Survival Rate Of Larvae Research Articles

Effects of Rotifer Feeding Frequency on Growth and Survival Rate of Early Larval Stages of Mud Crab, Scylla olivacea

Crustacean larvae have the characteristics of living as carnivorous organisms. This has an impact on the length of gut evacuation time which affects the feeding pattern of the larvae. The feeding strategy of mud crab larvae is modulated by the length of gut evacuation time. Another factor that can be subject to modulation is the frequency of feeding. This research aimed to evaluate rotifer frequency feeding of early larvae stages of mud crab, Scylla olivacea. This research was conducted at the Mariculture Fisheries Center, Ambon with an indoor system. This research began with carrying out parental maintenance to produce larvae. Larvae are fed with rotifers with different frequencies. The treatments were the frequency of feeding rotifers, namely: Treatment 1 (F1) was the frequency of 1x a day (9:00 am); Treatment 2 (F2) was a frequency of 2x a day (9:00 am & 13:00 pm) and Treatment 3 (F3) was a frequency of 3x a day (9:00am, 13:00pm & 17:00pm). Each treatment was given 3 replications. Based on the results of this study, it showed that feeding with a frequency of three times a day (F3 treatment) was able to have a positive effect on the survival rate of zoea larvae which on the third day was 58% and the fourth day was 22% higher than the F1 and F2 treatments. The growth of larvae showed that F3 treatment was higher than F1 and F2 on the sixth day with an increase in the absolute value of growth of 0.12044 mm compared to F1 of 0.05531 mm and F2 of 0.03253 mm. Keywords: frequency of feeding, growth, larvae, survival rate, mud crab

Improving the Quality of Tilapia Fish Seeds (Oreochromis Niloticus) with Selection Methods in Mina Ayu Group of Tabanan Regency Bali Province

Tilapia fish is much in demand because it has several advantages such as its distinctive taste that makes tilapia delicious after being processed in any way. Tilapia has the potential to be used as an export commodity in the form of fish fillets and the price is relatively cheap. The climate situation and the extent of freshwater fishing land are contributing factors in the development of tilapia cultivation in Indonesia. One of the efforts to increase efficiency and productivity in cultivation is fish spawning activities. Spawning activities are important for producing seeds or larvae. Female fish are 300 to 400 g and for males, 400 to 500 g, aged 5 months. Tilapia can colonize weighing 250 g and age 4 to 6 months, meaning the parent used in this study has been following the required. The maintained parent is a healthy, unformed, and complete morphological parent (SNI 01-61412009). The purpose of this study is to improve the quality of Tilapia fish seeds produced by the Mina Ayu Group of Tabanan Regency of Bali Province by a selective breeding method. Male and female tilapia broods are kept separately in hapa measuring 5x5x1m. In shelters, for the acceleration of gonad maturation before the fish are stocked in the spawning pond. The feeding given during maintenance is 2 to 3%. Individual selection methods can improve the quality and survival rate of tilapia fish larvae. The absolute length increased 1.5 cm and weight increased 0.950 mg/day with a survival rate of 80% to 90%.

Effect of egg size on the growth rate and survival of wild walleye pollock Gadus chalcogrammus larvae

AbstractTo clarify the survival process of walleye pollock larvae of the Japan Pacific stock in relation to the individual egg size, we estimated the original relative egg diameter from the diameter of the hatch check formed on larval sagittal otoliths. Significant positive correlations were obtained between egg diameter and embryonic body length, yolk sac volume, and lapillar otolith diameter in 3‐year groups (2013–2015 year classes) collected with a plankton net in Funka Bay. Embryos before hatching were without a check; however, checks were observed on all larval otoliths just after hatching. The check diameters showed significant positive regressions to age at collection (days after hatching) in 2014 and 2015 year classes, however not in the 2013 year class. Diameters of eggs collected with a ring net in Funka Bay gradually increased from 2013 to 2015 year classes. During the 2013–2015 spawning seasons, the proportion of adult females of the 2007 and 2009 year classes, which had relatively high abundances, gradually increased to higher proportions with age (43%, 57%, and <73%, respectively), indicating that the mechanism by which the eggs gradually became larger. The low water temperature experienced by the spawners ca. 2 months earlier, advancement in spawner age, and increase of repeat spawners (at least twice in their life time) would contribute to the increase in egg size and growth and survival rate of walleye pollock larvae.

