Iranian Journal of Fisheries Sciences
Volume:7 Issue: 1, Jul 2007

Effects of Daphnia magna enriched with cod liver oil (CLO) as a sourceof highly unsaturated fatty acid (HUFA) on growth, survival, stress resistance, andfatty acid composition of the Persian sturgeon larvae were evaluated. Daphniaenriched for three different time periods (3, 6, and 9 hours) and non-enrichedDaphnia were fed to the Persian sturgeon larvae (average weight 61.6±0.4mg)during 14 days. The highest n3-HUFA content was found in Daphnia enriched for 9hours (0.69mg g-1 DW) and the highest n3-HUFA content of the larvae was alsofound in those larvae fed with Daphnia enriched for 9 hours (2.39mg/g-1DW). Asignificant growth difference between larvae fed with enriched and non-enrichedDaphnia was observed (P<0.05), while survival rate did not significantly differamong the treatments (P>0.05). Furthermore, the highest pH stress resistance wasfound in those larvae fed with Daphnia enriched for 9 and 6 hours (P<0.05). Asalinity stress test did not show significant differences among the treatments.

The incidence of white spot disease in farmed Penaeus indicus inBusheher region was evaluated by analyzing 200 shrimp individuals between Juneand September, 2005. The samples were examined for clinical sign includingobservation of white spots on the cuticle and tissue. Samples were processed usingpolymerase chain reaction (Nested-PCR) test. The results showed that 24% of thesamples examined were clinically positive having white spots on their cuticles. Also,92% of the samples examined were positive in PCR examination. Furthermore, 70%of apparently healthy shrimp were positively identified using the by PCR test.

The induction of tetraploidy by means of cold, heat and multiple heatshock treatments was investigated on male fish from a growth-enhanced transgenictilapia C118 line, crossed with wild type females. After the development a newmultiple heat shock protocol (two heat treatments at 41oC in 60 and 80 min. afterfertilization for 5 min. per each), chromosome and X-gal in situ staining assaysdemonstrated the successful production of yolk sac tetraploid transgenic tilapia intwo out of 15 embryos examined in this trial via direct correlation between higherlevel of ß-galactosidase expression and karyotyping in the samples verifyingcomplete tetraploidy in this line. In the grown fish, there was evidence to suggestmosaicism or perhaps tetraploidy in at least two grown fish using the measurementof erythrocytes and karyotyping of the G1 offspring (P<0.05). There was, however,no evidence to indicate successful production of triploid G1 individuals followingcrossing of induced fish with wild type.

This paper examines the changes in the population biology and biomassof common kilka (Clupeonella cultriventris caspia) in the Iranian waters of theCaspian Sea from 1995-2004. For most years during this 10-year period, weestimated the age structure of the catch, length-weight relationship, von Bertalanffygrowth parameters, condition factor, sex ratios, maturity stages determined fromovarian analysis, natural and fishing mortality, age at first capture and biomass.Growth parameters were estimated as L∞=132mm, K=0.259/yr, t0=-1.285/yr. Theinstantaneous coefficient of natural mortality was estimated as 0.506/yr and theinstantaneous coefficient of fishing mortality varied during the 10-year periodbetween 0.125/yr to 1.487/yr. Biomass of the common kilka increased from about16,000mt in 1995 to more than 41,000mt in year of 2002. This increase in commonkilka was simultaneous with a sharp decline in anchovy kilka, changes inzooplankton abundance and composition, and especially increase in zooplanktonspecies used by common kilka. We concluded that at the present time, the stock ofcommon kilka is being over-fished.

The structure, ultrastructure and osmoregulatory function of the branchialchamber were investigated in Palaemon elegans (Rathke, 1837) by lightmicroscope, electron microscope and immunohistochemistry methods, respectively.Each chamber possesses a branchiostegite, 3 epipodites and 8 phyllobranchiate gills.The lamellae are attached along the two outer surfaces of the triangular gill axis.Ultrastructurally, numerous ionocytes are present along the innerside of thebranchiostegites and in the epipodites. A consistently high immunofluorescence ofNa+, K+-ATPase was observed along the basolateral sides of these ionocytes. Thegill lamellae are formed by a single axial epithelium made of H-shaped cells withthin lateral expansions and a basal lamina limiting hemolymph lacunae. A positivebut weak fluorescence of the Na+, K+-ATPase was found in lacunae sides of thelamellae cells. These findings show that in P. elegans, the epipodites and thebranchiostegites organs appear as the main site of osmoregulation and the gilllamellae are mainly devoted to respiration.

