Eastern Indian Research Articles

Length‐weight relationship of six demersal fish species from Gulf of Mannar, Bay of Bengal, Eastern Indian Ocean

Length‐weight relationship of six demersal fish species from Gulf of Mannar, Bay of Bengal, Eastern Indian Ocean

Prevalence of Insulin Resistance in Urban Indian School Going Children with Overweight/Obesity: A Cross-sectional Study

Background: Limited data are available for insulin resistance (IR) in children with over- weight/obesity from Indian subcontinent. Identifying predictors of IR in this population is important, as they may be used as a screening tool for future metabolic complications. Materials & Methods: This school based cross-sectional study was conducted in an Eastern Indian city. Anthropometry and blood pressure measurements were carried out as per the published guidelines. Venous blood samples were taken in a fasting state to measure plasma glucose, insulin, and lipid profile. IR was measured quantitatively by a homeostatic model of assessment (HOMA-IR). Results: A total of 545 (28.2%) children with overweight/obese were included. Male:Female ratio was 1:1.27. The overall prevalence of metabolic syndrome (MS) in these children was 21.8%. Around 32.3% of children had HOMA-IR of ≥2.5, and 22.2% had HOMA-IR of ≥3.16. The mean HOMA-IR in children with MS was 5.46 compared to 2.18 in those without MS. An increased risk of IR with low HDL, high triglyceride, increased waist circumference, and increased BP (both systolic and diastolic) was found. This means, the insulin resistance was commoner in children with over-weight/obesity and underlying MS. Conclusions: The present school based study found a high prevalence of insulin resistance among children with over-weight/obesity. This could predict an increased risk of future adverse cardio-vascular events in the study children. The findings of this study would help in planning and implementing primary prevention programs targeting weight management and life-style change in the school going children.

Differential genotypic signatures of Toll-like receptor polymorphisms among dengue-chikungunya mono- and co-infected Eastern Indian patients.

Dengue (DENV) and chikungunya (CHIKV) viral infections trigger high patient morbidity and mortality. Mono-/co-infection of these viruses activates innate immune response, triggering Toll-like receptor (TLR) pathways. The present study investigated the differential role of TLR3, 7 and 8 single-nucleotide polymorphisms (SNPs) between mono- and co-infected Eastern Indian patients. Interaction of TLR polymorphic variants with signal peptidase complex (SPC18) was explored which might affect immune signalling against DENV/CHIKV infections. Out of 550 febrile symptomatic patients, 128 DENV-CHIKV co-infected samples were genotyped for eight SNPs of TLR3 (rs3775290-chr4:186083063), TLR7 (rs179008-chrX:12885540, rs5741880-chrX:12869297, rs179010-chrX:12884766, rs3853839-chrX:12889539) and TLR8 (rs5744080-chrX:12919685, rs3764879-chrX:12906578, rs3764880-chrX:12906707) by PCR-RFLP along with 157 healthy individuals. Statistical analysis established genotypic association of TLR SNPs with DENV-CHIKV co-infection, and difference between mono- and co-infected patients and their role in determining high viral load (HVL) during competitive viral replication among co-infected patients. In silico protein-protein docking evaluated interactive effect of TLR variants with SPC18. The findings revealed patients with CC genotypes of TLR7 and 8 SNPs were significantly susceptible towards co-infection, whereas specific genotypes of TLR7 and 8 imparted protection against co-infection. Differential analysis between mono-/co-infected patients revealed distinct genotypic distribution of TLR3, 7 and 8 SNPs. Co-infected patients with TT-rs179010 exhibited DENV-HVL, whereas CHIKV-HVL was detected among patients with other genotypes. Molecular docking of TLR7-rs179008 Q variant and TLR8-rs3764880 V variant with SPC18 generated better free binding energy. This study underlined the importance of TLR7 and 8 SNPs towards mono-/co-infection of DENV/CHIKV, with certain genotypes associated with co-infection susceptibility. Moreover, it suggested a probable role of specific genotypes of TLR7 and 8 polymorphisms imparting high dengue/chikungunya viral load among co-infected patients.

