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The red porgy (Pagrus pagrus) and the common dentex (Dentex dentex) are Sparidae species of high commercial value, traded in the Greek market. In some cases, fish species identification from Greek fisheries is difficult for the consumer due to the strong morphological similarities with their imported counterparts or closely related species such as Pagrus major, Pagrus caeroleustictus, Dentex gibbosus and Pagellus erythrinus, especially when specimens are frozen, filleted or cooked. Techniques based on DNA sequencing, such as COI barcoding, accurately identify species substitution incidents; however, they are time consuming and expensive. In this study, regions of mtDNA were analyzed with RFLPs, multiplex PCR and HRM in order to develop a rapid method for species identification within the Sparidae family. HRM analysis of a 113 bp region of cytb and/or a 156 bp region of 16s could discriminate raw or cooked samples of P. pagrus and D. dentex from the aforementioned closely related species and P. pagrus specimens sampled in the Mediterranean Sea when compared to those fished in the eastern Atlantic. HRM analysis exhibited high accuracy and repeatability, revealing incidents of mislabeling. Multiple samples can be analyzed within three hours, rendering this method a useful tool in fish fraud monitoring.

TGF-β1/Smads is a classic signaling pathway, which plays important roles in the development process of organisms. Black porgy Acanthopagrus schlegelii and red porgy Pagrus major are valuable economic fishes, and their hybrid offspring show excellent heterosis traits. Yet the molecular regulation mechanism of the heterosis traits is less clear. Here, we explored the TGF-β1/Smads pathway’s molecular genetic information for heterosis in A. schlegelii ♂ × P. major ♀ (AP) and A. schlegelii ♀ × P. major ♂ (PA) in terms of growth and development. The mRNA expression levels of TGF-β1, TβR-I, TβR-II, and Smad2 genes in different developmental stages of A. schlegelii were detected. Furthermore, the expression levels of TGF-β1, TβR-I, TβR-II, and Smad2 genes in different tissues of adult (mRNA level) and larva (mRNA and protein level) of A. schlegelii, P. major, and their hybrids were determined by both real-time quantitative PCR and Western blot techniques. The results indicated the ubiquitous expression of these genes in all developmental stages of A. schlegelii and in all tested tissues of A. schlegelii, P. major, and its hybrids. Among them, the mRNA of TGF-β1, TβR-I, and TβR-II genes is highly expressed in the liver, gill, kidney, and muscle of black porgy, red porgy, and their hybrid offspring. There are significant changes in gene and protein expression levels in hybrid offspring, which indirectly reflect hybrid advantage. In addition, there was no correlation between protein and mRNA expression levels of Smad2 protein. The results provide novel data for the differential expression of growth and development genes between the reciprocal hybridization generation of black porgy and red porgy and its parents, which is conducive to further explaining the molecular regulation mechanism of heterosis in the growth and development of hybrid porgy.

It is commonly assumed in surveys that the likelihood of capturing or observing individuals of a given species is constant. Yet evidence is building that catchability, or the likelihood of catching an individual present at a site, can vary.We used 5465 paired trap-video samples collected along the southeast US Atlantic coast in 2015−2018 to estimate trap catchabilities of 6 reef fish species (gray triggerfish Balistes capriscus, red porgy Pagrus pagrus, vermilion snapper Rhomboplites aurorubens, black sea bass Centropristis striata, red snapper Lutjanus campechanus, white grunt Haemulon plumierii) as the ratio of trap catch to standardized site abundance from corresponding videos. Species-specific trap catchabilities were then related to 2 primary predictor variables: water temperature and percent of the visible bottom consisting of rocky substrate. Water temperature strongly influenced trap catchabilities for all species after standardizing for all other variables. The 4 warm-water species displayed strong positive relationships between catchability and temperature; of these species, the smallest absolute increase in catchability occurred for vermilion snapper (0.0 at ~14°C to 0.05 at ~28°C) and the largest occurred for white grunt (0.0 at ~14°C to 0.49 at ~28°C). The 2 cooler-water species displayed either a dome-shaped (red porgy) or negative relationship (black sea bass) between catchability and temperature. Furthermore, trap catchabilities for all species declined substantially (42−80%) as the percent hard bottom of the site in - creased. Only when catchability is properly accounted for can results be considered unbiased and subsequent management advice be considered accurate.

