Papers by Oliviero Mordenti
Scientific Reports, 2020
The reproductive performance of Octopus vulgaris broodstocks fed two different diets (mixed fish ... more The reproductive performance of Octopus vulgaris broodstocks fed two different diets (mixed fish [F group, BW 1,048.14 g] or mixed crustaceans [C group, BW 998.44 g]) was analyzed using an experimental recirculating aquaculture system consisting of a tank equipped with spawning and incubation chambers. A total of 8 females (F1–4; C1–4), and 8 males (M1–M8) were selected. DI of the C group females was significantly (p < 0.05) higher (3.0 ± 0.29%) than the F group (2.16 ± 0.67%). SGR in C group was significantly higher (1.43 ± 0.12%) than the F group (1.18 ± 0.25%). Egg clusters, number of clusters, number of clusters/kg BW, and total length were more favorable in the C group than the F group. The number of clusters/kg BW of C females was 2.5 times higher than that of F females (78.1 ± 6.5 vs 31.1 ± 13.3). The total eggs number, number of eggs/cm, number of eggs/kg BW in the C group were significantly (p < 0.05) higher compared with the F group; the number of eggs/kg BW and para...
Theriogenology, 2015
The aim of this work was to determine the effects of dark and light conditions on the E2, testost... more The aim of this work was to determine the effects of dark and light conditions on the E2, testosterone and thyroid hormones levels and on the gene expression levels (vitellogenin 1, vitellogenin 2, and estradiol receptor one) in European eels (Anguilla anguilla) during ovarian development induced by increasing doses of carp pituitary extracts (CPEs). The subjects were divided into 2 groups: 14-hour light:10-hour dark (Light Group) and 24-hour darkness (Dark Group). All the eels received intramuscular injections with CPE at a dosage of 10 mg/kg body weight (BW) once a week for the first 3 weeks, 20 mg/kg BW fourthsixth week, 30 mg/kg BW seventh-ninth week, and 40 mg/kg up to the end of the experiment (13th week). Vitellogenin and estradiol receptor expression levels did not show significant differences between the two housing conditions whereas in both groups vitellogenin mRNA increased starting from first CPE injection. Testosterone and 17-beta estradiol plasma levels were significantly greater in the Dark Group compared with the Light Group starting from the ninth and the 13th week, respectively. These results suggest that darkness could be a useful variable for standardizing gonadal maturation in eels kept in captivity.
Theriogenology, 2015
The aim of this work was to determine the effects of dark and light conditions on the E2, testost... more The aim of this work was to determine the effects of dark and light conditions on the E2, testosterone and thyroid hormones levels and on the gene expression levels (vitellogenin 1, vitellogenin 2, and estradiol receptor one) in European eels (Anguilla anguilla) during ovarian development induced by increasing doses of carp pituitary extracts (CPEs). The subjects were divided into 2 groups: 14-hour light:10-hour dark (Light Group) and 24-hour darkness (Dark Group). All the eels received intramuscular injections with CPE at a dosage of 10 mg/kg body weight (BW) once a week for the first 3 weeks, 20 mg/kg BW fourthsixth week, 30 mg/kg BW seventh-ninth week, and 40 mg/kg up to the end of the experiment (13th week). Vitellogenin and estradiol receptor expression levels did not show significant differences between the two housing conditions whereas in both groups vitellogenin mRNA increased starting from first CPE injection. Testosterone and 17-beta estradiol plasma levels were significantly greater in the Dark Group compared with the Light Group starting from the ninth and the 13th week, respectively. These results suggest that darkness could be a useful variable for standardizing gonadal maturation in eels kept in captivity.
The Israeli journal of aquaculture = Bamidgeh
Sexual maturity was induced in wild silver eel females of the European eel (Anguilla anguilla) us... more Sexual maturity was induced in wild silver eel females of the European eel (Anguilla anguilla) using a protocol similar to that successfully used for Anguilla japonica. Eels were injected for sixteen weeks with increasing doses of carp pituitary extract (10, 20, 30, and 40 mg CPE/kg body wt) and kept in natural light or completely dark conditions. In both groups, final oocyte maturation and ovulation were induced by injection of 17,20 h-dihydroxy-4- pregnen-3-one (DHP) at 2 mg/g body wt. All sixty eels turned out to be silver and actively migrant (58 in stage V and two in stage IV), showing a particularly high eye index (15.75±1.40), and distributed within three age classes (7-9 years). In the group kept in darkness, one of the four females ovulated 12 h after DHP injection in the thirteenth week. The remaining three females received the final (16th) CPE injection and ovulated 12-36 h after the DHP injection. In the group kept in light, two of the four females received the 16th CPE ...
