Disc Width Research Articles

Optic Nerve Head Morphological Variation in Craniosynostosis: A Cohort Study

To evaluate optic nerve head morphology in children with craniosynostosis versus healthy controls. Single-centre, prospective cohort study METHODS: Handheld optical coherence tomography (OCT) was performed in 110 eyes of 58 children (aged 0-13 years) with craniosynostosis. Inclusion criteria were as follows: normal intracranial pressure (ICP) on invasive overnight monitoring, or clinically stable ICP. The latter was defined as stable VA within 1 logMAR line and no papilloedema on fundoscopy for at least four months following OCT, and normal/stable visual evoked potentials. Control data for 218 eyes of 218 children were obtained from a published normative dataset. The main outcome measures were disc width, cup width, rim width and retinal nerve fibre layer (RNFL) thickness (nasal and temporal). Outcome measures were compared using three-way linear mixed model regression analysis (FGFR 1/2-associated craniosynostosis, non-FGFR 1/2-associated craniosynostosis, and controls). Out of 63 eligible children with craniosynostosis, handheld OCT imaging was successful in 110 eyes of 58 children (92%). Of these, 22 (38%) were female. Median subject age at OCT examination was 53 months (range: 2 to 157; IQR: 39 to 73). Twelve children (21%) had FGFR1/2-associated syndromes (Crouzon, n=6; Apert, n=4; Pfeiffer, n=2). Control data were available for 218 eyes of 218 healthy children. 122 controls (56%) were female. Median control age at OCT examination was 20 months (range: 0 to 163; IQR: 6 to 59). When comparing optic nerve head morphology in craniosynostosis (n=58) versus controls (n=218), disc width was 6% greater (p=0.001), temporal cup width was 13% smaller (p=0.027), rim width was 16% greater (p<0.001) and temporal RNFL was 11% smaller (p=0.027). When comparing FGFR1/2-associated syndromes (Crouzon, Apert and Pfeiffer syndromes, n=12) to the rest of the craniosynostosis group (n=46), disc width was 10% smaller (p=0.014) and temporal cup width was 38% smaller (p=0.044). This cohort demonstrated morphological differences of the optic nerve head in craniosynostosis, most markedly in Crouzon, Apert and Pfeiffer syndromes. These findings could help improve ophthalmological monitoring and surgical decision-making in children with craniosynostosis. Further work on longitudinal optic nerve head changes in syndromic and non-syndromic craniosynostosis would be valuable.

Sharks and rays at Pelabuhan Perikanan Samudera (PPS) Lampulo, Banda Aceh, Indonesia: Morphometric characteristics and differentiators based on multivariate analysis

Tropical marine environments are abundant and diverse; therefore, shark and ray research at fishing port PPS Lampulo, Banda Aceh City was carried out focusing on morphometric characteristics and differences based on multivariate analysis in July 2020 to identify sharks and rays that landed at fishing port PPS Lampulo, Banda Aceh City and determine their primary characteristics. The shark and ray samples used were from the Indian Ocean and the Malacca Strait and measured total length (TL), fork length (FL), and standard length (SL) for sharks and disc width (DW), TL, and disc length (DL) for rays. Principal component analysis (PCA) and discriminant analysis (DA) were performed on the morphometric data. The PCA analysis revealed that sharks and rays caught in Pelabuhan Perikanan Samudera (PPS) Lampulo, Banda Aceh City, can be divided into two distinct groups. The first group of sharks consists of species with large FL and SL morphometrics, namely P. kamoharai, C. plumbeus, P. glauca, and A. superciliosus. The second group of sharks consists of species with large TL morphometrics, specifically A. pelagicus and C. plumbeus. For the ray group, the first group comprises species with large TL and DW morphometrics, represented by A. ocellatus. The second group of rays consists of species with large DL morphometrics, namely P. sephen and H. jenkinsii. The results of DA revealed distinct differences in the size of sharks caught in the Indian Ocean and the Strait of Malacca, specifically in PPS Lampulo, Banda Aceh City. However, no significant differences in size were observed for the rays, regardless of whether their size was measured using DW, TL, or DL.