Red porgy ( Pagrus pagrus ) is a reef-associated, economically-important, winter-spawning, protogynous Sparidae species that appears to have declined in abundance in recent years along the southeast United States Atlantic coast. We used spatially-explicit generalized additive models built with fishery-independent chevron trap (1990–2021) and video data (2011–2021) to quantify the ways in which red porgy relative abundance and mean size varied across temporal, spatial, environmental, and habitat variables. Mean red porgy relative abundance from traps declined by 77% between 1992 and 2021, and declines were similarly large (69%) on video between 2011 and 2021. The largest two-year decline in relative abundance occurred early in the COVID-19 pandemic (2019–2021)– 32% in traps and 45% on video–despite already low abundance. Highest red porgy relative abundance from traps and video occurred in deep areas (i.e., 60–100 m) between southern North Carolina and north Georgia, and red porgy preferred low relief but continuous hardbottom habitats (i.e., pavement). We confirmed recent low recruitment of red porgy in the region based on the large increase in mean length (29%) and severe (~99%) declines of juvenile red porgy caught over the 32-year trap survey. Evidence suggests that recruitment failure is partially or mostly responsible for red porgy abundance declines, and, moreover, the regulation of harvest is unlikely to achieve sustainable management goals until recruitment increases.

Fish microbiome science is progressing fast, but it is biased toward farmed or laboratory fish species against natural fish populations, which remain considerably underinvestigated. We analyzed the midgut bacterial microbiota of 45 specimens of 12 fish species collected from the Gyaros Island marine protected area (Aegean Sea, Greece). The species belong to seven taxonomic families and are either herbivores or omnivores. Mucosa midgut bacterial diversity was assessed by amplicon metabarcoding of the 16S rRNA V3–V4 gene region. A total of 854 operational taxonomic units (OTUs) were identified. In each fish species, between 2 and 18 OTUs dominated with cumulative relative abundance ≥ 70%. Most of the dominating bacterial taxa have been reported to occur both in wild and farmed fish populations. The midgut bacterial communities were different among the 12 fish species, except for Pagrus pagrus and Pagellus erythrinus , which belong to the Sparidae family. No differentiation of the midgut bacterial microbiota was found based on feeding habits, i.e., omnivorous vs. carnivorous. Comparing wild and farmed P. pagrus midgut bacterial microbiota revealed considerable variation between them. Our results expand the gut microbiota of wild fish and support the host species effect as the more likely factor shaping intestinal bacterial microbiota.

Larvae of an unidentified Echinocephalus species were obtained from two fish species: red porgy or common seabream ( Pagrus pagrus ) and greater lizard fish ( Saurida undosquamis ) from the Red Sea. The prevalence of Echinocephalus sp. larvae in P. pagrus was 4.92% and 4.98% in S. undosquamis . The length, width, cephalic bulb, and spine shape and pattern of the larvae resembled Echinocephalus overstreeti . SSU gene sequences of larvae from P. pagrus and S. undosquamis were identical. Comparison of the SSU sequence to those available in GenBank showed that the larvae from P. pagrus and S. undosquamis are diagnosably distinct. Based on sequence similarity and published phylogenetic analysis, these larvae are most similar to an unknown species of Echinocephalus from an Australian sea snake ( Hydrophis peronii ). Despite morphological similarities of the Red Sea larvae to E. overstreeti , the SSU sequence differences show that they are not the same species.

Understanding the spatiotemporal dynamics of fish species is a central concern in fish ecology and crucial for guiding management and conservation efforts. We constructed a joint species distribution model (JSDM) to simultaneously estimate the spatiotemporal distributions and densities for 21 reef fish species in the southeastern United States (SEUS). The model separately estimates encounter probability and positive density, and accounts for unobserved spatial and spatiotemporal variation using latent factors, where the correlations among species are induced. We applied the model to video data collected from a large‐scale, fishery independent survey. A clustering method was applied to the results of the JSDM to group species based on spatial and spatiotemporal synchrony in encounter probability and positive density. We found strong spatial associations among most of the reef fish species. However, species did exhibit differences in occupied habitat that varied with latitude and/or depth. Within their area of occupied habitat, almost all the species share similar spatial pattern of average density. However, for some species, annual distributions were less correlated with their expected average distributions perhaps due to differing responses to underlying spatiotemporal drivers. Some species show significant declines in abundance, for example, black sea bass, red porgy, and blueline tilefish, while a small number of species showed evidence of shifts in distribution, for example, black sea bass. The findings suggest that spatiotemporal management strategies may be of limited utility for reducing bycatch in these highly mixed reef fisheries due to high spatial correlations in occupied habitat and spatial patterns in density. Species‐specific responses to environmental change may also influence the spatiotemporal structure of reef assemblages. This work suggests management attention is needed for some of the lesser known species as they are showing declining trends in abundance.

