Time Of Hatching Research Articles

Embryonic thermal manipulation reduces hatch time, increases hatchability, thermotolerance, and liver metabolism in broiler embryos

The broilers' health and growth performance are affected by egg quality, incubation conditions, and posthatch management. Broilers are more susceptible to heat stress because they have poor thermoregulatory capacity. So, it is crucial to develop a strategy to make chicks thermotolerant and cope with heat stress in post-hatch life. This study investigated the effects of embryonic thermal manipulation (TM) on different hatching parameters (hatch time, hatchability, and hatch weight), brain thermotolerance, and liver metabolism. Six hundred fertile Cobb 500 eggs were incubated for 21 d. After candling on embryonic day (ED) 10, 238 eggs were thermally manipulated at 38.5°C with 55% relative humidity (RH) from ED 12 to 18, then transferred to the hatcher (ED 19-21, standard temperature, 37.5°C) and 236 eggs were incubated at a standard temperature (37.5°C) till hatch. The samples were collected from the Control and TM groups on ED 15 and 18 of the embryonic periods. Hatchability was significantly higher (P < 0.05) in the TM group (94.50%) than in the control group (91.0%). Hatch weight did not differ significantly between the TM group (50.54 g) and the Control group (50.39 g). Most importantly, hatch time was significantly lower (P < 0.05) in the TM group than in the Control. In the D15 embryo brain, the mRNA expression of TRPV1,TRPV2, TRPV3, and the epigenetic marker H3K27 were significantly lower (P < 0.05) in the TM group compared to the Control group. However, in the D18 brain, the expression of TRPV1, TRPV2, and CRHR1 was significantly higher (P < 0.05) in the TM group than in the Control group. In the liver, the mRNA expression of SLC6A14 was significantly lower (P < 0.05) in the D15 TM group than in the D15 Control group. Conversely, the DIO3 mRNA expression was significantly higher (P < 0.05) in the D15 TM group than in the D15 Control group. The expression of GPX3, FOXO1, IGF2, and GHR in the liver was significantly higher in the D18 TM group compared to the D18 Control group (P < 0.05). In conclusion, increased expression of the aforementioned markers during the later embryonic period has been linked to reduced hatch time by increasing liver metabolism and thermotolerance capacity in the brain.

Warmer, earlier, faster: Cumulative effects of Gulf of Alaska heatwaves on the early life history of Pacific cod

Warming climates are creating unprecedented environmental conditions, such as more frequent and intense marine heatwaves (MHWs), that directly impact phenology and growth of fish and other marine organisms. Understanding individual phenological and growth responses to temperature is critical to predict species and population responses to climate change; however, doing so requires disentangling the effects of temperature on phenology, size, and growth in wild populations. We quantified the relationships between temperature and hatch timing, size-at-age, and early growth in a population of Pacific cod (Gadus macrocephalus) affected by recent MHWs in the Gulf of Alaska. Pacific cod juveniles were collected near Kodiak Island, Alaska, USA, across 11 years, categorized as before (2007, 2009–2010, 2012–2014), during (2015, 2016, 2019), and between (2017, 2018) multiple recent MHWs. We estimated age and growth with otolith structural analysis. Hatching occurred on average 14 days earlier during MHWs and 26 days earlier between than before MHWs. Approximately 53% and 16% of these respective shifts in timing were attributable directly to warmer temperatures during incubation. Size-at-age was similar across periods at younger ages (90 days), but approximately 7 mm and 11 mm larger than before MHWs at older ages (132 days) during and between MHWs, respectively. These differences in size-at-age were partially related to growth responses that differed among MHW periods. However, observed differences in growth rate could not account for the observed increases in size-at-age. We found that temperature alone could not explain the changes in growth and phenology; thus, factors such as parental effects, epigenetics, and selection likely contributed. Our results indicate that spawn timing, size, and growth relationships based on historical thermal responses should be questioned in population forecasting as the global climate continues to warm.

