Prey selection by flounder, Platichthys flesus, in the Douro estuary, Portugal

Prey selection by the flounder, Platichthys flesus (Linnaeus, 1758), in an estuarine nursery was investigated and the major factors influencing food choice by this species were assessed. Diet breadth was narrow, reflecting the low prey diversity observed in the benthos. A gradual ontogenetic shift from small prey such as amphipods to larger prey like polychaetes and bivalves was observed. Amphipods had positive electivity values in the upper estuary and negative values in the lower estuary.Polychaetes showed the inverse pattern. Bivalve electivity values were always positive. Differential selectivity throughout the estuary was mainly related to spatial segregation of flounders according to size, with the smaller individuals concentrating in the upper estuary and larger individuals concentrating in the lower estuary. Amphipods such as Corophium spp. play a crucial role in the flounder diet because of their small size, low mobility and diel activity pattern. As prey, the polychaete value increases throughout flounder ontogeny since the flounder size range is compatible with the larger mouth gapes and detection ability of larger fish. Bivalve electivity values for flounder are mainly related to high calorific values. The absence of Crangon crangon (Linnaeus, 1758) in the diet may be due to low water temperature since the cost–benefit involved in the capture of highly mobile prey is too high at low temperatures. It was concluded that flounder must use several sensory features to detect and capture prey in turbid estuarine waters and that field studies provide important background information on the actual predator preferences under natural conditions.     

The diet of blue whiting, hake, horse mackerel and mackerel off Portugal

This paper deals with the diets of blue whiting Micromesistius poutassou (Risso 1810), hake Merluccius merluccius (L. 1758), horse mackerel Trachurus trachurus (L. 1758), and mackerel Scomber scombrus (L. 1758) off Portugal and explores variations in fish length, water depth, latitude and season. All four species feed on fish; however, hake and mackerel are the first and second most important predators, respectively, blue whiting being the most important fish prey for both species. The diets of blue whiting and horse mackerel are composed mainly of crustaceans. Diet variations according to predator fish size are more important than either latitude or depth. In the diets of blue whiting, hake and horse mackerel, prey importance increases with predator size. For blue whiting and horse mackerel, diet variations with fish length and water depth are correlated: small fish are closely associated with coastal areas where they feed on copepods and decapod larvae. Seasonality in the diet is apparent for blue whiting, hake and mackerel. For blue whiting, the decapod Pasiphaea sivado is the most important prey in summer and autumn, being replaced by the euphausid Meganyctiphanes norvegica in winter. In the diet of hake, seasonality was characterised by the major importance of Macroramphosus scolopax in autumn, whereas the diet of mackerel consisted of zooplankton in summer, fish and decapods in autumn and decapod larvae in winter. Seasonal changes in the diet of horse mackerel correspond to a higher diversity of prey in autumn compared to other seasons (although euphausids are the main prey in all seasons). Seasonality in feeding activity is not as marked for the other species as it is for horse mackerel; the percentage of empty stomachs of horse mackerel is greatest in winter, when spawning takes place at the Portuguese coast.     

Diet composition of bluefin tuna (Thunnus thynnus L. 1758) in the Eastern Mediterranean Sea,Turkey

This study gives relevant information on the diet composition of the bluefin tuna (Thunnus thynnus) during the spawning period in the eastern Mediterranean Sea. The stomach contents of 218 bluefin tuna were sampled from 2003 to 2006 during the fishing season (May–June) aboard purse seiners operating in the northern Levantine Sea off the coast of Turkey. Stomachs were removed from the fish soon after landing and kept frozen at ?18°C until analysis. Prey items were classified into large taxonomic categories and preserved in 70% ethanol. A total of 745 different prey specimens belonging to 47 taxa were identified, including 34 species of fish, 11 of squid, and two of crustaceans. The most important fish and cephalopod prey belonged to the families Myctophidae, Carangidae, Chauliodontidae, Paralepididae, and Octopoda. This study marks the observation of myctophid fish in the stomach contents of bluefin tuna from the Mediterranean Sea. The paper offers some new information of regional importance and compares the feeding habits of the species to other regions, bringing confirmation on the opportunistic feeding ecology of the species in the enclosed Mediterranean Sea, where bluefin tuna seasonally occur as a strong cohort. New information on the diet composition of T. thynnus in the eastern Mediterranean Sea is revealed; the findings indicate that, depending on the abundance of the different prey species in the habitat, the dominant prey species can be distinctive.     

