Neil Duncan’s research while affiliated with IRTA Institute of Agrifood Research and Technology and other places

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Publications (92)


Automated Prediction of Spawning Nights Using Machine Learning Analysis of Flatfish Behaviour
  • Preprint

January 2025

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3 Reads

Abdul Qadir

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Neil J. Duncan

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[...]

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Aquaculture of the Sciaenidae Family: Main Species Cultured Worldwide and Emerging Species in Latin America, Offering New Opportunities for Aquaculture Diversification

August 2024

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121 Reads

Sciaenidae is the family of marine fish that has the highest aquaculture growth and production in the world. In this study, the global production, historical characteristics, biological aspects, and aquaculture technologies used for the Sciaenid species with the highest aquaculture production were compiled and analyzed to determine the success factors and bottlenecks that favored these species aquaculture development. This study also presents the state of technological aquaculture development in Sciaenid species in Latin America. The principal Sciaenid aquaculture species are large yellow croaker (Larimichthys crocea), red drum (Sciaenops ocellatus) and meagre (Argyrosomus regius), which together contribute 99.9% of the global aquaculture production of Sciaenid species. The aquaculture success of these three species is attributed to their suitable biology for aquaculture, high consumer demand, good market prices, government support, and prior empirical and/or scientific knowledge with other species that was transferrable to Sciaenidae, however, the aquaculture development of these species has not been free of errors. Principal bottlenecks in development include poorly planned marine spatial planning, the introduction of exotic species, the excessive use of fresh seafood-based feeds (especially in China), and inadequate genetic selection programs. In Latin America, eleven Sciaenidae species with biological attributes similar to the three established aquaculture species are being investigated. The technologies for the totoaba (Totoaba macdonaldi) and the Chilean croaker (Cilus giberti) are the most advanced. The technology developed and the positive and negative experiences of the Sciaenid aquaculture industry identified in this review should be considered to assist government decision-making for research and development of aquaculture in the family Sciaenidae.





Figure 5. Effect of arrGTH treatments on GSI of meagre during sexual differentiation. Data are the mean ± SD. Different letters denote significant differences (P < 0.05) amongst treatment groups.
Figure 8. Frequency or number of fish per treatment group that exhibited isolated sexually differentiated germ cells. Undifferentiated germs cells indicates fish in which no differentiated germ cells were observed; Isolated male germ cells, fish with one or more spermatogonia Stg B or higher; Isolated female germ cells, fish with one or more oocytes; Intersex -isolated female and male germ cells, fish that displayed both one or more spermatogonia Stg B or higher and one or more oocytes in the histological cuts.
Figure 9. Mean plasma 17β-Estradiol levels of meagre during sexual differentiation in arrGTH treatment groups and Control 0 at the start of the experiment (Week 0) and 4 days after the third weeks injection of the treatment (Week 3) of arrGTH or saline. Different letters indicate a significant (p<0.05) difference between week 0 and 3. The n for Control 0 was 16 and ranged from 6-8 for the different treatment groups.
Figure 11. Mean plasma 11 ketotestosterone levels of meagre during sexual differentiation in arrGTH treatment groups and Control 0 at the start of the experiment (Week 0) and 4 days after the third weeks treatment (Week 3) of arrGTH or saline. Different letters indicate a significant (p<0.05) difference between week 0 and 3. The n for Control 0 was 61 and ranged from 6-8 for the different treatment groups.
Treatment group names, number of fish per group (n) and brief description of the groups treatment.
In vivo effect of recombinant FSH and LH administered to meagre ( Argyrosomus regius ) at the initial stages of sex differentiation
  • Preprint
  • File available