Zircon and monazite geochronology from the Rengali-Eastern Ghats Province: Implications for the tectonic evolution of the eastern Indian terrane

The tectonic evolution of the Rengali Province and its eventual juxtaposition to the Eastern Ghats Province has important bearings on the geological evolution of the Eastern Indian terrane. New zircon and monazite age data from the Rengali Province and the northern-northwestern part of the Eastern Ghats are presented in this study to trace this evolutionary history. Monazite U-Th-total Pb data from the paragneissic rocks of the eastern Rengali Province show a metamorphic age of 2775 ± 18 Ma while an older age of 2943 ± 35 Ma from the same rock probably suggests an older metamorphic/magmatic event. Zircon U-Pb (LA-ICPMS) data from the northern part of the Eastern Ghats show 1230 ± 21 Ma and 1220 ± 9 Ma ages that we interpret as a major phase of high-grade metamorphism of the basement. Paragneissic rocks from the northwestern margin of the Eastern Ghats yields monazite ages of 966 ± 21 Ma and 555 ± 12 Ma respectively from the core and rim parts of monazite grains. Similar ages of 966 ± 25 Ma and 540 ± 12 Ma are reported from paragneissic rock occurring at the contact of Rengali Province and the Eastern Ghats. This younger (~555–540 Ma) age likely correlates to the amphibolite facies reworking of the granulitic lower crust which coincides with the emplacement of nepheline syenite at 556 ± 28 Ma (zircon U-Pb data) and the contact metamorphism of the ultramafic granofels at 553 ± 18 Ma (monazite data). Nepheline monzosyenite veins intruded the gneissic nepheline syenite at 506 ± 9 Ma (zircon U-Pb data). Emplacement of the monzosyenite veins within the felsic gneiss country at the northwestern margin of the Eastern Ghats at 490 ± 3 Ma (zircon U-Pb data) marks the last thermal imprint in response to large-scale shear-induced deformation at the northern/northwestern contacts of the Eastern Ghats. We infer that the Neoarchean (ca. 2943–2775 Ma) events possibly resulted from the ensuing convergent tectonics driven by lithospheric peeling (peel-back convergent tectonics). The Eastern Ghats and its Antarctic counterpart juxtaposed with the Rengali Province during ca. 1000–900 Ma and become a part of the Eastern Indian terrane. The Ediacaran-Cambrian (ca. 556–490 Ma) events imply the reactivation of the deep crustal Tonian-age shear systems in a transpressional tectonic setting.

New taxonomic and phylogeographic data on three nominal species of the genus Septaria Férussac, 1807 (Gastropoda: Cycloneritida: Neritidae)

Due to superficial morphological similarities, there is often confusion in the identification of some species of the genus Septaria. A combined analysis of the genital anatomy, morphometric and DNA, based on a portion of the COI gene, applied to three nominal species of this genus, confirmed the validity of Septaria tahitiana Eichhorst, 2016, and suggested that Septaria borbonica (Bory de Saint Vincent, 1804) is a subspecies of Septaria porcellana (Linnaeus, 1758), both taxa with disjunct distribution areas: Septaria borbonica in the western Indian Ocean and Septaria porcellana the western Pacific and eastern Indian Oceans. The possible presence of Septaria tesselata (Lamarck, 1816) in Mayotte (Comoros Archipelago) needs to be confirmed.

