Search Results (22)

This study presents, for the first time, the occurrence and community structure of wild fish inside marine aquaculture cages of gilthead seabream (Sparus aurata), European sea bass (Dicentrarchus labrax), greater amberjack (Seriola dumerili), meagre (Argyrosomus regius), and common dentex (Dentex dentex). Coexistence of farmed and wild fish was observed only in cages of gilthead seabream and European sea bass, with wild fish constituting 0.08% of the total sampled fish biomass. Twelve wild fish species from five families were recorded: Carangidae, Clupeidae, Mugilidae, Moronidae, and Sparidae. Bogue (Boops boops) and jack mackerel (Trachurus sp.) were the most abundant. Multivariate analysis indicated that location significantly influenced the wild fish community composition, while reared species and farming duration, along with their interaction, had no significant effect. Descriptive comparisons suggested potential differences in biometric traits of bogue and jack mackerel between reared species and farming duration. The findings highlight the need for further research on wild fish in cages to better understand the potential health and biosecurity risks they may pose. Full article

Estuaries are vital coastal ecosystems that support fish during key life stages such as spawning, feeding, and early development. This study investigates ichthyoplankton composition and abundance in the Sanquianga Tapaje estuarine system, located in the southern Eastern Tropical Pacific (ETP) of Colombia. Zooplankton samples were collected using bongo nets at 11 stations across four river mouths (Tapaje, Amárales, Sanquianga, and Guascama), alongside measurements of oceanographic parameters at 1 and 10 m depths. A total of 357 fish larvae were identified, representing 23 species and 11 families, with Engraulidae, Gobiidae, and Carangidae dominating the assemblage. Water column conditions reflected typical tropical estuarine dynamics, influenced by tidal action and freshwater input. Spearman’s rank correlation revealed strong positive associations between larval abundance and surface salinity (r_s = 0.81, p = 0.003), as well as dissolved oxygen saturation and concentration (r_s > 0.68, p < 0.021). Diversity indices (Shannon, Pielou, Whittaker) indicated high species turnover in transitional zones, and larval hotspots were associated with outer estuarine zones. Salinity and dissolved oxygen emerged as key drivers of ichthyoplankton distribution. These findings underscore the ecological complexity and nursery function of tropical estuaries, offering baseline data to inform biodiversity conservation, ecosystem monitoring, and adaptive management in Colombia’s Pacific region and across the ETP. Full article

Madagascar harbors a rich marine biodiversity, yet detailed knowledge of its fish species remains limited. Of the 1689 species listed in 2018, only 22% had accessible cytochrome oxidase I (COI) sequences in public databases. In response to growing pressure on fishery resources, this study aims to strengthen biodiversity monitoring tools. Its objectives were to enrich the COI database for Malagasy marine fishes, create the first 12S reference library, and evaluate the taxonomic resolution of different 12S metabarcodes for eDNA analysis, namely MiFish, Teleo1, AcMDB, Ac12S, and 12SF1/R1. An integrated approach combining morphological, molecular, and phylogenetic analyses was applied for specimen identification of fish captured using various types of fishing gear in Toliara and Ranobe Bays from 2018 to 2023. The Malagasy COI database now includes 2146 sequences grouped into 502 Barcode Index Numbers (BINs) from 82 families, with 14 BINs newly added to BOLD (The Barcode of Life Data Systems), and 133 cryptic species. The 12S library comprises 524 sequences representing 446 species from 78 families. Together, the genetic datasets cover 514 species from 84 families, with the most diverse being Labridae, Apogonidae, Gobiidae, Pomacentridae, and Carangidae. However, the two markers show variable taxonomic resolution: 67 species belonging to 35 families were represented solely in the COI dataset, while 10 species from nine families were identified exclusively in the 12S dataset. For 319 species with complete 12S gene sequences associated with COI BINs (Barcode Index Numbers), 12S primer sets were used to evaluate the taxonomic resolution of five 12S metabarcodes. The MiFish marker proved to be the most effective, with an optimal similarity threshold of 98.5%. This study represents a major step forward in documenting and monitoring Madagascar’s marine biodiversity and provides a valuable genetic reference for future environmental DNA (eDNA) applications. Full article