Maturation and spawning performance of hormonally-induced precocious female barramundi (Lates calcarifer) and implications of their use in selective breeding

Breeding programs for barramundi (Lates calcarifer) are impeded by the lack of control over the sexual development of broodstock. As a protandrous hermaphrodite, barramundi initially sexually mature as male at 2–3 years (2–4 kg body weight; BW), before changing sex to female at 4–6 years (>6–8 kg BW). Recently, precocious female barramundi have been generated using a single intramuscular estrogen implant, providing the potential to speed up the sex change process and implement same-age mating of male and female broodfish. However, the functional maturation of hormonally-induced precocious females and their ability to spawn and produce viable progeny remains untested.Male barramundi (~2.2 kg BW, 57.8 cm total length; TL) were hormonally induced to sex change using an estrogen implant. The precocious female barramundi were cannulated at 6 (T1), 8 (T2), 10 (T3), 11.5 (T4) and 13 (T5) months after sex change, with oocytes measured and staged to determine reproductive condition. At T3, four females (~4.2 kg BW, 67.8 cm TL) with oocytes >350 μm in size were transferred to a spawning tank along with four males to assess their spawning performances. Mass spawning events were induced at T3, T4 and T5, and eggs released on the first and second spawning nights were collected to determine rates of fertilization, hatching and larval survival at 24 and 48 h post-hatch.At each cannulation event (T1 - T5), several precocious females were confirmed to have mature oocytes and were considered ready for induced spawning. Conversely, in some individuals, only immature oocytes were during each cannulation event. The four precocious females induced to spawn generated large numbers of eggs, with 7.7 million (T3), 10.9 million (T4) and 9.1 million (T5) eggs obtained across the two nights of each mass spawning event. Fertilization of oocytes was not observed at T3 and was likely due to male inactivity. Spawning performance improved considerably for T4 and T5 spawns, with the highest fertilization rate (64%) and hatching rate (72%) observed during T5 - Night 1. Furthermore, larval survival at 24 and 48 h after hatching was 99% and 94%, respectively. Total larval production across both nights of the T5 spawn exceeded 3 million individuals. Spawning performances of precocious females were comparable to routine commercial stocks of large females (8–15 kg), and confirmed that precociously induced female barramundi can produce the quantity of seedstock required in existing selective breeding programs. Further research examining the factors involved in promoting oocyte growth and maturation is needed to enhance the rate at which mature precocious females are available for spawning.

Effects of three major nutrient contents, compost thickness and treatment time on larval weight, process performance and residue component in black soldier fly larvae (Hermetia illucens) composting

The cellulose content in vegetable waste (VW) is high and cannot be directly digested by black soldier fly larvae (BSFL). In this study, in order to treat VW using BSFL composting, kitchen waste (KW) is used as the only nutritional supplement for VW to analyze the effects of the different contents of crude protein (CP), crude fat (EE), carbohydrate (3C), compost thickness (CT), and treatment time on the larval weight (LW), survival rate (SR), dry matter reduction rate (DMR), bioconversion rate (BCR), physical and chemical properties of BSFL sand and changes in the microbial community. Our results showed that when the average 3C content increased by 40%, the average LW increased by 47.6%, and the SR, DMR, BCR, and organic matter (OM) content increased by 16.82%, 8.5%, 4.77%, and 3.86%, respectively. In contrast, when the average compost thickness increased by 5 cm, the average weight of BSFL decreased by 22.64%, while the SR of larvae, DMR, BCR, OM, and total nutrients (TN + P2O5 + K2O) decreased by 5%, 5.2%, 4.42%, 9.6%, and 0.78%, respectively. Germination test showed that BSFL sand alone could not be used as soilless culture substrate. After BSFL treatment, we found that the dominant phyla in BSFL sand were Firmicutes (95.77%), Proteobacteria (2.54%), Actinobacteria (0.74%), and Chloroflexi (0.6%). Our results indicate that BSFL composting is an effective method of treating VW, and 3C content and CT have a significant effect on BSFL composting.