Size and age at sexual maturity of female bluefin tuna (Thunnus thynnus L. 1758) from the Mediterranean Sea

The ovaries of 501 female eastern Atlantic bluefin tuna (Thunnus thynnus Linnaeus, 1758) captured in the Mediterranean Sea from May to September between 1998 and 2004 were analysed histologically. Body size at median sexual maturity (L₅₀) was 103.6 cm fork length (FL), while 100% maturity was reached above 135 cm FL. The age analysis, based on the count of the translucent zones of the first spiniform ray of the first dorsal fin, showed that most of the specimens with FL = L₅₀ were 3 years old while 100% maturity was reached between 4 to 5 years. The reported evidence indicates that for the eastern Atlantic bluefin tuna stock, the size and age of first sexual maturity of females was lower than in the western Atlantic stock.     

Feeding ecology and interannual variations in diet of southern bluefin tuna, Thunnus maccoyii, in relation to coastal and oceanic waters off eastern Tasmania, Australia

The diets of 1219 southern bluefin tuna, Thunnus maccoyii, from inshore (shelf) and offshore (oceanic) waters off eastern Tasmania were examined between 1992 and 1994. Immature fish (< 155 cm fork length) made up 88% of those examined. In all, 92 prey taxa were identified. Inshore, the main prey were fish (Trachurus declivis and Emmelichthys nitidus) and juvenile squid (Nototodarus gouldi). Offshore, the diversity was greater, reflecting the diversity of micronekton in these waters. Interestingly, macrozooplankton prey (e.g. Phronima sedentaria) were prevalent in tuna > 150 cm. The offshore tuna, when in subantarctic waters, ate relatively more squid than when in the East Australia Current. In the latter, fish and crustacea were more important, although there were variations between years. No relationship was found between either prey type or size with size of tuna. Feeding was significantly higher in the morning than at other times of the day. The mean weight of prey was significantly higher in inshore-caught tuna than in those caught offshore. We estimated that the mean daily ration of southern bluefin tuna off eastern Tasmania was 0.97% of wet body weight day⁻¹. However, the daily ration of inshore-caught tuna was ∼ 3 times higher (2.7%) than for tuna caught offshore (0.8%) indicating that feeding conditions on the shelf were better than those offshore. Our results indicate that the inshore waters of eastern Tasmania are an important feeding area for, at least, immature southern bluefin tuna. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic identity of YOY bluefin tuna from the eastern and western Atlantic spawning areas

We used 320 young-of-the-year (YOY) specimens of the highly migratory and overfished Atlantic bluefin tuna, Thunnus thynnus, Linnaeus 1758, to evaluate the hypothesis that Atlantic bluefin tuna comprises 2 stocks with spawning grounds in the Gulf of Mexico and in the Mediterranean Sea. Significant genetic differentiation at 8 nuclear microsatellite loci (F(ST) = 0.0059, P = 0.0005) and at the mitochondrial control region (Phi(ST) = 0.0129, P = 0.0139) was detected among YOY Atlantic bluefin tuna captured on spawning grounds in the Gulf of Mexico (n = 40) versus the western (n = 255) and eastern (n = 25) basins of the Mediterranean Sea. The genetic divergence among spawning populations, combined with the extensive trans-Atlantic movements reported for juvenile and adult Atlantic bluefin tuna, indicates a high degree of spawning site fidelity. Recognition of genetically distinct populations necessitates independent management of Atlantic bluefin tuna on spawning grounds and warrants evaluation of the level of mixing of populations on feeding grounds. The genetic pattern might not have been detected unless juvenile specimens or actively spawning adults had been sampled.     

