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Japanese threadfin bream Nemipterus japonicus (Bloch, 1791) is among the most abundant and commercially important species in Pakistan. From the coast of Pakistan, four demersal trawl surveys in October-November 2009 and May-June, August, October and November in 2010 were carried out. The purpose of this study is to estimate the population dynamics and status of the stock of the N. japonicus from Pakistani waters based on the research trawl surveys from the research area. The data consist of n=784 length-weight pairs and n=7 530 length frequency with the maximum length and weight of 29 cm and 358 g respectively. The length frequency data were analyzed using ELEFAN method in FiSAT computer package. The parameters of length and weight relationship were b=2.778, a=0.032 and R=0.973. The estimated von Bertalanffy growth function parameters were L=30.45 cm, K=0.270 year. Based on length-converted catch curve analysis the total mortality ( Z) during this study was estimated at 0.960 year. The natural mortality coefficient ( M) was 0.74 year using Pauly's equation (the annual average sea surface temperature was 27°C), therefore, the fishing mortality coefficients ( F) were 0.22 year. The yield per recruit analysis indicated that when t was 2, F was estimated at 1.2 and F at 1.1. When t was 1, F was estimated at 0.95 and F at 0.8. Because current age at first capture is about 1 year and F was 0.22, F is smaller than F and F, which indicated that the fishery is about in a safe condition. When using Gulland (1971) biological reference point, F was equals to M (0.74). The current fishing mortality rate of 0.22 was smaller than the target biological reference point. [ABSTRACT FROM AUTHOR]

A study was undertaken with the aim of reducing the concentration of cryoprotectants in surimi without adversely affecting frozen storage stability. Minced meat from a tropical fish, Nemipterus japonicus, was strained, water leached and mixed with different levels of sucrose-sorbitol (1:1) mixture (henceforth called sugar mixture), quick frozen at −35 °C and frozen stored at −20 °C. The surimi samples were subjected to storage stability studies for a period of 5 months. Water leaching resulted in slight absorption of water by meat and reduction in protein, fat and mineral contents. Surimi was found to have moderately white colour. Sensory evaluation studies were conducted on three products, viz., sausage, patty and cake, prepared using surimi containing different concentrations of sugar mixture. Sugar mixture content varying from 0% (control) to 4% in surimi resulted in products that were more acceptable to the taste panelists compared those with 6% and 8% sugar mixture. During frozen storage of surimi pH and total plate count remained nearly steady for all sugar mixture concentrations and throughout the storage period. Moisture content appeared to remain constant during storage, but decreased with increase in sugar concentration. The salt soluble nitrogen content of surimi and gel strength of sausage prepared from it decreased with storage period in all surimi samples, and increased with sugar mixture concentration. Expressible water content of surimi sausage showed an increasing trend with storage period of surimi and a decreasing trend with sugar mixture concentration. Sensory evaluation parameters-elasticity, sweetness and preference-remained more or less steady during storage. However elasticity and sweetness increased and preference decreased with sugar mixture concentration beyond 4%. Elasticity and gel strength of surimi sausage seemed to be much lower for control compared to even the lowest concentration of sugar (2%) used. A concentration of 2 to 4% sucrose-sorbitol mixture is well-accepted by the consumers in products-surimi sausage, patty and cake and at this range of concentration surimi could be well-preserved at −20 °C for at least 5 months. [ABSTRACT FROM AUTHOR]

Functional properties and antioxidant activity of pink perch ( Nemipterus japonicus) muscle hydrolysed by three different enzymes papain, pepsin and trypsin were studied. The protein hydrolysates produced by trypsin had an excellent solubility (98%) compared to pepsin (77%) and papain hydrolysate (74%). Conversely, the emulsifying activity index (ESI) and foaming abilities were affected by pH. DPPH radical scavenging ability, reducing power and metal chelating activity of protein hydrolysates increased with increase in concentration. Lipid peroxidation was strongly inhibited by 64% by protein hydrolysates produced by trypsin. The results revealed that the functional properties and antioxidant activities of pink perch were greatly affected by the enzymes used. [ABSTRACT FROM AUTHOR]

In the present study, protein of muscles of commercially important marine fishes Nemipterus japonicus and Exocoetus volitans were extracted by trypsin and their hydrolysis conditions viz., temperature, time, and enzyme to substrate concentration on degree of hydrolysis were studied by response surface methodology. The optimum values for N. japonicus was found as temperature, 30°C, hydrolysis time of 100 min an enzyme/substrate concentration of 1.59% whereas, for E. volitans muscle protein, optimum hydrolysis conditions were temperature, 30°C, hydrolysis time of 115 min and enzyme/substrate concentration of 1.67%. Furthermore, amino acid sequence of antioxidant peptides derived after chromatographic purification was identified by ESI-MS/MS. The analysis of peptides showed sequences as Glu-Ser-Asp-Arg-Pro (620.3 Da) and Gly-Trp-Met-Gly-Cys-Trp (747.3) for N. japonicus and E. volitans muscle, respectively. The peptides contained important antioxidant amino acids and acted as good antioxidant peptides to scavenge free radicals. [ABSTRACT FROM AUTHOR]

The differential distribution of cones in the various regions of the retina of the fish Nemipterus japonicus (Bloch) was studied. In tangential section two types of cones are observed viz single and double cones, double cones being greater in number than single cones. Of the total cones, double cones constitute 86% while single cones constitute only 14%. In most of the retinal regions, cones are in the square mosaic pattern. The temporal region has greater number of cones than the other retinal regions which were studied. The correlation coefficients for the temporal region with all other regions are invariably positive. The test shows that there is no significance between the eyes whereas significance is observed among the various retinal regions. The pattern of cone arrangement agrees with the bottom dwelling habit of the fish. The shape of the eye is modified by being slightly ablong with comparatively longer anterio-posterior axis. The retinal cup is more hollow at the temporal region than at the nasal region. [ABSTRACT FROM AUTHOR]

Morphometric comparison of the samples of Nemipterus japonicas populations from four different localities on the east coast of India is made. Analysis of covariance of morphometric characters reveals significance at 1% level for three characters. Character by character comparison of the means of locality-samples shows that there is clinal gradation in maxillary length (south to north) and pectoral length (north to south). The distance function (D) analysis shows that Kakinada is the farthest removed from other localities, and Visakhapatnam and Madras samples are nearer to each other. Paradeep sample occupied an intermediate position among the locality-samples. It is concluded that all Nemipterus japonicus populations along the east coast of India are from a single genetic population, with restricted and localized movements confined to the areas where they are caught. The observed distinctness of Kakinada sample appears to be due to phenotypic variation under the influence of low salinity. [ABSTRACT FROM AUTHOR]