Surgical outcomes and complications associated with ovariectomy in the southern stingray Hypanus americanus.

Southern stingrays (Hypanus americanus) are relatively large rays that are common and popular in public aquariums because of their size and gentle nature. In aquariums, as well as in the wild, female southern stingrays are fecund. They have a short gestation cycle and can sustain multiple pregnancies each year, each culminating with 2-10 young. This reproductive rate could quickly outpace capacity in managed care and result in a ray surplus. To prevent overpopulation, many aquaria have resorted to single sex groups with a preference for female-only populations. This is an effective way to control population growth, but forces the maintenance of two separated populations of rays; for females this interrupts normal reproductive cycling and replaces it with a protracted non-pregnant condition. An additional consideration is development of reproductive disease in females which is recognized by an enlarged, misshapen, and congested ovary with an abundance of cystic structures and an enlarged uterus with a thickened wall that is often filled with histotroph despite a non-pregnant status. There are no effective long-lasting medical treatments for this type of reproductive disease and mortality is often the result. This report describes a surgical technique for ovariectomy in southern stingrays including outcomes and complications. Ovariectomy as a surgical method prevents unwanted reproduction and has the benefit of reducing reproductive pathologies commonly observed in southern stingrays as they age. Seven stingrays 1-5.2 years old and 42-83.5 cm disc width underwent ovariectomy. After anesthesia, the ovary and a small amount of epigonal was excised via a left para-lumbar incision. Four of the seven rays survived five or more years post-procedure. Two rays died acutely of coelomitis and one ray died of complications unrelated to the procedure. This report details a surgical procedure for ovariectomy in southern stingrays including outcomes, complications, and recommendations.

Sexual dimorphism in the dwarf round ray Urotrygon nana.

This paper presents information on the morphological, morphometric, and dental sex differences in the dwarf round ray Urotrygon nana. We recorded 12 morphological traits, sex, the distribution pattern of dermal denticles, the number of tooth rows, and the tooth shape of 466 individuals. The disc width of females ranged from 50 to 172 mm and that of males ranged from 53 to 135 mm. A neuronal classification model and a correspondence analysis showed that female disc width was 21.5% broader, and the distance from the rostrum to the anus was 17.7% longer than that of males, whereas males presented 19.5% greater distance between the nostrils, 9.7% greater preorbital snout length, 6.8% greater cloaca to caudal-fin length, 2.7% greater interorbital distance, and 1.1% greater total length than females. The disc of adult males, including the abdominal cavity area, was densely covered with dermal denticles, which were slightly larger than those observed in females. Females presented homodont dentition with molariform teeth and a smooth lozenge-shaped crown with rounded margins. Males exhibited homodonty but with tooth morphology variations in individuals of different sizes (from molariforms to sharper cusp teeth). There were changes in disc shape (from subcircular to oval), distribution and size of dermal denticles (more abundant and larger), and tooth shape (from molariform to monocuspid teeth) during male development, from neonates to adults. U. nana exhibited sexual dimorphism in size, disc shape, number and shape of teeth, and distribution and size of dermal denticles.

Morphological Rule-Constrained Object Detection of Key Structures in Infant Fundus Image.

The detection of optic disc and macula is an essential step for ROP (Retinopathy of prematurity) zone segmentation and disease diagnosis. This paper aims to enhance deep learning-based object detection with domain-specific morphological rules. Based on the fundus morphology, we define five morphological rules, i.e., number restriction (maximum number of optic disc and macula is one), size restriction (e.g., optic disc width: 1.05 +/- 0.13 mm), distance restriction (distance between the optic disc and macula/fovea: 4.4 +/- 0.4 mm), angle/slope restriction (optic disc and macula should roughly be positioned in the same horizontal line), position restriction (In OD, the macula is on the left side of the optic disc; vice versa for OS). A case study on 2953 infant fundus images (with 2935 optic disc instances and 2892 macula instances) proves the effectiveness of the proposed method. Without the morphological rules, naïve object detection accuracies of optic disc and macula are 0.955 and 0.719, respectively. With the proposed method, false-positive ROIs (region of interest) are further ruled out, and the accuracy of the macula is raised to 0.811. The IoU (intersection over union) and RCE (relative center error) metrics are also improved .

