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The Falkland Islands conduct one of the few targeted skate fisheries in the world with total annual catches of several thousand tonnes.  This bottom trawl fishery is characterized by relatively low catch volumes and product yield that challenge commercial profitability. Recently, one Falkland Islands fishing company acquired a large proportion of the skate ITQ, and to optimise its fishing operations, proposed a research collaboration with the Falkland Islands Fisheries Department for assessing the performance of trawls equipped with either standard 110 mm codend mesh, or larger 300 and 400 mm meshes. The results of the trial confirmed the efficiency of larger mesh codends to decrease finfish bycatch by 97–98%. Additionally, trawls with 400 mm mesh significantly decreased the bycatch of commercially valueless small skates that would experience high discard mortality. As a result of the trial, the Falkland Islands Government implemented a regulatory licence condition of 400 mm codend mesh for targeted skate fishing. Besides greater production efficiency, vessel operators are incentivized by possible wider access throughout the fishing zone. Further initiatives are anticipated to develop management measures by individual species, continue improving conservation through bycatch mitigation in all fisheries, and diversify Falklands skate products in global markets. [ABSTRACT FROM AUTHOR]

Data were combined from surveys in 2013, 2018, 2019 and 2021 to examine biomass changes of the skate (Rajiformes) stock in waters around the Falkland Islands. The 2013 and 2019 surveys were research surveys for skate abundance and used 90 mm trawl mesh to capture species and size compositions. The 2018 survey was a mesh size trial, and the 2021 survey was a commercial exploration; both used 400 mm trawl mesh to target skates. All four surveys were compared for biomass by deselecting the proportions of skates per size interval caught in 90 mm mesh that would not have been caught in 400 mm mesh, calculated with the SELECT method. Estimated commercial-size skate biomass decreased for most species individually and approximately 61% overall. Estimated commercial-size skate biomass also decreased by as much south of 51° latitude, the area that was closed to skate target fishing since 1996, as north of 51° latitude, which has been maintained open to skate target fishing. The outcome is correlated with continuing skate bycatch in finfish trawls. [ABSTRACT FROM AUTHOR]

The Patagonian toothfish, Dissostichus eleginoides, is one of the largest predatory fishes inhabiting Southern Ocean waters spanning the Antarctic Polar Front (APF), a prominent biogeographic boundary restricting gene flow and driving species divergence between Antarctic and sub‐Antarctic waters. In the light of emerging threats to toothfish conservation and sustainability, this study investigated genetic [mtDNA sequences and genome wide nuclear single nucleotide polymorphisms (SNPs)] and morphological data to critically evaluate the taxonomic status of toothfish north (Chile and Patagonian shelf) and south (South Georgia and South Sandwich Islands) of the APF. mtDNA revealed reciprocally monophyletic lineages on either side of the APF with coalescent analysis indicating these diverged during the Pleistocene. Integration with data from other sources suggests the Chilean/Patagonian lineage is endemic. SNP analysis confirmed restricted nuclear gene flow between both groups and revealed a consensus suite of positive outlier SNPs compatible with adaptive divergence between these groups. Finally, several morphological features permit unequivocal assignment of individuals to either of the clades. Based on the genetic, phenotypic and ecological divergence, the authors propose that toothfish on either side of the APF be recognised as distinct species, with the name D. eleginoides used for toothfish occurring in South American waters north of the APF and toothfish south of the APF being classified using the new name D. australis reflecting their southern distribution. [ABSTRACT FROM AUTHOR]

Perciform fish of the suborder Notothenioidei radiated in the cold marine environments of the Southern Ocean around Antarctica where they evolved a diverse array of ecological forms. Despite their relatively high abundance and important roles in the Antarctic and sub-Antarctic ecosystems, many aspects of their life history are still poorly known. In the present study, age, growth and sexual maturity of channel bull blenny Cottoperca trigloides were analysed using the data of 28,229 specimens collected over the last 30 years in the southern part of the Patagonian Shelf in the Southwest Atlantic. It was found that C. trigloides features sexual dimorphism with males attaining larger sizes than females, an unusual characteristic for notothenioid fish. Males also had higher growth rates, older maximum ages and slower maturation. The peak in gonad maturation and spawning in C. trigloides was revealed to take place in austral winter, similar to other notothenioids from the Patagonian Shelf, thus matching larval hatch with the spring bloom of zooplankton. Sexual dimorphism may be advantageous for large territorial males during competitive interactions, particularly in an environment characterised by strong patchiness of rocky areas that are most suitable for spawning. Evolution of life history traits that placed C. trigloides close to the r-end within the r/K strategy continuum evolved by notothenioid fishes, enabled this species to successfully compete with other medium-large and large predators in resources-rich environment of the Patagonian Shelf. [ABSTRACT FROM AUTHOR]

Cephalopods have become an important global food source, but their sustainable management is challenged by unique life history characteristics associated with short lifespans and semelparous reproduction, high natural mortality rates, rapid and often nonasymptotic growth, and complex population structures. Weak stock-recruitment relationships together with the time-consuming work required for age validation and high-volume annual age determinations make traditional age-based modelling impractical. We propose that the best method for cephalopod assessment involves innovative depletion models, fitted with in-season data on catch numbers and fishing effort, to produce realistic estimates of stock biomass. A "fast lane" assessment approach is suggested that includes high-frequency data collection for separate, in-season stock assessments of each cohort to ensure sustainable exploitation of these short-lived resources. However, most cephalopod fisheries are data-poor and/or lack the infrastructure and resources needed to apply depletion methods; therefore, we also present alternative assessment methods that have been recently applied worldwide. We also offer suggestions for further research on the remaining challenges of cephalopod stock assessment and management. [ABSTRACT FROM AUTHOR]

Many large predatory fishes are in decline and tuna sustainability is high on the global agenda. Slender tuna (SLT), Allothunnus fallai, is data‐poor and a rare contemporary example of a globally unexploited temperate tuna. This study analysed 214 otoliths for age and growth of fish collected in the South Atlantic. Observed ages varied between 9 and 42 years for a size range of 68–90 cm fork length. We reveal important life history data for SLT before exploitation and underline the relevance of data‐poor stocks in understanding wider questions for exploited tuna. [ABSTRACT FROM AUTHOR]

