Oceanic Squid Research Articles

Factors affecting mercury concentrations in two oceanic cephalopods of commercial interest from the southern Caribbean

Mercury (Hg) concentrations have significantly increased in oceans during the last century. This element accumulates in marine fauna and can reach toxic levels. Seafood consumption is the main pathway of methylmercury (MeHg) toxicity in humans. Here, we analyzed total Hg (T-Hg) concentrations in two oceanic squid species (Ommastrephes bartramii and Thysanoteuthis rhombus) of an increasing commercial interest off Martinique, French West Indies. Stable isotope ratios reveal a negative linear relationship between δ15N or δ13C in diamondback squid samples. No significant trend was observed between δ34S values and T-Hg concentrations, contrasting with the sulfate availability and sulfide abundance hypotheses. This adds to a growing body of evidence suggesting Hg methylation via sulfate-reducing bacteria is not the main mechanism driving Hg bioavailability in mesopelagic organisms. All squid samples present T-Hg levels below the maximum safe consumption limit (0.5 ppm), deeming the establishment of a commercial squid fishery in the region safe for human consumption.

Interannual variability of body size and beak morphology of the squid Ommastrephes bartramii in the North Pacific Ocean in the context of climate change

Oceanic squids are typical species that sensitive to the environment change. Previous studies on oceanic squids mainly focus on its annually fluctuated abundance under the background of climate change. The changes of individual morphological sizes, including body and beak, have been observed in recent years. In this study, Ommastrephes bartramii, an important cephalopod species in North Pacific Ocean, has been selected to analyze the annual morphological changes of body and beak under different scales of climate events. Geometric morphometrics was used to analyze the shape variations of both upper beak and lower beak. The possible phenotypic plasticity of body and beak was also discussed in different aspects. Body size showed different variations among different climatic years. The size at the maturity stage in 2015 (El Niño year) was much smaller than that in other years for both sexes. The centroid size representing the beak size showed the significant difference between two types of Pacific Decadal Oscillation phases. The shapes of upper and lower beaks showed significant differences between small-scale climatic patterns in which El Niño or La Niña event occurred, displaying different growth patterns.

A review of Southern Ocean squids using nets and beaks

This review presents an innovative approach to investigate the teuthofauna from the Southern Ocean by combining two complementary data sets, the literature on cephalopod taxonomy and biogeography, together with predator dietary investigations. Sixty squids were recorded south of the Subtropical Front, including one circumpolar Antarctic (Psychroteuthis glacialis Thiele, 1920), 13 circumpolar Southern Ocean, 20 circumpolar subantarctic, eight regional subantarctic, and 12 occasional subantarctic species. A critical evaluation removed five species from the list, and one species has an unknown taxonomic status. The 42 Southern Ocean squids belong to three large taxonomic units, bathyteuthoids (n = 1 species), myopsids (n = 1), and oegopsids (n = 40). A high level of endemism (21 species, 50%, all oegopsids) characterizes the Southern Ocean teuthofauna. Seventeen families of oegopsids are represented, with three dominating families, onychoteuthids (seven species, five endemics), ommastrephids (six species, three endemics), and cranchiids (five species, three endemics). Recent improvements in beak identification and taxonomy allowed making new correspondence between beak and species names, such as Galiteuthis suhmi (Hoyle 1886), Liguriella podophtalma Issel, 1908, and the recently described Taonius notalia Evans, in prep. Gonatus phoebetriae beaks were synonymized with those of Gonatopsis octopedatus Sasaki, 1920, thus increasing significantly the number of records and detailing the circumpolar distribution of this rarely caught Southern Ocean squid. The review extends considerably the number of species, including endemics, recorded from the Southern Ocean, but it also highlights that the corresponding species to two well-described beaks (Moroteuthopsis sp. B and Psychroteuthis sp. B) are still unknown.

