Search Results (28)

Seabob shrimp Xiphopenaeus kroyeri is under heavy capture-pressure in the western Atlantic, requiring periods of fishing suspension to protect the propagation of the species in the wild. This work aims to describe the stages of gonadal development and the ovaries of X. kroyeri in trawling in the southeastern Atlantic Ocean of Brazil associated with climatic characteristics of temperature and precipitation. In total, 3658 specimens were captured in monthly collections from March 2019 to February 2020. The female gonads were classified macroscopically and microscopically according to the maturation stage and correlated with precipitation and temperature data. Five stages of maturation were observed: immature, initial maturation, advanced maturation, mature, and spawned. The highest percentage of mature females was found in May and July, and the average size of the female cephalothorax at the first gonadal maturation was 1.7 cm. The recruitment period was observed in April, with more juveniles. Precipitation showed a negative correlation with the number of mature females. April, May, and July are essential for the life cycle of the X. kroyeri population on the coast of Espírito Santo, Brazil. The results suggest that the current closed season for the species should be reconsidered. Full article

The marine environment is a rich source of new biotechnologies and products. Bottom trawling for shrimp species such as Xiphopenaeus kroyeri and Farfantepenaeus brasiliensis leads to the unintentional capture of non-target species, known as bycatch, which includes a variety of marine life that are often discarded without economic value. A common bycatch species on the southeast coast of Brazil is Olivancillaria urceus (O. urceus), a carnivorous gastropod that feeds mainly on bivalves. Despite its abundance, this species is still little studied, especially for biotechnological applications. Other gastropods such as Conus are known for their diverse and potent toxins, which offer great potential for pharmacological discoveries. In this study, an omics approach, including transcriptomics and proteopeptidomics, was applied to explore O. urceus at the molecular level. The transcriptome of the muscle foot/mantle led to the annotation of 19,097 genes via Gene Ontology, identifying 20 toxin-like transcripts identified considering the Gastropod class. The proteome fraction confirmed 2179 transcripts, including sequences with toxin activity, such as conotoxin precursors, Conodipine-P3, and BPTI/Kunitz domain-containing proteins. In addition, 9663 peptides of 1484 precursor proteins were detected in the peptide fraction, including 2 sequences representing neurotoxins. The identification of these sequences could lead to the discovery of new molecules with therapeutic potential. Full article

Metapenaeus monoceros is the second most abundant commercially important shrimp species caught along the Saudi Arabian Red Sea coast. However, knowledge of its life history and population dynamics in the region remains limited, posing challenges for sustainable management. This study assessed the growth, maturity, and mortality of M. monoceros based on fishery-independent samples collected from shrimp trawling grounds off Al Qunfudhah and Jizan (October 2022–September 2023). Altogether, 10,859 specimens were examined, with a carapace length (CL) ranging from 7.98 to 49.10 mm and a total weight (W) in the range of 0.41 to 41.28 g. The observed sex ratio was 1.56:1 in favor of females. The CL–W relationship was W = 0.0024∙CL^2.58. The seasonalized von Bertalanffy growth parameters were CL_∞ = 50.66 mm, K = 0.35 year⁻¹, t_anchor = 0.43 years, C = 0.64, and t_s = 0.61 years for females, and CL_∞ = 38.97 mm, K = 0.55 year⁻¹, t_anchor = 0.51 years, C = 0.84, and t_s = 0.39 years for males. Females reached their first sexual maturity at 21.12 mm CL. The exploitation rates (0.60 for both sexes) indicated overfishing. Spawning potential ratio analysis showed that the current fishing pressure reduces the spawning stock biomass to 23% of unexploited levels. A 50% reduction in fishing effort, extended seasonal closures, and selective gear modifications are recommended to rebuild the stock and ensure sustainability. Full article