Bioconversion of cyanobacteria by black soldier fly larvae (Hermetia illucens L.): Enhancement by antioxidants

Cyanobacterial blooms have been a global environmental problem for decades. Bioconversion by black soldier fly larvae (BSFL) has been widely reported to be a clean and efficient method to remove organic pollutants. In this study, BSFL bioconversion was used to treat cyanobacterial blooms. Antioxidants (a mixture of l-ascorbic acid [180 mg/kg fresh feed] and α-tocopherol [360 mg/kg fresh feed]) were added to compare bioconversion performance against a non-supplemented group. With increasing proportions of cyanobacteria (0%–25% dry mass), the bioconversion efficiency of the antioxidant group improved significantly compared to the control group, and the survival rate of larvae rose from 96.50–45.50% to 98.00–55.83% with antioxidant addition. The toxic effects of exogenous anti-nutrients could be reduced by the antioxidants through inactivation of trypsin inhibitor and enhancement of the microcystin-LR degradation rate. Overall, the BSFL bioremediation capacity was improved with addition of exogenous antioxidants, verifying both the effects and mechanism of antioxidant addition in promoting the bioconversion of cyanobacteria by BSFL and providing a basis for future application and study.

The effect of acclimation temperature and optimal temperature gradient for egg and larvae of silver moony (Monodactylus argenteus) during the early ontogenesis.

The early life history of a fish species is regulated by temperature, the most critical environmental cue. Thus, identifying the gradient of temperature that optimises the early development of a species is a prerequisite for standardising hatchery technology. Silver moony, Monodactylus argenteus is a tropical brackishwater ornamental fish that holds scope for the Indian and Global ornamental fish industry. This study unravels the effect of water temperature increments (26, 28, 30, 32, and 34°C) on embryonic development, hatching, and survival rate, as well as the growth profile and survival rate of larvae at 5days post-hatch (5 dph). Experiments were conducted to find out the optimal temperature gradient for egg incubation and early larval rearing. The experiment results revealed that the embryogenesis was accelerated at increasing temperatures, especially after the gastrula stage, and apparent differences were evident in each stage. However, the morphological development profile at each embryonic stage was similar throughout the temperature range. The incubation period differed significantly (P < 0.05) between the temperature gradients. The highest rates of hatching (90-100%) and survival after 12 hph were observed at 28 ºC and 30 ºC. Hatched-out larvae demonstrated the highest total length (1.92 ± 0.02µm) at 34°C, and the total length decreased at lower temperature levels. The yolk sac volume of larvae was shrunken with an increase in temperature, and a significant difference was observed between the studied temperatures. However, the oil globule diameter did not differ between the different temperatures. The total length and growth rate of 5 dph larvae were significantly different among the temperature treatments and increased with increasing temperature. In contrast, the survival rate of 5 dph larvae was highest at the range of 26 ºC and 30 ºC. The results indicated that the change in temperature from the spawning temperature (29 ± 1°C) negatively influenced embryogenesis and the early development of M. argenteus. Based on the experimental results, the growth and survival of embryo and larvae were found to be optimum at 28 to 30 ºC. This prediction is of great importance for the effective management in the hatchery production phase, and especially the temperature could be considered the critical environmental cue.

Production of recombinant Japanese eel (Anguilla japonica) growth hormones and their effects on early-stage larvae

Growth hormone (Gh) regulates somatic growth in fishes, particularly through the Gh - insulin-like growth factor-I (Igf-I) axis. In this study, recombinant Japanese eel Ghs with or without C-terminal peptides of human chorionic gonadotropin (CTP), which are known to prolong the half-life, were produced using the HEK 293 and CHO expression system. The effect of recombinant Gh administration to eel larvae on their somatic growth was investigated in short-term feeding experiments, and it was found that three types of recombinant Ghs with CTP (CTP-reGh, reGh-CTP and reGh-CTP × 2) were more effective in promoting somatic growth in eel larvae than recombinant Ghs without CTP. Among the three recombinant Ghs with CTP, reGh-CTP × 2 had the highest growth-promoting effects, however only when provided in the short term. After long-term administration of reGh-CTP × 2, there was no difference in growth between the Gh administrated group and the control group. The survival rate of eel larvae were not affected by recombinant Ghs. In addition, the mRNA expression of gh, Gh receptors, Igf-I and IGF-II were measured by quantitative real-time PCR, and significant reductions in the expression of gh, Gh receptors and Igf-I were observed. These findings provide useful tools to study the mechanisms of somatic growth and increase understanding of Gh regulation in anguillid eel larvae.

