Mangrove red snapper, Lutjanus argentimaculatus is a commercially important fish. The genetic stock structure of L. argentimaculatus from Indian waters was identified using mitochondrial ATPase 6 and ATPase 8, and cytochrome b (Cytb) genes. A 842 bp region of ATPase 6/8 genes and 1105 bp region of Cytb gene were amplified in 120 samples from six different locations along the Indian coast and obtained 58 and 66 haplotypes, respectively. The high haplotype and low nucleotide diversity values along with mismatch distribution, Tajima’s D and Fu’s Fs analysis suggested a genetic bottleneck events or founder effect, with subsequent population expansion in L. argentimaculatus. Coefficient of genetic differentiation (FST) values was low and nonsignificant for both ATPase 6/8 gene and Cytb genes indicating low genetic differentiation in L. argentimaculatus which can be managed as a unit stock in Indian waters.
In recent years, hygienic handling of fishery waste is demanded owing to the fact that the fishery waste is an ideal raw material for the preparation of bioactive compounds. In the present study, the effect of pre-processing storage (at 4 ± 2 C) of whole tilapia waste (WTW) on the properties of its protein hydrolysate derived using pepsin was evaluated. Fish protein hydrolysates (FPH) were prepared from 0, 24 and 48 h old ice stored WTW and designated as FPH-0, FPH-1, and FPH-2, respectively. Total amino acids, total essential amino acids and total hydrophobic amino acids of FPH samples increased with the storage period of raw material (WTW). Antioxidant activities such as DPPH (2, 2 diphynyl-1- picrylhydrazyl) free radical scavenging activity and ferric reducing power of FPH samples were dose dependent. FPH-0 had better antioxidant properties including linoleic acid peroxidation inhibition activity than FPH-1 and FPH2. The DNA nicking assay revealed the protective effect of FPH preparations against Fenton’s reaction mediated oxidative damage. FPH-2 had better emulsifying properties and foaming stability whereas the FPH-0 had relatively good foaming capacity. SDS–PAGE indicated the presence of peptides ranging from 116 to14.4 kDa in FPH-0 and less than 18 kDa in FPH-1 and FPH-2. The present study, clearly demonstrated that whole tilapia waste can effectively be converted to FPH and could be a potential ingredient in functional food and as a rich source of highquality protein in animal feed formulations.
Crude liver oil of leafscale gulper shark, Centrophorus squamosus was clarified by sequential degumming, decolorization and vacuum deodorization. The refined oil was added with ethyl acetate extract of seaweeds and various physiochemical parameters were evaluated in a time-reliant accelerated storage study. Significantly greater induction time was observed for the oil supplemented with Sargassum wightii and Sargassum ilicifolium (> 4.5 h) than other seaweed extracts and control oil (~1 h). Among different seaweeds, the ethylacetate extracts of S. wightii maintained the oxidation indices of the refined oil below the marginal limits after the study period. No significant reduction in C20–22 long chain fatty acids (1.19%) in the refined oil added with S. wightii was apparent, and was comparable with the synthetic antioxidants (1.07–1.08%). Spectroscopic fingerprint analysis of marker compounds responsible to cause rancidity signified the efficacy of S. wightii to arrest the development of undesirable oxidation products in the refined oil during storage. The antioxidant compounds, 15-(but-19-enyl)-hexahydro-13,16-dimethyl-11-oxo-1H-isochromen-8-yl benzoate (1) and 10-(but-13-en-12-yl)- 5-((furan-3-yl)propyl)-dihydrofuran-9(3H)-one (2) isolated from S. wightii appeared to play a major role to deter the oxidative degradation of refined oil thereby enhancing the storage stability.
The epizootics of vibriosis caused serious economic losses to farmers. Natural blooms of the pathogen can be prevented by sea cage management measures such as, changing the inner net of the cages, changing the location of the cages to relatively clean water (about 50 m apart) from the affected site and providing shade over the cages while the water temperature rises. Supplementation of the feed with immunostimulants and mineral mixture may be practised to improve the immune response against infection. Early diagnosis and sea cage management measures may prevent occurrences of the infection.
In recent years, it has been recognised that predatory fishes are rapidly declining in marine habitats. Hence, gathering information on biological characteristics such as dietary dynamics of predatory fishes has assumed importance. Considering this, the dietary dynamics of the predatory ribbonfish Trichiuruslepturusfrom Chennai coast was assessed by analysing the stomach condition and contents, with reference to body size. Representatives of the Order Clupeiformes (Index of relative importance, IRI 33.7%) comprising oilsardine, lesser sardines and anchovies were the major prey items of T. lepturus.Predation by T. lepturus was aided by morphological adaptations, such as dentition, hard and spinous gill rakers, short stomach, high body depth-total length ratio of 1: 17.1 and large mouth (gape area of 1534 mm2 in adult fish).With increasing body size, the capacity to predate upon relatively larger prey increased. The differences in diet composition between ribbonfish of small, medium and large size were well-represented byIRI, prey specific abundance and cluster analysis. The fish is a top predator (trophic level: 4.17) and a specialist feeder (niche breadth: 2.63). As specialist feeders have a narrow choice of food, they are more vulnerable to fishing. It is important that management of multispecies fisheries should focus more on the sensitive predatory species.
Charybdis (Goniohellenus) omanensis septentrionalis Türkay & Spiridonov, 2006 was collected from off the Kerala coast, Arabian Sea, India. This is the first record of the subspecies from India and the taxonomic characters are similar to the findings of Türkay & Spiridonov (2006) who described the subspecies for the first time. The present work also records molecular sequences from the mitochondrial cytochrome oxidase I gene (COI), used to determine the genetic identity of the species. Charybdis (Goniohellenus) omanensis septentrionalis Türkay & Spiridonov, 2006 was collected from off the Kerala coast, Arabian Sea, India. This is the first record of the subspecies from India and the taxonomic characters are similar to the findings of Türkay & Spiridonov (2006) who described the subspecies for the first time. The present work also records molecular sequences from the mitochondrial cytochrome oxidase I gene (COI), used to determine the genetic identity of the species.