This study offers an in-depth analysis of the mitochondrial genome of Selene dorsalis (Gill 1863), a species native to the Eastern Atlantic Ocean. The circular mitochondrial DNA molecule measures 16,541 base pairs and comprises 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA genes, and a control region (CR). The nucleotide composition exhibits a notable adenine-thymine (AT) bias, accounting for 53.13%, which aligns with other species in the Carangidae family. Most PCGs initiate with the ATG codon, with the exception of Cytochrome C oxidase subunit I, which starts with GTG. Analysis of relative synonymous codon usage reveals that leucine and serine are the most prevalent amino acids in the mitochondrial genome of S. dorsalis and its congeners (S. vomer and S. setapinnis). All tRNAs display the typical cloverleaf structure, though tRNA Serine (S1) lacks a dihydrouracil arm. Pairwise comparisons of synonymous and nonsynonymous substitutions for all PCGs yielded values below ‘1’, indicating strong purifying selection. The CR spans 847 bp, representing 5.12% of the mitochondrial genome, and is characterized by high AT content (62.81%). It is situated between tRNA-Pro (TGG) and tRNA-Phe (GAA). The CR contains conserved sequence blocks, with CSB-1 being the longest at 22 bp and CSB-D the shortest at 18 bp. Phylogenetic analysis, using Bayesian and Maximum-likelihood trees constructed from concatenated PCGs across 72 species, successfully differentiates S. dorsalis from other carangids. This study also explores how ocean currents and gyres might influence lineage diversification and parapatric speciation of Selene species between the Atlantic and Pacific Oceans. These results highlight the importance of the mitochondrial genome in elucidating the structural organization and evolutionary dynamics of S. dorsalis and its relatives within marine ecosystems. Full article

Coastal environments, such as bays, are essential to the development of fishery resources due to their economic and ecological importance. This paper presents an updated checklist of coastal marine fishes as part of a long-term monitoring program in Aratu Bay (2014–2024), Bahia state, eastern Brazil. A total of 109 species belonging to 58 families and 24 orders were cataloged. Five endemic species and ten species listed as at risk according to the IUCN criteria (from Vulnerable onwards) were identified. The Carangidae was the most representative family in terms of species number, followed by Gobiidae and Sciaenidae. The ichthyofauna was dominated by mobile invertebrate feeders and macrocarnivores. Two non-native species were observed in the region: the Muzzled blenny, Omobranchus sewalli and the mud sleeper Butis koilomatodon. Aratu Bay supports a diverse ichthyofauna with diverse trophic guilds and habitats, rendering it an important area for the feeding and development of economically valuable species, including those facing threats. Full article

To meet the requirements of amphibious exploration, ocean exploration, and military reconnaissance tasks, a pneumatic amphibious soft bionic robot was developed by taking advantage of the structural characteristics, motion forms, and propulsion mechanisms of the sea lion fore-flippers, inchworms, Carangidae tails, and dolphin tails. Using silicone rubber as the main material of the robot, combined with the driving mechanism of the pneumatic soft bionic actuator, and based on the theory of mechanism design, a systematic structural design of the pneumatic amphibious soft bionic robot was carried out from the aspects of flippers, tail, head–neck, and trunk. Then, a numerical simulation algorithm was used to analyze the main executing mechanisms and their coordinated motion performance of the soft bionic robot and to verify the rationality and feasibility of the robot structure design and motion forms. With the use of rapid prototyping technology to complete the construction of the robot prototype body, based on the motion amplitude, frequency, and phase of the bionic prototype, the main execution mechanisms of the robot were controlled through a pneumatic system to carry out experimental testing. The results show that the performance of the robot is consistent with the original design and numerical simulation predictions, and it can achieve certain maneuverability, flexibility, and environmental adaptability. The significance of this work is the development of a pneumatic soft bionic robot suitable for amphibious environments, which provides a new idea for the bionic design and application of pneumatic soft robots. Full article

The distribution of fish eggs and larvae (ichthyoplankton) reflects spawning and nursery areas as well as dispersal routes. This study’s goal is to demonstrate how the identification of ichthyoplankton species and stages and their spatial distribution among natural reefs (NRs) and artificial reefs (ARs) may serve as decision-making tools in conservation and fishery management. Natural reefs exhibited an eight-times higher abundance of eggs, as well as the highest abundance of larvae in the yolk-sac and preflexion phases. In contrast, ARs had the highest abundance of larvae in the flexion and postflexion phases. Natural reefs may serve as breeding grounds for Scaridae, Labridae, and Mugilidae; whereas, ARs may serve as breeding sites for Lutjanidae, Synodontidae, Carangidae, Fistularidae, and Haemulidae. Our study revealed differences between ARs and NRs, which demonstrate the potential of artificial reefs to expand the supply and settlement options of reef fishes and consequently can lead to increased fish production with potential benefits to adjacent fishing areas through connectivity. Thus, ARs as no-take sites can be effective tools for both fishery management and biodiversity conservation. The findings highlight the potential use of ichthyoplankton tools and the importance of considering both types of reefs in marine conservation and management efforts. Full article