Long-term changes in habitat and trophic level of Southern Ocean squid in relation to environmental conditions

Long-term studies of pelagic nekton in the Southern Ocean and their responses to ongoing environmental change are rare. Using stable isotope ratios measured in squid beaks recovered from diet samples of wandering albatrosses Diomedea exulans, we assessed decadal variation (from 1976 to 2016) in the habitat (δ13C) and trophic level (δ15N) of five important Southern Ocean squid species in relation to indices of environmental conditions—Southern Oscillation Index (SOI) and Southern Annular Mode (SAM). Based on δ13C values, corrected for the Suess effect, habitat had changed over the last 50 years for Taonius sp. B (Voss), Gonatus antarcticus, Galiteuthis glacialis and Histioteuthis atlantica but not Moroteuthopsis longimana. By comparison, mean δ15N values were similar across decades for all five species, suggesting minimal changes in trophic levels. Both SAM and SOI have increased in strength and frequency over the study period but, of the five species, only in Taonius sp. B (Voss) did these indices correlate with, δ13C and δ15N values, indicating direct relationships between environmental conditions, habitat and trophic level. The five cephalopod species therefore changed their habitats with changing environmental conditions over the last 50 years but maintained similar trophic levels. Hence, cephalopods are likely to remain important prey for top predators in Southern Ocean food webs, despite ongoing climate change.

Cephalopod beak sections used to trace mercury levels throughout the life of cephalopods: The giant warty squid Moroteuthopsis longimana as a case study

Cephalopods represent an important pathway for mercury transfer through food webs. Due to the general difficulties in capturing oceanic squid, beaks found in the diet of top predators can be used to study their life-cycles and ecological role. Using upper beaks of the giant warty squid Moroteuthopsis longimana (major prey in the Southern Ocean), we describe a method to assess mercury concentrations along the life of cephalopods through the segmentary analysis of beak sections (i.e. tip of the rostrum and subsections along the hood). Distinct total mercury concentrations in the different subsections support that beaks can be used to study mercury levels in different periods of cephalopods' life-cycle. Mercury values in the anterior (1.3–7.9 μg kg−1 dw) and posterior (7.8–12.5 μg kg−1 dw) subsections of the hood reflect juvenile and adult stages, respectively. Furthermore, these results confirm that mercury bioaccumulates continuously throughout the individuals' life, with adults doubling their mercury concentrations to juveniles.

Phylogenetic relationships and cryptic species in the genus Sthenoteuthis (Cephalopoda: Ommastrephidae) in the South China Sea

Large squids of the genus Sthenoteuthis are commercially relevant species that include two truly oceanic squids. They are large nektonic predators being widely distributed throughout tropical and subtropical waters of the Atlantic and Indo-Pacific Ocean. The present study investigates different morphs varying in size at maturity, and assesses the genetic divergence in Sthenotheutis in relation to geographic patterns in the South China Sea. We obtained sequences using a mitochondrial (cytochrome c oxidase subunit I) and a nuclear (Histone H3) gene marker from 111 individuals in 23 locations of the South China Sea. In combination with sequences available in public databases, we performed tests on DNA taxonomy, mostly based on molecular phylogenies. Our results suggest that the genus Sthenoteuthis includes at least three species. The Indo-Pacific purpleback squid Sthenoteuthis oualaniensis contains at least two genetically distinct lineages that can be considered separate species, a dwarf species and a medium-sized species, separated by both the mitochondrial marker and the more conserved nuclear marker. We also assessed whether the few cases of mitonuclear discordance could be the result of genetic introgression and past hybridization or incongruence lineage sorting. The medium-sized species is more widely distributed and dominant in the South China Sea than the dwarf species. The medium-sized species inhabits the whole South China Sea, whereas the dwarf species is restricted to the equatorial waters of the South China Sea. The medium-sized species has two further genetic clades, one distributed in the East Pacific Ocean and the other in the South China Sea. This high level of genetic differentiation is in agreement with the discriminant analysis on the morphological measurements, clearly separating the dwarf and medium-sized species, indicating the presence of a complex of pseudo-cryptic species in S. oualaniensis, clearly identifiable by differences in DNA sequences and in body size, and statistically differentiated in their body measurements.

A taste for squid: the diet of sperm whales stranded in Greece, Eastern Mediterranean

Sperm whales (Physeter macrocephalus) inhabiting the world's oceans, prey mainly on cephalopods, but also feed on fish when found in higher latitudes. However, the feeding habits of endangered Mediterranean sperm whales have received little attention with thus far only two individuals analysed for their stomach contents. This study expands the available knowledge using analysis of the stomach contents from nine individuals stranded in Greece between 2005 and 2014. 48,166 prey remains were examined in total and 28,258 of them were identified to show that sperm whales fed on 18 prey species (17 cephalopods and one teleost) from 14 different families. 15 of these species were deep-sea squids, which are not presently targeted by fisheries. The most important prey species, both in terms of numerical abundance (%N) and abundance by weight (%W), was the oceanic squid Histioteuthis bonnellii (%N = 48.4, %W = 66.3) followed by H. reversa (%N = 28.4, %W = 13.8) and Octopoteuthis sicula (%N = 8.5, %W = 17.2). Calf sperm whales consumed smaller cephalopods of these three prey species than non-calves, probably because larger cephalopods are more difficult to catch. The vast majority of ingested cephalopods were gelatinous, slow-swimming and small. Therefore, sperm whales inhabiting the Greek Seas and likely the whole eastern Mediterranean Sea, appear to target prey that are easy to catch, but need to be consumed in great numbers to fulfil the energy requirements of the whales.