Modic changes in the lumbar vertebral column of chondrodystrophic and non-chondrodystrophic dogs with intervertebral disc disease.

Modic changes (MC) are signs of vertebral pathology visible on magnetic resonance (MR) images that have been associated with low back pain (LBP) and disc degeneration in people. Multiple breeds of dogs also develop MCs and coincident back pain. However, the association between breed, MC, and spinal pathologies has yet to be fully elucidated. This study aimed to identify the prevalence of MC that occur spontaneously in the lumbar vertebral column of dogs diagnosed with intervertebral disc disease (IVDD) and examine their association with demographic criteria and the disc width index (DWI). Medical records and lumbar vertebral column MR images were examined from 104 dogs (831 intervertebral disc spaces and adjacent vertebrae), which were divided into three groups: chondrodystrophic dogs (CD; n =54) and non-chondrodystrophic dogs (NCD; n =30) with IVDD as the primary diagnosis, and control dogs (n =20) with other spinal diseases as their primary diagnosis. Increasing age and a diagnosis of IVDD were significantly associated with MC in dogs (p < 0.001 and p = 0.0062, respectively). In CD dogs with IVDD, Type 2 MC were most prevalent, whereas, in NCD dogs, Type 3 MC were the most prevalent type. Type 2 MC were distributed nearly equally across the lumbar vertebral column, while Type 3 MC were primarily detected at the level of L7-S1. This study demonstrated that MC developed spontaneously in dogs, are common in dogs diagnosed with IVDD, and the type observed varies by breed. Further research is needed to understand the pathogenesis of MC; however, the increased presence of Type 2 MC in CD dogs, similar to what is found in people with disc degeneration, suggests that CD dogs could serve as models for MC in people.

Size at sexual maturity, seasonal variation by maturity stages, and fecundity of the spotted round ray (Urobatis maculatus) and the thorny stingray (Urotrygon rogersi) from the northern tropical eastern Pacific.

Round rays (family: Urotrygonidae) are commonly caught as by-catch by shrimp trawl fisheries in the tropical eastern Pacific (TEP). However, little information on their life history and catch species composition exists for most round ray species, preventing the evaluation of the impact of fishing on their populations. The mean size at sexual maturity (DW50), seasonal variation by maturity stages, and fecundity for two round ray species caught during shrimp trawl research cruises in the south-eastern Gulf of California (northern TEP) were estimated using a multi-model approach and inference for the first time, to determine the part of the population of each species that is being affected by shrimp trawling. Disc width (DW) ranged from 7.0 to 30.9 cm for the spotted round ray (Urobatis maculatus), and 7.2-33.5 cm for the thorny stingray (Urotrygon rogersi), with females reaching larger sizes than males in both species. The DW50 was estimated at 12.8 and 11.8 cm DW for the males and females of U. maculatus, respectively, whereas for U.rogersi, it was 15.0 and 18.4 cm DW for males and females, respectively. Embryos were found in females ≥14.5 cm DW in both species. The maximum fecundity was five embryos for U. maculatus (mean = 3.1 ± 0.2 S.E., mode = 4), and six embryos for U. rogersi (mean = 3.0 ± 0.3 S.E., mode = 2). Fecundity and embryo size did not vary with maternal size. Male and female immature and mature individuals for both species, including pregnant females, were found in the catches in all seasons of the year. Our results can help determine the vulnerability of the studied species populations to fishing pressure from shrimp trawling in the northern TEP and guide the development of future monitoring strategies and conservation actions for these species, if necessary.