The Patagonian long-finned squid Doryteuthis gahi is an abundant commercial species within Falkland Island waters. The population consists of two temporally distinct spawning cohorts, inferred to have markedly different patterns of migration and timings of ontogenetic events. Ontogenetic migrations of each cohort were confirmed by analysis of the chemical composition of statoliths collected from both cohorts in two consecutive years. Trace element concentrations were quantified using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), to determine temporal and cohort-specific variation. Individual ablation craters, ablated in a transect from the nucleus to the rostrum edge, were aged to produce high-resolution elemental chronologies. Generalized additive mixed models (GAMM) indicated that cohort and life history stage had a significant effect on Sr/Ca and Ba/Ca ratios. Sr/Ca and Ba/Ca ratios were both negatively correlated with near-bottom water temperature, with Ba/Ca also potentially correlated to depth. Statolith elemental chronologies have useful applications as natural tags, discriminating between spawning cohorts. • Elemental chronologies of Ba and Sr were constructed for statoliths of Doryteuthis gahi using LA-ICP-MS. • Temporally distinct spawning cohorts had unique elemental chronologies. • Elemental chronologies displayed significant variation throughout ontogeny. • Cohort-specific chronologies were most dissimilar during 80–160 d post-hatching. • Sr/Ca and Ba/Ca ratios were both negatively correlated with near-bottom water temperature. [ABSTRACT FROM AUTHOR]

Population genetic structure of the Patagonian longfin squid Doryteuthis gahi was assessed across the Falkland Islands, central-southern Chile, and Peru. Microsatellite and mtDNA data partitioned samples into two groups: one consisting of the Peruvian samples, the other comprised the Chilean and Falklands samples, with no sub-structuring within either group. Recurrent demographic independence between groups can be linked to abrupt changes in continental shelf features between the Peruvian and central Chilean sites restricting adult dispersal. Phylogeographic analyses indicate a prolonged period of isolation between the Peruvian and Chilean–Falkland groups which may include divergence in allopatric glacial refugia. Both groups have experienced dissimilar historical population size dynamics with the Peruvian population exhibiting signals of size fluctuations, similar to other species in the area, that align with postglacial changes in the productivity of the Humboldt Current system. Genetic cohesion among central-southern Chilean and Falklands samples supports connectivity across current management boundaries and indicates that phenotypic differences between D. gahi from these areas reflect plastic responses to environmental heterogeneity. The study adds to evidence that loliginid squids typically display connected populations over large geographical areas unless specific oceanographic features restrict gene flow. Recognition of the Peruvian and Chilean–Falklands groups as distinct evolutionary significant units is recommended. [ABSTRACT FROM AUTHOR]

The Patagonian long-finned squid Doryteuthis gahi is an abundant commercial species within Falkland Island waters. The population consists of two temporally distinct spawning cohorts, inferred to have markedly different patterns of migration and timings of ontogenetic events. Ontogenetic migrations of each cohort were confirmed by analysis of the chemical composition of statoliths collected from both cohorts in two consecutive years. Trace element concentrations were quantified using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), to determine temporal and cohort-specific variation. Individual ablation craters, ablated in a transect from the nucleus to the rostrum edge, were aged to produce high-resolution elemental chronologies. Generalized additive mixed models (GAMM) indicated that cohort and life history stage had a significant effect on Sr/Ca and Ba/Ca ratios. Sr/Ca and Ba/Ca ratios were both negatively correlated with near-bottom water temperature, with Ba/Ca also potentially correlated to depth. Statolith elemental chronologies have useful applications as natural tags, discriminating between spawning cohorts. [ABSTRACT FROM AUTHOR]

Southern blue whiting Micromesistus australis support a substantial commercial fishery in South America. There is growing evidence of a high level of demographic independence between stocks associated with the two main spawning grounds, one in the SW Atlantic (SWA) and one in the SE Pacific (SEP), but the potential genetic structuring of these stocks is unknown. In this study adults collected from sites throughout SWA and SEP waters were genotyped at hypervariable microsatellite markers to investigate genetic structuring between and within regions. Allele frequency-based analyses reported highly significant genetic differentiation between regions, indicating low levels of allo-recruitment. Ancillary data on migratory behaviours support natal homing as a prominent stock isolating mechanism. Genetic differentiation was also detected among samples from around the Falkland Islands: kinship analyses indicated that this was due to non-random genetic relatedness within samples. Despite a general pattern of genetic homogeneity among SEP samples, the northernmost sample exhibited significantly high mean relatedness. The data indicate the occurrence of a further level of structuring within both regions that prevents complete mixing, specifically that schools may be hierarchically structured (from putative subpopulations down to kin-containing groups) and exhibit some degree of ontogenetic cohesion, which may also be a component of homing. The importance of homing and group cohesion as factors influencing resilience to, and recovery from, overexploitation is discussed. This study represents an important baseline for future genetic monitoring and assessment of M. australis . The need for such studies is emphasised by the observation of significantly lower levels of genetic variation among SWA samples, which may reflect genetic erosion, and the subsequent collapse of the SWA stock. [ABSTRACT FROM AUTHOR]

Argentine shortfin squid Illex argentinus (Ommastrephidae) is one of the most abundant cephalopods in the Southwest Atlantic, with total annual catch exceeding 1 mln t in some years. During its annual life cycle, I. argentinus perform long distance migrations, from their subtropical spawning grounds in Uruguay and southern Brazil to temperate feeding grounds on the Patagonian Shelf and back. Oceanography and squid distribution were studied during a research survey carried out in the south-eastern part of the Patagonian Shelf to reveal environmental cues that determine pathways of shelf to continental slope pre-spawning migrations. It was found that the outflows of less dense Patagonian Shelf Waters (PSW) over the slope may act as proxies determining the locations of I. argentinus migrations from the shelf to the slope. During maturation I. argentinus did not significantly change their buoyancy with females becoming slightly more buoyant with depth. Subsequent movement of mature I. argentinus to denser Sub-Antarctic Superficial waters (SASW) located at deeper depths (600–700 m) enable them to approach near-neutral buoyancy and therefore facilitate the distant pre-spawning migrations. [ABSTRACT FROM AUTHOR]

Doryteuthis gahi squid stocks in the Falkland Islands are assessed by depletion models which may include in-season recruitment pulses. Occurrences of in-season recruitment pulses are inferred by sharp peaks in CPUE, but this ad hoc approach does not distinguish between true recruitments into the fishery and aggregations of squid already in situ. Data were therefore investigated from 13 fishing seasons in which true recruitments could be identified by changes in D. gahi size distributions, and related to environmental variables of sea wind, sea surface temperature, and geostrophic currents. Changes in size distributions showed 30% of CPUE peaks to be true recruitments. Recruitment peaks followed a significant parabolic relationship between east-west and north-south sea wind vectors. Recruitment peaks occurring under west sea winds were characterized by a positive correlation between west and north wind speeds. Recruitment peaks occurring under east sea winds were characterized by a positive correlation between east and north wind speeds. The wind speed criteria were used to classify CPUE peaks in all D. gahi fishing seasons from 2002 to 2012. Among winter seasons, D. gahi abundance estimates correlated best with CPUE when depletion models included all recruitment peaks. Among summer seasons, which are shorter, abundance estimates correlated best with CPUE when depletion models included only the last overall peak. We hypothesize that identifying recruitment peaks improves the accuracy of depletion models, but time series must be sufficiently long for multi-peak models to fit optimally. [ABSTRACT FROM AUTHOR]