Influence of Alevinage Time in the Optimization of Tambaqui Biomass Production in Semi-Intensive Fish Farming in the Northern Region of Amazonas

Objective: To evaluate the weight mix for the market obtained with variation in the pre-fixed fingerlings time, for the cultivation of tambaqui (Colossoma macropomum) in a semi-dug tank. Theoretical framework: The parameters evaluated regarding resources are, the tanks, each of which has its own capacity, its own state variable, which includes fish biomass, growth function and mortality rate. And identifying potential alternatives and making better decisions that optimize biomass production are important, but that take into account the reduction of its environmental impact. Method: The model incorporates two types of input variables. The discrete event variable, which comprises the number of fish in each batch, the number of tanks available, the time between the arrival of fingerlings in the system and the frequency of classification by weight for the market. The second refers to the continuous time variable, involving the weight of the fish, dissolved oxygen (DO) available to the fish, and feed consumption. Results and conclusions: The analysis showed that the decision variables are the quantities of fish, with the premise of final weight of 0.5 kg, 1 kg and 2 kg which are related to the hatching time pre-fixed at entry as “30, 40, 50, 60, 70, 80, 90, 100 days” in phase I, results in the optimization of production, target weight for the market as a function of time, in layout scenarios of 5 and 10 tanks, with the premise of harvesting in both, with Mix weight with 0.5kg, 1kg and 0.5kg, 1kg, 2kg to maximize net profit. Considering that the transition between growth phases is a stochastic process, which satisfies the Markov property. It was possible to define the balance between the input and output of the system. Research implications: The study is of great relevance, as it describes a sequential queue through the growth phases in relation to time, capable of determining the optimization of production with weight mix to maximize net profit. Originality/value: The research reveals that it is possible to use queuing theory analyzes in stochastic processes, evaluating the transition between time phases, which satisfies the Markov property.

Comparison of the eggshell mammillary microstructure of Galliformes and Anseriformes

AbstractIn free‐living species, the comparison of eggshell microstructure focus mainly on species representing extremely different reproductive strategies or with phylogenetically divergent taxa. The purpose of this study was to compare the microstructure of the mammillary layer in two bird orders (Galliformes and Anseriformes) representing phylogenetically close precocials, and to relate eggshell microstructure to female body weight and egg characteristics. The results showed significant differences between the studied orders. The mammillary layer in Galliformes had more knobs, and consequently, the percent coverage with them was higher than in Anseriformes. The size of individual knobs did not differ significantly between the orders. The obtained results are consistent with the reports that the ossification at the time of hatching is more advanced in Galliformes, so representatives of this order must resorb more calcium from the eggshell. Egg parameters and female body weight were correlated significantly negatively only with the number of knobs per mm2 for Anseriformes and, to a lesser extent, for Galliformes, but not with the coverage per cent of knobs or the size of individual knobs. Only for the three largest species, which lay proportionally larger eggs than the other species studied, the number of knobs per mm2 was significantly lower, but no difference was found in the per cent coverage of knobs. Our results showed that order was a stronger predictor of microstructure than species. Different ossification patterns of the embryonic skeletal system described in these two orders could be the explanation for the observed differences in eggshell microstructure; however, more research is needed.