This study was conducted to examine the effects of regional wind changes on trawl fishing effort in Iskenderun Bay from 2017 to 2023 by analyzing meteorological data, daily fishing durations, and catch quantities. It was found that an increase in wind intensity reduced fishing durations by an average of 0.367 h. Northerly and easterly winds were observed to have higher speeds throughout the year, with the highest speeds reaching 14 m/s in March. Fishing activities were affected more by southerly and westerly winds due to the geographical structure of Iskenderun Bay. Seasonal variations were also detected, with fishing durations being longer at the beginning of the fishing season in autumn and decreasing in spring. Species such as red mullet, brushtooth lizardfish, and shrimp were identified as having a significant impact on fishing activities. The relationships between wind intensity, direction, and fishing durations were revealed through statistical analyses. It was shown that environmental and seasonal factors influenced trawl fishing effort in Iskenderun Bay. These results provided insights into the interactions between wind dynamics and fishing operations. Full article

Elasmobranch species are susceptible to anthropogenic stressors such as fishing activities, particularly the bycatch in bottom-trawl fisheries. Understanding the diversity, segregation, and population structure of species at risk of capture is critical for enhancing their conservation. This study evaluated the species composition and population structure dynamics of susceptible elasmobranch species caught as bycatch in the Mexican shrimp trawl fishery in the southern Gulf of Mexico. Data were collected by examining bycatch from 55 fishing trips conducted between 2013 and 2017 during closed and commercial fishing seasons. We analyzed the species composition, length, sex ratio, and maturity stages of susceptible species across zones, sampling seasons, and depth. Six dominant species (Rostroraja texana, Gymnura lessae, Narcine bancroftii, Pseudobatos lentiginosus, Squatina dumeril, Hypanus americanus) accounted for >98% of all captures and were found in all fishing zones, seasons, and depths. These species were caught in a range of sizes, from newborns to mature individuals, and showed both inter- and intraspecific segregation patterns across fishing zones, seasons, and depths. The elasmobranch composition and population structure in bycatch are influenced by ontogenetic segregation and bathymetric distribution of the species. Current Mexican shrimp trawl fishery regulations benefit the majority of elasmobranchs by providing comprehensive spatiotemporal protection and selective exclusion mechanisms. However, small-sized ray species and juveniles of larger species continue to face fishing pressure. The preset study highlights the southern Gulf of Mexico as an important reproductive area for demersal elasmobranchs and unravels their complex segregation behavior, leading to the identification of potential risk zones and seasons. The impacts of bycatch on the most susceptible elasmobranchs may be mitigated through improvements in trawl fishing technology and the implementation of additional temporal bans in specific trawling areas, enhancing species-specific conservation efforts. Full article

This study investigated the population dynamics, growth, reproduction, and parasitism of Penaeus aztecus over a 27-month period in Antalya Bay (Eastern Mediterranean). P. aztecus was the most abundant shrimp species, comprising 53.4% of the collected shrimp specimens. Abundance varied seasonally, with peak densities in summer. Males had a smaller mean carapace length (CL) of 25.8 mm compared to females at 30.2 mm. Females dominated larger size classes, with all individuals ≥ 46 mm CL being female. The sex ratio was balanced at 1:1, with no seasonal variations. Spawning occurred year-round, peaking in June, late summer, and November. Females displayed four ovarian stages, with the first mature size (FMS) at 36 mm CL. Parasitism by Epipenaeon ingens reduced the density of mature females, with 42% of potential spawners failing to develop gonads. The prevalence of parasitism showed seasonal variation and was inversely correlated with sea surface temperature (SST). Marine recruitment occurred from June to November, with a peak between July and September. Growth analysis revealed faster rates in females, while males reached a smaller maximum size. This study also identified inefficiencies in gear selectivity, with many juvenile shrimp (below recruitment size) being retained. Trawl efficiency improved with the use of turtle excluder devices (TEDs), which reduced bycatch of nontarget species, such as loggerhead turtles and cartilaginous fishes. The instantaneous total mortality rate (Z) ranged from 0.658 to 0.026 month⁻¹ for male shrimp and from 1.00 to 0.014 month⁻¹ for female shrimp, with survival sharply declining after recruitment, leaving only about 3.6% of individuals surviving beyond 10 months. Full article