December 2023

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301 Reads

Recombinant gonadotropins, follicle stimulating (rFSH) and luteinizing hormone (rLH), offer the potential to induce gametogenesis in prepubertal fish. This study aimed to determine the in vivo effect of Argyrosomus regius rFSH (arrFSH) and Argyrosomus regius rLH (arrLH) administered to prepubertal meagre juveniles at the initial stages of sex differentiation. Meagre single-chain recombinant gonadotropins, arrFSH and arrLH were produced with the CHO expression system by Rara Avis Biotec, S. L. Juvenile meagre, 9-months old with mean weight of 222 ± 36 g (mean ± SD) were randomly distributed into seven experimental groups (n = 8 per group) that were treated weekly for three weeks with an acute injection of 6, 12 or 18 μg kg ⁻¹ of arrFSH (groups, 6-arrFSH, 12-arrFSH and 18-arrFSH) or 6, 12 or 18 μg kg ⁻¹ of arrLH (groups, 6-arrLH, 12-arrLH and 18-arrLH) or saline solution (Control group). Two more groups (n=8) were set up and treated for 6 weeks, with 12 μg kg ⁻¹ of arrFSH or saline Control. The fish were held in a 10 m ³ tank with natural photoperiod (Feb. – March) and temperature 16.1 ± 0.4°C. At the start of the experiment (n = 8) and end of the three week experiment all fish were sacrificed and gonads dissected. Gonads were weighed, fixed in Bouin’s solution and processed for histological analysis. Blood was sampled from all fish at the start and end of the experiment (week 3 and 6) for 17β-estradiol (E2) and 11-ketotestosterone (11-KT) analysis. Juvenile meagre at the start of the experiment were in the initial stages of sexual differentiation, indicated by the presence of the ovarian or testes lumen that was surrounded by undifferentiated embryonic germ stem cells and somatic cells. At the end of the experiment, there was no significant difference in gonadosomatic index (GSI) amongst control (initial and saline treated) and the experimental groups. After three weeks of application of arrFSH, arrLH or saline all fish presented a similar gonadal structure as at the start of the experiment. However, the incidence of isolated developing germ cells (principally spermatogonia, spermatocytes, spermatids, but also perinucleolar stage oocytes) generally increased in arrGTH treated meagre. A mean of 44 % of meagre treated with arrFSH or arrLH presented isolate developing germ cells, mainly male cells. Plasma steroid levels of E2 decreased significantly from the start of the experiments to the end. At the end of the experiment there were no differences in plasma E2 amongst Control fish and rGTH treated fish. Plasma 11-KT showed no change from the start of the experiment to week 3. However, a significant increase was observed in the arrFSH group after six weeks of treatment compared to the start of the experiment and the control group on week 6. The application of arrFSH or arrLH to meagre at the initial stages of sex differentiation did not stimulate steroid production until week six and had a limited, but evident effect on the development of isolated germ cells. The rGTHs, arrFSH or arrLH did not stimulate large developmental changes in undifferentiated gonads. HIGHLIGHTS Exogenous recombinant gonadotropins administered to meagre did not advance sexual differentiation. Exogenous recombinant gonadotropins administered to meagre did not affect plasma estradiol. Exogenous recombinant FSH increased the proportion of meagre with isolated male germ cells. Exogenous recombinant FSH increased plasma 11-ketotestosterone in meagre treated for 6 weeks.

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Reproductive performance and egg and larvae quality from first generation peruvian grunt Anisotremus scapularis (Tschudi, 1846): a comparative analysis with spawns from wild broodstock

December 2023

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83 Reads

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1 Citation

Anisotremus scapularis is a marine fish distributed along the Peruvian coast that is commercially important in local markets. IMARPE started research on this species aimed to condition breeders and control reproduction in captivity and avoid dependence on wild broodstock. Therefore, the present study characterized and compared the reproductive performance, quality of eggs and larvae between a first generation domesticated broodstock (F1B) and a wild broodstock (WB). The F1B and WB broodstocks were conditioned in recirculation systems (RAS) to spawn naturally from August 2021 to August 2022. The following parameters were recorded for each spawn, the total number of eggs, percentages of viable eggs and fertilization, and hatching, and biochemical analyses on each spawn were performed. Progeny from each spawning were assessed for survival activity index (SAI), and at 20 days’ post-hatch (DPH), the temperature tolerance index (TTI) was analyzed. WB had significantly higher (P<0.05) egg production, egg diameter, oil globule diameter, and SAI than those of F1B. However, the percentage of viable eggs and hatching showed significantly higher values (P<0.05) in F1B spawns. A low correlation (r<0.50) was observed between the evaluated reproductive parameters in A. scapularis broodstock; nevertheless, it was significant in some cases. No significant differences were observed in protein, lipid, carbohydrate, or ash content in eggs, but ash content in the 20 DPH larvae differed, with higher values in F1B. A principal component analysis (PCA), indicated a strong relationship between F1B broodstock eggs and fatty acids DHA, 16:0, 18:1n-9, and 18:2n-6; whereas fatty acids 18:0, 20:4n-3, 22:5n-3, and EPA had a high connection with WB eggs. At 20 DPH, F1B larvae had a strong link with 18:1n-9, DHA, and 18:2n-6; while WB larvae were found to have a high association with 16:1n-7, EPA, 22:5n-3, and ARA. Based on these results we concluded that F1B broodstock has better egg quality in terms of egg viability and hatching rate and similarity in most larval quality parameters compared to WB, making the F1 domesticated broodstock (F1B) an alternative to establish a broodstock under captive conditions and thus contributing to the aquaculture development of the species.