Mercury levels in Southern Ocean squid: Variability over the last decade

The concentrations of total and proportions of organic mercury were measured in tissues of 355 individuals of 8 species of Southern Ocean squid (Alluroteuthis antarcticus, Bathyteuthis abyssicola, Filippovia knipovitchi, Galiteuthis glacialis, Gonatus antarcticus, Kondakovia longimana, Psychroteuthis glacialis and Slosarczykovia circumantarctica). Squid were caught around South Georgia (Scotia Sea) during 5 cruises, between the austral summers of 2006/07 to 2016/17 to evaluate temporal changes in bioaccumulation and tissue partitioning. Total mercury concentrations varied between 4 ng g−1 and 804 ng g−1 among all tissues. Net accumulation of mercury in muscle with size was observed in A. antarcticus, B. abyssicola and P. glacialis, but no relationship was found for S. circumantarctica and lower concentrations were observed in larger individuals of G. glacialis. Muscle tissues had the highest mercury concentrations in the majority of species, except for F. knipovitchi for which the digestive gland contained highest concentrations. In terms of the percentage of organic mercury in the tissues, muscle always contained the highest values (67%–97%), followed by the digestive gland (22%–38%). Lowest organic mercury percentages were found consistently in the gills (9%–19%), suggesting only low levels of incorporation through the dissolved pathway and/or a limited redistribution of dietary organic mercury towards this tissue. Overall, results are indicative of a decreasing trend of mercury concentrations in the majority of analysed species over the last decade. As cephalopods are an important Southern Ocean trophic link between primary consumers and top predators, these changes suggest decreasing mercury levels in lower trophic levels and an alleviation of the mercury burden on higher predators that consume squid.

Ontogenetic difference of beak elemental concentration and its possible application in migration reconstruction for Ommastrephes bartramii in the North Pacific Ocean

The migration route of oceanic squid provides critical information for us to understand their spatial and temporal variations. Mark-recapture and electronic tags tend to be problematic during processing. Cephalopod hard structures such as the beak, containing abundant ecological information with stable morphology and statolith-like sequences of growth increments, may provide information for studying spatio-temporal distribution. In this study, we developed a method, which is based on elemental concentration of beaks at different ontogenetic stages and sampling locations, to reconstruct the squid migration route. We applied this method to Ommastrephes bartramii in the North Pacific Ocean. Nine trace elements were detected in the rostrum sagittal sections (RSS) of the beak using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). For those elements, significant differences were found between the different ontogenetic stages for phosphorus (P), copper (Cu) and zinc (Zn). Sodium (Na), P and Zn were chosen as indicators of sea surface temperature (SST) and a regression model was estimated. The high probability of occurrence in a particular area represented the possible optimal squid location based on a Bayesian model. A reconstructed migration route in this study, combining all the locations at different ontogenetic stages, was consistent with that hypothesized in previous studies. This study demonstrates that the beak can provide useful information for identifying the migration routes of oceanic squid.

The ecological role of cephalopods and their representation in ecosystem models

Cephalopods, especially squids, are believed to have a structuring role in marine ecosystems as a link between different trophic levels, primarily due to their voracious prey consumption and high production rate. Cephalopod ecology, however, is still poorly understood as observational studies often give highly uncertain and variable results due to the peculiarities of cephalopod behaviour and biology, and their responsiveness to external drivers. This review evaluates our representation of cephalopods in ecosystem models and the insights given by these models on the role of cephalopods in our oceans. We examined ecosystem models from 13 regions to analyse the representation of cephalopods and compared their results to local trophic studies. Our analysis indicated that most ecosystem models inadequately include cephalopods in terms of model structure and parametrization; although some models still have the capacity to draw valuable conclusions regarding the impact and role of cephalopods within the system. Oceanic squid species have a major role linking trophic levels and food webs from different habitats. The importance of neritic species varies locally, but generally cephalopods have a substantial impact via their consumer role. To better understand the ecological role of cephalopods, improved representation of these species in ecosystem models is a critical requirement and could be achieved relatively easily to more accurately articulate the mechanisms regulating the ecological role of cephalopods.