Rock shrimps (Sicyonia dorsalis and Sicyonia typica) are commonly caught as bycatch during shrimp trawling along the Brazilian coast, but are not commercially exploited due to their small size and hard carapace. This study evaluated their spatio-temporal distribution, size classes, and sex ratio near the Almada River Estuary, Ilhéus, Bahia, Northeastern Brazil, and tested correlations between environmental factors and species abundance. Samples were collected monthly using double-rig trawl nets in the estuary and along transects at depths of 5–35 m. Bottom water and sediment samples were obtained for analyses of environmental factors. In total, 5336 individuals of S. dorsalis and 303 individuals of S. typica were collected. No individuals were recorded in the estuary. Both species were significantly more abundant between 25 and 35 m, where fine sediment with high levels of organic matter occurred. Considering the temporal variation, their abundance decreased during the rainy season, coinciding with increased river flow. Organic matter content, salinity, and water transparency were the primary environmental factors influencing abundance. Females were generally larger and predominant compared to males, likely due to life cycle dynamics. Despite being congeneric and sympatric, the species exhibited distinct population patterns, possibly to avoid niche overlap and competition. Full article

Shrimp trawl fishery is of significant importance in Saudi Arabia’s marine capture fishery sector. Al Qunfudhah and Jizan are the only ports along the southern Saudi Arabian coast of the Red Sea dedicated to shrimp fishing. This study evaluates the catch per unit effort (CPUE) of targeted shrimp species along with the associated retained bycatch and discard ratios across these two trawling locations. Using daily catch data from commercial shrimp trawlers specific to each port’s vessel type, this research provides the first comprehensive analysis of CPUE dynamics and fishing practices in these fishing grounds. The CPUE of target shrimps exhibited a wide range (0.01 kg h⁻¹ to 13.08 kg h⁻¹) with an overall mean of 1.37 ± 0.143 kg h⁻¹. Penaeus semisulcatus emerged as the predominant species (mean CPUE: 3.77 ± 0.28 kg h⁻¹), followed by Metapenaeus monoceros (mean CPUE: 0.1 ± 0.02 kg h⁻¹). Significant differences in CPUE were observed among species, including P. semisulcatus, Penaeus hathor, and Penaeus pulchricaudatus, although CPUE differences between the two fishing grounds were minor, likely due to their proximity and similar environmental conditions. The bycatch analysis identified a total of 72 species across 28 families, with significant variation in the relative ratios. Sepiidae species constituted 31.8% of the total bycatch, followed by Portunidae species (24.8%). Discard patterns also varied, with Gerres oyena being the most commonly discarded species (mean discard ratio: 11.37% ± 1.89%), followed by Equulites klunzingeri (mean discard ratio: 8.76% ± 2.00%). While CPUE differences between Al Qunfudhah and Jizan were modest, this study highlights the need for expanded spatial and temporal coverage to enhance future analyses. These findings underscore the importance of integrated data for a comprehensive understanding of fishing effort and bycatch dynamics, supporting sustainable fisheries management in the Red Sea. By addressing bycatch and discard practices, this research contributes to efforts to mitigate ecological impacts and promote sustainable resource use in Saudi Arabia’s fisheries sector. Full article

This study assessed catch composition, size selectivity, and fishing efficiency of demersal trawls targeting penaeid shrimp species in the Red Sea. It first compared the currently used diamond mesh codends in two fishing areas, Al Qunfudhah and Jazan, and then compared alternative square mesh codends to diamond mesh codends in Jazan. A total of 33 valid hauls were conducted in 2023, yielding 10,869 kg of total catch. The results showed that the square mesh codend significantly improved size selectivity, particularly for Penaeus semisulcatus and Metapenaeus monoceros, with L₅₀ (50% retention length) values closer to their size at first maturity. The fishing efficiency indicators revealed a reduced retention probability for undersized individuals with square mesh codends. Additionally, bycatch discard rates decreased, indicating potential benefits for ecosystem conservation. This study suggests incorporating square mesh codends into fishery management regulations to enhance size selectivity and reduce bycatch during Red Sea shrimp trawling. Establishing a legal minimum landing size requirement is recommended to complement these efforts and promote sustainable fishing practices. Full article

