basic biological information for the conservation and management of this fish stocks, scientific basis for the sustainable utilization of resources and genetic breeding. The main results are as follows:1. According to the 117 specimens collected from Jun 2013 to Jun 2015, the standard length（SL） of S. caldwelli ranged from 6.5 to 43.5 cm, 65.0 % of individuals were in 15.0-30.0 cm. The weigth（W） ranged from 8.5 to 1931.0 g and 70.1% were 8.5-600.0 g. The SLW relationship was described as: W=5.4140×10^-2 SL^2.7886. The age structure were simple, with a maximum age of 6 years, 40.7% of the individuals were 2 years old. The von Bertalanffy growth curves computed by observed lengthat-age data were expressed as and. The inflection point（ti） was 3.95 year with the SL was 35.82 cm and the W was 1167.54 g, and 72.1% of the individuals were no more than 35.82 cm. The age structures indicated that the S. caldwelli was subjected to over-fishing for the majority of catch individuals did not reach sexual maturity, which directly lead to the decrease of recruitment. The construction of the dams were also contributed to the decline of the population, which destroyed the spawning grounds and habitat of S. caldwelli.2. The muscle of S. caldwelli presented the highest moisture content, followed the roe, scale and skin（P<0.05）. The skin showed significantly higher crude fat content compared with the other tissues（P<0.05）. Crude protein content of the scale was the highest, and significantly higher than those of the other tissues, followed was the roe, muscle and skin（P<0.05）. The total amino acids content of the muscle was 18.08%, roe 23.21%, skin 11.91%, scale 50.64%. The values of total essential amino acid/total amino acid（TEAA/TAA） were 37.06%, 39.98%, 20.91% and 16.71% in the muscle, roe, skin and scale, respectively. Limiting amino acid contents were valine（Val） in the muslce, methionine（Met） + cystine（Cys） in the roe, phenylalanine（Phe） + tyrosine（Tyr） in the skin, and isoleucine（Ile） in the scale. The roe showed significantly higher DHA+EPA contents than the other tissues, and the scale significantly higher than the muscle（P<0.05）. In regard to the mineral element, Zn and Fe were the most abundant, Se was the lowest. Overall, these results demonstrated that the muscle and roe were rich in beneficial amino acids and fatty acids. Moreover, the scale contained large amounts of delicious amino acids, EPA and DHA. However, the skin showed relative lower nutritonal values.3. The genetic diversity and genetic structure of the 4 geopraphical populations（Longjiang, Quanzhou, Chalin and Hongjiang） were analyzed based on mitochondrial Dloop whole gene sequences, which consisting of 745 bp, had the typical vertebrate mitochondrial gene arrangement. The overall base composition is 31.9% for T, 20.1% for C, 21.2% for A, and 26.8% for G and 98.8% of the sequences were conserved sites. There were 8 haplotypes among 148 individuals. Nucleotide diversity index（π=0.00297） and Haplotype diverstity（h=0.7056） index together reveraled a low genetic diversity. The Genetic distance of 4 S. caldwelli populations were less than 0.30, suggesting that there was no genetics deviations for all of the 4 populations.4. We successfully constructed a microsatellite-enriched library to isolate microsatellite loci of S. caldwelli, and 200 clones were sequenced. 120 pairs of SSRprimers were designed afterwards, and from which 17 polymorphic microsatellite markers were screened out by PCR amplification. Using these polymorphic microsatellite markers, we analyzed the genetic diversity of the population of S. caldwelli collected from Longjiang, Quanzhou, Chalin and Hongjiang. A total of 136 different alleles were detected in all examined loci. The number of alleles ranged from 3 to 11, with an average number of about 8 per locus. The observed（Ho） and expected heterozygosity（He） ranged from 0.1556 to 1.0000 and 0.3993 to 0.8759, respectively. The polymorphism information content for these four populations were 0.524, 0.484, 0.339 and 0.605. With the lower effective number of alleles（Ne）, which were lower than 50 in Longjiang, Quanzhou and Chaling population, slightly greater than 50 in Hongjiang population, the Longjiang, Quanzhou and Chaling populations might face extinction risk in the short term, while with the time passing by, the same fate as the Hongjiang population.