Trial on artificial breeding and laviculture of giant razor clams (Cultellus maximus Gmelin, 1791)

The study was carried out with the aim of determining the reproductive parameters and performing the rearing of giant razor clams (Cultellus maximus Gmelin, 1791) at larval stage and postlarval stage with different diets. The results showed that the spawning rate was 62.22 ± 3.85%, the fecundity was 7.98 ± 0.67 million eggs/female, the relative fecundity was 48,081 ± 5,826 eggs/g female, the fertilization rate was 42.67 ± 4.47%, and the hatching rate was 44.19 ± 4.02%. The rearing at larval stage with different diets of algae was investigated ((T1.1): Nanochloropsis oculata + Isochrysis galbana; (T1.2): N. oculata + Chaetoceros muelleri; and (T1.3): N. oculata + Isochrysis galbana + C. muelleri). The results showed that T1.3 gave the survival rate, length and width of larvae, reaching 5.3 ± 0.91%; 1525.60 ± 48.90 μm and 918.20 ± 28.00 μm, respectively. The parameters obtained from T1.3 was significantly higher (P &lt; 0.05) than that of T1.1 and T1.2. The rearing at postlarval stage with different diets was also studied as follow: (T2.1): N. oculata + I. galbana + C. muelleri; (T2.2): using commercial feed (Lansy and Frippak); and (T2.3): combination of 50% of T2.1 + 50% of T2.2. The results showed that T2.1 gave the survival rate, growth in length and width of postlarvae, reaching 11.83 ± 3.89%; 5.72 ± 0.61 mm and 3.31 ± 0.14 mm respectively. Growth parameters of T2.1 were significantly higher (P &lt; 0.05) compared to that of T2.2 and T2.3.

A potential role of nettle (Urtica dioica) extract on growth, biochemical changes and reproductive performance of convict cichlid (Amatitlania nigrofasciata).

This study was carried out to investigate the effects of methanolic extract of nettle (Urtica dioica) on growth, reproduction, biochemical and immunological parameters of female convict cichlid (Amatitlania nigrofasciata). For this purpose, 54 fish were distributed in 3 treatments included: without supplementation (control), 0.1g (NE0.1), and 0.5g (NE0.5) nettle extract per kilogram feed over 56days. The highest final weight (4.2 ± 0.1g), weight gain (2.8 ± 0.1g), and specific growth rate (2.0 ± 0.0% day-1) were recorded in NE0.1 group. Higher and lower feed conversion ratio were obtained in control and NE0.1 treatments, respectively. Hepatosomatic and viscerosomatic indices in NE0.1 treatment were significantly lower compared with control treatment. Fish fed NE0.1 showed significantly lower glucose (55.2 ± 6.5mgg-1), cholesterol (28.4 ± 3.3mgg-1), and triglyceride (211.5 ± 39.0mgg-1) levels. Total protein (36.3 ± 3.4mgg-1) and albumin (2.7 ± 0.1mgg-1) showed a marked increase in NE0.1 treatment. Same trend was observed in C3, C4, and IgM concentrations. NE0.1 showed the highest number of eggs per female (183.7 ± 10.2), hatching rate (97 ± 0.7%), and larval survival rate at 3 days post hatch (86.3 ± 0.6%) compared with the other treatments. These findings indicated that 0.1g methanolic extract of nettle kg feed-1 could enhance growth, improve metabolic, and immune function of convict cichlid. Moreover, this study confirmed that appropriate dose of nettle can positively promote reproductive performance which makes it as a valuable and cost-effective herb in aquaculture industry.

Effect of aspartame on survival, morphological and molecular levels of Polyrhachis vicina Roger (Hymenoptera, Formicidae)

Aspartame is a food additive that is widely used in the food industry. Previous data have shown that aspartame is toxic to humans and animals. However, there are few reports on the effect of aspartame on social insects living in the soil. The present study was designed to evaluate aspartame toxicity for Polyrhachis vicina Roger. Five dosages of aspartame were fed to the workers and 40 mg/kg (acceptable daily intake, ADI) aspartame was chosen to feed the 4th instar larvae, pupae, females and males in P. vicina. The results showed that the effect of aspartame on the survival rate of workers was in a time and dose dependent manner. The survival rate of 4th instar larvae, pupae and males decreased at 40 mg/kg aspartame. Meanwhile, we found that aspartame toxicity can cause weight and morphological changes. These changes may be related to the abnormal gene expression of Ecdysone receptor, Tailless and Extradenticle of P. vicina (PvEcR, PvTll and PvExd) resulting from aspartame treatment. The present study confirms the effect of aspartame toxicity on P. vicina even at the ADI dosage.