A NEW MOORISH IDOL (TELEOSTEI, ZANCLIDAE) FROM THE EOCENE OF BOLCA, ITALY

The acanthuriform family Zanclidae, whose members are commonly known as moorish idols, has until now been comprised of two species, the extant Zanclus cornutus and the Eocene Eozanclus brevirostris. Herein, a new moorish idol, Angiolinia mirabilis n. gen. et sp., is described based on three specimens from the Eocene Pesciara site of the Bolca locality, northern Italy. Morphologically, Angiolinia mirabilis n. gen. et sp. appears to be intermediate between Eozanclus brevirostris and Zanclus cornutus and differs from them by having the following features: body depth 85–87% SL; head length 38.3–39.2% SL; third dorsal-fin spine reaching about 50% SL; pectoral disc width 23.2% SL; dorsal fin containing 31 or 32 rays; anal fin containing 26 or 27 rays; pectoral fin with 11 or 12 moderately elongate rays and caudal fin truncate. A comparative osteological analysis suggests that the family Zanclidae is defined by two morphological features, namely the presence of a broadly expanded and anteroventrally convex cleithrum forming the so-called pectoral disc together with the coracoid and having a large number of dorsal- and anal-fin rays. The Eocene acanthuriform Massalongius gazolai from Bolca represents the sister group to the Zanclidae. Within the zanclids, Eozanclus brevirostris represents the sister group to the pair formed by Angiolinia mirabilis n. gen. et sp. and Zanclus cornutus. This clade is supported by the shared possession of a single supernumerary spine on the first dorsal-fin pterygiophore, a single uroneural in the caudal skeleton, and all but the first two dorsal-fin spines distally filamentous.

A uniform analysis of debris discs with the Gemini Planet Imager II: constraints on dust density distribution using empirically informed scattering phase functions

ABSTRACT Spatially resolved images of debris discs are necessary to determine disc morphological properties and the scattering phase function (SPF) thatantifies the brightness of scattered light as a function of phase angle. Current high-contrast imaging instruments have successfully resolved several dozens of debris discs around other stars, but few studies have investigated trends in the scattered-light, resolved population of debris discs in a uniform and consistent manner. We have combined Karhunen-Loeve Image Projection (KLIP) with radiative-transfer disc forward modelling in order to obtain the highest-quality image reductions and constrain disc morphological properties of eight debris discs imaged by the Gemini Planet Imager at H-band with a consistent and uniformly applied approach. In describing the scattering properties of our models, we assume a common SPF informed from solar system dust scattering measurements and apply it to all systems. We identify a diverse range of dust density properties among the sample, including critical radius, radial width, and vertical width. We also identify radially narrow and vertically extended discs that may have resulted from substellar companion perturbations, along with a tentative positive trend in disc eccentricity with relative disc width. We also find that using a common SPF can achieve reasonable model fits for discs that are axisymmetric and asymmetric when fitting models to each side of the disc independently, suggesting that scattering behaviour from debris discs may be similar to Solar system dust.

Length-weight relationship for Potamotrygon wallacei (Carvalho, Rosa and Araújo, 2016) caught in the middle Negro River, Barcelos, Brazilian Amazon.

This research aimed to estimate the length-weight ratio (LWR) of the stingray Potamotrygon wallacei, known locally as the cururu, which was caught in streams and lakes in the middle Negro River region, Amazonas, Brazil. The stingrays were captured during the night (from 11 pm to 1 am) near the shores of streams and lakes, through active search using wooden canoes, head lanterns and scoop nets. The samplings were carried out in November 2017 (5 days), February (8 days), March (3 days) and April (2 days) of 2018, totaling 18 days of sampling. The total fresh weight was measured to 0.1 g of accuracy and the disc width to 0.1 cm accuracy. The parameters a and b of the equation W=a.DWb were estimated. This study provides new maximum length data for the cururu stingray.

Comparing optic nerve head parameters in two Spanish dog breeds using digital planimetry