Spawning of bluefin tuna in the black sea: historical evidence, environmental constraints and population plasticity

The lucrative and highly migratory Atlantic bluefin tuna, Thunnus thynnus (Linnaeus 1758; Scombridae), used to be distributed widely throughout the north Atlantic Ocean, Mediterranean Sea and Black Sea. Its migrations have supported sustainable fisheries and impacted local cultures since antiquity, but its biogeographic range has contracted since the 1950s. Most recently, the species disappeared from the Black Sea in the late 1980s and has not yet recovered. Reasons for the Black Sea disappearance, and the species-wide range contraction, are unclear. However bluefin tuna formerly foraged and possibly spawned in the Black Sea. Loss of a locally-reproducing population would represent a decline in population richness, and an increase in species vulnerability to perturbations such as exploitation and environmental change. Here we identify the main genetic and phenotypic adaptations that the population must have (had) in order to reproduce successfully in the specific hydrographic (estuarine) conditions of the Black Sea. By comparing hydrographic conditions in spawning areas of the three species of bluefin tunas, and applying a mechanistic model of egg buoyancy and sinking rate, we show that reproduction in the Black Sea must have required specific adaptations of egg buoyancy, fertilisation and development for reproductive success. Such adaptations by local populations of marine fish species spawning in estuarine areas are common as is evident from a meta-analysis of egg buoyancy data from 16 species of fish. We conclude that these adaptations would have been necessary for successful local reproduction by bluefin tuna in the Black Sea, and that a locally-adapted reproducing population may have disappeared. Recovery of bluefin tuna in the Black Sea, either for spawning or foraging, will occur fastest if any remaining locally adapted individuals are allowed to survive, and by conservation and recovery of depleted Mediterranean populations which could through time re-establish local Black Sea spawning and foraging.     

Food habits, ontogenetic diet shift and selectivity in Zeus faber Linnaeus, 1758

The feeding habits of Zeus faber Linnaeus, 1758 were studied by examining digestive tracts in I2 size classes of individuals. It is a stenophagus species which begins life feeding almost exclusively on zooplankton until it is about 80 mm long, then switches gradually from zooplankton to small demersal fish, and finally when > 140 mm switches to feeding exclusively on benthic and demersal fish. Mysids were the most important food component in Z.faber < 141 mm and Cepola macrophthalma (Linnaeus, 1758) in Z.fiber > 140mm. The switch to fish prey was followed by a greater body weight per unit length. Z.faber > 140 mm selected primarily for small-and intermediate-sized C. macrophthalma (and to a lesser extent for Callionymus maculatus Rafinesque-Schmaltz, 1810, Gaidropsarus sp. and Trigla Iyra Linnaeus, 1758). Our results suggested that the ratio of vertical to horizontal dimension of prey, the motion and coloration of prey as well as the visual capabilities and perceptual potentialities of Z. faber may all in a synergetic fashion account for prey type and size selection and the positive relations found between the size of Z.faber and the size and variance of its ingested prey. Possible co-evolutionary relationships between Z.faber and C. macrophthalma are also discussed.     

Feeding behavior of yellowfin tuna around two insular regions of the western Atlantic Ocean

The yellowfin tuna is a very abundant tropical tuna species in the western equatorial Atlantic Ocean and an important fishery resource for the Brazilian tuna fleet. In this study we performed stable isotope analysis to better understand the spatial trophodynamics and dietary changes in yellowfin tuna around two insular marine protected areas in Brazil. A total of 65 yellowfin tuna specimens measuring between 47 and 138 cm LT (total length) were sampled around the archipelagos of Fernando de Noronha (FNA; n = 34) and Saint Peter and Saint Paul (SPSPA; n = 31) between July 2018 and September 2019. Bayesian mixing models and generalized additive models were used to investigate the contributions of four different prey items (zooplankton, cephalopods, fish larvae, and flying fish) to yellowfin tuna diet in each area and their potential changes in relation to predator growth. The four prey items were found to have different overall contributions between the two studied areas, with zooplankton being the most important prey in FNA, whereas flying fish was the most relevant prey to the species' diet in SPSPA. Significant changes in the species diet by size were also found, with fish smaller than 90 cm (TL) having a more generalist diet and larger animals relying more on consuming larger and more nutritious prey (i.e., flying fish). Our results suggest that these two marine protected areas play an important role in ocean dynamics, providing important and different foraging grounds for the development of this predator species.     