Legacy and emerging per- and poly-fluoroalkyl substances in surface seawater from northwestern Pacific to Southern Ocean: Evidences of current and historical release

Knowledge on distribution of per- and poly-fluoroalkyl substances (PFASs) in open oceans is limited. By taking part in the 32nd Chinese Antarctic Research Expedition, 41 surface seawater samples were collected in the northwestern Pacific Ocean (NW-PO), eastern Indian Ocean (E-IO) and Southern Ocean (SO), and 23 PFASs comprised of legacy perfluoroalkyl carboxylic acids, perfluoroalkyl sulfonate acids and some new emerging homologs such as 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) were measured. The concentrations of the total PFASs decreased in the order of NW-PO>E-IO>SO. Perfluorooctanoic acid (PFOA) was the most dominant, followed by perfluorooctane sulfonate (PFOS). The PFOA concentration declined exponentially with the offshore distance, while such trend was not obvious for PFOS and other legacy PFASs, suggesting that PFOA was mainly derived from the ongoing land-based emissions, while PFOS was mainly from historical residues. 6:2 Cl-PFESA was identified (<11.1–170 pg/L) in the oceanic waters with relatively high level at the sites near Australia. Multiple receptor models indicated that PFASs in the SO were mainly contributed by atmosphere input, while those in the NW-PO and E-IO were originated from land sources. Isomeric profiles of PFOA showed that telomere-based source became more outstanding than electrochemical fluorinated production in recent years.

OSTEOLOGY OF PARABROTULA PLAGIOPHTHALMUS (OPHIDIIFORMES: BYTHITOIDEI: BYTHITIDAE)

Parabrotula (Zugmayer 1911a), included in the family Bythitidae (Ophidiiformes), is a genus of small viviparous mesopelagic fishes with two valid species. Parabrotula plagiophthalmus is known from collections made worldwide except in the eastern Indian, eastern Pacific, and western South Atlantic Oceans; most specimens are from the North Atlantic Ocean. Most anatomical data for P. plagiophthalmus are limited to aspects of external anatomy, the reproductive system, and meristic data that can be gathered through radiographs; virtually no data on other aspects of the osteology of P. plagiophthalmus are available. In this study, we describe the skeleton of P. plagiophthalmus from cleared and stained specimens and computed tomography data. Many aspects of the skeleton of P. plagiophthalmus are reduced (subopercle; ceratobranchial 5; gill rakers; gill filaments; distal radials of median pterygiophores; caudal skeleton; posttemporal; supracleithrum; scapula; distal pectoral radials; pelvic girdle and fins; scales) or absent (mesethmoid; nasal; pterosphenoid; intercalar; infraorbital bones; endopterygoid; coronomeckelian; supramaxilla; pharyngeal toothplates). All bones of the skull are extremely thin dermal or perichondral ossifications, with little to no endochondral components. The vomer supports a variable number of teeth (0–3). The pars autopalatina and its ossification are separated from the pars metapterygoidea and pars quadrata and their ossifications; the thin ectopterygoid bridges these elements of the suspensorium. The lower jaw is very large compared with all other elements of the viscerocranium. The pectoral radial plate was never observed to be divided into separate radial elements. We discuss the skeleton of Parabrotula in the context of other taxa but call attention to the need for further comparative studies of the anatomy of ophidiiform fishes.

Emerging threat of bluetongue in Eastern and North-Eastern Indian states

Albeit bluetongue (BT) in India is endemic to southern and western parts, eastern and north-eastern parts of the country didn't experience any outbreak or reported active disease. However, sero-epidemiology indicates bluetongue virus (BTV) is in circulation in animals and vectors of eastern and north-eastern states of India. Moreover, in recent years BTV has been isolated from sheep, Culicoides midges and goat from this region that substantiate the notion. All the epidemiological components of BT, viz. susceptible hosts, suitable climatic conditions for propagation of vectors, competent vectors are present that pose emerging disease threat in eastern and north-eastern parts of India. Hence, further surveillance and preparedness are recommended to avoid future BT outbreak, if any.