The optic discs of dogs exhibit considerable size, shape, and colour variations, depending on the degree of myelination. This variability makes the interpretation of lesions difficult, owing to the lack of reference patterns. This study aimed to compare optic nerve head (ONH) parameters determined by digital planimetry (DP) in two pure-bred dogs, Spanish Greyhound (SG) and Spanish Water Dog (SWD). The vertical and horizontal diameters, area, circularity, and the proportion of the ONH at the tapetal or non-tapetal zone (top height and bottom height) were calculated using image treatment software and compared between breeds.Significant between-breed differences were detected for all parameters, with SWD exhibiting greater height, width, area, top height, and lower circularity of the ONH than SG. Linear regression revealed that age significantly influenced mean disc height (R2 = 0.310; p = 0.0001), mean disc width (R2 = 0.280; p = 0.0001), mean disc area (R2 = 0.281; p = 0.0001), and circularity (R2 = 0.243; p = 0.0001). The multiple regression model significantly predicted mean disc height, width, and area [(S) (R2 = 0.715; p = 0.001), (R2 = 0.742; p = 0.001), and (S) (R2 = 0.736; p = 0.001), respectively], based on age and breed. Excellent concordance was observed between the measurements of experienced and novice researchers, and there were no differences between the parameters measured by the researcher and those obtained by the software. Planimetric ONH measurements can be easily performed by novice operators using a portable fundus camera and digital computer software. These results may be of considerable clinical value, but further studies are required because of the great variability of the ONH in dogs.

Eccentric debris disc morphologies – II. Surface brightness variations from overlapping orbits in narrow eccentric discs

ABSTRACT We present Paper II of the Eccentric Debris Disc Morphologies series to explore the effects that significant free and forced eccentricities have on high-resolution millimetre-wavelength observations of debris discs, motivated by recent ALMA images of HD53143’s disc. In this work, we explore the effects of free eccentricity, and by varying disc fractional widths and observational resolutions, show for a range of narrow eccentric discs, orbital overlaps result in dust emission distributions that have either one or two radial peaks at apocentre and/or pericentre. The narrowest discs contain two radial peaks, whereas the broadest discs contain just one radial peak. For fixed eccentricities, as fractional disc widths are increased, we show that these peaks merge first at apocentre (producing apocentre glow), and then at pericentre (producing pericentre glow). Our work thus demonstrates that apocentre/pericentre glows in models with constant free and forced eccentricities can be both width and resolution dependent at millimetre wavelengths, challenging the classical assertion that apocentre/pericentre glows are purely wavelength dependent. We discuss future high-resolution observations that can distinguish between competing interpretations of underlying debris disc eccentricity distributions.

Establishment of a 2-dimensional echocardiographic protocol and reference parameters for clinically healthy southern stingrays (Hypanus americanus).

To establish an echocardiographic technique and 2-dimensional reference parameters for southern stingrays (Hypanus americanus). A second objective was to compare echocardiographic measurements obtained from animals of different sex, size, environment, handling technique, and position. 84 presumed healthy, wild, semiwild, and aquarium-housed southern stingrays. Animals, anesthetized and manually restrained, were positioned in dorsal recumbency, and echocardiography was performed. A subset of this population was also imaged in ventral recumbency for comparison. Echocardiography was feasible, and reference parameters were established for this species. While some standard measurements could not be assessed due to body habitus, all valves, chambers, and the conus were clearly visualized in the majority of animals. Statistical significance was reached for some variables when comparing animals from different environments and handling methods, but these differences were not considered clinically relevant. The data were therefore separated into 2 subsets of echocardiographic reference parameters based on disc width since some of the measurements were dependent on body size. This approach mostly separated the sexes due to strong sexual dimorphism. Limited information is available regarding cardiac disease in elasmobranchs; most of the available information on cardiac physiology focuses on a few shark species. Two-dimensional echocardiography is a noninvasive tool utilized to evaluate cardiac structure and functionality. Southern stingrays are one of the most commonly displayed elasmobranchs in public aquaria. This article expands on the growing body of information regarding veterinary care in elasmobranchs and provides clinicians and researchers with another diagnostic modality to utilize in screening for health/disease.

