Search Results (19)

The Eastern Aegean Sea hosts a diverse assemblage of elasmobranchs, many of which are vulnerable or endangered. This study presents a fishery-independent assessment of species composition, catch characteristics, and spatial patterns in bottom trawl fisheries between Lesvos Island and Ayvalik. A total of 48 surveys were conducted between September 2022 and October 2024, identifying nine elasmobranch species, with Scyliorhinus canicula (small-spotted catshark) and Mustelus mustelus (common smooth-hound) dominating the catch. Biological parameters, sex ratios, and condition upon capture and release were recorded, while catch per unit effort (CPUE) and diversity indices were used to evaluate temporal patterns. The survival probability was negatively affected by the trawl duration and elevated temperatures, emphasizing the need for mitigation measures. Spatial models revealed high-density zones that likely function as foraging or nursery grounds. Seasonal shifts in community composition were also evident. Many non-commercial species were discarded irrespective of their size or condition. These findings underscore the ecological importance of this understudied region and support the need for spatially explicit, species-specific management strategies, including gear selectivity improvements, seasonal closures, and Electronic Monitoring. The study offers a critical baseline for enhancing the sustainability of elasmobranch populations in the Eastern Mediterranean. Full article

The post mortem exam is important in diagnosing and investigating wildlife diseases. It is even more important to monitor the population of species that are not easily observed in the wild, such as otters. Of the 13 otter species, 11 are endangered due to many factors, such as climate change, pollution, or urbanisation. The authors present a review of the patterns of mortality of free-ranging otters worldwide, aiming to improve the knowledge of otter mortality and the role of mortality studies in their conservation. The main cause of death in aquatic otters is vehicle collision; hence, sea otter deaths are associated with shark attacks and imprisonment in fishing gear. It is possible to conclude that humans and human activity play a significant role in the mortality of these animals. In the future, a more standardised analysis of otter carcasses is necessary to understand their threats and diseases and design significant measures to protect these species. Full article

Rehabilitation of marine mammals is performed throughout the world, yet the impact of rehabilitation on individuals and populations is questionable given the lack of robust information on the rehabilitation process and post-release monitoring in most cases. The goals of this study were to perform a systematic review of existing literature on marine mammal rehabilitation between 2000–2023 to determine the current state of rehabilitation and to evaluate the rehabilitation and conservation factors that could be used to build a framework to assess the health of rehabilitation programs worldwide. A total of 418 publications encompassing 52 species of marine mammal were included in the systematic review. Rehabilitation efforts focused mostly on pinnipeds, and North America was the most represented region. Data are scarce for both short- and long-term post-release survival across species. Reports about species threatened with extinction were significantly more likely to include information about conservation parameters than those species of least concern. A meta-analysis demonstrated a fairly strong fit of the dimensions of the proposed framework for a rehabilitation health index. Further refinement would strengthen the utility of this tool for both rehabilitation and conservation programs. Full article

The arrival of a new invasive alga, Rugulopteryx okamurae, in the Strait of Gibraltar (SoG) in 2015 marked an unprecedented milestone in the North African and, later, in the European marine ecosystems. Nowadays, it is colonising vast infralittoral areas and significantly modifying some habitats and associated communities of the southern Iberian Peninsula. In recent expeditions, a high amount of free drifted thalli of this alga has been detected in different circalittoral and bathyal habitats of the northern SoG and the Alboran Sea. The present study combines quantitative data of this alga obtained with the use of a remotely operated vehicle (ROV) and a bottom otter trawl. The coverage–entanglement level of the drifted thalli on circalittoral and bathyal benthic invertebrates (e.g., not covering, covering only the basal part, covering one-third of the invertebrate, etc.) was also annotated from picture frames taken in locations with abundant drifted thalli. In underwater images, drifted thalli were mainly detected in circalittoral and bathyal bottoms of the northern SoG and the north-western Alboran Sea, between 50 to ca. 450 m depth. Nevertheless, abundant drifted thalli were also detected in bottom otter trawl samples from circalittoral bottoms of the north-central and north-eastern Alboran Sea. Small benthic organisms (e.g., encrusting sponges, hydrozoans, etc.) generally displayed low coverage–entanglement levels of drifted thalli. Nevertheless, large sessile and colonial benthic organisms with a complex three-dimensional morphology (e.g., gorgonians, colonial scleractinians) reached high levels of R. okamurae thalli entangled in different parts of their colonies. The drifted R. okamurae thalli entangled in these colonial suspension feeding organisms may hinder their feeding capability in the long term, resulting in habitat deterioration in the near future. Full article