The anatomy and development of the tails at the posterior part of the mantle were studied in several groups of Recent and extinct coleoid cephalopods; substantial differences in their formation were revealed. Males of the Recent loliginid squid Alloteuthis spp. form their tail by increased growth of the anterior part of the gladius with simultaneous growth of the posterior mantle. As a result, the gladius rolls longitudinally in the tail forming a pseudoconus. The attenuated tail in males of the squid Lycoteuthis springeri (Lycoteuthidae) is supported from inside by the special rod-like apical vacuolated cartilage. Adults of both sexes of recent Onykia robsoni and O. robusta form a carrot-shaped flexible chitinous rostrum supporting the attenuated tail. Adults of several Jurassic belemnites formed an elongated epirostrum posterior to their orthorostrum; the structures differed in growth and microstructure. Counts of growth microincrements within the orthorostrum and epirostrum were used to date their formation and estimate the age of belemnites. The development of the long rigid tail and the corresponding shift of the fin to the middle part of the mantle streamline the body and possibly facilitate the animal's movement in the water by gliding. The analogous tail formation in several independent groups points to its adaptive nature for the development of a more mobile adult phase in species of coleoid cephalopods. [ABSTRACT FROM AUTHOR]

Some 290 species of squids comprise the order Teuthida that belongs to the molluscan Class Cephalopoda. Of these, about 30–40 squid species have substantial commercial importance around the world. Squid fisheries make a rather small contribution to world landings from capture fisheries relative to that of fish, but the proportion has increased steadily over the last decade, with some signs of recent leveling off. The present overview describes all substantial squid fisheries around the globe. The main ecological and biological features of exploited stocks, and key aspects of fisheries management are presented for each commercial species of squid worldwide. The history and fishing methods used in squid fisheries are also described. Special attention has been paid to interactions between squid fisheries and marine ecosystems including the effects of fishing gear, the role of squid in ecosystem change induced by overfishing on groundfish, and ecosystem-based fishery management. [ABSTRACT FROM AUTHOR]

Information from genetic (microsatellites and mtDNA Control Region) and previously collected otolith (trace element fingerprinting of otolith core and edge) markers was jointly interpreted to describe dispersal and gene flow in the Patagonian hoki ( Macruronus magellanicus ), an intensively harvested marine fish with seasonal migrations between spawning and feeding grounds. Spawning adults from a Chilean (Pacific) spawning site and three feeding ground samples (one from Chile and two temporal samples from the Falkland Islands (Atlantic)) were analysed. The data indicated a high level of Atlantic/Pacific connectivity by means of non-natal homing of individuals to spawning aggregations. Against this background of regional connectivity however, genetic data support the existence of a reproductively isolated population within the overwintering stock. Otolith core results are compatible with reproductive isolation being effected by natal homing to an Atlantic spawning site and/or local adaptation. The discordance between geopolitically defined Atlantic and Pacific management stocks and underlying biocomplexity, and implications for sustainability, are discussed. The study highlights the importance of intraspecific variation in homing behaviours in shaping population structure and the merit of employing complementary analytical approaches. [ABSTRACT FROM AUTHOR]

The eastern Pacific jumbo squid ( Dosidicus gigas) is one of the largest and most abundant squid of the world ocean. To reveal possible interannual variability in the life span, statoliths were used to determine the age of mature females belonging to two modal size groups (<490 and >500 mm mantle length) collected before (1991-1996), during (1997-1998), and after (1999-2011) a strong El Niño event in Peruvian waters. We found that water temperatures encountered between the third and sixth months of ontogenesis had the strongest negative effect on age. Together with a weaker but significant negative effect of temperatures encountered during early life (first to third months) and later ontogenesis (seventh and eighth months), these temperature parameters (along with other environmental factors) were important in determining whether a given animal had a 1-year life cycle (early maturation and small size) or a 1.5- to 2-year life cycle (delayed maturation and large size). The possible cause of a sudden increase in abundance of large D. gigas in 2000-2001 is discussed. [ABSTRACT FROM AUTHOR]

The channel bull blenny Cottoperca gobio (Notothenioidei, Perciformes) is the largest species of the family Bovichtidae that inhabits both the shelf and upper slope around the southern tip of South America. It is a common non-retained bycatch species during finfish bottom trawl fisheries on the Patagonian Shelf in the Southwest Atlantic. The present study aimed to address previously unknown aspects of its spawning, egg development and early larval growth by maintenance of adults in an aquaculture facility. The fish spawned in the beginning of austral spring (early September), adhering the eggs to the wall of the tank in a band of about 120 cm long, and 20-25 cm wide, estimated to contain ~170,000 eggs. Before and after spawning, the body colouration of both sexes changed displaying marked sexual dimorphism. The male did not guard the spawning site. Egg sizes varied between 2.1 and 2.4 mm. Eggs had a characteristic oil droplet inside. Embryogenesis lasted 50 days, constituting 305 accumulated degree-days. Newly hatched larvae were 7.8-8.1 mm total length, having the oil droplet inside their yolk sac. The yolk sac feeding period lasted approximately 9 days. Anterior part of the larval body was heavily pigmented such that pigmentation could be used for identification purposes. C. gobio occupied the very r-end of the r/K continuum among demersal notothenioid fish, characterised by high fecundities, small eggs and larvae, lack of parental care and high growth rates enabling it to populate the vast areas of the Patagonian Shelf whilst competing with other abundant large demersal fish predators. [ABSTRACT FROM AUTHOR]

Cretaceous heteromorph ammonites of the suborder Ancyloceratina had a striking ontogenetic change in their shell shape. Juveniles had virtually all possible types of coiling of their shells, ranging from regular planispiral and orthoconic to torticonic, hamitoconic and gyroconic. The adults uncoiled the last whorl of their shell forming a U-shaped recurved body chamber with the aperture facing upward. Examination of ribbing pattern and its resolution in various parts of the living chamber in 11 species revealed that the ribs were less developed and had some traces of wear on the inner surface of the hooked chamber, being well developed both on the lateral and outer lower parts. This could indicate that the adult animals were semi-loosely hooked (Ancyloceras, Macroscaphites) or permanently clipped (Scaphites, Hoploscaphites) onto either horizontal or upwardly angled stipes of non-calcified algal macrophytes or branched animals. Comparison of the adult mode of life with those of modern cephalopods suggested that ammonites of the suborder Ancyloceratina had developed a stationary brooding phase that could have several ecological advantages over free-swimming monomorph ammonites. [ABSTRACT FROM PUBLISHER]