First Records and Descriptions of Early Life Stages of Cephalopods from Rapa Nui (Easter Island) and the Nearby Apolo Seamount

New records of early life stages of cephalopods are presented based on planktonic collections carried out around Easter Island (Rapa Nui; 27°7′S, 109°21′W) and at the nearby Apolo Seamount (located at ∼7 nautical miles southwest from Easter Island) during March and September 2015 and March 2016. A total of 13 individuals were collected, comprising four families (Octopodidae, Ommastrephidae, Chtenopterygidae, and Enoploteuthidae) and five potential genera/types (Octopus sp., Chtenopteryx sp., rhynchoteuthion paralarvae, and two undetermined Enoploteuthid paralarvae). Cephalopod mantle lengths (ML) ranged from 0.8 to 4.5mm, with 65% of them (mainly Octopodidae) corresponding to newly hatched paralarvae of ∼1mm ML, and 35% to rhynchoteuthion and early stages of oceanic squids of around 1.5–4.5mm ML. These results provide the first records on composition and presence of early stages of cephalopods around a remote Chilean Pacific Island, while also providing a morphological and molecular basis to validate the identity of Octopus rapanui (but not Callistoctopus, as currently recorded), Ommastrephes bartramii and Chtenopteryx sp. around Rapa Nui waters. Despite adult Octopodidae and Ommastrephidae having been previously recorded at these latitudes, the current findings provide evidence to suggest that the northwest side of Easter Island, and one of the nearby seamounts, may provide a suitable spawning ground for benthic and pelagic species of cephalopods inhabiting these areas. For Chtenopterygidae and Enoploteuthidae, this is the first record for the Rapa Nui ecoregion.

Defensive Ball Formation in Oceanic Squid Paralarvae

The head withdrawal reflex is a behavior that has been reported in young pelagic squids (paralarvae) and involves retraction of the head, arms, and proboscis (fused feeding tentacles) into the mantle cavity when the animals are disturbed. The present study investigated which artificial stimuli (mechanical, chemical, or light) trigger this behavior in three oceanic ommastrephid squid species: Sthenoteuthis oualaniensis, Eucleoteuthis luminosa, and Todarodes pacificus. All stimuli triggered ball formation and chromatophore expansion. During the early paralarval stage, the head was completely withdrawn into the mantle cavity, and the squid formed a ball posture with expanded orange chromatophores. This response might make it difficult for predators to recognize and consume the squid or it might facilitate feeding.

Relating abundance of purpleback flying squid Sthenoteuthis oualaniensis (Cephalopoda: Ommastrephidae) to environmental parameters using GIS and GAM in south-eastern Arabian Sea

The distribution pattern of purpleback flying squid and the relationship between its abundance and environmental variables in the south-eastern Arabian Sea were analysed using a geographical information system (GIS) and a generalised additive model (GAM). Highest abundances were observed during December and January within 10 and 13°N and 71 and 72°E around the Lakshadweep Islands. The mean abundance in the area was 4.21 tonnes/km2 and the maximum sustainable yield (MSY) was estimated as 0.63 million tonnes. GAM indicated that very high squid abundance was associated with low values of dissolved oxygen (6.01–6.27 mg/L), sea surface temperature (28.03–28.62°C), pH (7.75–8.56), salinity (30.42–34.48 psu), chlorophyll-a (0.4–0.6 mg/m3), zooplankton biomass (0.23–0.64 mL/m3), and shallow 20°C isotherm (101.2–134.7 m) and mixed layer depth (17.8–29.8 m). As a carnivore from paralarval stages, S. oualaniensis depends on secondary and tertiary production to sustain its population for which primary production is used up. In the tropical Arabian Sea where temperature differences are not so pronounced, S. oualaniensis distribution was found to be related to a low but very narrow sea surface temperature (SST) band. There is sufficient fishable biomass in the area to possibly launch a new targeted oceanic squid fishery from the western seaboard of India.