Motherhood in the Realm of Eastern Indian and Himalayan Art: An Iconographic Study of Visual Forms of Prajñāpāramitā from the National Museum, Delhi

This paper aims to outline and explore the development of iconographic forms and metaphysical grounding of one of the most venerable and distinguished Buddhist female deities, Prajсāpāramitā. The Buddhist female pantheon gained a paramount pre-eminence with the idolization of Prajñāpāramitā, establishing the significance of female figure and, especially, mother symbolism during the early medieval period under the liberal patronage of the Pala dynasty of Eastern India. The religious imageries and practices of this deity gradually disseminated to the adjoining Himalayan kingdoms of Nepal and Tibet through pedagogic and religious linkages, and became an integral part of their society. To understand the factors of cross-cultural assimilation through the study of representational forms and its metaphysical grounding, the paper explores and shows the metaphorical meaning of ‘prajсā’ propounded in the Prajñāpāramitā discourse, and its representation in cultic icons of the goddess Prajñāpāramitā and the manuscript. This thematic narrative opens up new avenues of interpretations on gender-subjectivity in Buddhist cosmology and pantheistic belief system which are touched upon in this paper. The idea of pronouncement and expansion of female-oriented texts and icons is highlighted through a study of select devotional icons of this deity, Prajсāpāramitā, from the collection of the National Museum, Delhi.

Vertical distribution of blue Shark (Prionace glauca) in The Indian Ocean

Each fish species tends to choose a suitable environment suitable for its survival and reproduction horizontally and vertically. Blue shark (Prionace glauca) is the dominant catch of pelagic sharks by-catch in the Eastern Indian Ocean longline tuna fishery, with about 70% of the total sharks caught in this fisheries. This study aims to provide the information and the vertical analysis distribution of blue sharks based on temperature and depth in the Indian Ocean. The scientific observer collected 2,951 set-by-set longline fishing data based on Research Institute For Tuna Fisheries (RITF) from January 2006 to December 2018, on which the present analysis was made. The mini logger was used to measure the vertical distribution of blue sharks in the longline fisheries. This result indicated that blue shark was caught between 75.18-445.46 m depth, with 84% of which live at thermocline area (70-300 m depth), and 16% lived in underlayer area (&gt;300 m depth). Blue sharks distributed in the underlayer area have a larger body size than those in the thermocline area with a size &gt;180 cmFL compared to 50-170 cmFL in the thermocline area.

MJO induced diurnal sea surface temperature variations off the northwest shelf of Australia observed from Himawari geostationary satellite

High frequency coupling between the tropical upper ocean and atmosphere at diurnal time scales is being recognised to be important for the behaviour of large scale climate modes such as the Madden Julian Oscillation (MJO). Sea surface temperature (SST) variability in the Eastern Indian Ocean warm pool and on the Northwest Shelf of Australia is strongly influenced by the MJO activity. In this study, we use the hourly Himawari-8 geostationary satellite SST data to understand the modulation of the amplitude of SST diurnal variations in the region by the MJO during two austral summer seasons of 2015–16 and 2016–17. The high temporal and spatial resolutions of the Himawari-8 SST data are able to capture the temporal and spatial variability of diurnal SST amplitude. Our results show that the MJO onset (active phase) is preceded by strong diurnal SST variations during the MJO suppressed phase. The amplitudes of the SST diurnal variations are mainly modulated by surface wind variability in the region, as denoted by their spatial and temporal correlations. The very strong El Niño event in 2015–16 may have significantly weakened the MJO activities in the region, resulting in prolonged MJO suppressed phase, high diurnal SST variation and mean SST. This study provides background knowledge for future research on how the diurnal SST variation in the region may influence the progression of the MJO events.