Light reflecting structures (iridophores) were examined in live Doryteuthis gahi with mantle lengths (ML) between 50 and 420 mm, both during trawl surveys onboard ship and in shallow-water spawning grounds (10–15 m depth) by SCUBA divers around the Falkland Islands. Several types of iridophores were distinguished based on their shape, colour reflection and position on the body. Ventrally, silvery iridophores cover pigmented organs such as the eyeballs and ink sac and might be used for countershading the squid body. Pink iridophores (splotches) cover the whole mantle, head, fins and arm bases. Green-red iridophores on the dorsal side of the eyeballs, as well as pink splotches on the dorsal and lateral mantle, head and arm bases can be either uncovered or masked by overlaying chromatophores. Two specific bright green stripes of iridophores develop under the fins only in females with ML >80 mm; these may be involved with distant sex recognition, both in forming unisex schools and in ‘preliminary mating’ in the twilight feeding grounds located at the shelf edge. During solitary egg laying in shallow waters, females mask these green stripes almost completely using the overlying chromatophores. [ABSTRACT FROM AUTHOR]

Abstract: Long-term investigations of three abundant nektonic squid species from the Southwest Atlantic, Illex argentinus, Doryteuthis gahi and Onykia ingens, permitted to estimate important population parameters including individual growth rates, duration of ontogenetic phases and mortalities. Using production model, the productivity of squid populations at different phases of their life cycle was assessed and the amount of biomass they convey between marine ecosystems as a result of their ontogenetic migrations was quantified. It was found that squid are major nutrient vectors and play a key role as transient ‘biological pumps’ linking spatially distinct marine ecosystems. I. argentinus has the largest impact in all three ecosystems it encounters due to its high abundance and productivity. The variable nature of squid populations increases the vulnerability of these biological conveyers to overfishing and environmental change. Failure of these critical biological pathways may induce irreversible long-term consequences for biodiversity, resource abundance and spatial availability in the world ocean. [Copyright &y& Elsevier]

Abstract: The Patagonian Shelf ecosystem is considered to be a wasp-waist ecosystem controlled by medium-sized planktivores Patagonian squid Doryteuthis gahi, rock cod Patagonotothen ramsayi, and southern blue whiting Micromesistius australis. After the collapse of southern blue whiting stocks in 2004–2007, its role was overtaken by rock cod, which exhibited a 20–30 fold increase in catches and CPUEs. P. ramsayi is an important food source for all predatory fish; representing about half of the food consumption in hakes, toothfish, kingclip, and some skates. Its importance increases with increasing size of predator with rock cod gradually substituting a similar-sized squid. The explosion of rock cod abundance coincided with an increase of seasonal immigrants preying on this species (hakes and kingclip) that may have changed their migratory timing and patterns for better use of this food resource. [Copyright &y& Elsevier]

Rock cod Patagonotothen ramsayi (Regan, 1913) is one of the most abundant fish of the family Nototheniidae inhabiting the Patagonian Shelf and upper Slope in the southwest Atlantic. Recently, P. ramsayi became an important commercial species around the Falkland Islands with annual catch of 60,000-75,000 t. The present study aimed to reveal previously unknown aspects of reproductive biology of P. ramsayi during the first successful maintenance of adults for more than a year in an aquaculture facility with running seawater. The fish spawned at the end of austral winter. During spawning, males changed their coloration dramatically, occupied artificial shelters on the bottom and showed aggressive territorial behaviour. Egg masses were light-yellow to light-orange irregular spongiform. They were negatively buoyant, but located outside shelters and were ignored by males. Egg diameters varied between 2.1 and 2.3 mm, and the number of eggs per egg mass ranged from 26,800 to 123,400. Embryogenesis lasted 28-32 days. Total lengths of newly hatched larvae ranged from 6.2 to 6.7 mm. The yolk sac feeding period lasted approximately 11 days, during which the larvae showed negative phototaxis. One-month-old larvae attained 8.8-9.0 mm in length. This study confirms that P. ramsayi exhibit the reproductive strategy typical for nototheniid species occupying low-latitude peripheries of their distributional range, characterised by a combination of r-features (small eggs and larvae, high fecundity) and K-features (territorial behaviour and possible nest guarding). [ABSTRACT FROM AUTHOR]

Abstract: The microstructure of the gladius cone was investigated in six species of nektonic squid: shallow-water Loligo gahi (Loliginidae), pelagic eurybathic Illex argentinus, Todarodes pacificus, Dosidicus gigas (Ommastrephidae), and deepwater Onykia ingens (Onychoteuthidae) and Gonatus antarcticus (Gonatidae) using state-of-the-art microscopy. Apart from L. gahi, all other species had septa-like layers in the gladius cone, which for the first time were investigated in detail and compared with those in extinct Cretaceous belemnites Hibolithes sp. and Pachyteuthis sp., and spirulid Cyrtobelus sp. It was found that the organic layers of the gladius cone in recent squid can be homologized with the organic components of the shell in fossil phragmocone-bearing coleoids. The septa-like layers in modern gladius cones therefore represent a vestigial phragmocone composed of organic septal rudiments of the ancestral phragmocone that has lost the siphuncle and gas-filled chambers. The well-developed rostrum in onychoteuthids and small rostrum of the gladius in ommastrephids and gonatids can be seen as homologous with the belemnoid rostrum, which may indicate a close phylogenetic relationship between belemnites and at least some squid. Possible evolutionary pathways of the reduction of the functional phragmocone in squid ancestors are discussed. Several features such as the loss of shell calcification, deep water speciation, and the structure of the equilibrium organ point to a deep-water origin of squids. [Copyright &y& Elsevier]

Abstract: Nektonic squids are the dominant group in the Falklands Islands’ fishery representing >75% of the total annual catch. Among these squids, the benthopelagic Loligo gahi is an important link between zooplankton and fish in the shelf food web. It is preyed upon by diverse and numerous demersal and benthopelagic fishes, penguins and marine mammals, and is harvested by fishermen. Pelagic squids, Illex argentinus, Onykia ingens, and Gonatus antarcticus though seasonally very abundant, are scarce in fish diet because of the absence of specialised pelagic predators. This ecological niche is shared between humans (targeting Illex) and penguins (targeting Onykia and Gonatus). Martialia hyadesi though was abundant in some years in the past, it has now virtually disappeared from the shelf ecosystem. The biomass produced by L. gahi remains in the Falkland waters, whereas that of pelagic squid is transported out of the shelf either to the northern Patagonian slope (I. argentinus) or to deeper waters around the islands (O. ingens and G. antarcticus). Generally squids occupy the ecological niche of epipelagic fish on the Falkland shelf and slope. [ABSTRACT FROM AUTHOR]