Flathead grey mullet (Mugil cephalus) juveniles exhibit consistent proactive and reactive stress coping styles

August 2023

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61 Reads

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3 Citations

Aquaculture

Stress coping styles (SCS) are defined as a coherent set of individual physiological and behavioural differences in stress responses that are consistent across context and over time. Nowadays, an increased attention has been paid to fish welfare in aquaculture production and to consistent behavioural response to stress in captivity, since these aspects present direct implications on fish health, quality and farming productivity. Therefore, the present study aimed to evaluate the differences between proactive and reactive stress coping styles and their consistency over time and across contexts in flathead grey mullet Mugil cephalus juveniles reared in captivity. Fish were submitted to two runs of a set of behavioural tests, with a four-months interval: one group test (risk-taking test) and three individual tests (restraining, predator and confinement tests), followed by the quantification of blood cortisol and glucose concentrations (control and post-stress). Results confirmed the existence of proactive and reactive SCS in mullet juveniles and demostrated that behavioural responses in most of the tests were consistent over time (between runs) and across contexts (among tests). Fish that crossed from the safe to the risky area in the risk- taking test also displayed higher activity and escape attempts and lower basal levels of cortisol and glucose than fish than did not cross. This work reported for the first time the consistency of stress coping styles over time and across contexts in M. cephalus juveniles. Due to the increased interest in understanding adaptive mechanisms underlying consistent individual behaviours in response to stressful situations, are of interest for the aquaculture industry to improve productive performance of this fish species. Further studies are required to investigate how different selective pressures might influence the expression and consistency of SCS over time and across contexts.


Spawning induction for Latin American fishes

June 2023

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268 Reads

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7 Citations

Reviews in Aquaculture

Aquaculture offers solutions to meet the growing global demand for fish, and reports from the UN-FAO indicate that aquaculture production in Latin America (LA) has grown at rates above the world average in recent years. One of the major constraints in the diversification of LA aquaculture is the control of reproduction in several popular native fish species for which difficulties in captive propagation have not yet been sufficiently overcome. This article reviews the use of hormone treatments to promote reproduction in females of these native fish species. LA has played a key role in the history of development of hormone administration, including the first hormonally induced spawning. That contribution is included in a historical overview of the discovery of the major hormones used in fish culture. The review provides a summary of difficulties to propagate females of various native fishes and the effects of administering hormones to enhance reproduction. Induced spawning of certain freshwater species was mainly achieved with pituitary extracts or human chorionic gonadotropin (hCG), although gonadotropin-releasing hormone analogues (GnRHa) treatments are being researched, and successful studies suggest that low doses may be more effective. Research on new and emerging aquaculture species has applied both gonadotropins (Gths) and GnRHa-based treatments, and GnRHa treatments have shown potential for marine species. However, native marine species new to aquaculture have also been conditioned to spawn spontaneously without hormones. Finally, we proposed future lines of research to examine reproductive strategies and GnRHa-based hormone treatments to improve reproductive control for economically important fish species of LA.