Participatory Livelihood Vulnerability Assessment (PLVA) of the Forest Dwellers: A Study of Fifteen Tribes and Particularly Vulnerable Tribal Groups (PLVAs) in the Eastern Indian Region

Participatory Livelihood Vulnerability Assessment (PLVA) of the Forest Dwellers: A Study of Fifteen Tribes and Particularly Vulnerable Tribal Groups (PLVAs) in the Eastern Indian Region

Experience with Burn Prevention Program in North Eastern India

Burn injuries are one of the most devastating of all injuries and a major global public health concern. Though burn injuries cause lots of morbidity and mortality in India, community-based interventions in the forms of multi-strategic and multi-focused preventive programs are however lacking. This study, undertaken in the North Eastern Indian state of Assam, aims at reducing the incidence of burn accidents, morbidity and mortality of burn injuries through focused attention towards sensitizing the community with well-structured preventive program. Participatory community seminars, use of print, electronic and social media and lectures and demonstrations in schools were the tools used in the preventive programs. Analysis of inpatient and outpatient records of burn injured patients treated in the burn unit and scoring system in school education program and social media participants helped in assessment of the impact of Burn Preventive Programs (BPP). For convenience of assessment, comparative analysis of the results in early (Block I) and later part (Block II) of the study period was made. Results showed significant reduction of percentage of patients reporting from the areas where BPP was implemented. There was also reduction in %TBSA burn in majority patients in Block II in comparison to Block I. Water was used to extinguish fire in 48.9% patients in Block I and 78.0% patients in Block II. Water was also used to cool burn wounds by 52.3% patients in Block I, and 83.4% patients in Block II. While 80.9% people made inappropriate topical application on the wounds in Block I, only 34.6% did so in Block II. Increased awareness amongst general people was reflected by increased percentage of patients reporting to burn unit within 7 hours of injury and significant reduction of firecracker burns from 21.9% (Block I) to 7.8% (Block II). Similarly, improved awareness amongst the students was evident from the improved scoring by majority students and reduction in burns amongst them in the later part of Block II. The results indicate that BPP has got positive impact in the society.

On the Indian species of Eurycarcinus A. Milne-Edwards, 1867, Heteropanope Stimpson, 1858, and Pilumnopeus A. Milne-Edwards, 1867 (Decapoda: Brachyura: Pilumnidae)

Abstract Five species of pilumnid crabs assigned to Eurycarcinus A. Milne-Edwards, 1867, Heteropanope Stimpson, 1858, and Pilumnopeus A. Milne-Edwards, 1867, have been reported from India: E. orientalis A. Milne-Edwards, 1867, E. bengalensis Deb, 1999, H. glabra Stimpson, 1858, H. neolaevis Deb, 1995, and P. convexus (Maccagno, 1936). The identity of E. bengalensis is confused and the species had been provisionally transferred to Heteropanope. Examination of the types however, confirms the affinities of the species with Eurycarcinus and consequently extends the range of the genus to the eastern Indian Ocean. A re-examination of the types of H. neolaevis show that it is a junior subjective synonym of Aniptumnus quadridentus (De Man, 1895), and is the first record of the genus from India. Eurycarcinus integrifrons De Man, 1879, is also formally recorded for the first time from India.

The Horizontal Distribution of Siliceous Planktonic Radiolarian Community in the Eastern Indian Ocean

The plankton radiolarian community was investigated in the spring season during the two-month cruise ‘Shiyan1’ (10 April–13 May 2014) in the Eastern Indian Ocean. This is the first comprehensive plankton tow study to be carried out from 44 sampling stations across the entire area (80.00°–96.10° E, 10.08° N–6.00° S) of the Eastern Indian Ocean. The plankton tow samples were collected from a vertical haul from a depth 200 m to the surface. During the cruise, conductivity–temperature–depth (CTD) measurements were taken of temperature, salinity and chlorophyll a from the surface to 200 m depth. Shannon–Wiener’s diversity index (H’) and the dominance index (Y) were used to analyze community structure. There was a total of 168 plankton species, composed of Acantharia, Phaeodaria, Polycystina, Collodaria and Taxopodida (monospecific—Sticholonche zanclea, Hertwig is the only recognized species). Hence, it included both celestine-based and siliceous organisms, which are also described here for the first time from this region. Total radiolarians ranged from 5 to 5500 ind/m−3, dominated by co-occurrences of Sphaerozoum punctatum and Stichonche zanclea species at the south-equator zone (SEQ)-transect 80° E and equator zone (EQ)-transect Lati-0. The possible environmental variables were tested through RDA analysis; although no result was obtained for the full species dataset, the samples from the equatorial transect related strongly to mixed-layer chlorophyll a concentration and those of a north–south transect to surface silicate concentrations or mixed-layer nitrate were significantly correlated (p &lt; 0.01) to the radiolarian community. Our results indicate that the silicate and chlorophyll-a concentrations are the two major factors affecting the radiolarian distribution along two of the investigated transects (southern equator and equator) in the study area.