Arkhipkin, A. I., and Laptikhovsky, V. V. 2010. Convergence in life-history traits in migratory deep-water squid and fish. – ICES Journal of Marine Science, 67: 1444–1451.The life-history traits of two species of nektonic squid, Onykia ingens and Gonatus antarcticus, and Patagonian toothfish Dissostichus eleginoides, all from the Southwest Atlantic, are reviewed to reveal the extent to which their life cycles have converged. All three follow similar ontogenetic migration, with spawning and egg development in meso-bathypelagic water over the continental slope. Larvae and small juveniles ascend to epipelagic water to feed and grow near the slope. Juveniles and immature adults migrate to the shelf and use it as their feeding grounds. After this period of fast growth on the shelf, the adults descend back to deep water to spawn. The potential advantages that such a life cycle gives to migratory deep-water animals over obligate bathypelagic and benthic fauna are discussed. The most likely cause of ontogenetic migration of juvenile deep-water organisms to the shelf, with the resulting fast growth, is to increase individual fecundity during the adult deep-water phase. Escape from predation and resource utilization at the next trophic level are also examined, but found to be less plausible explanations. Larger, mature animals have higher fecundity, bigger eggs, and larger, better-developed hatchlings, all of which enhance the survival rates of the species at the early stages of their ontogenesis. [ABSTRACT FROM PUBLISHER]

Abstract: The red cod Salilota australis (Moridae) is an abundant fish that inhabits shelf and slope waters around the southern tip of South America. Despite its wide distribution in the Southwest Atlantic, red cod spawns predominantly in areas adjacent to two upwelling areas created by the cold-water Falkland Current in the west and southwest of the Falkland Islands. After their winter migrations from the Patagonian Shelf, red cod aggregate in dense spawning schools at depths between 180 and 200m in the periphery of these upwellings in water densities of Sigma–t between 26.55 and 26.65kg/m3. The timing (September–October) and extent of the spawning peak of red cod correspond well with the spring peak in primary production in the water. Red cod spawn near upwelling areas with western–northwestern direction of water flow that produce eddies with warmer sea surface temperatures (∼2°C warmer) than the eastern eddies. Thus red cod make effective use of the Falkland Islands oceanography, spawning upstream in highly productive upwelling waters and then dispersing their pelagic larvae downstream in the warmer western branch of the Falkland Current over the Patagonian Shelf. [ABSTRACT FROM AUTHOR]

Abstract: Trace element fingerprints of edge and core regions in otoliths from 260 specimens of Patagonian hoki, Macruronus magellanicus, were analyzed by LA-ICPMS to reveal whether this species forms one or more population units (stocks) in the Southern Oceans. Fish were caught on their spawning grounds in Chile and feeding grounds in Chile and the Falkland Islands. Univariate and multivariate analyses of trace element concentrations in the otolith edges, which relate to the adult life of fish, could not distinguish between Atlantic (Falkland) and Pacific (Chile) hoki. Cluster analyses of element concentrations in the otolith edges produced three different clusters in all sample areas indicating high mixture of the stocks. Cluster analysis of trace element concentrations in the otolith cores, relating to juvenile and larval life stages, produced two separate clusters mainly distinguished by 137Ba concentrations. The results suggest that Patagonian hoki is a highly mixed fish stock with at least two spawning grounds around South America. [Copyright &y& Elsevier]

Abstract: The ontogenetic, seasonal, bathymetric and regional variations in the feeding spectrum of 922 specimens of southern blue whiting Micromesistius australis and 512 specimens of hoki Macruronus magellanicus were studied on the Falkland Islands’ shelf (Southwest Atlantic) between November 1999 and April 2003. A total of 49 different prey items were found in the stomach contents of the two species, with the hyperiid Themisto gaudichaudii and Euphausiacea being amongst the most important prey. Although the species composition did not change over fish size, the proportions of individual prey items in their diets did, with an increase in T. gaudichaudii and Euphausiacea with increasing fish size in southern blue whiting. The opposite occurred in hoki. Seasonal variations in the diet were found to mirror the seasonal abundance of prey around the Falkland Islands for the two species. Intra-specific differences in the diet of both predators reflected the distribution of prey, which in turn was determined by the water structure in the two regions sampled, leading to very different diets. In the limited time that the two species occupied the same space there was little or no competition resulting in almost total segregation of their trophic niches in space and time. [Copyright &y& Elsevier]

Abstract: Trace elemental signatures of otolith nuclei and edges were analysed by LA-ICP-MS in 514 specimens of the highly migratory oceanic fish southern blue whiting, Micromesistius australis australis, that were caught in their two distant spawning grounds located in the Southwest Atlantic (Patagonian Shelf around the Falkland Islands) and Southeast Pacific (shelf and slope of the southern Chile). The elemental fingerprints in the otolith edges, accumulated during the adult life of M. a. australis were spawning-site specific. Using just four elements (Li, Mg, Sr and Ba), the correct allocation of fish to their sampling areas situated in either Chilean or Falkland spawning grounds was about 90%, meaning the adult fish have a close affinity to their respective spawning grounds. Despite this, chemical concentrations in their otolith cores revealed two clusters of signatures, with the majority of Chilean fish (more than 80%) grouped into Cluster 1, which is characterized by lower Sr concentrations, and about 80% of Patagonian fish grouped into Cluster 2, which is characterized by higher Sr concentration. This most likely indicates that the Chilean spawning population consists of about four fifths of the native fish plus about one fifth of migrants from the Atlantic, and vice versa. Possible ways of the population interchange and migrations of Chilean and Patagonian fish were discussed contributing to identification of their stock status. [Copyright &y& Elsevier]

Arkhipkin, A. I., Baumgartner, N., Brickle, P., Laptikhovsky, V. V., Pompert, J. H. W., and Shcherbich, Z. N. 2008. Biology of the skates Bathyraja brachyurops and B. griseocauda in waters around the Falkland Islands, Southwest Atlantic. – ICES Journal of Marine Science, 65: 560–570.The distributions and length compositions of two large, abundant skates, broadnose skate Bathyraja brachyurops and grey-tail skate B. griseocauda, were studied using an extensive dataset (∼48 000 skates) collected from the commercial fishery and research cruises on the southeastern Patagonian Shelf around the Falkland Islands between 1992 and 2006. Bathyraja brachyurops mostly inhabit the shelf at depths shallower than 250 m, whereas B. griseocauda are found deeper (>250 m), off the shelf break and slope. Small individuals of both species are most segregated spatially. Growth increments on caudal thorns and vertebral centra revealed that B. brachyurops grow slower and have a shorter lifespan, attaining a maximum total length of 125 cm at 20 years, compared with B. griseocauda (∼150 cm at 28 years). Maturity is attained at 8–10 years for male and female B. brachyurops, and at 15 and 17 years for B. griseocauda, respectively. Spawning takes place on spatially segregated spawning grounds, B. brachyurops reproducing above the shelf break, and B. griseocauda just below the shelf break throughout the year, with a smaller proportion of females of both species laying eggs in winter. [ABSTRACT FROM PUBLISHER]