Ontogenic changes in habitat and trophic ecology in the Antarctic squid Kondakovia longimana derived from isotopic analysis on beaks

The life histories of cephalopods are still not well described. Stable isotopic analysis of cephalopod beaks is an effective method to study the habitat and trophic ecology of this group of organisms. As beaks grow continuously throughout squid’s life without replacement, we hypothesised that analysing different sections along the beak will provide information on the ontogenetic shifts during the individual’s lifetime. Here we used the Southern Ocean squid Kondakovia longimana as a model species to test the reliability of this method along the beaks of Antarctic species. Growing patterns show that beaks grow throughout the squid lifetime by a continuous deposition of material. This new material can influence the results of the stable isotopic analysis. δ13C and δ15N values (from − 26.3 to − 20.6‰ and from + 3.2 to + 8.2‰, respectively) from different beak regions indicated that K. longimana inhabits regions spanning a wide latitudinal range, and the trophic level at which it feeds increases throughout its lifetime. Stable isotopic analysis of different sections of the cephalopod beak is a reliable technique to study habitat and trophic ecology throughout Antarctic squid’s lifetime. Stable isotopic results showed an increase in δ15N values from the tip of the rostrum to the end of the hood and crest, in the upper beak, and to the free corner of lateral wall and wing in the lower beak. Our results also suggested that the upper beak is the best beak to study ontogenetic shifts, mainly in initial stages of the cephalopods’ life, presenting lower values of δ15N than the lower beak.

New record of Abralia (Heterabralia) siedleckyi Lipinski, 1983 (Cephalopoda: Enoploteuthidae) from south-eastern Arabian Sea with some remarks about its biology

Specimens of oceanic squid, Abralia (Heterabralia) siedleckyi Lipinski, 1983 were collected from the south-eastern Arabian Sea using midwater trawl (horizontally at 200 m depth) during night operations in two cruises on 18 April 2015 and 26 February 2017. Description and morphological measurements of the specimens are provided. The record of this mesopelagic squid from the Arabian Sea is an addition to the cephalopod fauna of the Indian Ocean and India. The statolith based age analysis indicates that a 29.1 mm dorsal mantle length specimen had 93 day’s age with a growth rate of 0.31 mm DML/day.

The complete mitochondrial genome of the oceanic squid: Chiroteuthis picteti (Oegopsida, Chiroteuthidae)

The mitogenome sequence of Chiroteuthis picteti Joubin, 1894 (Oegopsida, Chiroteuthidae), a species of Oceanic squid, was first determined in the genus Chiroteuthis as well as in the family Chiroteuthidae. The circular genome of C. picteti is 20,851bp in size, has six duplicated genes (cox1, cox2, cox3, atp6, atp8, and tRNAAsp). The mitogenome of C. picteti has high A + T content (71.6%) similar to other Oegopsid (A 38.2%; C 18.3%; G 10.1%; T 33.4%). The mitogenome of C. picteti, the first reported of its genus, will be useful for inferring the phylogenetic relationships among the members of Chiroteuthidae, within the Oegopsids.

Updated molecular phylogeny of the squid family Ommastrephidae: Insights into the evolution of spawning strategies

Two types of spawning strategy have been described for ommastrephid squids: coastal and oceanic. It has been suggested that ancestral ommastrephids inhabited coastal waters and expanded their distribution into the open ocean during global changes in ocean circulation in the Oligocene. This hypothesis could explain the different reproductive strategies in oceanic squids, but has never been tested in a phylogenetic context. In the present study, we assess the coastal-to-open-ocean hypothesis through inferring the evolution of reproductive traits (spawning type) of ommastrephid squids using the phylogenetic comparative method to estimate ancestral states and divergence times. This analysis was performed using a robust molecular phylogeny with three mitochondrial genes (COI, CYTB and 16S) and two nuclear genes (RHO and 18S) for nearly all species of ommastrephid squid. Our results support dividing the Ommastrephidae into the three traditional subfamilies, plus the monotypic subfamily Todaropsinae as proposed previously. Divergence times were found to be older than those suggested. Our analyses strongly suggest that early ommastrephid squids spawned in coastal areas, with some species subsequently switching to spawn in oceanic areas, supporting previous non-tested hypotheses. We found evidence of gradual evolution change of spawning type in ommastrephid squids estimated to have occurred since the Cretaceous.