Differentiating morpho-functional patterns of the five most common deep-sea benthic anglerfishes (Lophiiformes) from Andaman and Nicobar Islands (eastern Indian Ocean)

Anglerfishes are widely distributed from shallow to deep-water habitats occupying different ecological niches. To explain this adaptability, we performed a morpho-functional study on common benthic anglerfishes inhabiting the Indian deep-sea waters. Sensory capabilities of species were examined using the morphology and morphometry of sagitta otoliths (related to detection sound and hearing) and eye size (related to visual communication). We also performed an analysis of the degree of functional niche overlap using fish body traits to understand the coexistence of species. Otoliths showed a morphological pattern similar to that of other anglerfishes: an archaesulcoid sulcus acusticus and variability in the irregularity of the dorsal margin. This last feature affected the allometric relationships between the otolith morphometry and fish length, as well as the otolith relative sizes of each species. The findings suggested that bigger otoliths are associated with the increase of depth distribution of species up to 1000 m, from which it decreases. Our hypothesis is that anglerfishes with irregular otolith shapes could be linked to more nocturnal feeding behaviour because they were characterized by greater eye sizes. The results also indicated interspecific significant differences in functional traits providing a low niche overlap. Therefore, our study supports the hypothesis of an environmental and ecological specialization of benthic anglerfishes.

A MORPHOMETRIC STUDY OF THE PROXIMAL END OF DRY ADULT FEMORA

Background: A good understanding of morphometric measurements of the proximal femur is essential in order to decrease the risk of complications associated with orthopedic surgeries performed in the proximal femur due to traumatic injury, metabolic or vascular causes, and to achieve proper alignment of prosthesis to be implanted. The purpose of this study is to evaluate morphometry of neck of femur in Eastern Indian population. Materials and Methods: The study was conducted on 50 dry adult femora [30 Right(R) and 20 Left(L)] available in the department of Anatomy of Medical College Kolkata, India. Results: a) Mean and Standard Deviation (SD) of Vertical length of Head of femur was Right side: 38.56±2.50mm and Left side: 38.07±3.43mm. b) Mean and SD of Width of neck of femur was Right side: 28.84±2.71mm and Left side:28.09±2.29mm. c) Mean and SD of length of Neck of femur on anterior aspect was Right side:26.37±2.92mm and Left side:26.12±3.42mm. d) Mean and SD of length of Neck of femur on posterior aspect was Right side:31.65±2.75mm and Left side:26.69±3.11mm. e) Neck-shaft angle on both sides were calculated. Conclusion: Indian dimensions of proximal end of femur are different as compared to that of the values in other parts of the world. Present study will be useful for crafting suitable implants used for surgical correction of fracture neck femur in East Indian population. KEYWORDS: Morphometry, Neck-shaft angle, Implant, Prosthesis, Width of neck, Vertical length of head of femur, Length of neck.