Microbiological Control of Incubation

Introduction. The microbiological monitoring occupies a special place in ensuring the epizootic well-being of the poultry farms, allowing predicting the spread of infectious diseases in birds. By studying the microbiological profile during the incubation period and determining the sensitivity of the isolated microorganisms, the “working” antibacterial drug can be selected by the time of chicken hatching. This will enable timely prevention of the infectious diseases. If the research is started with the first biological control (at the 7.5th day of incubation), then in case of high microbial contamination during the incubation process, the additional measures can be taken to prevent the infectious diseases: adjustment of the treatment scheme of the hatching eggs or chickens at the hatching, selection of the drug depending on the results obtained. Therefore, the aim of this study has been to determine the species and quantitative composition of the pathogenic and opportunistic pathogenic microflora during the incubation of the meat crosses chickens’ eggs in the poultry farm settings of the Omsk region.Materials and Methods. The 240 air samples and 40 samples of the upper respiratory tract mucous membrane scrapings of the bred broiler chickens and 60 samples of the dead embryos were examined. The air contamination of the incubation cabinets was established by the sedimentation method on the 7.5th; 11.5th; 18.5th day, and the air in the hatching cabinets on the 21.5th day of incubation.Results. When examining the air samples in the incubation cabinets, the predominance of the staphylococci and enterococci was found, in the hatching cabinets — bacteria of the E. coli group (Esch. coli.) and enterococci. When analysing the upper respiratory tract scrapings of the broiler chickens and the material from the dead embryos, the microorganisms of the Enterococcaceae and Staphylococcaceae families turned out to be the dominant species, to a lesser extent Enterobacteriaceae. A large number of the following microorganisms were detected in the scrapings: E. faecalis (38.5%), S. aureus (31.6%), E. agglomerans (11.4%), E. coli (8.8%), C. freundii (7%), P. aeruginosa (0,9%), E. faecium (0,9%). When examining the dead embryos, E. faecalis (44.7%), S. aureus (25.5%), and E. coli (12.8%) were isolated most often. Among the associations, S. aureus / E. Faecalis and S. aureus / E. faecalis / E. coli occupied a leading place both in the study of scrapings and in the study of dead embryos.Discussion and Conclusion. The conducted research, which enabled determining the species and quantitative composition of the pathogenic and opportunistic pathogenic microflora during the incubation of the meat crosses chickens’ eggs, has revealed that the microbiocenosis of the upper respiratory tract is directly related to the air microflora. By regular monitoring the air environment in the incubator, it is possible to control the recontamination of chickens at the hatching by examining just the air samples. This is a more affordable, less costly and traumatic for the bird method. Understanding the real epizootic situation allows determining the most efficient measures to reduce the microbial contamination during the incubation period, as well as select the optimal antibacterial drug, in case of finding the bacterial infection in the poultry stock.

Effects of pre-heating of broiler breeder's eggs on hatchability, chick quality, overall performance, and welfare traits in broilers.

This study aimed to investigate the effects of varying pre-heating practices (12-h: PH12; 8-h: PH8; 4-h: PH4 and 0-h or no pre-heating: PH0) of broiler breeder's eggs prior to incubation on hatching, chick quality, overall performance, and welfare traits in broilers. A total of 960 eggs obtained from Ross 308 breeders at 45 weeks were used for pre-heating manipulations and 480 chicks for broiler experiment. Apparent fertility was higher in PH0 (94.6%) and PH4 (94.5%) treatments than in PH8 (91.6%) and PH12 (90.6%); hatchability of fertile and set eggs was higher in PH4 and PH12. PH4, PH8, and PH12 treatments significantly accelerated the average hatching time compared to PH0. General chick quality was not affected by pre-heating treatments. However, chick length was significantly lower in PH0 chicks than PH12. Pre-heating manipulations did not change the overall broiler performance. Welfare characteristics were similar among treatments, while only hock burn was better in PH8 broilers. In conclusion, pre-heating of broiler breeder eggs for 4 to 12 h improved hatching success by lowering embryonic mortality and shortened the average hatching time compared to no pre-heating, and did not cause any significant alteration in chick quality, overall performance, and welfare characteristics.

Effect of Entomopathogenic Fungi to Eggs and Nymphs Survival of Halyomorpha halys (Hemiptera: Pentatomidae) Under Laboratory Conditions.

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is becoming a major pest of Greece's agricultural production, including tree fruit. Until now, the control of this pest has been based on conventional methods, with the application of chemical insecticides being the primary option. However, the wide distribution of H. halys, in combination with the large area of tree fruit production in Greece, raise the need for alternative control methods. In this study, we investigated the possibility of implementing microbial control agents for managing H. halys. Eggs and nymphs of H. halys were treated with 15 native entomopathogenic fungal isolates and their virulence was evaluated in the laboratory. After treatment, egg hatching time was recorded for 7days and ranged from 4.5 to 7.0days. Nymphal survival was recorded daily for 7days following application and ranged from 2.1 to 6.6days for second instar nymphs and 3.7 to 6.8days for fourth instar ones. Beauveria varroae isolate displayed the highest toxicity to all H. halys stages that were tested and could be considered a promising biocontrol agent of this insect. Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.οκ.