RIASSUNTO – Indagine preliminare sullo spettro alimentare e la maturazione gonadica in rombo (Sco... more RIASSUNTO – Indagine preliminare sullo spettro alimentare e la maturazione gonadica in rombo (Scophthalmus maximus L.) selvatico del nord Adriatico – Il presente studio preliminare è stato condot-to al fine di determinare la composizione della dieta naturale e lo stato di maturazione gonadica in ripro-duttori di rombo catturati nell'alto Adriatico con l'obiettivo di costituire uno stock di riproduttori e di otte-nere la deposizione in cattività. La dieta è risultata composta sia da pesci che crostacei presenti in mag-giore quantità nel tubo digerente delle femmine il cui indice di replezione è sempre risultato più elevato di quello dei maschi. Nelle femmine catturate in settembre le gonadi sono risultate immature mentre gli esemplari pescati in novembre hanno evidenziato uno stato di maturazione iniziale. KEY WORDS: wild turbot, feeding habits, prey items, gonad maturation. INTRODUCTION – The European aquaculture turbot production in 1999 was 4093 t of which approximately 28...
Artificial reproduction in eels is very challenging due to their peculiar life cycle. No informat... more Artificial reproduction in eels is very challenging due to their peculiar life cycle. No information is yet available on the influence of photoperiod on the sexual development of wild silver eels in captivity. Previous studies have demonstrated the photoperiod to influence sexual maturation of eels showing that dark conditions lead to a better reproductive performance in terms of a greater gonadal maturation and a higher egg production and spawning record. This study aimed to investigate the physiological mechanisms leading to different outcomes in light or dark conditions on the gonadal steroidogenesis in wild female European silver eels during pituitary extract treatment. The variation of the body weight index and gonadosomatic index suggested a positive effect in dark conditions. Sexual steroids (androgens and estrogens) showed a significant difference in plasmatic concentration in the animals kept in the dark suggesting a better wellness reproductive situation in this particular...
A review of the studies carried out from 2010 to 2013 on the reproduction of the European eel: ef... more A review of the studies carried out from 2010 to 2013 on the reproduction of the European eel: effects of photoperiod, evaluation of different populations, a new recirculating system, first successful weaning test.
Aquaculture Research, 2015
ABSTRACT This study aimed to compare the fertility of eggs between artificially matured female si... more ABSTRACT This study aimed to compare the fertility of eggs between artificially matured female silver eels that spawned spontaneously and those that were spawned by manual stripping. The effects of the two methods of spawning on ovulation and fertilization rate were also investigated. For this purpose, 18 wild female European eels captured in Bonello lagoon (North Adriatic Sea) were carp pituitary extract-injected to undergo sexual maturation and ovulation; a final injection of 17,20β-dihydroxy-4-pregnen-3-one (DHP) was administered when at least 30% of the oocytes were fully transparent. After the DHP-injection, nine eels were transferred to a new closed recirculating aquaculture system, where they were housed with spermiating males (sex ratio 4/1) to allow spontaneous spawning (SPT-group); the remaining nine eels were transferred to a 250 L tank and ovulation was checked at four-hourly intervals by manual stripping (STR-group). The number of eggs per female in the SPT-group was significantly greater than that in the STR-group. Furthermore, fertilization rates in the SPT-group were notably higher than those observed in the STR-group. Significantly, the best performances were obtained among eels in which at least 50% of oocytes were fully transparent at the time DHP was administered. We conclude that the fertility of eggs from spontaneously spawning eels is superior to that of eggs acquired by strip-spawning and artificial fertilization.