Poverty and Food Insecurity Disparities and Their Causes in the Eastern Indian State of Odisha

This article discusses the key factors that influence poverty and food insecurity. The study involved 645 households in 4 villages of 2 districts (one developed and one undeveloped) in Odisha, an eastern Indian state. Odisha’s per capita income was taken as the dividing line for the segregation of districts into developed (more than average) and undeveloped (less than average). Poverty and food insecurity composite indices and probit and logit analyses revealed that: (a) in the developed district, education and caste are significant factors in determining the household poverty level, whereas education plays a vital role in the undeveloped district in deciding poverty level; (b) food insecurity is significantly affected by education, caste and assets in the developed district and by education and agriculture as the primary occupation in the undeveloped district; (c) education is derived as the common determinant of poverty as well as food insecurity; and (d) the inference drawn from the results is that, whatever the economy (developed or undeveloped), education was the most significant and common factor in determining both poverty and/or food insecurity at household level of the areas studied. However, it should not be misinterpreted that education is the only indicator that can resolve the complex issues of poverty and food insecurity. Based on area needs, a comprehensive approach with special focus on these significant indicators revealed from this research would be helpful in addressing poverty and food insecurity.

Opposite response of strong and moderate positive Indian Ocean Dipole to global warming

A strong positive Indian Ocean Dipole (pIOD) induces weather extremes such as the 2019 Australian bushfires and African floods. The impact is influenced by sea surface temperature (SST), yet models disagree on how pIOD SST may respond to greenhouse warming. Here we find increased SST variability of strong pIOD events, with strong equatorial eastern Indian Ocean cool anomalies, but decreased variability of moderate pIOD events, dominated by western warm anomalies. This opposite response is detected in the Coupled Model Inter-comparison Project (CMIP5 and CMIP6) climate models that simulate the two pIOD regimes. Under greenhouse warming, the lower troposphere warms faster than the surface, limiting Ekman pumping that drives the moderate pIOD warm anomalies; however, faster surface warming in the equatorial western region favours atmospheric convection in the west, strengthening equatorial nonlinear advection that forces the strong pIOD cool anomalies. Climate extremes seen in 2019 are therefore likely to occur more frequently under greenhouse warming. The strength of a positive Indian Ocean Dipole (pIOD) is set by sea surface temperature gradient across the equatorial Indian Ocean. Modelling shows warming will increase strong pIODs but decrease moderate pIODs, as faster surface warming in the west sets up conducive conditions for the strong events.

Review of the assessment of two stocks of Antarctic minke whales (eastern Indian Ocean and western South Pacific)

An in-depth assessment of an eastern Indian stock (I-stock) and a western South Pacific stock (P-stock) of Antarctic minke whales distributed between 35°E and 145°W was carried out by the Scientific Committee of the International Whaling Commission (IWC/SC) from 2001 to 2014 using data mainly collected from 1985 to 2004. This paper is a synthesis and summary of the outcomes of that assessment, although research on this species has been ongoing since 2014. The assessment integrates information from a wide range of topics including systematics, survey methods, direct catches, population structure, abundance, spatial distribution, biological information, population dynamics, species interactions, pollutants and interactions with marine debris. At least two stocks (I-stock and P-stock) are found between 35°E–145°W, with a soft boundary between 100°E and 165°E. Two sets of agreed circumpolar estimates of abundance from IWC assessment cruises (termed ‘CPII’ – 1985/86–1990/91, and ‘CPIII’ – 1991/92–2003/04) were obtained; a null hypothesis of no change in overall abundance between CPII and CPIII was not rejected. The results of a Statistical Catch-at-Age Analysis (SCAA) applied to the two stocks revealed that (1) abundance increased from 1930 until the mid-1970s, anddeclined over the period from the mid-1970s until the late-1980s and (2) trends in abundance over the most recent 20 years were relatively flat for the I-stock but decreasing for the P-stock. Although the primary focus at the start of this assessment was to try to understand abundance trends during the 1985–2004 period, it expanded to increasing knowledge on the life history of this species. The assessment also advanced many aspects of analytical methods.