Transcriptome Profiling Based on Larvae at Different Time Points After Hatching Provides a Core Set of Gene Resource for Understanding the Metabolic Mechanisms of the Brood-Care Behavior in Octopus ocellatus.

The metabolic processes of organisms are very complex. Each process is crucial and affects the growth, development, and reproduction of organisms. Metabolism-related mechanisms in Octopus ocellatus behaviors have not been widely studied. Brood-care is a common behavior in most organisms, which can improve the survival rate and constitution of larvae. Octopus ocellatus carried out this behavior, but it was rarely noticed by researchers before. In our study, 3,486 differentially expressed genes (DEGs) were identified based on transcriptome analysis of O. ocellatus. We identify metabolism-related DEGs using GO and KEGG enrichment analyses. Then, we construct protein–protein interaction networks to search the functional relationships between metabolism-related DEGs. Finally, we identified 10 hub genes related to multiple gene functions or involved in multiple signal pathways and verified them using quantitative real-time polymerase chain reaction (qRT-PCR). Protein–protein interaction networks were first used to study the effects of brood-care behavior on metabolism in the process of growing of O. ocellatus larvae, and the results provide us valuable genetic resources for understanding the metabolic processes of invertebrate larvae. The data lay a foundation for further study the brood-care behavior and metabolic mechanisms of invertebrates.

Ecotoxicological Effects of Silver Nanoparticles (Ag-NPs) on Parturition Time, Survival Rate, Reproductive Success and Blood Parameters of Adult Common Molly (Poecilia sphenops) and Their Larvae

Nanoparticles (NPs) can display toxicological effects on aquatic organisms. This study investigates ecotoxicological effects of Ag-NPs on reproductive and blood parameters of adult common molly (Poecilia sphenops) and their larvae. During the LC50 96 h test, female fish were exposed to concentrations of 0, 5, 15, 25, 35, 45 and 60 mg L−1 of Ag-NPs, while larvae were exposed to 0, 3, 5, 10 and 15 mg L−1. Finally, we aim to evaluate the effects of 0, 5, 10 and 15 mg L−1 of Ag-NPs on parturition time, reproductive success and hematological parameters of the mature fish exposed to sub-lethal concentration during a 62-day period. We also evaluated the survival rate of larvae. The results show a positive correlation between mortality rate and Ag-NP concentration. Values for LC50 96 h in adult fish and larvae were 26.85 mg L−1 and 6.22 mg L−1, respectively. A lack of parturition and reproductive success were seen in fish that underwent chronic exposure to Ag-NPs (15 mg L−1). The results show that RBC, WBC and hematocrit were significantly decreased in fish exposed to Ag-NPs. In addition, the serum concentrations of total protein, albumin, cholesterol and triglycerides were significantly increased in fish submitted to Ag-NPs (concentrations of 5–15). In conclusion, submitting a fish to higher concentration than 10 mg L−1 has adverse effects on reproductive system and blood parameters.

The First Commercially-Scaled Study on the Influence of Long Dark and Light Photoperiod Manipulation on the Egg and Larvae Performance of Rainbow Trout (Onchorhynchus mykiss)