Identification of small juvenile scombrids from northwest tropical Australia using mitochondrial DNA cytochrome <Emphasis Type="Italic">b</Emphasis> sequences

Small juveniles of the nine species of scombrids in Australian waters are morphologically similar to one another and, consequently, difficult to identify to species level. We show that the sequence of the mitochondrial DNA cytochrome b gene region is a powerful tool for identification of these young fish. Using this method, we identified 50 juvenile scombrids collected from Exmouth Bay, Western Australia. Six species of scombrids were apparent in this sample of fish: narrow-barred Spanish mackerel (Scomberomorus commerson), Indian mackerel (Rastrelliger kanagurta), frigate tuna (Auxis thazard), bullet tuna (Auxis rochei), leaping bonito (Cybiosarda elegans), and kawakawa (Euthynnus affinis). The presence of Indian mackerel, frigate tuna, leaping bonito, and kawakawa is the first indication that coastal waters may be an important spawning habitat for these species, although offshore spawning may also occur. The occurrence of small juvenile S. commerson was predicted from the known spawning patterns of that species, but other mackerel species (Scomberomorus munroi, Scomberomorus queenslandicus, Scomberomorus semifasiciatus) likely to be spawning during the sampling period were not detected among the 50 small juveniles analyzed here.     

Electrophysiological properties of the L-type Ca(2+) current in cardiomyocytes from bluefin tuna and Pacific mackerel

Tunas are capable of exceptionally high maximum metabolic rates; such capability requires rapid delivery of oxygen and metabolic substrate to the tissues. This requirement is met, in part, by exceptionally high maximum cardiac outputs, opening the possibility that myocardial Ca(2+) delivery is enhanced in myocytes from tuna compared with those from other fish. In this study, we investigated the electrophysiological properties of the cardiac L-type Ca(2+) channel current (I(Ca)) to test the hypothesis that Ca(2+) influx would be large and have faster kinetics in cardiomyocytes from Pacific bluefin tuna (Thunnus orientalis) than in those from its sister taxon, the Pacific mackerel (Scombe japonicus). In accordance with this hypothesis, I(Ca) in atrial myocytes from bluefin tuna had significantly greater peak current amplitudes and faster fast inactivation kinetics (-4.4 +/- 0.2 pA/pF and 25.9 +/- 1.6 ms, respectively) than those from mackerel (-2.7 +/- 0.5 pA/pF and 32.3 +/- 3.8 ms, respectively). Steady-state activation, inactivation, and recovery from inactivation were also faster in atrial myocytes from tuna than from mackerel. In ventricular myocytes, current amplitude and activation and inactivation rates were similar in both species but elevated compared with those of other teleosts. These results indicate enhanced I(Ca) in atrial myocytes from bluefin tuna compared with Pacific mackerel; this enhanced I(Ca) may be associated with elevated cardiac performance, because I(Ca) delivers the majority of Ca(2+) involved in excitation-contraction coupling in most fish hearts. Similarly, I(Ca) is enhanced in the ventricle of both species compared with other teleosts and may play a role in the robust cardiac performance of fishes of the family Scombridae.     

A PCR-based method for diet analysis in freshwater organisms using 18S rDNA barcoding on faeces

The development of DNA barcoding from faeces represents a promising method for animal diet analysis. However, current studies mainly rely on prior knowledge of prey diversity for a specific predator rather than on a range of its potential prey species. Considering that the feeding behaviour of teleosts may evolve with their environment, it could prove difficult to establish an exhaustive listing of their prey. In this article, we extend the DNA barcoding approach to diet analysis to allow the inclusion of a wide taxonomic range of potential prey items. Thirty-four ecological clade-specific primer sets were designed to cover a large proportion of prey species found in European river ecosystems. Selected primers sets were tested on isolated animal, algal or plant tissues and thereafter on fish faeces using nested PCR to increase DNA detection sensitivity. The PCR products were sequenced and analysed to confirm the identity of the taxa and to validate the method. The methodology developed here was applied to a diet analysis of three freshwater cyprinid species that are assumed to have similar feeding behaviour [Chondrostoma toxostoma toxostoma (Vallot 1837), Chondrostoma nasus nasus (Linnaeus, 1758) and Barbus barbus, (Linneaus 1758)]. These three species were sampled in four different hydrographic basins. Principal Component Analysis based on prey proportions identified distinct perilithon grazer and benthophagous behaviours. Furthermore, our results were consistent with the available literature on feeding behaviour in these fish. The simplicity of the PCR-based method and its potential generalization to other freshwater organisms may open new perspectives in food web ecology.     

