Sowerby's beaked whale is a deep-diving cetacean species specialized to live in the deep waters of the North Atlantic, including offshore Irish waters. Sightings of Sowerby's beaked whales in this area are infrequent and a substantial increase in our knowledge of their presence comes from recent static acoustic monitoring (SAM) and passive acoustic monitoring (PAM). However, most information on this species has been derived from stranding records, which provide opportunistic insights into this elusive species' cryptic life history. Here we report on the live stranding of a 1200 mm long neonate and an adult 5 m female Sowerby's beaked whale in July 2015 and on the stranding of a 4.9 m pregnant female in September 2020 with a 495 mm long male foetus in the south-west of Ireland. These stranding events provide an important insight into the reproductive life history of this species and provide further evidence that Sowerby's beaked whales calve in offshore Irish waters.

The strontium-to-calcium ratio (Sr/Ca) in aragonitic shells and statoliths often depends on temperature, and has been investigated for its potential availability as a sclerochronological record of the temperatures experienced during the life of the animal. Only a few cephalopod species have been subjected to rearing experiments to validate the temperature dependence of statolith Sr/Ca despite the strong demand for estimating their historical ecology, particularly of migratory squid populations. In this context, we examined the relationship between temperature and statolith Sr/Ca in the spear squid, Heterololigo bleekeri, by maintaining wild-caught immature individuals at one of three constant temperatures: 12, 14 or 16°C. A portion of statolith precipitated during the experiment was optically identified by daily increment analysis, and then subjected to Sr/Ca measurement using an electron probe micro-analyser. Regression analysis (N = 29) demonstrated the dependence of statolith Sr/Ca on temperature and the relationship was estimated as an equation Y = 9.93 (±0.29) − 0.11 (±0.02) X. However, ~90% of the total residual variance was accounted for by the among-individual variation of statolith Sr/Ca within each temperature group. Consequently, the 95% confidence interval ranged over ± 7.85°C when the temperature was estimated by inserting a Sr/Ca value into this equation. The statolith Sr/Ca values are unlikely to provide reliable estimates for absolute temperatures, but it may allow reconstruction of a time-series of relative temperatures experienced by a particular individual.

Fisheries constitute a major threat to marine mammals globally. To evaluate the impact of small-scale fisheries (SSF) on regional under-studied marine mammal populations, we tested a novel and cost-effective approach at three data-limited locations of the central and eastern Mediterranean Sea. Using off-the-shelf GPS loggers to track SSF activities and systematic surveys to map the distribution of marine mammals, we assessed the probability of co-occurrence between SSF and marine mammals by reporting areas of spatial overlap. Spatial overlap between SSF and the core zones of marine mammal distribution (ranging between 21.85–35.4%) was observed in all three locations, indicating potential interaction hotspots. The probability of co-occurrence in those areas varied from 0.5–2.9% depending on the species. The resulting overlap between fishing activity and marine mammals may pose a threat in both directions: higher risk of species entanglement and economic burden on fishers due to gear damage. Despite the spatial and temporal limitations of this pilot study, the proposed approach can provide baseline information on SSF-marine mammal co-occurrence, particularly in financially limited regions. If applied on a larger scale, our method may be used to inform future conservation actions with the aim to reduce pressure on key populations.

An opportunistic sighting of an Indo-Pacific humpback dolphin (Sousa chinensis) was reported in the nearshore waters off the east Liaodong Peninsula, China. This is the first at-sea sighting in this area, and the northern-most sighting record of this species with a distance >3000 km away from the nearest described conspecific population located in the mid-China. The present sighting occurred in close proximity to the location at which another Indo-Pacific humpback dolphin was found by-caught in 2003. The sighted individual could not be identified through the existing photo-identification catalogues of this species in China (>3500 individuals). Therefore, we suggest that a population of Indo-Pacific humpback dolphins that was never reported might exist in the north of the Yellow Sea.