Comparing co-occurring species may provide insights into how aspects of ecology may play a role in influencing their microbial communities. During the 2019 commercial shrimp trawl season off coastal Georgia, swabs of skin, gills, cloaca, and gut were taken for three species of batoids (Butterfly Ray, Bluntnose Stingray, and Atlantic Stingray) and one shark species (Atlantic Sharpnose) for high-throughput sequencing of the V4 region of the bacterial 16S rRNA gene. White muscle was analyzed for stable isotopes (δ¹³C and δ¹⁵N) to evaluate potential niche overlap in these four sympatric mesopredators. Significant differences were found in both δ¹³C and δ¹⁵N signatures across species, suggesting a degree of resource partitioning. When examined within tissue type, the host species had a weak effect on β-diversity for cloaca and skin, with no differences found for gill and gut samples. However, network analysis metrics demonstrated a stronger species-specific effect and distinct microbial community relationships were apparent between the shark and batoids, with the former having tighter networks for both internally- and externally-influenced tissues (gut/cloaca and skin/gills, respectively). Despite overlapping habitat use, species’ microbiomes differed in their organizational structuring that paralleled differences in stable isotope results, suggesting a mediating role of species-specific ecology on bacterial microbiomes. Full article

The northeastern waters of Guishan Island constitute one of the crucial fishing grounds for coastal trawl fishery in Taiwan and have been exploited for many decades. To construct the marine ecosystem and to examine the interactions among trophic levels of fisheries resources in the waters of Guishan Island, historical catch, catch composition, biological information, fishing effort, environmental data such as sea surface temperature, salinity, and nutrients were analyzed using Ecopath with Ecosim. The results indicated that the longline and drift net fisheries have a very minor incidental catch of cetaceans, with a fishing mortality (F) of 0.01 year⁻¹ and an exploitation rate (E) of 0.03. The F and E were 0.308 year⁻¹ and 0.617 for small skates and rays, and were 0.261 year⁻¹ and 0.580, respectively, for small sharks. The F and E of the dolphinfish, Coryphaena hippurus, an important pelagic species, were 0.411 year⁻¹ and 0.245, respectively. Fisheries had negative impact on major commercial species except the dolphinfish and the oil fish, Lepidocybium spp., which benefited from the reduction of their predators or competitors. The keystone species of the Guishan Island marine ecosystem is phytoplankton, which has the lowest trophic level and great biomass, and is an important energy source of the ecosystem. The influences of zooplankton and anchovy rank as second and third, respectively, with regard to the keystone species in the ecosystem due to their great biomass. Regarding the biomass of less abundant species, carangids had the highest influence followed by hairtail due to their feeding habits. The results of simulations using Ecosim indicated that the hairtail, small sharks, skates and rays, mackerels, and marine eels will benefit if fishing efforts are reduced by 30%. On the other hand, the biomass of phytoplankton, zooplankton, demersal benthivores, and shrimps will decrease due to the increase in the biomass of their predators. Full article

The mantis shrimp Rissoides pallidus (Giesbrecht, 1910) is a rarely reported crustacean species in the central Mediterranean Sea. In December 2020, during a trawl survey off Mazara del Vallo harbor (Strait of Sicily), two specimens of R. pallidus were captured on coastal detritus and coastal terrigenous mud bottoms at about 132 and 152 m depths. Additional information specific to biometrics, bottom types, depth preference, habitats, and geographic distribution of this crustacean species are provided. Full article