Length-weight relationship of six coastal fish species from Gulf of Mannar,South-east coast of India

The parameters ‘a’ and ‘b’ of length weight relationship of 6 species (Scolopsis vosmeri (Bloch, 1792), Engyprosopon macrolepis (Regan, 1908), Bleekeria murtii Joshi, Zacharia&Kanthan, 2012), Centriscus scutatus Linnaeus, 1758, Samaris cristatus Gray, 1831 and Iniistius bimaculatus Ruppell, 1829) are reported from the Gulf of Mannar, South east coast of India. The fish samples were collected from experimental trawling conducted twice a month during the period August to December 2012 and September to December 2013 at a depth ranging from 8.5 to 20.5 m. Three hauls were made in a day with each haul of one hour duration. The total length of the gear was 32 m with a cod end mesh size of 30 mm. The total length of the fish was measured to the nearest 0.1 cm and weight to the nearest 0.1 g.     

Type and ultrastructure of Didymocystis wedli and Koellikerioides intestinalis (Digenea,Didymozoidae) cysts in captive Atlantic bluefin tuna (Thunnus thynnus Linnaeus, 1758)

Tissue encapsulation, one of the most common tissue reactions to invading parasites, is the hallmark sign of didymozoid (Digenea, Didymozoidae) infections in fish. Investigated were the types of intermediate filaments and ultrastructure of the connective tissue capsule elicited by the presence of didymozoids in the gills and intestine of Atlantic bluefin tuna (Thunnus thynnus Linnaeus, 1758). The evaluation was done performing TEM microscopy of two tissue‐embedded didymozoid species, along with monoclonal antibodies labeling (anti‐fish collagen type I, anti‐human cytokeratin, anti‐vimentin antibodies). Ultrastructure of Didymocystis wedli (Ariola, 1902) (prevalence = 61.75%, abundance = 28.91) encapsulated in gill filaments and Koellikerioides intestinalis ( Yamaguti, 1970 ) (prevalence = 54.65%, abundance = 10.96) in the intestinal submucosa showed that the thin parasitic hindbody tegumentum was directly embedded in layers of connective tissue bands. Only a few cellular elements (lymphocytes, fibroblasts and fibrocytes) infiltrated the connective tissue capsule, which differed between the two didymozoid species in thickness, not in the type of filaments expressed. Cysts showed positive reaction to extracellular collagen as well as appearing positive for the cytoskeletal intermediate filaments vimentin and cytokeratin.     

Immature Pacific bluefin tuna, <Emphasis Type="Italic">Thunnus orientalis</Emphasis>, utilizes cold waters in the Subarctic Frontal Zone for trans-Pacific migration

The habitat and movements of a Pacific bluefin tuna were investigated by reanalyzing archival tag data with sea surface temperature data. During its trans-Pacific migration to the eastern Pacific, the fish took a direct path and primarily utilized waters, in the Subarctic Frontal Zone (SFZ). Mean ambient temperature during the trans-Pacific migration was 14.5 ± 2.9 (°C ± SD), which is significantly colder than the waters typically inhabited by bluefin tuna in their primary feeding grounds in the western and eastern Pacific (17.6 ± 2.1). The fish moved rapidly through the colder water, and the heat produced during swimming and the thermoconservation ability of bluefin tuna likely enabled it to migrate through the cold waters of the SFZ.     

Size related variability in the summer diet of the blackfin tuna (Thunnus atlanticus Lesson, 1831) from Tobago,the Lesser Antilles

Blackfin tuna (Thunnus atlanticus) is a small epipelagic oceanic species known only from the western Atlantic. In Tobago, the Lesser Antilles, blackfin tuna is caught by the artisanal fishery. The diet of this species was examined during the summer of 2004 for fish landed at the Charlotteville fish market in Tobago. T. atlanticus ranged from 32 to 91 cm FL (0.7–12.4 kg). Overall numerical abundance of prey items comprised fish (48%), crustaceans (46%) and cephalopods (6%). Prey species included small pelagics such as anchovies (ranked as most important prey overall), juveniles of larger pelagics such as jacks, juveniles of fish found in coral reef communities as adults, e.g. squirrelfishes, and some mesopelagic species. The importance of major diet categories differed significantly with predator size, with fishes becoming more important and crustaceans less important with increasing size of the blackfin tuna. This study has improved our scant knowledge of the blackfin tuna diet in the Lesser Antilles.     

