International Journal of Aquatic Biology
Volume:1 Issue: 4, Aug 2013

In this study, 160 fishes were randomly collected from commercial catch by a cone net in Babolsar Port from January to October 2010. The biological features of specimens were measured. 2+ years old fishes made the dominant age group with 33.75% and 1+ and 5+ years old had the least frequency (8.75%). Relationship between length and weight indicated negative allometric growth pattern (b=2.581). The Von-Bertalanffy growth parameters were calculated as L=131.57 mm, k=0.26 and t0=-1.02. Growth performance index was 1.66 and the total mortality (Z), natural (M) and fishing (F) mortality coefficients were 0.9 year, 0.43 and 0.47, respectively. The exploitation ratio (E) was calculated as 0.52.

Two sialic acid specific lectins Episesarma tetragonum agglutinin–1 and 2 were purified from the hemolymph of the Mangrove crab, Episesarma tetragonum. The major lectin was purified using CNBr-activated sepharose 4B conjugated to fetuin. N-acetyl glucosamine containing buffer was used for elution. The hemagglutination activity of purified lectin was inhibited by glycoproteins containing Siaα, 2-3Galβ, 1-4 GlcNAc linkages. On SDS-PAGE, the molecular weight of calcium dependent lectin was observed to be 70 kDa. Lectin had the maximum activity at a wide range of pH (6.5 – 9.5) and temperature (0 - 40 °C). The physicochemical characteristics of the minor agglutinin showed that its hemagglutinating activity was calcium dependent, optimum at pH 8 – 9.5 and temperature 0 – 37 °C. The only potent inhibitor of minor lectin was bovine submaxillary mucin. An attempt was also made to purify minor lectin by affinity chromatography using bovine submaxillary mucin coupled to CNBr-activated sepharose 4B column. The lectin was eluted with elution buffer containing ethylene diamine tetra acetate. Strong inhibition of purified minor lectin by bovine submaxillary mucin and non-inhibitory action of de-O-acetylated bovine submaxillary mucin suggested that the lectin was O-acetyl sialic acid specific.

High mortality and labor costs are associated with first-feeding sturgeon culture, particularly during the period of dietary transition from live to formulated feed. Therefore we investigated the effects of various feeding treatments on the survival and growth of the Persian sturgeon (Acipenser persicus) larvae during a 20-day culture period. Three replicate groups (250 fish/replicate) of firstfeeding larvae were fed according to four main feeding regimes: (1) live food (live nauplii of brine shrimp Artemia urmiana); (2) indirect transition (5 days live food followed by gradual transition to formulated diet); (3) direct transition (using different combinations of live and formulated diet from the start feeding onwards); (4) formulated feed (FD) from the start feeding. Results indicated that growth and survival were higher in the indirect transition feeding regime than in other regimes. Based on our study, Co-feeding of A. persicus should start five days after prior feeding with live food.

Length-weight relationships (LWRs), relative condition factor (Krel), relative weight (Wr) and optimal length (Lopt) were calculated for five important commercial fishes from Iranian waters of the Persian Gulf and Oman Sea. Samples were collected from 2011 and December 2012 in 11 stations in three Iranian provinces (Hormuzgan, Khozestan and Sistan and baluchestan) using trawl and gillnets. Also, length-length relationships (LLRs) for Pampus argenteus and Scomberomorus commerson were computed. The values of the exponent b in the length-weight relationship ranged from 2.593 for S. commerson to 2.995 for P. argenteus. Krel varied between 1.01 ± 0.08 for Parastromateus niger and 1.06 ± 0.41 for P. argenteus. Also, Wr ranged from 59.12 ± 47.74% for S. commerson to 107.78 ± 107.29% for Eleutheronema tetradactylum. The Lopt were calculated for all five species. A negative allometric growth was found in S. commerson, while other four species (E. tetradactylum, Otolithes ruber, P. niger and P. argenteus) had isometric growth. The length-weight and length-length relationships presented here are for the first time in the Iranian coastal waters of the Persian Gulf and Oman Sea, which can provide a basis for fisheries management.

Studies on reproductive biology are essential to assess culture potential of a fish species. Mystus tengara is a popular food fish as well as preferred as an ornamental fish in West Bengal. Till date detailed report on reproductive biology of this fish species in the agro-climatic context of West Bengal is lacking. Therefore, the present work was aimed to study the detailed reproductive biology of Mystus tengara with an emphasis on sex ratio, length at first sexual maturity, cycle of gonadal maturation and spawning periodicity using standard methods. Results of the study revealed female dominance of the species over male in the population. However, the males showed earlier maturation than females. Five gonadal maturity stages namely immature, maturing, mature, ripe and spent were identified both for female and male fishes. Monthly study of gonadosomatic index (GSI), condition factor and mean ova diameter revealed that the breeding season for this fish species extended from May to September with a single spawning month in July. Total spawning behaviour along with synchronous oocytes development was also observed in this fish species.

Length-weight relationship of Harpiosquilla raphidea from Banten Bay waters was studied from 146 males and 186 females ranging from 38 to 354 and from 37 to 348 mm, respectively. The following equations were obtained Ln W = 5.164 + 2.478 Ln X (for males), Ln W = 5.333 + 2.596 Ln X (for females) and Ln W = 5.264 + 2.549 Ln X, Ln X (pooled). The ‘b’ values (2.5497) found not near to 3 indicating allometric growth being matched up with the cube law. The ANCOVA indicated not much variation between the ‘b’ values for males and females. In general, the growth rate of the mantis shrimp H. raphidea almost the same or not much different from other mantis shrimp species of the order Stomatopoda.

Genetic diversity of Garra rufa was studied using 6 polymorphic microsatellite DNA loci. The specimens of G. rufa were collected from the Kheirabad and Maroon rivers. Despite high importance of this species, there is no genetic information about its population structure. A total of 133 alleles were detected at the 6 loci across the two populations. The Kheirabad population exhibited a lower genetic variation (Ho=0.429 and He=0.850) than the Maroon one. The average numbers of observed alleles in the Kheirabad and Maroon populations were 11.8 and 10.3, respectively. The genetic similarity and distance between the two populations were 0.721 and 0.326, respectively. It seems that Maroon population live under better conditions in contrast to the Kheirabad one. Diminution of genetic variation within examined populations decreases its adaptation to environmental alterations. Based on the results of this study, we can identify two different Garra rufa populations in the Khuzestan Province.

It has been postulated that the building of the Manjil and Tarik dams on Sefidroud River has led to the body shape variation of Capoeta gracilis in up- and downstream populations due to the isolation. In this study, Geometric morphometric approach was used to explore body shape variations of Capoeta gracilis populations in up- and downstream Manjil and Tarik dams in Sefidroud River from south of the Caspian Sea basin. The shape of 90 individuals from three sampling sites were extracted by recording the 2-D coordinates of 13 landmark points. PCA, CVA, DFA and CA analysis were used to examine shape differences among the populations. The significant differences were found among the shape of the populations and these differences were observed in the snout, the caudal peduncle and the head. The present study indicated the body shape differences in the populations of Capoeta gracilis in the Sefidroud River across the Manjil and Tarik dams, probably due to the dam construction showing anthropogenic transformation of rivers influences body shape in an aquatic organism.