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Background Evolutionary origins of derived morphologies ultimately stem from changes in protein structure, gene regulation, and gene content. A well-assembled, annotated reference genome is a central resource for pursuing these molecular phenomena underlying phenotypic evolution. We explored the genome of the Gulf pipefish ( Syngnathus scovelli ), which belongs to family Syngnathidae (pipefishes, seahorses, and seadragons). These fishes have dramatically derived bodies and a remarkable novelty among vertebrates, the male brood pouch. Results We produce a reference genome, condensed into chromosomes, for the Gulf pipefish. Gene losses and other changes have occurred in pipefish hox and dlx clusters and in the tbx and pitx gene families, candidate mechanisms for the evolution of syngnathid traits, including an elongated axis and the loss of ribs, pelvic fins, and teeth. We measure gene expression changes in pregnant versus non-pregnant brood pouch tissue and characterize the genomic organization of duplicated metalloprotease genes ( patristacins ) recruited into the function of this novel structure. Phylogenetic inference using ultraconserved sequences provides an alternative hypothesis for the relationship between orders Syngnathiformes and Scombriformes. Comparisons of chromosome structure among percomorphs show that chromosome number in a pipefish ancestor became reduced via chromosomal fusions. Conclusions The collected findings from this first syngnathid reference genome open a window into the genomic underpinnings of highly derived morphologies, demonstrating that de novo production of high quality and useful reference genomes is within reach of even small research groups.

The wahoo, Acanthocybium solandri (Cuvier, 1832), an uncommon scombrid species for the Mediterranean, is hereby reported for the first time from Maltese waters. Details of this unusual capture, and characteristics of the specimens recovered are provided, as well as a brief discussion on dynamics of its introduction in the Mediterranean Sea, and its distribution in this area. In addition, two individuals of the parasitic nematode Anisakis pegreffii Campana-Rouget et Biocca, 1955 (Anisakidae) were found from the stomach of one of the specimens.

Background The family Rhadinorhynchidae is a common group of acanthocephalans parasitizing various marine and freshwater fishes. The current knowledge of the pattern of mitogenomic evolution of the rhadinorhynchid acanthocephalans is still extremely limited. The monophyly of the Rhadinorhynchidae and the phylogenetic status of several of its included genera and subfamilies remain under debate. Methods The complete mitogenomes of Micracanthorhynchina hemirhamphi and Rhadinorhynchus laterospinosus were sequenced and annotated for the first time on the basis of the specimens collected from the Asian pencil halfbeak Hyporhamphus intermedius (Cantor) (Beloniformes: Hemiramphidae) and the frigate tuna Auxis thazard (Lacepède) (Scombriformes: Scombridae), respectively. Phylogenetic analyses of Acanthocephala were performed on the basis of the concatenated amino acid sequences of 12 protein-coding genes (PCGs) of mitogenomes using maximum likelihood (ML) and Bayesian inference (BI), respectively. Results The complete mitogenomes of M. hemirhamphi and R. laterospinosus are 17,272 bp and 13,567 bp in length, which both include 36 genes, containing 12 PCGs (missing atp8 ), 22 transfer RNA (tRNA) genes, and two ribosomal RNAs ( rrnS and rrnL ), plus two noncoding regions. Additionally, several tRNA gene rearrangement events occurred in the mitogenomes of both M. hemirhamphi and R. laterospinosus . Phylogenetic results supported the traditional rhadinorhynchid genus Micracanthorhynchina as a distinct lineage from Rhadinorhynchidae and Cavisomatidae. Conclusions The mitogenome of M. hemirhamphi represents the largest mitogenome of acanthocephalan reported so far. The mitogenome of R. laterospinosus is the smallest mitogenome of the order Echinorhynchida, which also represents the first mitogenomic data for the genus Rhadinorhynchus and also for the Rhadinorhynchidae sensu stricto. Comparative mitogenomic analyses revealed the gene arrangements of R. laterospinosus and M. hemirhamphi represent two new types of mitochondrial gene arrangement reported in Acanthocephala. Moreover, mitogenomic phylogenies further confirmed the validity of the family Micracanthorhynchinidae and suggested a sister relationship Micracanthorhynchinidae + (Rhadinorhynchidae + Cavisomatidae) within Echinorhynchida. Graphical Abstract Created in BioRender. Hardy, H. (2025) https://BioRender.com/mo3g1wr