Engin, S., 2022. The first commercially-scaled study on the influence of long dark and light photoperiod manipulation on the egg and larvae performance of rainbow trout (Onchorhynchus mykiss). Journal of Coastal Research, 38(1), 196–203. Coconut Creek (Florida), ISSN 0749-0208. Spawning success, number of eyed-egg, and larval growth performance of rainbow trout are largely affected by a variety of biotic and abiotic factors. The photoperiod is important in initiating or suppressing breeding timing and gonadal maturation that varies by species. The aims of this study were to investigate the effect of two different commercial photoperiod manipulations on the growth of total eyed eggs, egg diameter, and larvae under specific fish farm conditions. The control group (outdoor broodstock ponds and natural sunlight) fish were fed using a commercial broodstock feeding protocol in September and transferred to the hatchery in February for spawning. The female and male broodstocks were exposed to direct photoperiod (Experimental Group 1: M1), and for the adapted photoperiod (transition from light to dark periodically, Experimental Group 2: M2) they were exposed to 18 hours of light and 6 hours of darkness between January and April. The M1 group were exposed to a direct application of 18 hours of dark and 6 hours of light, and a transition from light to dark for 18 hours and from dark to light for 6 hours was applied to M1 that was completed over 48 days with a daily decrease of 17 minutes. The results of the trials showed that larval growth was higher in the groups treated with long light and long dark, 18 hours light/6 hours dark and 18 hours dark/6 hours light compared to the control group, and statistically significant difference between larval survival rate and daily weight gain was observed between all three groups (p < 0.05). As a result, at the end of the photoperiod, applications and larvae breeding performed for one year under commercial operating conditions were compared, and larvae with higher survival and growth rates were obtained with long light and long dark application.

Evaluation of different substrates for multiplication and waste reduction potential of black soldier fly, Hermetia illucens (Stratiomyidae: Diptera)

The influence of five different wastes namely, vegetable, fruit, kitchen, fish slaughter, and rice moth rearing (wastes), was evaluated on the multiplication, development, and waste reduction potential of black soldier fly, Hermetia illucens under laboratory conditions. The survival rate of larvae, prepupae weight per unit weight of wastes, adult fecundity, and longevity were the highest in kitchen and vegetable wastes. The lowest rate of survival and least weight of prepupae was recorded in the fish slaughter wastes. Kitchen wastes and rice moth rearing wastes recorded the lowest feed conversion ratio and residence time requirement. Bioconversion rate, pupal weight, and survival percentage of pupae were recorded to be the highest in kitchen waste. The results indicated that black soldier fly larvae could degrade kitchen and rice moth rearing (wastes) wastes and these parameters can be used to upscale the biomass production of this detritivore insect with suitable development parameters.

Establishment of a rotavirus-infected zebrafish model and its application in drug screening.

Rotavirus (RV) is one of the main pathogens that induce infantile diarrhea and by now no effective drugs are available for RV-induced infantile diarrhea. Thus the development of novel models is of vital importance for the pathological research of RV-induced infantile diarrhea, as well as the progress of the associated treatment strategy. Here we introduced for the first time that RV-Wa strain and RV-SA-11 strain could infect 5 dpf(day post fertilization) and 28 dpf larvae, to induce infantile diarrhea model that was highly consistent with the clinical infection of infants. RV infection significantly changed the signs, survival rate and inflammation of larvae. Some important indicators, including the levels of RV antigen VP4 and VP6, the in vivo RV tracking, and the RV particles were also analyzed, which collectively demonstrated that the model was successfully established. More importantly, we also determined the potentials of the proposed RV-infected zebrafish model for anti-viral drug assessment. In conclusion, we established a RV-infected zebrafish model with formulated relevant indicators both larvae and adult fish, which might be served as a high throughput platform for antiviral drug screening.

Organophosphate-based flame retardant (tris(1,3-dichloro-2-propyl) phosphate) reduces fecundity and impairs embryonic development in marine invertebrates

Context It is important to understand how marine invertebrates may be affected by tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), as an organophosphorus flame retardant. Aim The present research verified the hypothesis that TDCIPP would adversely affect the growth, development and reproduction of Crepidula onyx (phylum Mollusca) and Tigriopus japonicus (phylum Arthropoda). Methods Effects of chronic exposure for the whole life cycle were examined at two concentrations of TDCIPP chosen on the basis of results from preliminary range-finding test. Key results Exposure to 1 and 10 μg L−1 of TDCIPP significantly reduced larval and juvenile survival rate and shell length in C. onyx. TDCIPP caused adverse reproductive effects, including abnormal embryonic development, which led to non-viable broods and the malformation of larvae. Exposure to TDCIPP resulted in a 100-fold increase in incidence rate of abnormal larva formation. In T. japonicus, exposure to TDCIPP (10 μg L−1) resulted in non-viable broods and a significant reduction in the number of eggs and number of nauplii. Conclusions Larval survival, larval growth, fecundity, and embryonic development were identified as the TDCIPP-affected ecological endpoints in the marine invertebrate C. onyx and T. japonicus. Implications From a management perspective, these results can help us assess the ecological risk posed by TDCIPP.

