Reproductive biology of Hemitripterus villosus in the Bohai Strait,China

To understand the reproductive biology of Hemitripterus villosus in the Bohai Strait,and fill the key knowledge gap in verifying reproductive seasonality and documenting gonadotropin dependent reproductive cycle of this species,a year-round detail study was conducted for the first time.In total,263 individuals were randomly sampled off the coasts of the Bohai Strait.Results show that and the overall female-to-male ratio(1.35:1)did not differ significantly from the 1:1 sex ratio.The length and weight relationship for females and males were regressed,depicting an isometric growth for both sexes.Four reproductive phases of the complete gonadotropin dependent reproductive cycle in both sexes were identified.The monthly variations in the gonadosomatic and hepatosomatic indexes for both sexes further indicated that this species spawns a single batch of eggs per year and the peak spawning period is from October to December.The average diameter of eggs ranged from 2.10 to 3.57 mm.The length at first sexual maturity was 224.87 mm for females and 241.26 mm for males.Significant positive relationships between absolute fecundity and fish size,and also gonadal weight were observed.H.villosus from the Bohai Strait exhibited smaller body size,smaller egg diameter,lower gonadosomatic index,lower absolute fecundity,and higher population extinction risk than the other populations’studied previously.Our findings contribute to understanding the status of this isolated westernmost population,and we emphasize that more efficient protection measures for the species and control measures are urgently required to improve the coastal environment in the Bohai Strait.

Reproductive Biology of the Striped Seabream Lithognathus mormyrus （Linnaeus, 1758） from AI-Haneah Fishing Site, Mediterranean Sea, Eastern Libya

Reproductive biology of L. mormyrus was studied using monthly samples totaling 224 fish obtained from AI-Haneah fishing site, eastern Libya Mediterranean Sea. Lengths of the examined fish ranged between 11.5 cm and 23.4 cm. Corresponding weights were 24.5 g and 160.8 g. The minimum values of the condition factors, KF and Kc, were 1.38 and 1.21 at the average fish length of 12.4 cm. These values increased with increases in length until they reached maximum values of 1.59 and 1.41 at the length of 22.1 cm. The high values of KF and Kc, Gonado-Somatic Index and oocyte diameter maintained during May, June, July, and August and the monthly changes in gonadal condition, indicated that summer was the breeding season of L. mormyrus. The oocyte diameter ranged between 379± 25.3 μ and 1,511 ± 143.3μ （n = 76） with an average of 895 ± 111.3 μ. The sex ratio was in favor of females during all months of the study. The overall sex ratio was 1 ： 1.52. Length at first maturity, Ls0, for L. mormyrus was found to be 14.15 cm for males and 14.45 for females. Overall average of absolute fecundity was 4,342±557 egg per fish （n = 45）. The overall average of relative fecundity was 234± 181 egg per cm. Absolute fecundity increased with increasing fish length.

Reproductive Biology of Splendid Ponyfish Leiognathus Splendens(Cuvier,1829)in Myeik Coastal Waters,Myanmar

Reproductive biology of Leiognathus splendens was studied by using the samples collected from the catches of trawl fisheries in Myeik coastal waters during January to December 2014.Spawning takes place throughout the year,with a peak during April-May and September-December.The observed length at first maturity was 9.0 cm total length in males and 8.4 cm in females.The mean gonadosomatic index was more prominently in females(2.5)than males(1.5).Sex ratio(1 male:1.1 females)also indicates the general dominant of females over males Fecundity varied from 6120 to 58412 eggs.Relationship of fecundity to fish length,fish weight and ovary weight showed that fecundity is more related to the gonad weight(r=0.9)than length(r=0.8)and weight of fish(r=0.7).

Spatial and temporal distributions and some biological aspects of commercially important fish species of Lake Tana,Ethiopia

Objective:To know spatial,temporal distributions and some biological aspects of commercially important fish species of Lake Tana.Methods:Distribution of fish species in Lake Tana was studied from November 2009 to October 2012 based on samples collected every other month using gillnets of 60,80,100,120 and 140 mm stretched mesh sizes.Labeobarbus species,Clarias gariepinus,Oreochromis niloticus,and Varicorhinus beso are commercially important fish species and form 68%,18%,14%and 0.5%of the pooled experimental fish catch.There was significant variability among years and sampling sites of both temporal and spatial aspects;Mann-Whitney U tests were used for pair wise comparisons of sites and years.Results:The composition of Labeobarbus spp.and Varicorhinus beso shows significant decline.On the other hand,the composition of Oreochromis niloticus did not change,but Clarias gariepinus increased by 100%by catch composition.The most likely explanations for the total decline in abundance of fish species are the increase of the illegal commercial gillnet fishery targeting their spawning aggregations in the wetlands and river mouths,and the increasing trend of the degradation of spawning and nursery habitats both in the lake and major tributary rivers of the catchment area.Conclusions:There should be a need for urgent development of a management plan focusing on ensuring sustainable utilization of a resource by fishing effort,gear mesh size and gear type restrictions,and controlling the spawning grounds from different types of human encroachment and designing closing seasons and spawning grounds during the breeding seasons of different fish species of Lake Tana.

Reproductive biology of female sawcheek scorpionfish,Brachypterois serrulata(Richardson,1846)(Teleostei;Scorpaenidae)from Visakhapatnam Coast,India

We examined the reproductive biology of sawcheek scorpionfish,Brachypterois serrulata,collected from Visakhapatnam fish landing center(fishing area covered 16.98°-20.20°N,82.19°-86.53°E).We studied the annual reproductive cycle,fecundity,size at first maturity,mode of spawning with periodical changes and histological preparations.Size distribution and size at sexual maturity were calculated as 108 mm TL for females.The mean gonado somatic index values of female increased rapidly from January to December,and reached its peak during January and February.The fecundity of the fish species is determined by the size and weight of the individuals.The fecundity varied from 1896 to 20,488,with an average of 5721.90 ova.