Life history (length-weight relationship, conditional factors, reproductive aspects), stomach contents and nursery ground of stingray in the Arafura Sea

Stingrays are a resource that is vulnerable to overfishing and habitat degradation. The research was conducted to obtain data and information that is still lacking and much needed for the utilization and protection of stingrays, including; life history, stomach contents, and nursery ground. The study was conducted in October - November 2018 by exploratory, including taking stingrays by trawling and measuring habitat conditions with Conductivity, Temperature, and Depth. The results showed a total stingrays are 744 individuals, weighing 2,986.6 kg and 24 species. Individual stingrays have a width disc range of 9-134 cm and a weight of 20-67000 g. The growth pattern of stingrays is generally allometric, except for Gymnura zonura. The average value of the relative condition factors is generally >1, except for Aetomylaeus maculatus and Brevitrygon walga. Stingrays have an unbalanced sex ratio, gonads consist of 43% adolescent and 57% mature, and the number of neonates is 1-6 /parent. The correlation between clasper length and disc width is generally positive, except for Hemitrygon longicauda. Of the stomach contents of all stingray species, 64 % is shrimp, Himantura leoparda which have various prey. The area east of Aru and west of Papua are the locations used as nursery grounds by most various stingrays. Nursery grounds of Stingray is generally shallow coastal areas with low oxygen, eutrophic and high turbidity. The results of this study are expected to be used as a basis for managing stingray resources in the Arafura Sea and further research is recommended to be carried out in four different seasons.

Age and Growth Characteristics of Okamejei kenojei in the West Sea of South Korea According to Coronal Vertebral Microstructure

In this study, the growth and age characteristics of Okamejei kenojei in the West Sea of South Korea were examined, and specimens were collected by bottom trawls from January to December 2019. The relationship between disc width (L) and body weight (W) was W = 6.1 × 10−3 L3.40. Age was determined by measuring annuli on the vertebral centrum surface, which forms around June every year. The spawning period was extrapolated from monthly changes of the gonadosomatic index in June–July. The relationship between the vertebral centrum radius and disc width, which was analyzed separately for females and males, was determined as L = 16.159R0.6145 and L = 15.543R0.6851, respectively. Finally, O. kenojei growth, that is, the disc width (L) at a certain age (t), was expressed using the von Bertalanffy growth equation as Lt = 58.70(1 − e−0.21(t+0.12)) for females and Lt = 53.94(1 − e−0.26(t+0.05)) for males. This study provides basic data on the age characteristics of O. kenojei for future research and more efficient fish stock management.

The first record of gravid spiny butterfly ray (Gymnura altavela) in the northern Mediterranean Sea, with description of near-term foetuses.

This paper describes the first record of the critically endangered gravid female spiny butterfly ray, Gymnura altavela (Linnaeus, 1758), in the northern Mediterranean and simultaneously the only record of the species in this century for the Adriatic Sea. The female (173 cm disc width and 43.25 kg total weight) was captured at c. 200 m, off Vlorë in the southern Adriatic Sea off Albania on 12 May 2022. Upon necropsy, seven near-term foetuses (mean 328 ± 6.47 mm disc width and mean 355 ± 20.06 g in total weight) were transported for further in-vitro incubation. These results represent the deepest capture for the species, as well as the largest litter size and largest size at birth in the Mediterranean Sea, which indicates the need for further research.

Multi-decade catches of manta rays (Mobula alfredi, M. birostris) from South Africa reveal significant decline

Manta rays (Mobula alfredi and M. birostris) are poorly understood in South Africa, despite their ecological importance and charismatic appeal. This study analyzed a 41-year dataset from the KwaZulu-Natal bather protection program to investigate catch per unit effort between 1981-2021. We used Generalized Additive Models and the probability of encounter to assess annual and seasonal trends, as well as the effect of location and moon phases on catch rates. We also evaluated the size composition and demographics of caught manta rays using the same dataset. Our analysis revealed a significant decline in overall manta ray catches since the late 1990s (p&amp;lt;0.0001), with increased catch rates during summer, suggesting seasonal visitation to South African waters. We found that manta rays were caught at least once in all 46 netted beaches along the 350 km span of coastline, but with significantly more catches in the Central Area, between Anstey’s beach in the north and Mtwalume in the south. We also observed that moon phase had an effect on manta ray presence, with significantly more catches during spring tides at new and full moon phases. Over half of the caught individuals were juveniles, and a total of 841 individuals (52% of the total catch) belonged to the confirmed juvenile size class (1400-2500 mm disc width). We further found that a greater proportion (70%) of juveniles were caught in the southernmost sampled area, from Hibberdene in the north to Mzamba in the south. These findings highlight the importance of South African waters as a seasonal habitat for manta rays along the southern African coastline. The significant decline and spatial-temporal patterns we observed have critical implications for management and conservation efforts. Our study provides valuable baseline data for future research and underscores the need for continued monitoring and protection of these iconic marine species.