Roa-Ureta, R. and Arkhipkin, A. I. 2007. Short-term stock assessment of Loligo gahi at the Falkland Islands: sequential use of stochastic biomass projection and stock depletion models – ICES Journal of Marine Science, 64, 3–17. Two short-term stock assessment models are combined to examine the pre-season, in-season, and post-season dynamics of the Loligo gahi fishery off the Falkland Islands over four consecutive fishing seasons. A stochastic biomass projection model (SBPM) projects a pre-season survey-based biomass estimate from the date of the survey to the start of the season. A stock depletion model (SDM) assesses in-season biomass from commercial daily catch-and-effort data. The SBPM projects the SDM biomass estimate at the end of the season to a post-season date of spawning. Combining the SBPM and the SDM helps to clarify the spatio-temporal functioning of the stock and to assess the comparability of survey- and fishery-based estimates of biomass. For the first 2005 season, projected length frequencies indicate two pulses of recruitment onto the fishing grounds. Survey-based projections of biomass were lower than equivalent fishery-based estimates. Over two surveys, the sex ratio was balanced, suggesting full recruitment of both sexes onto the fishing grounds, and the ratio of survey-projected to fishing-estimated biomass was constant. This constant is interpreted as a scaling factor between survey biomass and absolute biomass. [ABSTRACT FROM PUBLISHER]

The Falklands’ rockcod Patagonotothen ramsayi was aged successfully using whole and sectioned otoliths. Marginal increment analysis showed that one opaque and one translucent zone were laid down each year. Counting daily rings in juvenile fish and back calculating to their assumed hatch dates validated the first annulus. Readings taken from scales and otoliths showed good agreement with no significant difference between them ( P>0.05). Inter- and intra-reader comparisons also showed good agreement. The maximum estimated age was found to be 14 years and the calculated von Bertalanffy growth curve L T =33.77(1 −e −0.25year( t+1.07)) showed that P. ramsayi is a relatively slow growing fish that attains 5–6 cm L T in its first year and after which grows approximately 3 cm per year until 4 years. Males seemed to have a slightly lower growth rate but attained a greater maximum size than females. The formation of annuli in the otoliths of P. ramsayi seems to coincide with periods of high reproductive activity with both peaks in GSI and the prevalence of translucent margins occurring in July. [ABSTRACT FROM AUTHOR]

During austral spring 2000, the diet of Gentoo penguins, Pygoscelis papua, was studied and compared to prey availability, assessed by trawl and plankton surveys, in waters adjacent to a number of colonies along the coast of West Falkland. There was good agreement in size and abundance of key prey species in the penguin diet and from the plankton and trawl surveys. The diet of birds breeding adjacent to shallow sheltered waters was dominated by demersal species, in particular crustaceans, Munida spp. whilst birds breeding adjacent to deeper exposed waters generally preyed upon pelagic species of fish, Falkland herring Sprattus fuegensis and squid, Moroteuthis ingens. Gentoo penguins generally foraged at depths of up to 30 m, relatively close to the coast, and illustrated a certain degree of selection of prey species where possible, thus providing evidence that they are not fully opportunistic predators. [ABSTRACT FROM AUTHOR]

We quantified elemental signatures in statoliths of 718 Patagonian longfin squid (Loligo gahi) collected in the vicinity of the Falkland Islands (southwest Atlantic) and at sites on the Patagonian Shelf and coastal Peru. All squid were assigned to a spawning cohort by size, spawning condition, and back-calculated spawning date based on daily increments in statoliths. The remaining statolith was then analyzed for six elemental ratios (Mg/Ca, Mn/Ca, Sr/Ca, Cd/Ca, Ba/Ca, and Pb/Ca) using high-resolution inductively coupled plasma mass spectrometry (ICP-MS). Elemental concentrations in the statoliths were broadly similar to other biogenic aragonites. Differences in Sr/Ca ratios in statoliths among geographic locations were generally consistent with a negative correlation between Sr/Ca and temperature. Variations in statolith Cd/Ca and Ba/Ca values confirmed that during winter months, the squid were foraging deeper in the water column. Both Mg/Ca and Mn/Ca ratios in statoliths decreased with squid size, probably corresponding to a decrease in the contribution of the organic component of the statolith. Elemental signatures in the statoliths of L. gahi varied significantly geographically and between spring- and autumn-spawned cohorts, which must therefore have spent significant portions of their life histories in different environments. [ABSTRACT FROM AUTHOR]

Fishery statistics for two abundant commercial squid, Illex argentinus (Ommastrephidae) and Loligo gahi (Loliginidae), in Falkland Islands waters (southwest Atlantic) between 1987 and 1999 were analysed. The areas of the highest densities of the two species are usually separated, with I. argentinus most abundant to the north-west of the Islands in February–May and L. gahi to the south-east in February–May and August–October. However, in some years, I. argentinus intrude in great numbers into nursery or feeding areas of L. gahi in April and May. It could, therefore, affect, either directly (via predation) or indirectly (by competition for food), the abundance and recruitment of the second cohort of L. gahi, exploited around the Islands between April and October. Catch per unit effort (CPUE) of I. argentinus in February–March did not correlate with that of L. gahi in February–May. In contrast, the CPUE of I. argentinus in April–May was negatively correlated with that of L. gahi in April–May and August–October of the same year. Possible reasons for these inverse abundance patterns of the two squid species, and their implications for fisheries management are discussed. [Copyright &y& Elsevier]

Understanding the spatial and temporal dynamics in marine fish populations is essential for the development of effective adaptive management strategies. Many marine fish species undergo ontogenetic shifts in abundance, with the utilization of productive shelf-based habitats during early life-history stages. For instance, in the shelf ecosystem around the Falkland Islands, a dynamic Patagonian toothfish population undertakes an early life-history ontogenetic migration after recruitment from spawning areas off southern Chile and the Burdwood Bank. To better understand the spatial-temporal dynamics for this species, Bayesian species distribution models were used to (1) identify oceanographic drivers of recruitment success; (2) assess the spatial-temporal distribution patterns; and (3) describe the habitat preferences and ecological interactions during a six-year study period (2015–2020) on the Patagonian Shelf. The presence of seasonal mesoscale eddies linking the Sub-Antarctic Front with the Falkland Current appear to be of primary importance for the survival of toothfish eggs and larvae on the shelf after transport from offshore spawning areas over the Burdwood Bank and southern Chile. Results indicate persistent recruitment hotspots for newly-settled Patagonian toothfish to the north-east, along with opportunistic areas to the south and west of the Falkland Islands, coinciding with the main areas of upwelling and high productivity. During years of low recruitment, juveniles are largely constrained to sheltered inshore regions to the north-west of the Falkland Islands. Spatial distribution patterns during post-settlement ontogenetic migrations are progressive, characterised by age-structured hotspots that differ according to depth, current velocity, oxygen, mixed-layer thickness, the abundance of competitors (icefish – Champsocephalus esox) and prey (rock cod – Patagonotothen ramsayi). The temporal shift in the range and intensity of hotspots is linked to levels of recruitment and subsequent cohort strength, which in turn appears to be driven by oceanographic processes. Understanding the environmental influences on recruitment dynamics is a key step in assessing connectivity within these discrete spatial groups on the Patagonian Shelf, and how their variability can influence the adult population over time. • D. eleginoides follow discrete ontogenetic migration pathways on the Patagonian shelf. • Mesoscale eddies lead to increased abundance. • Spatial patterns are opportunistic becoming persistent with age. • Hotspots in abundance characterised by high oxygen concentrations. • Age-specific preferences for depth, and ecological interactions. [ABSTRACT FROM AUTHOR]