Fecal glucocorticoid metabolites (FGMs) have been used as a non-invasive and indirect measurement of the complex stress response in a variety of species. Animals in facilities under managed care allow for the longitudinal study of FGMs in a controlled environment. Animal histories often include environmental, husbandry, and medical notes that can be matched to FGM concentrations to aid in the physiological validation of adrenal stimulation and response. The goal of this study was to demonstrate analytical validations using two enzyme-linked immunosorbent assays (EIA) to measure FGMs from northern sea otters (Enhydra lutris kenyoni) under human care (Seattle Aquarium, Seattle, WA, USA) and to determine baseline and stress response spike levels for individual sea otters. Individual variation was found among the four subjects in the study with fecal baseline levels ranging from 20.2 to 83.7 ng/g for cortisol-immunoreactive metabolites and 52.3 to 102 ng/g for corticosterone-immunoreactive metabolites. As a retrospective study, 39 percent of hormone peaks were associated with notes and most FGM spikes were associated with veterinary procedures or days in which enrichment items were provided and produced an excitatory response. Monitoring baseline FGMs levels and events associated with hormone peak values may provide insight into effective husbandry management to improve the overall welfare of sea otters and other marine mammals. Full article

Currently, the illegal wildlife trade is one of the most profitable illegal enterprises in the world. The aim of our study was to determine the situation with respect to wildlife trade in Slovenia, which is mainly a transit country, before changes to the Schengen borders came into effect. The volume of trade is significant but not extensive. The most common endangered species involved in illegal trade in Slovenia are the brown bear, the peregrine falcon, the date mussel, the lady’s slipper orchid, the common snowdrop, the cyclamen, the sea turtle, the otter, and various reptile species. The smuggling of shells (date shells), ivory (ivory products), certain plants, and various hunting trophies (bears, big cats) has decreased in recent years. Nevertheless, counteracting crimes continues to be important for the conservation of some species in Slovenia, notably the lynx, and for the reduction of poaching. Improvements are needed in the detection and prevention of wildlife crime, especially in light of changes made to the Schengen borders and the consequent inclusion of new trading partners for Slovenia. The lack of people properly trained to identify, detect, and investigate wildlife crime is especially acute. Full article

Conventional and varietal heavy mineral studies of the earliest Eocene Hermod S2 Member (Mbr) sandstones in the Greater Alvheim area of the northern North Sea have revealed marked lateral variations and more subtle vertical evolution in provenance signature. Major variations are of geographic rather than stratigraphic nature as biostratigraphy reveals that all investigated sandstones are coeval. The provenance variations show an organized pattern, with sandstones in the north showing a different signature than those in the south. The position of the sandstones relative to the East Shetland Platform (ESP) is inferred to be the main control on provenance, with sediment input from at least two different point sources. Sediment supplied from both catchments is predominantly recycled in nature, given the mineralogical maturity of the heavy mineral assemblages, consistent with the evidence for widespread Permo-Triassic and Devonian sediments on the ESP. However, some direct supply from metasedimentary (Moine and Dalradian) basement is implied by the sporadic occurrence of unstable minerals. The southern catchment incorporated a greater exposure of Permo-Triassic sandstones than the northern catchment. The Permo-Triassic part of the catchment can be reconstructed as comprising equivalents of the Foula and Otter Bank sandstones present to the west of Shetland, with the majority of the Foula section having been stripped off prior to Hermod S2 deposition, exposing Otter Bank equivalents for erosion and redeposition. However, remnant Foula-like sandstones remained exposed further south on the ESP until at least the earliest Eocene since Foula-type garnet signatures are found in the Forties Sandstone Mbr of the central North Sea. In addition to lateral differences, stratigraphic evolution of provenance can also be detected in the Hermod S2 Mbr, with variations in key provenance-sensitive parameters related to a sea-level rise that reduced the extent of alluvial storage and altered the geological framework of the hinterland. Full article

As biodiversity continues to decline across the globe, conservation of wildlife species and the ecosystems they inhabit is more important than ever. When species dwindle, ecosystems that depend on them are also impacted, often leading to a decrease in the life-giving services healthy ecosystems provide to humans, wildlife, and the global environment. Methods of wildlife conservation are complex and multi-faceted, ranging from education and advocacy to, research, restoration, and rehabilitation. Here, we review a conservation program focused on helping recover the federally listed threatened southern sea otter (Enhydra lutris nereis) population. We describe the development of unique rehabilitation methods and steps taken to advance the program’s conservation impact. Understanding this evolution can inform conservation efforts for other vulnerable species and their ecosystems. Full article