Yumurta Kabuğu Kalınlığı, Yumurta Ağırlığı ve Şekil İndeksinin Çıkış Penceresi ve Hindi Civcivlerinin Cinsiyeti Üzerine Etkileri

The effects of eggshell thickness (EST), shape index (SI) and egg weight (EW) on the hatch window (HW), hatching time (HT), gender of hatched turkey poults hatched were investigated. Total of 150 commercial Hybrid Converter breed turkey hatching eggs obtained from a turkey meat producing integration were used. The effects of these parameters on HW and HT and gender were analyzed via ANOVA-GLM. The hatching window was 656th – 688th hours, and the procedure concluded during the 688th hour of incubation. The incubation was divided into three partitions as early (656 – 667h), midterm (668 – 676h) and late hatches (677 – 688h), with the final 32 hours of incubation divided into 7 partitions (7P) from 1 to 7 as (656 – 664h, 665 – 668h, 669 – 672h, 673 – 676h, 677 – 680h, 681 – 684h and 685 – 688h). A significant relation between EST and gender was found as eggs with thicker EST female chicks hatched more than males (p˂0.05). There was no correlation between gender and EW and SI (p˃0.05). Meanwhile, the number of hatches for 7P, EST, EW and SI were not found to affect the hatch window of turkey eggs (p˃0.05).

Lethal and Sublethal Effects of Cyromazine on the Biology of Musca domestica Based on the Age-Stage, Two-Sex Life Table Theory.

Cyromazine is a triazine insect growth regulator insecticide that is recommended for control of Musca domestica worldwide. Cyromazine is highly effective in causing mortality of M. domestica; however, some aspects of its lethal and sublethal effects on the biology of M. domestica are still unknown. The present study explored lethal and sublethal effects on several biological traits and population parameters of M. domestica. Concentration-response bioassays of cyromazine against third-instar larvae of M. domestica exhibited sublethal and lethal effects from concentrations of 0.03 (LC10), 0.06 (LC25), and 0.14 (LC50) μg/g of a larval medium. Exposure of M. domestica larvae to these concentrations resulted in reduced fecundity, survival, longevity and oviposition period, and delayed development of immature stages (i.e., egg hatch time and larval and pupal durations) in the upcoming generation of M. domestica. The values of population parameters such as intrinsic rate of increase, finite rate of increase, net reproductive rate, age-specific survival rate and fecundity, and age-stage life expectancy and reproductive value, analyzed using the age-stage and two-sex life table theory, were significantly reduced in a concentration-dependent manner in comparison with the control group. In conclusion, the study highlights the significant effects of cyromazine on the biology of M. domestica that could help suppress its population in cases of severe infestations.

Effects of parental exposure to amitriptyline on the survival, development, behavior, and gene expression in zebrafish offspring

In mammals, parental exposure to amitriptyline (AMI) has been proven to contribute to congenital disabilities in their offspring. However, no studies have paid attention to the adverse effects of parental exposure to amitriptyline on fish offspring. In this study, we exposed adult zebrafish (F0) to AMI (0.8 μg/L) for 21 days. Subsequently, these zebrafish (F0) were allowed to mate, and their offspring (F1) were collected to culture in clean water for 5 days. The mortality rate, average hatching time, and heart rate at 48 h post-fertilization (hpf) of F1 were investigated. Our results showed that parental exposure to AMI induced tachycardia and increased mortality in F1 zebrafish. Under a light/dark transition test, F1 larvae born from AMI-exposed parents exhibited lower locomotor activity in the dark period and decreased thigmotaxis in the light period. The transcriptome analysis showed that parental AMI exposure dysregulated some key pathways in their offspring. Through the prediction of key driver analysis, six differentially expressed genes (DEGs) were revealed as key driver genes involved in protein processing in endoplasmic reticulum (hspa5, hsp70.1, hsp90a), ribosome (rps27a) and PPAR signaling pathway (pparab and fabp2). Considering that the concentration of AMI residual components in natural water bodies may be over our test concentration (0.8 μg/L), our findings suggested that toxicity of parental exposure to the offspring of fish should receive greater attention.

Pre-fertilization gamete thermal environment influences reproductive success, unmasking opposing sex-specific responses in Atlantic salmon (Salmo salar).