The Falkland Islands marine environment host a mix of temperate and subantarctic species. This review synthesizes baseline information regarding ontogenetic migration patterns and trophic interactions in relation to oceanographic dynamics of the Falkland Shelf, which is useful to inform ecosystem modelling. Many species are strongly influenced by regional oceanographic dynamics that bring together different water masses, resulting in high primary production which supports high biomass in the rest of the food web. Further, many species, including those of commercial interest, show complex ontogenetic migrations that separate spawning, nursing, and feeding grounds spatially and temporally, producing food web connections across space and time. The oceanographic and biological dynamics may make the ecosystem vulnerable to climatic changes in temperature and shifts in the surrounding area. The Falkland marine ecosystem has been understudied and various functional groups, deep-sea habitats and inshore-offshore connections are poorly understood and should be priorities for further research. [ABSTRACT FROM AUTHOR]

A mesopelagic scaled squid, Pholidoteuthis massyae, was found for the first time in the south-west Atlantic, and an epi-mesobathyal octopus, Muusoctopus eureka, was found in shallow waters of the Falkland Islands almost a century after its last record there. These new records are tentatively attributed to recent climatic changes in oceanic waters of the southern hemisphere. Deimatic behaviour was recorded for the first time in an inkless octopus. [ABSTRACT FROM AUTHOR]

Abstract: We report on the extraordinary findings of several endemic species of North Pacific deepwater fish and squid on the continental slope of the Falkland Islands in the Southwest Atlantic, namely the giant rattail grenadier Albatrossia pectoralis (Macrouridae), pelagic eelpout Lycodapus endemoscotus (Zoarcidae) and squid Gonatopsis octopedatus (Gonatidae). These deepwater dwellers might have moved more than 15,000km from their common species ranges with Pacific Deep Water along the western slopes of both Americas and through the Drake Passage. Our findings provide further evidence of the possible role of deepwater currents in the dispersal of bathypelagic and benthopelagic animals from one polar region to another across various climatic zones of the world ocean. [Copyright &y& Elsevier]

• Trials of fishing gear proved only SEDs to be highly efficient. • 96 % of reported seal mortalities occurred before SED implementation. • Underwater footage confirmed seals safely escaped from trawls equipped with the SED. • Partnership with the fishing industry was fundamental to the mitigation process. In the Falkland Islands, the South American fur seal and South American sea lion spatially overlap and interact with bottom-trawling fisheries. Until 2015, interactions of these species with the Patagonian bottom trawl squid fishery were uncommon. During the second fishing season 2017 a dramatic increase in seal interactions was observed, with a corresponding increase in incidental mortalities. Various mitigation measures were applied, seal exclusion devices (SEDs) fitted inside a net extension inserted between the trawl net and cod-end being the most efficient. The SEDs became mandatory in the fishery in September 2017. Since then, the number of seal mortalities remains negligible. SED efficiency is monitored by 100 % observer coverage. To the best of our knowledge, the Falkland Islands Patagonian squid fishery is currently the only trawl fishery in the Southwest Atlantic with full observer coverage and SED usage. It is hoped in the near future similar mitigation measures extend to other coastal countries whose fisheries also interact with these otariids. [ABSTRACT FROM AUTHOR]

Globally, cephalopods support large industrial-scale fisheries and small-scale to partly large-scale local artisanal fisheries. They are of increasing economic importance as evidenced by the rapid rise in their global landings from 1950 to 2014. Cephalopods are sensitive to environmental variability and climate change and many if not all species show wide fluctuations in abundance. This is most evident in ommastrephid nerito-oceanic squid since their life cycle is associated with boundary currents that are changing with climate change. The inter-annual variability in catch presents challenges for fishers and managers due to the 'boom-or-bust' nature of the fishery. A key barrier to rational management of squid fisheries is the low level of development of fishery forecasting. Despite substantial progress made in relating squid population dynamics to environmental variability and change, several challenges remain to develop forecast products to support squid fisheries management. Ideally, squid fisheries management needs a forecasting system that includes all time-scales of forecasting, and especially short - and medium-terms forecasts. The present overview first provides current knowledge of the effects of climate change and variability on squid population dynamics, challenges and opportunities to advance ecological-fishery forecast products, and finally a roadmap is proposed for future development of forecasts products to support squid sustainable fisheries management. As for the adoption of specific forecasting methods to the squid fishery management process, what is important is the relationship between needs, feasibility, and the ultimate success of a forecast will be determined by whether it is used by end-users. [ABSTRACT FROM AUTHOR]

• Life-history parameters indicate Macrourus carinatus is vulnerable to overexploitation. • Maximum age recorded in our sample was 53 years. • Long life-span was matched with late reproduction of 12–14 years. • Our data support dimorphism in this species with females growing larger than males. In light of their life-history characteristics, deep-sea fishes display a higher vulnerability to overfishing than most other groups of fish, and their exploitation may not be sustainable even at low levels. In the Falkland Islands, increasing efforts have been made to target deep-sea species, such as the ridge-scaled grenadier Macrourus carinatus , in the waters off the continental slope. Research findings relating to the age and growth of this species remain conflicting, largely as a result of non-representative sampling of the population, inappropriate ageing methods, and the absence of age validation. We show how M. carinatus display life-history characteristics typical of the deep-water fish community, such as a long life (53 years), late age at maturity (females = 14.00 years; males = 12.28 years), slow growth and low levels of natural mortality (females = 0.104 year−1; males = 0.117 year−1) that highlight the susceptibility of M. carinatus to overfishing. In particular, validated age estimates obtained using improved ageing criteria indicate that longevity is up to 28 years greater than previously reported estimates. M. carinatus were shown to be sexually dimorphic in size, with females growing larger (females = 31.49 cm pre-anal length [PAL]; males = 24.97 cm PAL) compared to males. Updated biological parameter estimates indicate M. carinatus are far more vulnerable to fisheries exploitation than previously thought. A precautionary approach must be followed and conservation measures put in place to ensure sustainable management of a directed fishery or bycatch of M. carinatus and other similar deep-sea species. [ABSTRACT FROM AUTHOR]

The article reports a sighting of penis enlargement in a deep-water squid. The study involves a mature moribund male of the greater hooked squid which was count on the Patagonian slope south of the Falkland Islands. According to the authors, during the maturity assessment for which the mantle of the squid was opened, the penis of the squid suddenly started to erect. It notes that several spermatophores were ejaculated from the penis tip following the elongation.