The study compares the isotopic niche (δ13C–δ15N) of three species of penaeid shrimps (Xiphopenaeus kroyeri, Artemesia longinaris and Litopenaeus schmitti) that are targets of fishing in south-eastern Brazil. The two hypotheses raised are based on the niche theory, in which the coexistence between organisms that have similar dietary demands is possible due to trophic partitioning: (i) shrimp species that share the habitat have segregated isotopic niches; and (ii) stages of maturity and genders vary with the trophic habitat (δ13C) and/or trophic position (δ15N). In multispecific fishing grounds, the isotopic niches of the shrimp species were segregated or had low overlap, indicating trophic partitioning. The intraspecific comparison of δ13C and δ15N showed a similar trend in all species. For δ13C, the values were more enriched in adult individuals than in juveniles, but similar between males and females. For δ15N, adult individuals also had more enriched values, and males were more enriched than females. The results confirm the hypotheses raised, and the assumptions of niche theory apply to these penaeid shrimps.

The spiny butterfly ray Gymnura altavela (Linnaeus 1758) is classified as Endangered by the International Union for Nature Conservation (IUCN) and considered Critically Endangered in the Mediterranean Sea and South-west Atlantic. Despite its status, few studies on the population biology and genetics for the species are available, undermining conservation efforts. In the present study, we evaluated the taxonomic status of Gymnura altavela along both sides of the Atlantic using COI sequences. Our genetic data support the existence of two genetically differentiated G. altavela lineages (West and East Atlantic) and further studies are required to evaluate the hypothesis that these lineages could, in fact, be cryptic species within this endangered batoid's genus.

Since 2017, a sea anemone species has been registered in central Portugal with a morphology comparable to Phymactis papillosa, from the Pacific shore of south and central America. In this paper, we have collected two individuals from Cascais, Portugal, extracted their DNA and amplified and sequenced the internal transcribed spacers I and II, markers frequently used in Cnidaria barcoding. The sequences obtained were compared with the ones available on GenBank, using the Basic Local Alignment Search Tool (BLAST) on the NCBI website. This procedure allowed the identification of P. papillosa. This is the first confirmed record of P. papillosa in European coasts. Citizen science data suggest occurrences in the Alentejo coast (south-west Portugal) and Mediterranean coast around Murcia, although no genetic or morphological confirmations of these records have been made. The potential effects of this species introduction are discussed.

The present study aims to investigate the reproductive biology of the small pelagic Sardinella aurita Valenciennes, 1847 in the Canary Islands, to enable its reliable assessment and advise on appropriate management measures for a fishing resource showing a declining trend in landings. Reproductive biology and sexual patterns of round sardinella were examined from monthly random samples of commercial catches landed by the artisanal purse-seine fleet. The landings' length frequencies, ranging between 9–32 cm (based on the total lengths, TL), were recorded from 2013–2019. The overall mean value of TL was 20.9 cm, with annual mean values between 20–22 cm, except in 2016 (TL = 19 cm). The overall sex ratio M:F was 1:0.92, with males significantly predominant. Sex ratios fluctuated as a function of size and month: females were more abundant in the larger length classes, as well as before and after spawning, whereas males were more abundant in the smaller length classes and during spawning. Based on gonad maturity stages and gonadosomatic index, round sardinella spawns during almost all the year, with a peak in January–February and a resting period during October–November. The length at first maturity was estimated at TL of 18.2 cm, notably smaller than the value obtained for the NW African coastal waters where the demographic structure in round sardinellas' landings is totally different.