Between May 2023 and November 2024, 611 specimens of the narrow-barred Spanish mackerel, Scomberomorus commerson (Lacepède, 1800), were collected from artisanal landing sites along the Syrian coast (eastern Mediterranean Sea) to assess stock status in a data-poor fishery. Age was estimated using a multilayer perceptron neural network trained on fork length (FL); the oldest was age 5 + (109.58 cm). Growth conformed to the von Bertalanffy growth function, with K = 0.275 y −1 (95% CI: 0.266–0.284), FL ∞ = 127 cm (95% CI: 125.69–128.31). The length–weight relationship indicated negative allometric growth ( b = 2.89); and the growth performance index ( Φ ′) was 3.65, reflecting moderate growth potential. Total mortality ( Z ) was 1.22 y −1 , comprising natural mortality ( M ) = 0.49 y −1 and fishing mortality ( F ) = 0.73 y −1 , yielding an exploitation rate ( E ) of 0.60. This exceeds the E 0.5 threshold (0.389) for 50% biomass depletion, confirming overfishing. Sensitivity analysis showed E > E 0.5 across biologically plausible ranges of FL ∞ and K values. A fuzzy logic expert system produced a fishing vulnerability (FV) index of 50.9 and a population growth potential (FP) index of 33.2, indicating high susceptibility to fishing and low recovery capacity. The age structure was severely truncated: only 0.82% reached age 5 + , far below the 12–20 years reported in less-exploited populations. We recommend: (i) a minimum landing size of 75 cm FL, (ii) seasonal closures from May to July to protect spawning aggregations, and (iii) enhanced monitoring of artisanal fisheries. Despite uncertainties, integrating artificial neural networks and fuzzy logic offers a robust, transferable approach for stock assessment in data-limited, conflict-affected regions.

Three individuals of Grammatorcynus bilineatus (Rüppell, 1836), Double-lined Mackerel, were recorded in local fish market in Terengganu, Malaysia. Although in Malaysia G. bilineatus previously has been recorded from East Malaysia, the species has not been recorded from Peninsular Malaysia. Therefore, the specimens described herein represents the first record of G. bilineatus from Peninsular Malaysia. Detailed morphometric and meristic data are presented along with brief diagnostic characters.

The diversity of parasite communities is mainly driven by evolutionary history, as well as the ecology of the host species. To test whether the diversity of the parasite community of four related Stromateidae (Pisces: Scombriformes) is related to evolutionary history (the host phylogeny) or the host’s geographical distribution, we analyzed the metazoan parasite fauna of four species of fishes of this family, from the Pacific and Atlantic coasts of South America. Studied species were Peprilus snyderi (samples from Callao, Perú, and Antofagasta, Chile), Peprilus medius (Chorrillos, Perú), Peprilus paru (Rio de Janeiro, Brazil) and Stromateus stellatus (Talcahuano, Chile). Our multivariate analysis strongly suggests that the diversity of the parasite fauna of the studied fishes is driven mainly by the host’s geographical distribution and not the host phylogeny.

There been increasing interest in polymetallic nodule mining within the Clarion-Clipperton Zone (CCZ). Polymetallic nodule mining within NORI-D will release a sediment plume within the water column and a previous mining collector test within the Nauru Ocean Resources Inc. (NORI-D) contract area released surface pollution from mining tailings. The mid-water plume, as well as accidental surface pollution, indicate that polymetallic nodule mining could impact surface plankton. Although the ichthyoplankton within the eastern tropical Pacific have been well-studied, recent data from within polymetallic nodule mining licence areas is lacking. Environmental Expedition C5e conducted an environmental baseline assessment of both pelagic and benthic fauna within the NORI-D region of the CCZ, which included the opportunistic collection of ichthyoplankton. Ichthyoplankton were collected within NORI-D from November–December 2021 using two plankton nets and a Remotely Operated Vehicle (ROV). Here, we present a checklist of ichthyoplankton within the NORI-D licence area during this winter campaign. Eighteen samples were collected and identified through morphology, with a limited number identified through genetic sequencing. Specimens were from five orders, including Argentiniformes, Stomiiformes, Myctophiformes, Beloniformes and Scombriformes. This checklist will aid contractors and scientists conducting work within the CCZ to examine how wastewater discharge from polymetallic nodule mining could impact fish reproduction and ichthyoplankton survival.