In a parasitic survey of the native and introduced fishes in the ZayandehrudRiver, 5 Myxobolus spp. were found in the gills, fins and skin of examined fishspecimens. They include M. varicorhini from fin and M. samgoricus from skin ofCapoeta damascina, M. musajevi from gills of Capoeta capoeta gracilis, Myxoboluscristatus from Capoeta aculeata, and M. saidovi from Alburnus sp. Data on thelocation in the hosts comparing with previous records are provided. Theepidemiological importance of Myxobolus spp. in Zayandeh-rud River is alsopresented. In the present paper the occurrence of five Myxobolus spp. all fromendemic fishes from Zayandeh-rud River (A new locality) are recorded from twonew hosts; Capoeta damascina, Capoeta aculeata. M. varicorhini and M. saidoviare recorded for the first time from Iranian freshwater fishes.

The surface morphology of resting eggs of Anostracan species from EastAzerbaijan Province of Iran and that of Artemia urmiana was compared usingScanning Electron Microscopy (SEM). Anostracan fauna of East Azerbaijantemporary pools were determined as follows:Chirocephalus skorikowi (Chirocephalidae), Branchinecta orientalis (Branchinectidae),Streptocephalus torvicornis (Streptocephalidae), Branchinella spinosa (Thamnocephalidae)and Artemia urmiana (Artemiidae). However other species may also exist in thesepools. Therefore, evaluating the morphology of these cysts by SEM appeared toaccentuate that study of cyst ornamentation is a valuable taxonomical factor andmore importantly that it can be used to identify the species even when the adults arenot present at the time of sampling or in the absence of water.

Cryopreservation of semen from the Caspian brown trout (Salmo truttacaspius) and effects of extender type, freezing and thawing rates on fertilizationability were studied. After assessment of semen quality, one part of semen wasdiluted with three parts of different extender and decanted into 0.5ml straws.Freezing was carried out at two freezing levels, 1.5cm and 2cm above surface ofliquid nitrogen. The semen was thawed at 5°C for 90s, 15°C for 45s or 25°C for 30sin water baths and used for fertilization. Using the extender: 0.3 M glucose +10%methanol +10% egg yolk, and 0.6 M sucrose 10% DMSO + 10% egg yolk, yieldedthe highest post-thaw fertilization rates, with 67.05%±8.76 and 59.78%±5.08 eyeingrates, respectively. No significant differences were found in the fertilization rateswith two freezing levels (P>0.05), however eyeing and hatching rates were higherfor 2cm above the surface of the liquid nitrogen than for 1.5cm. Thawing ofcryopreserved semen was best using the 25°C water bath for 30s and significantdifferences were seen in the eyeing rates between 25°C and 5°C or 15°C (P<0.05).Significant interactions (P<0.05) were found between effects of extender type andthawing rates and extender type and freezing rates.

Antibody production and clinical efficacy (relative percent survival RPS)were measured in 40±5g rainbow trout after immunization with two types ofStreptococcus iniae vaccines consisting of formalin killed cells (FKC) and FKCenriched with the bacterial extracellular products (ECP) administered byintraperitoneal (i.p), immersion and oral routes at 16±1°C for 18 weeks. Nosignificant difference was found in antibody levels among the fish i.p immunizedwith FKC enriched with ECP plus Freunds'' adjuvant (FA), FKC plus FA and FKCvaccines (P>0.05), whilst the antibody production was significantly higher in thesethree groups than fish immunized by immersion and oral routes of FKC and FKCenriched ECP (P<0.05). Also, fish immunized by immersion route with FKC showedsignificantly higher antibody titer than fish orally vaccinated with FKC with or withoutECP until 12 weeks post-immunization (P<0.05). No significant difference was found inantibody titer between orally vaccinated fish and control groups (P>0.05). The RPSsranging 82.6-100, 73.9-95 and 73.9-91.7% were obtained in the fish intraperitoneallyimmunized with FKC enriched ECP plus FA, FKC plus FA and FKC vaccines,respectively, compared to 0% survival for the control fish. Also, RPS in fish vaccinatedby the immersion route was in the range 45.8-30.4% after 18 weeks post-vaccination.Efficacy of oral vaccination of fish with FKC plus ECP was in range of 8.7-29% and thatof fish orally vaccinated with FKC resulted in 8.7-20.8% protection.