Turbidity amplifies the non‐lethal effects of predation and affects the foraging success of characid fish shoals

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Comparative feeding strategies of yellowfin tuna around St Helena and adjacent seamounts of the South Atlantic Ocean

Yellowfin tuna are the mainstay of the traditional tuna fisheries in St Helena waters, but there is limited knowledge of their ecology and feeding behaviour in the area. In this study yellowfin tuna stomach contents were used to assess spatio-temporal changes in feeding strategy and consider the role of tuna in the local ecosystem. Comparisons of the feeding spectra of yellowfin tuna between inshore regions of St Helena and oceanic seamounts demonstrated that in both areas the species was largely piscivorous. In inshore waters yellowfin consumed more neritic fauna, including significant numbers of crab megalopa, whereas around seamounts the diet included a greater diversity of epi- and mesopelagic fish and squids. The most important fish prey species in inshore waters was the St Helena butterflyfish Chaetodon sanctahelenae, and around seamounts was the pufferfish Lagocephalus lagocephalus. Results indicate that the diet spectrum of yellowfin tuna in St Helena waters is relatively similar to those of conspecifics living in waters with relatively low productivity, with strategies indicative of food-poor ecosystems. The availability of coastal fauna may make areas around islands and seamounts more attractive for feeding aggregations of yellowfin tuna, compared to the open ocean. The relatively unselective feeding of yellowfin tuna means that stomachs can provide valuable data on the species diversity, particularly in remote areas with limited opportunities for dedicated research expeditions.     

Koi herpesvirus infection in experimentally infected common carp Cyprinus carpio (Linnaeus, 1758) and three potential carrier fish species Carassius carassius (Linnaeus, 1758); Rutilus rutilus (Linnaeus, 1758); and Tinca tinca (Linnaeus, 1758) by quantitative real‐time PCR and in‐situ hybridization

Only single cells in the carrier fish species Carassius carassius (Linnaeus, 1758) for koi herpesvirus (KHV) are infected in contrast to large numbers in the susceptible species common carp Cyprinus carpio (Linnaeus 1758). Several species of the family Cyprinidae have been described as virus carrier species, showing no clinical signs of a KHV disease but able to transmit the virus to other susceptible fish. In this study, 72 common carp Cyprinus carpio (Linnaeus, 1758), 36 tench Tinca tinca (Linnaeus, 1758), 36 crucian carp Carassius carassius (Linnaeus, 1758) and 36 common roach Rutilus rutilus (Linnaeus, 1758) were experimentally infected with KHV (isolate “Israel”) by immersion and kept at 20°C. The fish were euthanized at 12 timepoints over a period of 90 days and virus DNA was quantified in tissues by a real‐time TaqMan PCR. Whereas KHV‐DNA was found in Cyprinus carpio for up to 90 days, the virus DNA was detectable only in single individuals of Rutilus rutilus, Tinca tinca and Carassius carassius for up to 25 days after experimental virus exposure. Tissue samples of Cyprinus carpio and Carassius carassius were screened by in‐situ hybridization. Positive signals were found in various organs of the common carp tested crucian carp. In the latter species a much smaller number of virus‐positive stained cells was detected compared to the infected carp.     

Diets of hooded seals (Cystophora cristata) in coastal waters and drift ice waters along the east coast of Greenland

To provide data on the diets of hooded seals (Cystophora cristata) in the Greenland Sea, seals were collected for scientific purposes on expeditions conducted in the pack ice belt east of Greenland in September/October 1999, 2002 and 2003 (autumn), July/August in 2000 (summer), and February/March in 2001 and 2002 (winter). The results from analyses of stomach and intestinal contents from captured seals revealed that their diet was comprised of relatively few prey taxa. The squid Gonatus fabricii and polar cod (Boreogadus saida) were particularly important, whereas capelin (Mallotus villosus) and sand eels (Ammodytes spp.) occasionally contributed more. These four prey items constituted 60-97% of the diet biomass. Gonatus fabricii was the most important food item in autumn and winter, whereas polar cod dominated the summer diet, with important contributions from G. fabricii and sand eels. The latter was only observed on the hooded seal menu during the summer period, whereas polar cod, which was an important component during the autumn survey, was almost absent from the winter samples. During the latter survey, capelin also contributed to the hooded seal diet. Samples obtained from hooded seals in more coastal waters indicated a more varied diet based on fish such as polar cod, redfish (Sebastes sp.) and Greenland halibut (Reinhardtius hippoglossoides).