Species Composition and Protection of Fish Eggs and Larvae in Spawning Ground of Liaodong Bay

[Objective] The paper was to explore the species composition, number distribution and seasonal dynamics of fish eggs and larvae in Liaodong Bay in 2008. The protection and exploitation status of spawning ground in Liaodong Bay was analyzed, and the corresponding protection measures were put forward. [Methods] The species composition of fish eggs and larvae in spawning ground of Liaodong Bay was investigated by horizontal trawling associated with vertical trawling with zooplankton net in May, July, September and October in 2008. [Result] It was found that 7 724 eggs and 229 larvae of fishes belonging to 32 taxa were collected, in which 29 taxa were identified as species, belonging to 9 genera, 21 families and 28 orders, 2 taxa were identified to only family level, and one failed to be identified. The main spawning groups were Cynoglossus joyneri, Engraulis japonicus, Johnius belengerii, Larimichthys polyactis, Konosirus punctatus, Sardinella zunasi, and Scomberomorus niphonius, and the main spawning ground was found in northern waters and Changxing Island waters in Liaodao Bay. There was slightly less spawning species in 2008 compared with 1998, especially the number of fish eggs and larvae decreased greatly. [Conclusion] The effective measures for protection of spawning grounds in Liaodong Bay are suggested, including control of fishing intensity, development of artificial reefs, establishment of germplasm resources reserves, and standardization of compensation standards for marine ecological damage.

Influences of ultrasound on hatching of the fish eggs

The effects of ultrasound on the hatching of the goldfish (Carassius auratus auratus) and loach (Paramisgurnus dabryanus (sauvage)) cytulas were studied. The ultrasound with certain frequencies can accelerate the development of cytulas, induce the embryos to break membrane earlier, increase the survival rate of larvas, and increase 50% hatching rate of loach cytulas at lower temperature.

Application of artificial intelligence for separation of live and dead rainbow trout fish eggs

In this study a visual machine technology-based intelligent system was developed and evaluated for separation and recognizing the alive and dead eggs of rainbow trout fish.The features derived from imagery processing of alive and dead eggs were used as the decision-making variables in the classifier.Multi-layer Perceptron neural network(MLP)and Support Vector Machine(SVM)models were used as the classifiers.With paired t-test,10 effective features were selected from 15 features for classification.The k-fold cross validation method was used for better evaluation the classifiers.By changing the size of the training data set from 80%to 20%,the classifier ability and stabilitywere evaluated.The results showed that in the training phase,all the mean values of the statistical indices forMLP and SVMclassificationswere complete for all categories(100%of the classification was predicted correctly).Also,in the test phase,the performance indicators of both classifiers were very satisfactory(the average accuracywas 99.45%).Therefore,it is possible to use both classifierswith certainty for separation the rainbow trout fish eggs.

Composition and ecological distribution of ichthyoplankton in eastern Beibu Gulf

Surveys were conducted in four seasons in the eastern Beibu Gulf from July 2006 to November 2007, to determine the ichthyoplankton composition, abundance, as well as environmental factors impacted on their spatiotemporal distributions. The fish eggs and larvae were sorted from 303 zooplankton quantitative samples, in which at least 1 order, 60 families, 31 genera and 61 species of fish eggs and larvae were identified. The species number was highest in summer whereas lowest in winter. With the most abundant fish egg （the average density was 2.41 ind./m3）, spring was the main spawning season, while the greatest mean density of fish larva was 1.35 ind./m3 in summer. In the whole year around, fish eggs had the trends to aggregate in the nearshore of Guangxi coast, fish larvae were more abundant in the northern water. Relationships between fish eggs and larvae abundance and environmental factors were analyzed by using the Yield-Density model. The spatio- temporal distribution of ichthyoplankton in eastern Beibu Gulf was closely related to the Chl a concentration, and the optimal temperature, salinity and Chl a were 19.4-21.7℃, 31.8-33.1 and 1.5-4.8 mg/m3, respectively. Additionally, the distribution of fish larvae could be effected by ocean currents in summer and autumn.