From 1 June 2010 in the Italian coastal waters of the Northern Adriatic Sea, trawl fishery within three nautical miles became banned. This activity was previously allowed for some species as an exception to legislation. In order to evaluate the consequences both on demersal resources and economic yields of the trawl which will oblige fishermen to trawl beyond three miles, a pilot study was performed. Twenty hauls comparing catch discard and income between hauls within and external to three nautical miles were performed. Results highlighted differences in catch composition both for landing and discard. Landing per unit of effort and discard per unit of effort did not differ in relation to distance from the coast, while income was higher for offshore hauls than inshore ones even if not significantly. Fishery management is a complex task, and the results of this study can contribute to the debate providing new insights into the consequences of the regulation on the trawling within three nautical miles. Considering the high amounts of discard, the habitat damages caused by otter trawling, the presence of juveniles in coastal waters and data regarding fishermen income, this study supports the actual European Community regulation on coastal trawling. Full article

The impact of otter trawling on the relationship between functional traits of benthic invertebrates and specific biogeochemical processes were investigated in the oligotrophic Cretan Sea. The fishery is managed through a seasonal closure during the summer. During two seasons (winter and summer) replicate samples were taken from the field from a commercial trawl ground and an adjacent control area. Environmental parameters related to sediment biogeochemistry were measured including particulate organic carbon, sedimentary organic carbon, bottom water and sedimentary chlorophyll a and phaeopigment concentrations as well as benthic oxygen consumption. A significant impact of trawling was recorded only for bottom water chlorophyll and sedimentary organic carbon. Furthermore, the links between species traits and specific ecosystem processes were affected by trawling, highlighting the importance of unique functional modalities on ecosystem functioning. The traits that mostly influenced benthic biogeochemistry in the control sites were related to bioturbation and burrowing activities. In contrast, in the trawled sites, the associated traits were related to more opportunistic lifestyles and deposit feeding species that do not act as bioturbators. Thus, under trawling disturbance, this shift can decouple the species-sediment relations and affect nutrient cycling. Full article

An opportunistic investigation into ecosystem instability in Kachemak Bay (KBay), Alaska, has led us to investigate exposure to toxic algae in sea otters. We used gene expression to explore the physiological health of sea otters sampled in KBay in May 2019. We found altered levels of gene transcripts in comparison with reference sea otters from clinically normal, oil-exposed, and nutritionally challenged populations sampled over the past decade. KBay sea otters were markedly divergent from the other groups for five genes, which indicated the involvement of neurological, cardiac, immune, and detoxification systems. Further, analyses of urine and fecal samples detected domoic acid in the KBay sea otters. In combination, these results may point to chronic, low-level exposure to an algal toxin, such as domoic acid. With a warming climate, the frequency and severity of harmful algal blooms in marine environments is anticipated to increase, and novel molecular technologies to detect sublethal or chronic exposure to algal toxins will help provide an early warning of threats to the stability of populations and ecosystems. Full article

The Beibu Gulf in the northwestern South China Sea is one of the world’s most productive fishing grounds, yet its biotic resources appear to be in rapid decline because of overexploitation. Assessments of the health status of the fisheries’ resources in the gulf provide a foundation for their conservation and management. As fish accounted for 84% to 97% of the total catch in the Beibu Gulf in the period 1962–2017, a Fish-based Index of Biotic Integrity (F-IBI) was developed for the Beibu Gulf, and data from otter trawl surveys during the period 1962–2017 were used to measure variations in the fish community. The assessment revealed a generally downward trend in total fish catch density (kg/km²), catch density of 12 traditional commercial demersal fish species, and percentage of nektonic-feeding species, but an upward trend for the percentage of fishes with a planktivorous or detritus diet, percentage of pelagic species, and percentage of the dominant species. The dominant species varied greatly over the 50 year period and showed a tendency towards small-sized species. The synthetic F-IBI variable showed a downward trend and has indicated a ‘fair’ state since 1998. The decline in the F-IBI over the last three decades suggests that anthropogenic disturbances, especially overfishing, have had a serious impact on the fish community of the Beibu Gulf. The F-IBI is currently at risk of becoming ‘poor.’ Consequently, we suggest that rigid and enforceable fishery management measures should be taken by both China and Vietnam to prevent further deterioration of the fisheries’ resources in the gulf. Full article