Biological observations and new maximum reported sizes for two threatened rays: ornate eagle ray Aetomylaeus vespertilio and mangrove whipray Urogymnus granulatus from the Gulf of Mannar, India

Abstract Record-sized specimens of the ornate eagle ray Aetomylaeus vespertilio and mangrove whipray Urogymnus granulatus were caught by single-day trawlers off Pamban Island in the Gulf of Mannar, Tamil Nadu, India during 2021 and 2022. All were landed at the Pamban Therkuvadi Fish Landing Centre (FLC). The largest ornate eagle ray was 384 cm disc width (DW) and weighed 530 kg, setting a new global record for the species, as the previous maximum size was reported to be 300 cm DW. This specimen was landed on 19 July 2021. Another large specimen of this species (360 cm DW and total weight of 453 kg) was caught and landed on 12 August 2022. The landed mangrove whipray was 153 cm DW and 150 kg total weight, larger than the previously reported maximum size of 141 cm DW. The morphometrics, stomach contents and reproductive state were studied. One of the eagle rays was a pregnant female with three full-term embryos in the uterus, while the whipray was a spent female. The main prey species in the stomach of eagle ray was big-eye scad Selar crumenophthalmus. The mangrove whipray had fed on a range of fish (pigface bream, goatfish, silverbellies, silverbiddies and lesser sardine) and octopus.

Seasonal variation in space use and residency of the southern eagle ray Myliobatis tenuicaudatus in a temperate ecosystem

The environmental conditions determining the distribution of the southern eagle ray Myliobatis tenuicaudatus are mostly unknown. We tracked 40 southern eagle rays using a network of 28 acoustic receivers deployed in Coffin Bay and a second array of 6 receivers deployed along the Fleurieu Peninsula, both in South Australia, to investigate the spatiotemporal changes in space use and residency and the influence of biotic (disc width, sex) and abiotic (water temperature, salinity, tides, moon illumination, time of day) factors. We also assessed the efficacy of a small sanctuary zone to reduce anthropogenic pressures. Tagged southern eagle rays in Coffin Bay were semi-permanent residents (residency index ~ 0.35), with a seasonal exodus from late autumn to spring, high residency from mid-spring to mid-autumn, and selection of Kellidie Bay (located within Coffin Bay). Most (67%) rays were detected in the Kellidie Bay Sanctuary Zone, but spent &lt;15% of their time in Coffin Bay within the sanctuary. Individual variation in the amount of time spent in the Kellidie Bay Sanctuary Zone was high, ranging 0-42%. In contrast, tagged southern eagle rays along the Fleurieu Peninsula had high site fidelity throughout the year (residency index ~ 85%). Our study provides new information on space use and movement patterns of southern eagle rays, highlighting that intraspecific variation should be accounted for in future management considerations.

Multiple datasets confirm range extension of the sicklefin devil ray Mobula tarapacana in the western North Atlantic Ocean off the eastern USA

Abstract The sicklefin devil ray (Mobula tarapacana) is a large, pelagic ray which is listed as Endangered by the International Union for Conservation of Nature (IUCN). Mobula tarapacana is thought to have a circumglobal, yet patchy distribution, and has not been verified extant off the eastern USA. Here, we report 180 sightings of M. tarapacana with a total of 361 individuals, collated across five datasets from aerial survey operations and incidental sightings in the waters off the US East Coast and Gulf of Mexico, between 1996 and 2022. This study extends the northern range of M. tarapacana in the Gulf of Mexico to 29°N, and in the Atlantic to 40°N. Seasonal trends were observed off the north-eastern coast of the USA, with M. tarapacana only present in the summer months. Measurements from high resolution digital aerial imagery found M. tarapacana off the New York coast to be adults and subadults with an average disc width of 268 cm (±25, range 232–316 cm). This study provides important spatial and temporal data for management, as well as informing areas for future research on M. tarapacana in the western Atlantic.