The southern Java waters are characterized by a strong upwelling process, making the region a potential hotspot for fishing activities, including the largehead hairtail, Trichiurus lepturus Linnaeus, 1758. This study provides data on various aspects of T. lepturus in the southern Java waters, including reproductive biology, growth parameters, mortality rates, spawning potential ratio (SPR), and yield per recruit ( Y/R ). The results are intended to help sustain the management of T. lepturus fisheries in the southern Java waters. A total of 19 587 fish specimens were collected monthly between January 2019 and December 2021 from fishermen’s catches in the southern Java waters at the Palabuhanratu Archipelago Fishing Port, West Java Province, Indonesia. The data collected involved information on length, weight, sex, and gonads. Length-frequency data were analyzed using various fisheries assessment models. A length–weight relationship follows a positive allometric growth pattern. The sex ratio was slightly female-biased. Gonadal maturity stages (GMS) and the gonadosomatic index (GSI) indicated a prolonged spawning period. The length at first maturity ( L m50 ) males and females was estimated at 84.5 cm and 77.0 cm, respectively. The von Bertalanffy growth equation of T. lepturus in southern Java waters is L t = 131.67(1 – e –0.22( t + 0.5094) ). Total mortality ( Z ), natural mortality ( M ), and fishing mortality ( F ) were 1.60 year −1 , 0.44 year −1 , and 1.16 year −1 , respectively. The spawning potential ratio (SPR) was 26%, and the yield per recruit ( Y / R ) analysis suggested that the current fishing effort is above the maximum sustainable yield level. Trichiurus lepturus in southern Java waters is experiencing high fishing pressure, which may compromise its reproductive potential and long-term sustainability. Management measures should be implemented to regulate the fishing effort and ensure the sustainable exploitation of this vital fishery resource.

Fish availability in the coastal landing center highlights the assumption of stocks in the marine fishing zone of the ocean. This study, therefore, aimed to analyze the availability of marine fishes in the Bangladesh Fisheries Development Corporation (BFDC) landing center, Cox’s Bazar, Bangladesh between January 2021 and May 2021. A total of 54 species were recorded, of which 42 were marine fishes, 7 were shellfishes and 5 were large fishes. The dominant orders were Perciformes (56%), Scombriformes (17%) and Clupeiformes (10%). More than 56% of the total marine fishes were classified as Least Concern, nearly 10% were categorized as Near Threatened and 2% were marked Vulnerable. The dominant orders of shellfish were Portunidae (43%), followed by Penaidae (29%), Loligonidae (14%) and Octopopidae (14%). Shrimp Penaeous monodon had the highest consumer demand, whereas consumer demand for non-conventional shellfish was comparatively low. Most of the shellfish were categorized as Least Concern. Among large fishes, the wider availability of sharks (five species) and rays (two species) was observed in the winter and monsoon season, although the consumer demand for those large fishes was low. The Vulnerable sharks and rays were Sphyma zygaena and Mobula birostris. This study elucidates the present scenario of marine fishes in the BFDC fish landing center, Cox’s Bazar, Bangladesh.

The biological information for many species of the family Nomeidae is scarce, given the difficulty of capturing these species in the oceanic environment. A specimen of the twospine driftfish, Psenes sio Haedrich, 1970, was collected in the northern Gulf of California with a bottom trawl net at the depth of more than 250 m. This specimen represents the northernmost record of this species to date, and provides valuable information on this fish, such as maximum weight and height recorded, vertical distribution and latitudinal range, in addition to meristic counts and body morphometry.