Cephalopods are harvested in increasingly large quantities but understanding how to control and manage their stocks, and tracking the routes of the consumption that exploits them, lag behind what has been developed for exploiting finfish. This review attempts to redress the imbalance by considering the status of the major cephalopod stock species and the traceability of cephalopod seafood along the trade value chain. It begins with a general overview of the most important exploited cephalopods, their stock status and their market. Four major cephalopod resources are identified: the three squid species Todarodes pacificus, Dosidicus gigas and Illex argentinus; and one species of octopus, Octopus vulgaris. The techniques and problems of stock assessment (to assess sustainability) are reviewed briefly and the problems and possible solutions for assessing benthic stock such as those of octopuses are considered. An example of a stock well managed in the long term is presented to illustrate the value of careful monitoring and management: the squid Doryteuthis gahi available in Falkland Islands waters. Issues surrounding identification, mislabelling and illegal, unreported and unregulated (IUU) fishing are then reviewed, followed by a discussion of approaches and techniques of traceability as applied to cephalopods. Finally, some of the mobile apps currently available and in development for tracking seafood are compared. This review concludes with observations on the necessity for the strengthening and international coordination of legislation, and more rigorous standards for seafood labelling and for taxonomic curation of DNA sequences available in public databases for use in seafood identification. [ABSTRACT FROM AUTHOR]

Fishery discards supplement food for many seabirds, but the impacts of declining discards are poorly understood. Discards may be beneficial for some populations but have negative impacts by increasing bycatch risk or because they are junk-food. The Falkland Islands support > 70% of global black-browed albatross Thalassarche melanophris populations, which feed on discards. However, the effect of discards on population demographics, and implications of fishery management changes, are unknown. We analysed stomach contents of black-browed albatross chicks across eight breeding seasons (2004–2020) from New Island, Falkland Islands, to assess variation in discard consumption and how this relates to foraging conditions and breeding success. Across years, 68%–98% of samples contained natural prey, whilst 23%–88% of samples contained fishery discards. Discard consumption was positively related to fishery catches of hoki Macruronus magellanicus and sea surface temperature anomalies SSTA (°C), and negatively related to breeding success. These results suggest a diet-switching behaviour for Falkland Islands albatrosses, whereby birds switch from preferred natural prey to suboptimal discards when environmental conditions, and hence natural feeding opportunities, are unfavourable. Crucially, this study highlights that fishery discards do not compensate for poor natural foraging conditions for breeding albatrosses in the long term. [ABSTRACT FROM AUTHOR]

Effective marine ecosystem monitoring is critical for sustainable management. Monitoring seabird diets can convey important information on ecosystem health and seabird–fishery interactions. The diet of breeding black-browed albatross (Thalassarche melanophris) has previously been assessed using stomach content analysis (SCA) or stable isotope analysis (SIA), but not both methods together. Combining dietary sampling approaches reduces biases associated with using single methods. This study combines SCA and SIA to study the diet of black-browed albatross chicks, with a specific focus on fishery discard consumption, at two Falkland Islands colonies (New Island 51°43′S, 61°18′W and Steeple Jason Island 51°01′S, 61°13′W) during two consecutive breeding seasons (2019 and 2020). SCA provided high taxonomic resolution of short-term diet and priors for stable isotope mixing models, with multiple measures of dietary items (e.g. numeric frequency N%, frequency of occurrence FO%). By contrast, SIA of down feathers provided a single and more integrated dietary signal from throughout chick development. Although the two methods disagreed on the dominant prey group (SCA—crustacean; SIA—pelagic fish), the complementary information suggested a chick diet dominated by natural prey (SCA: 74%–93% [FO], 44%–98% [N]; SIA: minimum 87%–95% contribution). Nonetheless, SCA revealed that a high proportion of breeding adults do take discards. We detected consistent colony-specific diets in relation to prey species, but not in relation to higher discard use. Overall, discard consumption was highest in 2020, the year characterised by the poorest foraging conditions. Our results have implications for fisheries management and future dietary studies assessing discard use. [ABSTRACT FROM AUTHOR]

Trace element signatures of otolith edges and cores from 335 austral hake (Merluccius autralis) were analysed using LA-ICPMS from samples collected in Chilean and Falkland Islands' waters, in order to provide potential insights into stock discrimination and migrations. Fish were caught in two locations in Chile and four locations in the south-west of the Falkland Islands Shelf. Univariate and multivariate analyses of trace element signatures in the edges of otoliths, representing adult fish, were not able to distinguish between samples collected in Chile and the Falkland Islands. Cluster analyses based on Ward’s similarity/distance metric suggested that it was possible to identify two groups from core signatures. Further analyses of this perceived clustering of the core concentrations revealed that this was largely due to the wide spread of Sr/Ca ratios in the otoliths’ cores. Gaussian finite mixtures using MCMC methods confirmed that Sr/Ca ratios form two separate distributions with significantly different mean values while concentrations of other elements showed no evidence of the presence of two or more distributions. The results suggest that there is only one spawning stock of austral hake with spawning situated in and around the Chilean fjords (43°30’S– 47°S) and the variation in Sr/Ca ratios likely suggests complex salinity structuring in this area. [ABSTRACT FROM AUTHOR]

Abstract: Due to the lack of suitable high-resolution archives, regional and continental-scale climate dynamics of southern South America are not well understood. Shells of the long-lived, shallow-marine bivalve mollusk, Eurhomalea exalbida (Dillwyn), are likely to contain information on the past water temperatures. As yet, however, no rigorous calibration study has been presented so that growth history traits and the reliability of shell oxygen isotope-based temperature estimates remain unknown. Shell growth patterns and oxygen isotope ratios of four young specimens of E. exalbida from the Falkland Islands (Southwest Atlantic) were analyzed and cross-calibrated with environmental parameters. Results indicate that E. exalbida likely captured the full seasonal temperature amplitude in its shell. Annual growth line formation occurred between fall and early winter. The most remarkable finding, however, was that E. exalbida formed its shell with an offset of −0.48 to −1.91‰ from expected oxygen isotopic equilibrium with the ambient water. If this remained unnoticed, paleotemperature estimates would overestimate actual water temperatures by 2.1–8.3°C. With increasing ontogenetic age, the discrepancy between measured and reconstructed temperatures increases exponentially, irrespective of the seasonally varying shell growth rates. We attribute this finding to a pH increase in the extrapallial fluid during ontogeny favoring a dominance of the (isotopically lighter) carbonate ions over (isotopically heavier) bicarbonate ions. When this disequilibrium fractionation effect is taken into account, E. exalbida can serve as a high-resolution paleoclimate archive for mid to high latitudes of southern South America providing quantifiable temperature estimates, even from single fossil specimens. [Copyright &y& Elsevier]