Insects are the most evolutionarily and ecologically successful group of living animals, being present in almost all possible mainland habitats; however, they are virtually absent in the ocean, which constitutes more than 99% of the Earth’s biosphere. Only a few insect species can be found in the sea but they remain at the surface, in salt marshes, estuaries, or shallow waters. Remarkably, a group of 13 species manages to endure long immersion periods in the open sea, as well as deep dives, i.e., seal lice. Sucking lice (Phthiraptera: Anoplura) are ectoparasites of mammals, living while attached to the hosts’ skin, into their fur, or among their hairs. Among them, the family Echinophthiriidae is peculiar because it infests amphibious hosts, such as pinnipeds and otters, who make deep dives and spend from weeks to months in the open sea. During the evolutionary transition of pinnipeds from land to the ocean, echinophthiriid lice had to manage the gradual change to an amphibian lifestyle along with their hosts, some of which may spend more than 80% of the time submerged and performing extreme dives, some beyond 2000 m under the surface. These obligate and permanent ectoparasites have adapted to cope with hypoxia, high salinity, low temperature, and, in particular, conditions of huge hydrostatic pressures. We will discuss some of these adaptations allowing seal lice to cope with their hosts’ amphibious habits and how they can help us understand why insects are so rare in the ocean. Full article

E. coli was isolated from the Salish Sea (Puget Sound) ecosystem, including samples of marine and fresh water, and wildlife dependent on this environment. E. coli isolates were assessed for phenotypic and genotypic resistance to antibiotics. A total of 305 E. coli isolates was characterized from samples collected from: marine water obtained in four quadrants of the Salish Sea; select locations near beaches; fresh water from streams near marine beaches; and fecal samples from harbor porpoises (Phocoena phocoena), harbor seals (Phoca vitulina), river otters (Lontra canadensis), and English sole (Parophrys vetulus). Isolates were evaluated using antimicrobial susceptibility typing, whole-genome sequencing, fumC, and multilocus sequence typing. Resistance and virulence genes were identified from sequence data. Of the 305 isolates from Salish Sea samples, 20 (6.6%) of the E. coli were intermediate, and 31 (10.2%) were resistant to ≥1 class of antibiotics, with 26.9% of nonsusceptible (resistant and intermediate resistant) E. coli isolates from marine mammals and 70% from river otters. The proportion of nonsusceptible isolates from animals was significantly higher than samples taken from marine water (p < 0.0001). A total of 196 unique STs was identified including 37 extraintestinal pathogenic E. coli (ExPEC)-associated STs [ST10, ST38, ST58, ST69, ST73, ST117, ST131, and ST405]. The study suggests that animals may be potential sentinels for antibiotic-resistant and ExPEC E. coli in the Salish Sea ecosystem. Full article

Ice thickness and bed topography of fast-flowing outlet glaciers are large sources of uncertainty for the current ice sheet models used to predict future contributions to sea-level rise. Due to a lack of coverage and difficulty in sounding and imaging with ice-penetrating radars, these regions remain poorly constrained in models. Increases in off-nadir scattering due to the highly crevassed surfaces, volumetric scattering (due to debris and/or pockets of liquid water), and signal attenuation (due to warmer ice near the bottom) are all impediments in detecting bed-echoes. A set of high-frequency (HF)/very high-frequency (VHF) radars operating at 14 MHz and 30–35 MHz were developed at the University of Kansas to sound temperate ice and outlet glaciers. We have deployed these radars on a small unmanned aircraft system (UAS) and a DHC-6 Twin Otter. For both installations, the system utilized a dipole antenna oriented in the cross-track direction, providing some performance advantages over other temperate ice sounders operating at lower frequencies. In this paper, we describe the platform-sensor systems, field operations, data-processing techniques, and preliminary results. We also compare our results with data from other ice-sounding radars that operate at frequencies both above (Center for Remote Sensing of Ice Sheets (CReSIS) Multichannel Coherent Depth Sounder (MCoRDS)) and below (Jet Propulsion Laboratory (JPL) Warm Ice Sounding Explorer (WISE)) our HF/VHF system. During field campaigns, both unmanned and manned platforms flew closely spaced parallel and repeat flight lines. We examine these data sets to determine image coherency between flight lines and discuss the feasibility of forming 2D synthetic apertures by using such a mission approach. Full article