Aquaculture, 2014
There is very little scientific literature about the impact of Eel virus European X (EVEX) on eel... more There is very little scientific literature about the impact of Eel virus European X (EVEX) on eels held under artificial reproduction condition, and its effective role in eel decline is uncertain and still unclear. Following a disease outbreak of European eels, farmed in an experimental hatchery in Italy, a sample of the affected animals was analyzed to determine the cause of illness. Virological isolation, PCR assay and molecular characterization revealed the presence of EVEX in the diseased animals. The complete N, P, M and G gene regions were amplified by using novel primers specific for EVEX. The EVEX strain identified in this study was phylogenetically close to the known EVEX isolates; however, this Italian isolate diverges and localizes in a separated branch of this cluster. In addition, some unique amino acid changes in three out of four analyzed viral proteins differentiated the Italian virus from reported EVEX sequences which, although few in number, do cover different geographical areas and a 30-year time span. Molecular data are needed to gain further insight into the genetic variability of EVEX, to better define its phylogenetic and evolutionary relationships and to unravel the existence of different circulating strains. Examination of samples caught in the same area failed to detect the presence of EVEX infection. These results strongly indicate that the presence and risk factors associated with EVEX infection are not well established and further study should be performed in this field, in particular on stress and temperature dependence for disease development.
Journal of Applied Ichthyology, 1997
Survival rate, sex ratio and zootechnical performances were evaluated on 168 kg of Anguilla angui... more Survival rate, sex ratio and zootechnical performances were evaluated on 168 kg of Anguilla anguilla elvers (0.45 gj weaned into three groups (Al, A2, A3) at initial densities of 800, 1600 and 3200g m-j, respectively. In order not to modify the sex ratio, animals weaned at the different densities were maintained separately during the trials, and no size grading was performed at the fattening phase.
Journal of Applied Ichthyology, 2006
ABSTRACT Seabass (SBS) and seabream (SBM) juveniles were reared with the goal of obtaining three ... more ABSTRACT Seabass (SBS) and seabream (SBM) juveniles were reared with the goal of obtaining three different final densities (SINT = 40 kg m−3; INT = 20 kg m−3; SEM = 0.2 kg m−3) to ascertain the effects thereof on the welfare of the fish. Significant blood metabolites and hepatic glycogen were determined every 3 months and at harvest. Trials lasted 18 months in seabass and 17 months in seabream. At the end of experiment the main biometric productive parameters and quality of body composition were also recorded. Regarding intensively reared seabass (SINT-SBS, INT-SBS), the plasma triglycerids, total cholesterol and transaminases (AST, ALT) were always significantly higher than in semi-intensively maintained fish (SEM-SBS). At the final sampling in the SINT-SBS batch, the total protein and glucose were also markedly increased. Conversely, at harvest the liver glycogen content decreased in SINT-SBS (34 ± 8 mg g−1 liver) with respect to INT-SBS (57 ± 12 mg g−1 liver) and SEM-SBS (63 ± 11 mg g−1 liver). No differences among groups were observed for creatine kinase (CK) and lactate dehydrogenase (LDH). With regard to seabream, SINT-SBM and INT-SBM constantly showed plasma triglycerids and total cholesterol as being significantly higher when compared to SEM-SBM. In the final two blood samplings, SINT-SBM exhibited the most elevated values for LDH. At harvest, AST, ALT, total protein and glucose markedly increased in SINT-SBM, whereas liver glycogen content was reduced (22.5 ± 9 mg g−1 liver), more than in INT-SBM (70 ± 16 mg g−1 liver) and SEM-SBM (75 ± 20 mg g−1 liver). In both seabass and seabream, body composition was very similar in the different stocking densities, except for total cholesterol. Total n-3 polyunsaturated fatty acid (PUFA) in seabream was significantly different from fish of the semi-intensive groups; however, nutritional values and fatty acid profiles were equally good. The intermediate final density of seabass and seabream at 20 kg m−3 seemed to give the best results in terms of their well being when compared to fish reared at 40 kg m−3. The absence of differences in blood metabolites and hepatic glycogen levels between the intensive batch and the semi-intensive groups until harvest was a reference to the positive status of the fish. A density of 20 kg m−3 can be considered acceptable for farm strategy planning for raising healthy on-growing seabass and seabream juveniles.
Journal of Applied Ichthyology, 2001
... The large-scale retail of stocks of fish products has meant that the consumer is not always a... more ... The large-scale retail of stocks of fish products has meant that the consumer is not always aware of the ... For the other morphological traits, the standard length was also significantly higher in the SB-II fish, while the ... 22 SAS Institute, 1989: SAS/STAT Guide for Personal Computers ...