Marine resources exploitation through bottom trawling affects marine ecosystems; thus, management should consider the presence of sensitive species as ecosystem health indicators. Epibenthic organisms such as sea pens are widely used to assess benthic conditions, as their populations are declining where trawling is intense. The Pomo/Jabuka Pits fishing ground in the Adriatic Sea, subject to various management measures over the years, is a nursery for European hake and hosts a small, but dense, population of Norway lobster and a remarkable abundance of pink shrimp. The sea pen Funiculina quadrangularis shares its habitat (sandy-muddy bottoms) with these crustaceans. Through UnderWater TeleVision surveys conducted from 2012 to 2019, F. quadrangularis abundance and distribution were quantified in relation to changes in the spatiotemporal distribution of fishing efforts. The average density (n/m²) of colonies was calculated for three periods: BEFORE implementation of measures (before 1 July 2015), during an INTERMEDIATE period in which limitations changed (2 July 2015 to 31 August 2017), and AFTER the implementation of a Fishery Restricted Area (from 1 September 2017). F. quadrangularis revealed an increase in density where fisheries were closed, even after a short period. This showed how management measures can positively influence epibenthic communities and that sea pens can be indicators of impact and/or recovery of habitats. Full article

Vulnerability of each stock in the catches from trawl fisheries in the Gulf of Thailand was assessed by productivity susceptibility analysis. Separate assessments were made based on type of trawler (otter-board, pair and beam) and vessel size (SS, S, M, L and XL, according to gross tonnage). Catches were distinctly different among trawler types and were dominated by demersal fishes, pelagic fishes and shrimps in the otter-board, pair and beam trawlers, respectively. The stocks of over 200 taxa were included in the study; high-vulnerability taxa were found for all trawl types and sizes, except the beam trawler size S. Only seven (7) taxa were classified as high vulnerability, including four (4) teleost taxa, namely Saurida elongata, Plotosus spp., Gymnothorax spp. and Sphyraena spp., and three (3) elasmobranch taxa, namely Carcharhinus spp., Brevitrygon heterura and Neotrygon kuhlii. Meanwhile, as many as 26 high-medium vulnerability taxa were found in catches by otter-board trawler size L, which included not only fishes but also cephalopods. Trends and variation in fish landings of 20 high and high-medium vulnerability taxa were analyzed. Eighteen (18) taxa showed monotonic trends, both continuous and discontinuous, in their time series of annual landings, but not Muraenesox spp. nor Uroteuthis spp. The long-term variations in fish landings ranged mostly between 40% and 50%. The short-term variations showed positive absolute and relative skewness, i.e., mostly between 10% and 20%. Results of this study highlight the taxa that require a precautionary approach for fishery management and warrant comprehensive fish stock assessment. Such data will allow more accurate determination of their status compared to the reference points and facilitate better management of trawl fisheries in the Gulf of Thailand. Full article

The age and growth of Urotrygon microphthalmum were studied using specimens captured between March 2010 and March 2012 as by-catch in the shrimp trawl fishery off the coast of the state of Pernambuco, Brazil. A total of 347 vertebrae were read, 161 from males (81.6–249.55 mm) and 186 from females (86.15–298.1 mm). The estimated average percentage index (IAPE) ranged from 0.71% to 4.33% (mean = 2.5%) in vertebrae from specimens with 1 and 6 band pairs, respectively. In the present study, the different approaches to validation produced variable results (partially valid growth zones). We then decided to discuss the growth of the species considering the formation of an annual ring. There were statistically significant differences in growth between the sexes. The best model to describe male growth was the von Bertalanffy growth model for two phases (VBGM TP) with growth parameters L_∞ (maximum theoretical length) = 230.35 mm, k (growth constant) = 1.00, t₀ (theoretical age of size zero) = −0.76 years and for females it was the von Bertalanffy with birth size (VBGM L₀) model with parameters L_∞ = 282.55 mm, k = 0.37. The age of maturity for males and females was 1.52 and 2.02 years, respectively, and the maximum age observed was 5.5 and 8.5 years, respectively. Despite being a fast-growing species, Urotrygon microphthalmum is threatened, probably due to the high mortality levels from shrimp trawling in a very narrow range of the shelf where all the life stages are captured. Full article