The environment gametes perform in just before fertilization is increasingly recognized to affect offspring fitness, yet the contributions of male and female gametes and their adaptive significance remain largely unexplored. Here, we investigated gametic thermal plasticity and its effects on hatching success and embryo performance in Atlantic salmon (Salmo salar). Eggs and sperm were incubated overnight at 2°C or 8°C, temperatures within the optimal thermal range of this species. Crosses between warm- and cold-incubated gametes were compared using a full-factorial design, with half of each clutch reared in cold temperatures and the other in warm temperatures. This allowed disentangling single-sex interaction effects when pre-fertilization temperature of gametes mismatched embryonic conditions. Pre-fertilization temperature influenced hatch timing and synchrony, and matching sperm and embryo temperatures resulted in earlier hatching. Warm incubation benefited eggs but harmed sperm, reducing the hatching success and, overall, gametic thermal plasticity did not enhance offspring fitness, indicating vulnerability to thermal changes. We highlight the sensitivity of male gametes to higher temperatures, and that gamete acclimation may not effectively buffer against deleterious effects of thermal fluctuations. From an applied angle, we propose the differential storage of male and female gametes as a tool to enhance sustainability within the hatcheries.

The Use of a Vision System for Monitoring Chick Embryos in Incubator

Background: Determine the quality of hatching eggs and control the process of their embryonic development, it is necessary to perform candling of eggs, which makes it possible to identify and eliminate the causes of low hatching of chicks. Contribution: The proposed vision system for processing images of chicken eggs makes it possible to distinguish fertilized eggs from unfertilized ones, which makes it possible to change the parameters of the incubator in the event of a large number of dead embryos. Method: With the help of the National Instruments Vision Assistant module, which simplifies the collection, reproduction and storage of images recorded using a video camera connected via a FireWire interface, an incubator vision system has been developed. Results: The yield of healthy chicks is increased due to the periodic automatic candling of eggs and the timely regulation of parameters during the incubation process. Conclusion: Being able to monitor embryo development more closely allows you to determine the optimal time to change incubation parameters, such as humidity, to create the best conditions for egg hatching, leading to more efficient chick production. Similarly, the ability to use different light and temperature conditions to influence chick hatch time can allow for a faster incubation process and hatch healthy chicks in a shorter period of time.

From Field Data to Practical Knowledge: Investigating the Bioecology of the Oak Lace Bug-An Invasive Insect Species in Europe.

Corythucha arcuata, commonly known as the oak lace bug (OLB), is an insect species originally native to North America that has become an invasive species of significant concern in Europe. This invasive pest has been observed in various European countries, raising concerns about its impact on forest ecosystems. In 2015, it was first documented in Romania, further highlighting the need for research on its bioecology and life cycle. This study investigated the bioecology of the OLB in the southern region of Romania, focusing on its life cycle, development, and population dynamics. The results indicated that the OLB has three generations per year and overwinters in the adult stage in sheltered locations. Temperature significantly influenced the timing of egg hatching, nymph appearance, and adult development, with variation observed between generations. Additionally, a life table analysis provided insights into the population dynamics of the OLB in its natural environment, revealing variation in egg laying trends across generations. This research contributes to a better understanding of the OLB's bioecology and provides essential data for forest managers developing science-based management strategies to mitigate its impact. By elucidating the life cycle and development patterns of the OLB in southern Romania, this study aids in the development of predictive models and life tables tailored to the region. These findings empower forest managers with the knowledge needed to make informed decisions for effective OLB management, ultimately preserving the health of forest ecosystems.

Novel hatching cue in the neotropical damselfly Megaloprepus caerulatus: larval adaptation and maternal constraint

The evolution of sibling cannibalism as a maternal strategy is particularly challenging to explain when nurseries are shared among multiple females. Such is the case for the damselfly, Megaloprepus caerulatus, whose females lay eggs in bark above the water line in large, water-filled tree holes. Asynchronous egg hatching appears to be a maternal bet-hedging strategy to increase the chances that cannibalistic offspring hatch during windows of opportunity, which occur after the remaining large larvae emerge, having eaten all others. We investigated the proximate causes of asynchronous hatching. By monitoring the pattern of egg hatching under ambient temperature in an insectary, we found that egg hatching co-occurred with lower ambient temperatures, which decreased with increasing rainfall. Treating fully developed eggs to a lower temperature for two hours triggered increased hatching relative to controls at ambient temperature. Dissection of control clutches indicated that embryonic development of siblings was asynchronous. Results suggested that the hatching trigger is adaptive. Rainfall assures a recharge of the larval habitat with water and provides wet conditions essential for neonate mobility on bark. Only 40% of neonates in a 4-day drying treatment survived; none survived the 8- and 14-day treatments. This novel hatching trigger should increase the number of neonates entering the nursery after rains, constraining a mother’s control over the timing of egg hatch, while increasing the competition among related and unrelated offspring for limited windows of opportunity in the shared nursery.