Journal of Anatomy, 2014
European eels live most of their lives in freshwater until spawning migration to the Sargasso Sea... more European eels live most of their lives in freshwater until spawning migration to the Sargasso Sea. During seawater adaptation, eels modify their physiology, and their digestive system adapts to the new environment, drinking salt water to compensate for the continuous water loss. In that period, eels stop feeding until spawning. Thus, the eel represents a unique model to understand the adaptive changes of the enteric nervous system (ENS) to modified salinity and starvation. To this purpose, we assessed and compared the enteric neuronal density in the cranial portion of the intestine of freshwater eels (control), lagoon eels captured in brackish water before their migration to the Sargasso Sea (T0), and starved seawater eels hormonally induced to sexual maturity (T18; 18 weeks of starvation and treatment with standardized carp pituitary extract). Furthermore, we analyzed the modification of intestinal neuronal density of hormonally untreated eels during prolonged starvation (10 weeks) in seawater and freshwater. The density of myenteric (MP) and submucosal plexus (SMP) HuC/D-immunoreactive (Hu-IR) neurons was assessed in wholemount preparations and cryosections. The number of MP and SMP HuC/D-IR neurons progressively increased from the freshwater to the salty water habitat (control > T0 > T18; P < 0.05). Compared with freshwater eels, the number of MP and SMP HuC/D-IR neurons significantly increased (P < 0.05) in the intestine of starved untreated salt water eels. In conclusion, high salinity evokes enteric neuroplasticity as indicated by the increasing number of HuC/D-IR MP and SMP neurons, a mechanism likely contributing to maintaining the body homeostasis of this fish in extreme conditions.
Italian Journal of Animal Science, 2010
During 2006, trials about induced reproduction and larval rearing of chub were carried out with t... more During 2006, trials about induced reproduction and larval rearing of chub were carried out with the aim to compare results obtained from broodstocks stocked in captivity with those of specimens caught in a river and immediately stripped. In Autumn 2005, a total of 35 chubs, were collected by electrofishing in an Apennine river and stocked in a 10m 3 outdoor basin supplied with well water. The fish were fed with natural and balanced feeds. During the month of May 2006, other 8 fluent and mature broodstocks (5 males and 3 females) were fished by hook in the same area of origin of the other chubs (water temperature = 19°C), and immediately stripped. After fertilization, the eggs were disagglutinated and transported to the hatchery. Incubation took place in Zugg bottles at the temperature of 20±1°C (C1). At the same time, broodstocks from the outdoor basin were transferred inside the hatchery subdividing them in 2-1.5m 3 tanks (C2, C3) connected with a closed circuit system. Water temperature was 17±1°C. All the males (12) were treated with carp pituitary (3mg/kg b.w.) (Lukovicz and Proske, 1971; Linhart et al., 1995) in coincidence of the second injection of females. The females of the two sub-groups (C2, C3) were treated with two different dosages of carp pituitary (5 and 10 mg/kg b.w.) divided in two fractions (1/10 and 9/10), injected at 24 h interval. After stripping and fertilization, the same method of eggs incubation used for the wild chubs was applied. On day 4, hatching took place and ranged between 85% (C3) and 90% (C1). The larvae of the different groups were reared in 3-500l tanks connected to a closed circuit and fed with Artemia salina nauplii (420±20µm) until day 11 when a cold extruded micronized feed for marine larvae was also supplied. The total substitution took place on day 20. The number of larvae obtained per kg b.w./batch was between 15,817 (C2) and 18,441 (C3). On day 30, larvae had reached a mean length of 16mm in the three groups without significant differences and body weight ranged from 20.7mg (C2) to 21.5mg (C3) as found by Harzewili et al. (2003). The survival rate resulted 70% (C1), 69% (C2) and 71% (C3).