Opportunistic acoustic recordings of (potential) orangeback flying squid Sthenoteuthis pteropus in the Central Eastern Atlantic

Abstract Squids are fast swimmers that are difficult to catch by nets and to record with echosounders in the open ocean. A rare detection of orangeback flying squid Sthenoteuthis pteropus in the Central Eastern Atlantic Ocean off the coast of Senegal was accomplished during the MAFIA oceanographic survey carried out between Brazil and the Canary Islands in April 2015. Although net sampling did not yield any subadult or adult individuals, dozens were visually detected from the vessel jumping out of the water at night and displaying their characteristic dorsal photophore patch. A few squids were caught with fishing lines and identified at the species level. The acoustic echograms revealed distinctive previously unobserved acoustic echotraces that seemed to be caused by those squids, which were the only new species detected at that station (over a bottom depth ranging from 4010 to 5215 m, between 10° 45′ N 22° 41′ W and 10° 53′ N 22° 40′ W). The acoustic response and swimming behaviour shown by those echotraces reinforced this hypothesis. The (potentially) squid recordings dove rapidly (0.19 m/s to 0.48 m/s) from around 10 m below the mesopelagic fish layer, which had migrated to the subsurface at night (35 m depth), to depths of 70–95 m, and swam upward, apparently attacking fish from below. The morning squid migration to deeper waters (250–300 m) was also recorded acoustically. Downward movements of squid swimming at speeds of 0.22 m/s were calculated from the echogram, while the mesopelagic migrating fish swam at 0.27 m/s reaching 250 m depth. Sv120 − Sv38 averaged 2.7 ± 3.2 dB for the squid echotraces while the mesopelagic layer showed values of −8.8 ± 0.9 dB. These ranges agreed with values in the literature and from theoretical models. This study provides more insight into the migrating behaviour of oceanic squids, a species group that is poorly represented in the acoustic literature due to challenges in studying them.

Using seabirds to map the distribution of elusive pelagic cephalopod species

The distribution of oceanic cephalopod species is not fully understood but seabirds, which feed on cephalopods and cover vast oceanic areas, might work as samplers and mappers of the occurrence of this elusive group. We tracked 17 wandering albatrosses Diomedea exulans at Bird Island, South Georgia (54° S, 38° W) over the austral winter (breeding period) with GPS-loggers, activity recorders and stomach temperature probes. At logger retrieval, diet composition was accessed via stomach flushings of the tagged individuals. Wandering albatrosses captured circumpolar and rarer oceanic squid in all water masses of the Southern Ocean (i.e. Antarctic, sub-Antarctic and subtropical waters), complementing much of the knowledge about the cephalopod distribution in the Atlantic sector of the Southern Ocean. Some cephalopod species showed a distribution range wider than expected, with oceanic fronts not functioning as ecological barriers as previously thought. This suggests they might be capable of overcoming these frontal regimes and even take advantage of their dynamics as migration pathways

Feeding ecology, isotopic niche, and ingestion of fishery-related items of the wandering albatross Diomedea exulans at Kerguelen and Crozet Islands

Feeding ecology and isotopic niche of the wandering albatross Diomedea exulans were investigated in the poorly studied population on the Kerguelen Islands and compared to that on the Crozet Islands. Fish (48% by mass) and cephalopods (46%) were similarly important in chick food at Kerguelen, while cephalopods (87%) dominated the diet at Crozet. Fish prey included mainly deep-sea species, with the Patagonian toothfish Dissostichus eleginoides being the main item. Cephalopod beaks were identified, most of which were from adult oceanic squids. Albatrosses preyed upon the same taxa at both localities, but in different proportions. Histioteuthis atlantica (30% by number), Galiteuthis glacialis (13%), and Kondakovia longimana (10%) were the main squid prey at Kerguelen, while K. longimana (35%) and H. eltaninae (23%) dominated at Crozet. Chick feather δ15N values were higher in wandering albatrosses than in other oceanic seabirds of the 2 communities, indicating that the wandering albatross is an apex consumer together with the sperm whale and sleeper shark that have similar δ15N values. Satellite-tracked wandering albatrosses foraged in local subantarctic waters and farther north, with some Crozet birds overlapping with those from the Kerguelen population in western Kerguelen waters. Anthropogenic items (e.g. plastic fragments, hooks) were found in half the food samples. All fishery-related items were from the local toothfish fishery. The high number of hooks from Crozet indicated the presence of a fairly large number of illegal longliners in the area during the Austral winter 1998. A review of the feeding habits of Diomedea spp. highlights the need for more dietary investigations to achieve effective conservation and management of this endangered group of charismatic seabirds.