Selecting Suitable Behavioural Tests to Identify Proactive and Reactive Stress Coping Styles in Flathead Grey Mullet (Mugil cephalus) Juveniles

June 2023

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61 Reads

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3 Citations

Applied Animal Behaviour Science

Identifying Stress Coping Styles (SCS) in new species of interest for aquaculture has important implications for its future domestication and adaptation to captivity. Individual variability allows to select the potential positive characteristics for fish production. The main aim of this study was to identify phenotypic individual differences and characterize proactive and reactive SCS in flathead grey mullet (Mugil cephalus) juveniles by exposing fish to different stress situations and evaluating their individual and group responses to level behavioural and physiology. Juveniles were subjected to one group test (risk-taking) and five individual tests (predator, first feeding after stress, restraining, new environment and confinement). All assays were repeated twice, with a one-month interval between tests. Blood samples were taken from each individual (before and after stress) to quantify cortisol and glucose plasma concentrations. Flathead grey mullet juveniles exhibited a high inter-individual variability with two extremes of behaviours: proactive and reactive profiles that were characterized by opposed behavioural (activity time and escape attempts) and physiological (levels of cortisol and glucose) responses to stress and were consistent over time and across contexts. The flathead grey mullet juveniles showed differences in their predisposition for risk taking. Likewise, the Principal Component Analysis showed that three individual stress tests (predator, restraining and confinement tests) were reliable to characterize SCS in this fish species. This work reported for the first time the existence of stress coping styles in M. cephalus juveniles and the selection of a set of reliable behavioural tests to identify phenotypic profiles in flathead grey mullet. These results might be of interest for the aquaculture industry to improve fish welfare and health and to adjust management protocols for rearing this fish species in captivity.


Citations (56)


... Cortisol levels in fish exposed to an acute stress were significantly higher than in unstressed (control) fish, in the three matrices evaluated, confirming previous results obtained in plasma for this fish species (Thomas et al. 1980;Linares-Cordova et al. 2024) and validating the reliability of skin mucus and fin matrices to quantify cortisol as a stress biomarker. Likewise, results from other species analysing skin mucus and fin matrices for cortisol quantification after an acute stress were similar to the present study, with significantly higher cortisol levels than in unstressed fish: (i) in European seabass D. labrax, common carp C. carpio and rainbow trout O. mykiss submitted to transport for 1.5 to 3 h in aerated bags (dissolved oxygen > 6 ppm; temperature: 12-14 °C) (Bertotto et al. 2010); ...

Reference:

Quantifying cortisol in mucus and fins as alternative matrices to validate proactive and reactive stress coping styles in flathead grey mullet (Mugil cephalus) juveniles
Flathead grey mullet (Mugil cephalus) juveniles exhibit consistent proactive and reactive stress coping styles
  • Citing Article
  • August 2023

Aquaculture

... Genetic information is essential for aquaculture and fisheries management [17], supporting selective breeding for improved traits, enhanced disease resistance, genetic diversity maintenance, and sustainable practices. Furthermore, it facilitates product traceability, species conservation and adaptation to environmental changes, all vital for responsible and effective management of fish populations and ecosystems. ...

Spawning induction for Latin American fishes

Reviews in Aquaculture

... A wide range of expression systems have been used for rGTH production and the Chinese hamster ovary (CHO) cells have been found to produce rGTH glycosylated proteins with terminal sialic acids that have high biological activity in vivo (Molés et al., 2020). The rGTHs have been successfully used to overcome reproductive dysfunctions in adult cultured fish and rFSH has proved to stimulate spermatogenesis in Senegalese sole (Solea senegalensis) (Chauvigné et al., 2017(Chauvigné et al., , 2018, European eel (Anguilla anguilla) (Peñaranda et al., 2018), flathead grey mullet (Mugil cephalus) (Ramos-Júdez et al., 2021 and meagre (Zupa et al., 2023) and oogenesis in flathead grey mullet (Ramos-Júdez et al., 2021. The entire process of spermatogenesis from spermatogonia through to motile spermatozoids and the entire process of oogenesis from perinuclear oocytes through to viable ovulated ova was induced using a combination of rFSH and rLH administered to adult flathead grey mullet arrested in the early stages of gametogenesis (Ramos-Júdez et al., 2021. ...