This study provides the first socio-ecological overview of the Seriola dumerili fishery occurring in the Balearic Islands. This pelagic top-predator is among the five most valued fish resources of the Balearic community. Despite its ecological importance and potential vulnerability to aggregation fishing, few studies address the ecology of this large Carangidae species. Shining a light on its ecology is vital to ensure adequate species conservation and the sustainable and effective management of the fishery. Historical catches from 1950–1999, alongside detailed landing data for the last 21 years, were analysed to identify potential patterns in ecological and socio-economic factors. Significant inter-annual variability among the years was found in historical catches of greater amberjack, while catches and mean prices of the different size categories revealed significant results between seasons and months, respectively. Additionally, the purse seine fleet accounted for the highest percentage of S. dumerili catches. CPUE did not appear to change greatly between months and years after the annual 8-month fishing ban imposed in 2011 and therefore a re-evaluation of the closure was intended. Overall, this study suggests seasonality influences the S. dumerili fishery in the Balearic Islands, within which ecological influences show a higher regulating power than socio-economic factors. Full article

Estimating genetic diversity and population structure with polymorphic markers might provide information for the better management of fish that have economic importance. We used the Chilean jack mackerel, Trachurus murphyi, a pelagic species distributed in the south Pacific Ocean, to test the population genetic structure across its distribution. A total of 522 samples were collected from 11 locations in 2008, to be analyzed using six loci microsatellites. We conducted traditional genetic analyses to describe the genetic diversity of T. murphyi and whether it shows spatial genetic structure. The results showed a high genetic diversity across locations (Ho = 0.551 to 0.980; He = 0.676 to 0.959). Estimates for the population structure showed a low and non-significant pairwise F_ST in all comparisons. We supported the non-genetic differentiation previously reported with the used microsatellite panel. Further comparative temporal studies should be conducted to identify the stability of this pattern. Overall, this study reinforces the hypothesis that, in the Pacific Ocean, Chilean jack mackerel correspond to a large single population. Full article

Otoliths are paired calcified structures in the inner ear of teleosts that function in hearing and balance. In this study, the use of otolith morphometrics and shape analysis were explored to delineate the redfin species under the genus Decapterus from the Sulu Sea, Philippines, namely, Decapterus kurroides, D. smithvanizi, and D. tabl. Results showed that the mean otolith shapes are unique within species (p < 0.001). The otolith size-related (OW—otolith weight, OL—otolith length, OH—otolith height, OA—otolith area, and OP—otolith perimeter) and shape-related (RE—rectangularity, SQ—squareness, EL—ellipticity, RO—roundness, AR—aspect ratio, FF—form factor, CO—compactness, and CI—circularity) morphometric indices also showed significant variations (p < 0.001) among the three species. Distinct regions differentiating D. kurroides from the other two species were seen along the dorsal margin of the otoliths, which was supported by its significantly higher values for OH (size-related index) and RO (shape-related index). In addition, the morphometric indices showed significant variations (p < 0.001), except for RE. Furthermore, it was revealed that the size-related indices were able to separate D. kurroides from the other two species, which turned out to be indifferent. The results provided relevant data on the use of otoliths as an additional confirmatory tool in species delineation of the identified redfin species, and, therefore, offer opportunities of applying the same method in delineation and, eventually, identification of species from other genera, especially those that closely resemble each other. Full article

A recent study was performed to assess the morphometric variation of otoliths of the Decapterus kurroides collected in the northern Sulu and southern Sibuyan seas in delineating fish stocks. Seven of the otolith morphometric descriptors (otolith length, OL; otolith height, OH; otolith weight OW; otolith area, OA; otolith perimeter, OP; ellipticity, EL; and aspect ratio, AR) demonstrated a significant positive correlation with fish length and six (rectangularity, RE; squareness, SQ; roundness, RO; circularity, CI; compactness, CO; and form factor, FF) demonstrated a significant negative correlation. In terms of intraspecific comparisons, almost all the otolith morphometric descriptors were significantly different between the two sites (except RE and OH). Further, principal component (PC) analysis showed that direct otolith morphometric descriptors such as OL, OH, OW, OA, and OP explained 61.71% of the differences (PC1). In contrast, derived otolith descriptors such as EL, AR, and CO explained 22.00% of the variations (PC2) for a total of 83.71% explained variations with the eight otolith morphometric descriptors. Statistics reveal that D. kurroides from the Sibuyan Sea have significantly larger, heavier, and more elliptical otoliths than those from the Sulu Sea. Results suggested that the D. kurroides from Sulu and Sibuyan seas are two different phenotypic stocks. Further studies such as otolith microchemistry, genetics, other life history-based studies, and present exploitation levels should be carried out to supplement the results of this study to fully establish the D. kurroides stock structures within Philippine waters. Full article