This brief review focuses on health and biological function as cornerstones of fish welfare. From the function-based point of view, good welfare is reflected in the ability of the animal to cope with infectious and non-infectious stressors, thereby maintaining homeostasis and good health, whereas stressful husbandry conditions and protracted suffering will lead to the loss of the coping ability and, thus, to impaired health. In the first part of the review, the physiological processes through which stressful husbandry conditions modulate health of farmed fish are examined. If fish are subjected to unfavourable husbandry conditions, the resulting disruption of internal homeostasis necessitates energy-demanding physiological adjustments (allostasis/acclimation). The ensuing energy drain leads to trade-offs with other energy-demanding processes such as the functioning of the primary epithelial barriers (gut, skin, gills) and the immune system. Understanding of the relation between husbandry conditions, allostatic responses and fish health provides the basis for the second theme developed in this review, the potential use of biological function and health parameters as operational welfare indicators (OWIs). Advantages of function- and health-related parameters are that they are relatively straightforward to recognize and to measure and are routinely monitored in most aquaculture units, thereby providing feasible tools to assess fish welfare under practical farming conditions. As the efforts to improve fish welfare and environmental sustainability lead to increasingly diverse solutions, in particular integrated production, it is imperative that we have objective OWIs to compare with other production forms, such as high-density aquaculture. However, to receive the necessary acceptance for legislation, more robust scientific backing of the health- and function-related OWIs is urgently needed.

Since July 2019, Gyaros island in the central Aegean Sea, enjoys the status of a partial Marine Protected Area (MPA), allowing for exploitation by small-scale fishers following specific spatio-temporal restrictions. The need for assessing the effectiveness of the MPA in the future, led MAVA Foundation to fund a knowledge survey project aiming to serve as a baseline for future reference. A series of experimental fishing surveys took place with static nets, the outcomes of which are presented herein. From June 2018 to September 2020, a series of 8 fishing excursions with a total of 40 experimental fishing sets with bottom static nets were realized in 5 set locations around Gyaros island, inside the MPA protection zone. A total of 75 species were identified; the most abundant species, in terms of biomass, being: parrotfish -Sparisoma cretense , red scorpionfish- Scorpaena scrofa , common spiny lobster- Palinurus elephas , red porgy- Pagrus pagrus , little tunny–- Euthynnus alletteratus , Mediterranean moray- Muraena helena , lesser spotted dogfish - Scyliorhinus canicula , forkbeard- Phycis phycis , surmullet- Mullus surmuletus , common cuttlefish- Sepia officinalis and common Pandora- Pagellus erythrinus . A comparison with similar data in adjacent areas outside the MPA allowed for assessing the effectiveness of the MPA based on four indicators: species diversity index, species relative biomass index, key predator species abundance, and alien fish abundance. Based solely on the experimental fishing trials, the MPA seems to be functioning, since both species diversity and abundance were higher within the protected area. However, its performance may still not be considered as optimal, as this is indicated by the large proportion of undersized key predators (e.g. groupers), although more abundant and larger than the ones residing outside the MPA.

Monitoring programs often collect presence–absence data to understand range expansions or contractions, metapopulation dynamics, alien species invasions, or spatial and temporal trends in relative abundance. Using the proportion of sites occupied by a species is misleading, however, if surveys routinely fail to detect species that are present. We used chevron traps paired with underwater videos (N = 1555) in a binomial (presence–absence) generalized additive modeling framework to quantify how environmental conditions, habitat characteristics, and the number of individuals at each site (i.e. site abundance) influenced the detection probabilities of economically important reef fish species in the southeastern USA. After accounting for variable site abundance, trap detection probabilities declined 40% for red porgy Pagrus pagrus, 65% for gray triggerfish Balistes capriscus, and 75% for vermilion snapper Rhomboplites aurorubens as percent hard bottom increased from 0 to 100%. Increasing water temperature caused red porgy trap de tection probability to decline modestly, while for gray triggerfish and vermilion snapper it increased substantially. Underwater video was more likely to de tect black sea bass Centropristis striata, red porgy, and gray triggerfish when site abundance and water clarity were high and the video camera was facing down-current. Using multiple gears simultaneously, we quantified the ways in which predictor variables influenced the sampling process, which will help in designing surveys that maximize detection probability. Our results also suggest that pairing video cameras to trawls, fisheries acoustics, or nets allows for the estimation of detection probabilities.