Lethal and sublethal effects of carlina oxide on Tetranychus urticae (Acari: Tetranychidae) and Neoseiulus californicus (Acari: Phytoseiidae).

Tetranychus urticae Koch, is a polyphagous and damaging pest, presenting several resistant populations worldwide. Among new and more environmentally friendly control tools, botanical pesticides represent a valuable alternative to synthetic ones within integrated pest management strategies. Accordingly, we investigated the lethal and sublethal effects of carlina oxide isolated from Carlina acaulis (Asteraceae) roots on T. urticae and its natural enemy, the predatory mite, Neoseiulus californicus (McGregor). Carlina oxide (98.7% pure compound) was used for acaricidal tests on eggs, nymphs, and adult females of T. urticae (concentrations of 312.5, 625, 1250, 2500 and 5000 μL L-1 ), and eggs and females of N. californicus (1250 and 5000 μL L-1 on eggs and females, respectively). Behavioral two-choice tests were also conducted on phytoseiid females. Carlina oxide toxicity was higher on T. urticae females than nymphs (median lethal dose 1145 and 1825 μL L-1 , respectively), whereas egg mortality and mean hatching time were significantly affected by all tested concentrations. A decreasing daily oviposition rate for T. urticae was recorded with concentrations ranging from 625 to 5000 μL L-1 , whereas negative effects on the population growth rate were recorded only with the three higher concentrations (1250, 2500 and 5000 μL L-1 ). No toxic effect on N. californicus females was found, but a strong repellent activity lasting for 48 h from application was recorded. Carlina oxide reduced longevity and fecundity of T. urticae adults, but not of N. californicus. This selective property allows us to propose it as a novel active ingredient of ecofriendly acaricides for T. urticae management. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Comparison of Diploid and Triploid Atlantic Salmon (Salmo salar) Physiological Embryonic Development

Diploid and triploid Atlantic salmon show distinct physiological differences including heart, brain, and digestive system morphology, propensity for certain deformities, temperature tolerance as eggs and once hatched, and different nutritional requirements. Whilst several studies have looked in detail at the rate of embryogenesis in diploid salmon, no study has compared the rate of embryogenesis between ploidies from fertilisation to hatch. This study based its assessment on a seminal paper by Gorodilov (1996) and used the same techniques to compare the rate at which triploid and diploid embryos developed morphological characteristics. Whilst no significant difference was found, this study provides well-needed justification for the assumption that both ploidies develop at the same rate and gives scientific weight to studies which involve manipulation at these stages of development. Two factors that did differ, however, were the timing of hatch, and mortality. Triploids hatched more quickly than diploids and reached 50% hatch at a significantly earlier point. Triploids also suffered from a significantly higher rate of mortality.

Vertical Patterns in Lake Sturgeon (Acipenser fulvescens) Larval Drift within Two Rivers Directly Connected to Green Bay, Lake Michigan

Fish larvae in riverine environments often disperse (e.g., drift) from areas of egg deposition at the time of hatch. Several components of drift can be important in terms of survival including timing, distribution in the water column, and body size. The longitudinal and cross-sectional aspects of larval lake sturgeon (Acipenser fulvescens) drift from upstream spawning sites have received considerable study. However, the vertical distribution of larval lake sturgeon in the water column has not been comprehensively evaluated with respect to river size, water depth, the size of larvae in drift over the entire drift period, and the effectiveness of traditional sampling gear (D-frame nets) designed to collect larvae along the river bottom. In 2013, we sampled larval lake sturgeon drifting from upstream spawning sites in the Menominee and Oconto Rivers (Wisconsin, USA) using traditional D-frame nets and custom fabricated sampling nets that vertically partitioned the water column. Drifting larval lake sturgeon were observed from the river bottom to the top of the water column in both systems. Vertical net section was a significant predictor of total larval catch with the highest catch occurring in nets towards the center of the water column but was dependent on net location within the rivers’ cross section and downstream distance from spawning locations. 42% of larvae captured across both rivers were outside of the sampling capability of the traditional D-frame nets (i.e., fish would have drifted over the top). Studies seeking to describe larval production for lake sturgeon, as well as other fish species that exhibit drift in larval dispersal, need to consider a balance between net design and sampling the vertical/cross sectional profiles of rivers. Size-based vertical drift may also have consequences for studies seeking to estimate genetic parameters (e.g., diversity and parentage).