Male germ cell proliferation and apoptosis in sexually immature meagre Argyrosomus regius (Asso, 1801) treated with recombinant follicle stimulating hormone

... During the reproductive phase, when eggs are produced, lipids are mobilized from the liver and primarily from the muscle to the gonads. [41] The most commonly analyzed tissues for verifying OCP contamination in fish are typically the muscle, liver, and gills. [4] Few studies evaluate the presence of OCPs in fish roe. ...

Lipid and fatty acid composition of muscle, liver, ovary, and peritoneal fat in wild flathead grey mullet (Mugil cephalus) according to ovarian development
  • Citing Article
  • December 2022

Theriogenology

... In addition, cortisol interacts at many levels with other hormones in a wide variety of cross-target metabolic interactions (Mommsen et al. 1999;Lawrence et al. 2017). Above all, cortisol plasma levels in diurnal vertebrate and particularly in diurnal fishes, as Mugil cephalus, have been demonstrated to vary according to the circadian rhythm, or alternating light/dark phases, being lower during the dark phase when fish are less active, and increasing significantly at the beginning of the light phase, and when fish resume active swimming and feeding behaviour (Brüning et al. 2015;Jiménez-Rivera et al. 2022). ...

Characterization of the different behaviours exhibited by juvenile flathead grey mullet (Mugil cephalus Linnaeus, 1758) under rearing conditions

SPANISH JOURNAL OF AGRICULTURAL RESEARCH

... As part of efforts to better understand processes involved in OFM and ovulation in teleosts, changes in global gene expression as the follicle progresses through OFM and ovulation naturally (e.g., [30,[33][34][35][36]) or in response to in vivo hormone treatments with GTHs (e.g., [37,38]) have been investigated. A large set of differentially expressed genes representing a wide array of functions were identified using RNA-seq to compare transcriptomes of follicles collected after oocyte maturation but before ovulation from wild type and nPR-knockout Zebrafish supporting extensive actions transmitted through the nPR during later stages of OFM [30]. ...

Transcriptome analysis of flathead grey mullet (Mugil cephalus) ovarian development induced by recombinant gonadotropin hormones

... which is parasitized by a nematode. The low infection rate of this parasite in M. cephalus could be influenced by their preference to feed in the mid-water column (Ramos-Júdez and Duncan 2022), where most intermediate hosts cannot be found. ). ...

Feeding habits and the influence of pellet diameter on the feeding responses of the flathead grey mullet (Mugil cephalus) in captivity
  • Citing Article
  • June 2022

Animal Feed Science and Technology

... Therefore, the objective of the present study was to validate cortisol quantification in skin mucus and fins as less severe methods and as reliable as in plasma samples; to measure cortisol concentrations in flathead grey mullet (M. cephalus) juveniles, a cosmopolitan fish species that contributes to food security in some regions of the world as a product from fisheries and aquaculture (Crosetti, 2016;Ramos-Júdez et al. 2022); and to provide physiological evidences supporting behavioural SCS characterization by means of behavioural tests of response to stress. ...

Recombinant Fsh and Lh therapy for spawning induction of previtellogenic and early spermatogenic arrested teleost, the flathead grey mullet (Mugil cephalus)

... Six S. senegalensis breeders, three males and three females, were used for producing three full-sib families using in vitro fertilizations as described for the proof-of-concept experiment by Ramos-Júdez et al. (2021). Briefly, females were selected by maturity status and induced to ovulate with an injection of 5 μg kg −1 of GnRHa (Sigma code L4513, Sigma), whilst no hormones were used on males. ...

Low sperm to egg ratio required for successful in vitro fertilization in a pair-spawning teleost, Senegalese sole ( Solea senegalensis )

... This result matches with the natural feeding habit of the species, which feeds on suspended plant materials and forages the bottom (Cardona, 2016). The same feeding habits were identified in juveniles held in tanks by Jimenez-Rivera et al. (2021), in contrast with Ghion (1986) which identified that although eating in all parts of the tank, the feeding increased when juveniles were fed at the surface. According to the present results, slow-sinking or fast-sinking feeds would meet the preferred feeding habits in the flathead grey mullet. ...

Characterization of the different behaviours exhibited by juvenile grey mullet (Mugil cephalus) under rearing conditions