Brazil is a tropical country with remarkably diverse marine habitats that harbour a rich diversity of fish. Only a small portion of this fish diversity has been investigated for parasites, and thus the diversity of their trematode parasites remains unexplored. Moreover, only 5 out of 184 known digenean trematode species of marine fish in Brazil have been genetically characterised. The Hemiuridae Looss, 1899 is the second most speciose trematode family in marine fishes from Brazil but, in many ways, it remains a neglected group. Forty-three trematode specimens from nine fish species were collected from the coastal zone off Rio de Janeiro, Brazil. Trematodes were found in the stomach of 14 specimens of 9 fish species belonging to 8 families (Carangidae, Clupeidae, Haemulidae, Muraenidae, Percophidae, Pinguipedidae, Trichiuridae, and Triglidae). Trematode specimens were studied using morphological and molecular genetic analyses. A total of eight hemiurid species from four genera, Ectenurus, Lecithochirium, Myosaccium, and Parahemiurus were identified. This paper reports on new host records for four species of hemiurids, adds a new record on the geographical distribution for one species, and provides the first DNA sequence data supplemented with the detailed description of morphology for five species. Phylogenetic analyses supported that the subfamily classifications of the Hemiuridae—based entirely on morphological characters—needs to be reconsidered, taking into account a wider range of information sources. Full article

The age and growth of fish populations is a critical issue for stock assessment, population dynamics and fishery management. Spawner biomass, mortality, growth, recruitment and age at maturity can be misconstrued if the age estimator is inaccurate. Age can be estimated by annuli count, but this requires expertise and is expensive. Otolith weight (OW) is a good indicator of how long a fish has lived, because OW increases during an individual’s life. Seriola lalandi is a migratory fish and is an important resource for local fishermen in northern Chile. Aspects of its biology, i.e., age and growth, remain unknown, at least for the population annually arriving in northern Chile. Fish of a known age (n = 105; from 5.5 to 25.7 cm in FL) from yellowtail aquaculture facilities at Universidad de Antofagasta allowed us to estimate the growth rate of OW, and fish obtained from local fishermen (n = 71; from 37.9 to 109 cm in FL) allowed us to estimate the age and growth of S. lalandi from the analysis of OW, without the need for calibration. The following four models were fitted with the known ages and fork lengths: the von Bertalanffy growth function, the Gompertz and logistic models and the seasonalized von Bertalanffy growth function. The latter model showed the best adjustment (according to the Akaike information criterion) with the following parameters: L_∞, 98.58 cm.; K, 0.59; t₀, 0.07; t_s, 0.84; and C, 0.97. Full article

Geographic isolation, a relatively low species richness and high endemism make oceanic islands excellent natural laboratories for ecological and evolutionary studies. Here we used Baited Remote Underwater stereo-Video systems (stereo-BRUVS) to investigate the taxonomic, trophic and size structures of fish assemblages from pelagic and mesophotic reef ecosystems in the smallest archipelago of the equatorial Atlantic Ocean, the Saint Peter and Saint Paul’s Archipelago (SPSPA). The occurrence of steep reef walls favors studies on the ecological connections between pelagic and reef ecosystems. We performed five pelagic stereo-BRUVS deployments and fourteen benthic stereo-BRUVS deployments, totaling 1440 min of footage. We recorded 14 species from eight families in the pelagic ecosystem, with Carangidae and Balistidae as the most diverse families. The most abundant species were Elagatis bipinnulata (Quoy and Gaimard, 1825), Melichthys niger (Bloch, 1786), and Caranx crysos (Mitchill, 1815), which together accounted for over 75% of the total relative abundance. The carnivores were the most diverse and abundant trophic group. On the mesophotic reefs, 41 taxa were recorded, with carnivores and planktivores being the most diverse, whereas omnivores were the most abundant. Here, the most abundant species were M. niger, Azurina multileneata, Chromis vanbebberae, Seriola rivoliana, Caranx lugubris and Stegastes sanctipauli. Nine species were recorded in both ecosystems, with Melichthys niger, Caranx lugubris and S. rivoliana being the main species linking them (i.e., occurring in both). These species are known to forage in both pelagic and mesophotic reef ecosystems, and thus represent potential ecological links between them. Such links combined with the endangered status of some species, suggest the need for an integrated management strategy in this remote archipelago. Full article

Epitheliocystis is a disease caused by a wide variety of host-specific intracellular bacteria infecting fish gills. In the Mediterranean Sea, epitheliocystis has been recently associated with a novel genus of beta-proteobacteria, the Ca. Ichthyocystis genus. In the present study, we report a case of epitheliocystis in a wild-caught specimen of pompano Trachinotus ovatus in Crete, Greece. Molecular analysis of partial 16s rRNA sequence led to the discovery of a putative novel species of the Ca. Ichthyocystis genus. Investigation of the phylogenetic relationship between closely related sequences deposited in NCBI suggests that bacterial ancestors in gilthead seabream might have a pivotal role in the differentiation of genus. Full article