A new way to understand migration routes of oceanic squid (Ommastrephidae) from satellite data

AbstractVisible Infrared Imaging Radiometer Suite (VIIRS) Boat Detection (VBD) data have been widely used to study the patterns of fishing grounds and their linking to fishery targets, particularly species mainly caught by jiggers. In line with most species in the Ommastrephidae family, the population of Todarodes pacificus is made up of various splinter cohorts concerning the timing and location of hatching. Therefore, the satellite‐recorded fishing grounds consist of groups with complex age structures and different migration directions within cohorts. This study examined the age composition of harvestable stocks (age spectrum) of T. pacificus in the Japan Sea based on an early life history individual‐based model of T. pacificus and VBD data. Using the age spectrum, we analysed the relationship between fishery effort and the age of the target group. It was found that jiggers most prefer individuals around 310 ± 20 days. Furthermore, the correlation between ambient water temperature and fishing effort revealed that T. pacificus migrated to colder waters, reaching the coldest waters at 250 ± 7.5 days before moving back towards warmer waters. We discussed a possible way to use the age‐temperature relationship to analyse the flow of VBD distributions to record the movements related to the migration of the fishing target. The results show migration‐like trajectories, which are initially parallel to the isotherm, gradually deflect towards lower temperature sides over several months, sharply turn for about a month and then move back with a slight angle to the isotherms. The method provides a potential framework to improve our understanding of the active migration of oceanic squid.

Effect of microfibers induced toxicity in marine sedentary polychaete Hydroides elegans: Insight from embryogenesis axis

Presence of surgical face masks in the environment are more than ever before after the COVID-19 pandemic, and it poses a newer threat to aquatic habitats around the world due to microfibers (MFs) and other contaminants that get discharged when these masks deteriorate. The mechanism behind the developmental toxicity of MFs, especially released from surgical masks, on the early life stages of aquatic organisms are not well understood. Toxicity test were developed to examine the effects of MFs released from surgical facemask upon deterioration using the early gametes and early life stages of marine sedentary polychaete Hydroides elegans. For MFs release, cut pieces of face masks were allowed to degrade in seawater for different time points (1 day, 30 days and 120 days) after which the fibers were obtained for further toxicity studies. The gametes of H. elegans were exposed to the MFs (length < 20 μm) separately for 20 min at a concentration of 50 MFs/ml before fertilization. In addition, we also analyzed the experimental samples for heavy metals and organic substances released from face masks. Our findings demonstrated that gametes exposed to MFs affected the percentage of successful development, considerably slowed down the mitotic cell division and significantly postponed the time of larval hatching and also produced an adverse effect during embryogenesis. When the sperm were exposed fertilization rate was decreased drastically, whereas when the eggs were exposed to MFs fertilization was not inhibited but a delay in early embryonic development observed. In addition the release of heavy metals and other volatile organics from the degrading face masks could also contribute to overall toxicity of these materials in environment. Our study thus shows that inappropriately discarded face masks and MFs and other pollutants released from such face masks could pose long-term hazard to coastal ecosystems.

The proportion of the egg berried female crabs and the hatching time based on differences in the eggs colour of the blue swimming crab in the crab box apartment

Fishermen in Pagagan Village who get the egg-berried female (EBF) of blue swimming crabs can store them in the Crab Box Apartment that has been provided on the coast so that the crabs incubate their eggs. The placement of EBF crabs in the crab box apartment showed fishermen actively participating in sustainable crab management. The EBF crabs are quite varied, especially in egg colour (yellow, orange, brown, and grey). This study used descriptive analysis to identify the EBF crab’s hatching time based on the egg colour that is incubated in the crab apartment. The result showed that the EBF crabs with yellow eggs have an average hatching time of more than 7 days. The orange eggs are, on average 5 days, the brown eggs are about 3 days, and the grey eggs are only 1 day. These hatching time records can also improve the implementation of the crab box apartment, which is a way to minimize the presence of EBF crabs in the supply chain and increase compliance, which leads to sustainability.