Monitoring the reproductive status of resident and migrant Atlantic bluefin tuna in the Strait of Gibraltar

Two distinct contingents of Atlantic bluefin tuna (ABFT), migrants and residents, occur in the Strait of Gibraltar (SoG). Long-term residents are commercially exploited all year round using hook and line gears, whereas migrants are caught by traps in springtime as they pass through the SoG towards Mediterranean spawning grounds. While reproductive features of migrants have been widely studied, the life history of residents remains poorly investigated. The relative contribution of this subpopulation to ABFT eastern stock productivity is therefore unknown. Reproductive traits of resident ABFT were monitored throughout the year, and were compared with those of migrants crossing the SoG in spring. To assess maturation timing, gonads were classified into maturation stages based on histological features. Our results indicate biometric and reproductive differences between SoG residents and migrants. ABFT caught by hook and line gears were smaller on average than those collected from traps. The females sampled from the hook and line fishery in May and early June showed, on average, significantly lower GSI values than those caught by trap. In contrast, the GSI values of males sampled in May were not significantly different between gears. Histological analyses showed a more advanced reproductive condition in trap-caught migrants. Delayed maturation schedules of residents in comparison to migrants would result in less egg production and poorer larval survival rates. The present findings encourage further investigation of reproductive schedules in unstudied subpopulations for a better understanding of ABFT dynamics.

The effect of different salinity levels on larval growth and survival of Farfantepenaeus aztecus (Ives, 1891) (Decapoda: Penaeidae)

This study was designed to determine the effects of five different salinity levels (25, 30, 35, 40 and 45 ppt) on the survival rate of Farfantepenaeus aztecus larvae from Nauplius5 to post-larvae1 (N5-PL1). For this purpose, 50 larvae that reached the N5 stage were stocked in 2-L round bottom glass flasks in five replications and were grown up to the PL1 stage at 27.6±0.4°C. At the end of the study, as the highest survival (44.00±23.15) in protozoal stages were obtained at 35 ppt salinity levels, the lowest survival 14.00±4.89) were found at 25 ppt salinity levels (P&amp;lt;0.05). The highest survival rates from the M1 stage to the PL1 stage was obtained at 35 ppt (24.40±19.51), 30 ppt (23.20±18.14) and 40 ppt, respectively. The survival rates at 25 and 45 ppt salinity levels were found statistically different from those of 30, 35, and 40 ppt (P&amp;lt;0.05). The results of this study show for the first time that the optimum salinity level is the range of 30-40 ppt for larval culture obtained from the North-eastern Mediterranean population of brown shrimp that is the West Atlantic natural origin.

SURVIVAL RATE of TIGER GROUPER LARVA (Epinephelus fucoguttatus) HOUSEHOLD SCALE ON THE NORTH COAST of BALI

Tiger grouper (Epinephelus fuscoguttatus) hatchery at the household scale has contributed to the increase in national grouper seed production. The main problem in tiger grouper cultivation is the availability of superior seeds. Where superior tiger grouper seeds must have fast growth, be resistant to new environments, low FCR, have perfect morphology and be resistant to. Superior seeds of tiger grouper can be seen from the value of Survival Rate (SR), where superior seeds will have a much higher SR when maintained. The purpose of this study was to determine the Survival Rate of tiger grouper hatchery in household-scale hatcheries located on the North Coast of Bali as the main parameter and water quality as a supporting parameter. Methods of data collection is done by using 4 ways: survey, active participation, observation, and interviews. Survival rate data analysis was carried out by performing calculations based on the SR calculation formula and analyzed descriptively. The results of observations of water quality are classified as good for the value of Salinity (33-35 ppt), Temperature (28-29.4 oC), and DO (6-6.5 ppm). While the pH value can be said to be not good for tiger grouper hatchery and rearing with a pH value of (7.3-7.4). The result of the calculation of the Survival Rate is 20% with a total of ± 24,000 seeds. From the percentage of survival rate, it can be said that the survival rate of tiger grouper larvae in this household-scale hatchery is still low. However, it should be noted that a low survival rate in grouper hatcheries does not always affect the value of profits and losses of a grouper hatchery business.