Italian Journal of Animal Science, 2010
Growth performances of sunshine bass (initial m.b.w.=200±50 g) were examined in 3 different reari... more Growth performances of sunshine bass (initial m.b.w.=200±50 g) were examined in 3 different rearing conditions: concrete square basins (HSB-1); raceways (HSB-2); natural ponds (HSB-3). Fish received the same extruded feed (prot. 48.8%; lip. 17.8%). The trial lasted 16 months in HSB-1 and HSB-2 and only 12 months in HSB-3 due to unfavourable welfare status and low growth performances. At harvest (after 16 months), sunshine bass reached a satisfactory mean weight without significant differences between groups. HSB-2 fish were longer with a smaller circumference, probably due to different hydrodynamics of the raceway. Glucose, cholesterol, triglycerides, protein, lactic dehydrogenase (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), creatine kinase (CK), glycogen of plasma or tissue were not affected by rearing conditions as well as the proximate composition and the fatty acid profile of the fillet.
Aquaculture International, 2013
This study aimed to describe the response variability of female silver eels in terms of gonad dev... more This study aimed to describe the response variability of female silver eels in terms of gonad development and eggs production to a standardized gonadotropic treatment (Carp pituitary extracts-CPE), and to relate this variability to population characteristics. For this purpose, sexual maturation, ovulation, and fertilization were induced in two eel populations coming from different locations in Adriatic Sea (Comacchio-CM and Marano-Grado-MG lagoons), and after that, their reproductive capacity was valuated. External (Silver index-SI, Eye index-EI, Pectoral fin length index-PFLI, Condition factor-K) and hormonal (17b-estradiol-E2, testosterone-T) parameters were measured, and some subject/group were killed for histological and lipid analysis and age determination. Morphometric parameters showed the CM-Group to have highest values of Body weight (BW), Body length (BL), and K, while MG-Group presented highest PFLI and Gonadosomatic index (GSI) values. Regarding hormonal analysis, the CM-Group showed significantly higher T and E2 levels than the MG-Group, both groups showed considerably rapid increase at T5 (5th injection). A positive trend in gonadal development was found through histological evaluation; a more regular maturation was observed in the MG-Group, whereas the CM-Group presented an exponential oocytes development starting from T10 (10th week), which led to an anticipated spawning. Lipid content showed significant differences in T0 (start study), post-ovulation, and Control (30th week) between CM and MG eels. As to zootechnical performances, while MG eels released spontaneously into the water, the CMs were stripped in order to check ovulation. The MG eels were statistically the most productive with 40.1 ± 6.33 % BW of eggs released. Furthermore, CM females ovulated mainly between the 19th and 22nd week (77.8 % spawned eels) instead in the MG's ovulation goes from the 24th to the 28th week (100 % spawned eels). As fertilization is of concern, in both groups fertilized eggs were obtained with no difference in larvae production. These results seem to indicate that bigger dimensions, higher K, and larger lipid content (Comacchio eels) could fasten gonadic maturation without positively influencing reproductive performance of animals, both in term of quantity and quality of
Aquacultural Engineering, 2014
ABSTRACT The objective of the present study was to obtain spontaneous reproduction in captivity o... more ABSTRACT The objective of the present study was to obtain spontaneous reproduction in captivity of the European eel (Anguilla anguilla) by using a new closed recirculating aquaculture system provided with spawning and incubation chambers. The influence of two levels of water-flow rates (Low-Flow: 0.8+/-0.05 L/s and High-Flow: 2.4+/-0.05 L/s) on the spawning, fecundity and egg quality was also investigated. For this purpose 12 silver eel females were induced with increasing doses of carp pituitary extract (10, 20, 30 and 40 mg CPE/kg BW). Twenty-four hours after the last CPE injection, each female ovulation was induced by injecting a DHP-solution and then transferring them to a new closed recirculating aquaculture system, where they were maintained for 16 h with spermiating males (sex ratio 4/1) in order to obtain spontaneous reproduction. The reproduction was tested with 6 females in Low-Flow rate conditions and 6 females in High-Flow rate conditions. The results showed that the designed closed-loop system made it possible to carry out a more spontaneous reproduction for more than 80% of the females that underwent standardized gonadotropic treatment and favored the automatic and complete transfer of the eggs to the hatchery. The results also point out that high or low water current conditions in the tank do not hinder the mating and the emission of gametes by the breeders, but the High-Flow rate in the two incubation chambers showed unsuitable hydrodynamic conditions for embryonic development resulting in a constant loss of viable eggs which reached a mortality of 100% among females with the highest incubation density.
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Papers by Oliviero Mordenti