Recent losses of seagrass beds have resulted in a decrease in seagrass-associated fishes, highlighting the need for the improved management of such habitats and resources. Analyses of feeding patterns of fish associated with seagrass habitats are useful for understanding their habitat dependence, which contributes to achieving their effective conservation. The gut contents of 61 fish species were examined to clarify the food habits of subtropical seagrass fishes in Nagura Bay, Ishigaki Island, southern Japan. A cluster analysis based on dietary overlaps showed that the seagrass fish assemblage comprised six trophic groups (small crustacean, large crustacean, detritus, plant, fish and zooplankton feeders). Small and large crustacean feeders were the most abundant, followed by detritus, plant and fish feeders. Zooplankton feeders were represented by only two species. Ontogenetic changes in food preference were recognized in four species, including Lutjanus fulviflamma, Ostorhinchus ishigakiensis, Gerres oyena and Siganus fuscescens. Small individuals of the four species generally fed on small crustaceans or detritus, subsequently switching to other larger prey items with growth (e.g. crabs, shrimps and seagrass fronds). The most important food items for the assemblage comprised harpacticoid copepods, shrimps, crabs and detritus, representing high cumulative gut volumes for all fishes. Some species showed diets remarkably different from those determined for fishes in other seagrass beds off a nearby neighbouring island, evidence of the food-use patterns of seagrass fishes varying on a small spatial scale. Such dietary flexibility may increase the adaptability of fishes to seagrass beds characterized by significant variations in available food resources.

A new species belonging to the genus Trophoniella Hartman, 1959 (Polychaeta: Flabelligeridae) was described from the coastal area of Civitavecchia (Northern Tyrrhenian Sea). The species was collected in gravelly coarse sands from Posidonia oceanica beds at around 7 m depth. Trophoniella cucullata sp. nov. clearly differs from all other congeners species primarily by the distribution of the sediment grains on the body and by the starting point of the anchylosed neurohooks. Diagnostic morphological traits for the identification of the species are discussed. The description of Trophoniella cucullata sp. nov. in the same P. oceanica biocenosis where other species have been recently reported in the Northern Tyrrhenian Sea, testifies to the role of this marine phanerogam as a biodiversity hotspot.

The octopus fishery in the southern tip of South America is based on Enteroctopus megalocyathus. It is fished on both the Atlantic and Pacific coasts, but no study has yet investigated the genetic variability of this octopus, which is frequently collected as bycatch. The genetic identity and diversity of E. megalocyathus from specimens caught by the king crab fishery along the Beagle Channel in southern Chile was investigated using sequences of three mitochondrial (16S rRNA, COI and COIII) and one nuclear (rhodopsin) markers. Homologous sequences from other Enteroctopodidae were included to determine the genetic variability of E. megalocyathus. In addition to E. megalocyathus, genetic data allowed us to identify Muusoctopus eureka, a species also collected by the king crab fishery. Enteroctopus megalocyathus was found to be genetically similar to E. zealandicus; the genetic distances between these two species were low, 0% (16S rRNA), 0.2% (COI) and 0.6% (COIII), which was also confirmed by the phylogenetic topologies, as both species are in the same clade. Enteroctopus megalocyathus has low levels of genetic diversity, as shown by haplotype and nucleotide diversity values for the mitochondrial markers (Hd = 0.06–0.32; π = 0.0001–0.003), and null diversity for the nuclear marker. All the haplotypic networks resolved with the mtDNA markers showed shared haplotypes among E. megalocyathus, E. magnificus and E. zealandicus. The low genetic diversity of E. megalocyathus can be attributed to both the geological history of South America and the life history of the species, rather than to the king crab fishery.

Suckerfish attached to dolphin species have been extensively reported worldwide, yet such association has been rarely seen in the tropical and shallow waters of South America. In Brazil, the Guiana dolphin Sotalia guianensis is distributed along almost the entire extent of the coast and only one case of association with suckerfish has been published. Here we report on a sharksucker Echeneis naucrates associated with a young Guiana dolphin on the north-eastern coast of Brazil. The juvenile dolphin with an attached sharksucker was observed on two occasions separated by a 47-day period; we hypothesize the occurrence of host attachment fidelity. The present report adds information to better discuss the ecological interactions between echeneids and dolphins, and expands the baseline information on cetacean species serving as host to suckerfish.