Number Of Seals Research Articles

Estimating the stock size of harbor seals (Phoca vitulina richardii) in the inland waters of Washington State using line-transect methods.

Harbor seals (Phoca vitulina richardii) in the inland waters of Washington were reduced by predator control programs in the twentieth century, but stocks have rebounded since being protected in the 1970s. Three management stocks are recognized, but there is little information on their current abundance. We conducted 38,431 km of aerial line-transect surveys throughout the range of these stocks in 2013–2016, sighting a total of 4,678 groups of harbor seals. Line-transect analysis with Beaufort sea state as a covariate provided estimates of the number of seals in the water. We then incorporated tagging data from 15 instrumented seals to develop correction factors, both for seals missed in the water while diving, and those that were on shore. Tagging data were modeled with generalized linear mixed models to provide estimates of the proportions diving and hauled out. After applying these correction factors, we estimated that the Hood Canal stock contained 1,368 seals (CV = 16.8%), the Southern Puget Sound stock contained 1,976 seals (CV = 20.5%), and the Washington Northern Inland Waters stock contained 7,513 seals (CV = 11.5%). This study presents a non-traditional approach to estimating the size of Washington inland waters harbor seal stocks, which may also be applicable to other species for which survey and tagging data are available.

Status of pinnipeds on mid-Atlantic ridge islands, South Atlantic Ocean

The status of pinnipeds on mid-Atlantic ridge islands is reviewed to detect trends that may relate to climate change. Small numbers of southern elephant seals Mirounga leonina breed on Gough Island (40°S, 10°W) and at Bouvetoya (54°24′S, 03°21′E) where numbers remained small over ~ 68 years. Vagrant southern elephant seals wandered farther north to tropical Saint Helena Island (15°57′S, 5°41′W) in historical times but have not been recorded there more recently. This suggests a contraction of their distributional range, as manifested in the decline in numbers to imminent extinction at Gough Island. At Gough Island and at Tristan da Cunha (37°05′S, 12°17′W), leopard seals Hydrurga leptonyx and Antarctic fur seals Arctocephalus gazella are occasional seasonal transients from Antarctic and sub-Antarctic islands and the circumpolar sea ice farther to the south. Large populations of Antarctic fur seals A. gazella and sub-Antarctic fur seals A. tropicalis breed at Bouvetoya and Gough Island, respectively. The current state of both populations is uncertain as other populations of conspecifics in the South Atlantic and South Indian oceans are in decline ostensibly contingent upon reduced food availability, likely precipitated by climate change.

Estimation of In‐Water Density and Abundance of Harbor Seals

ABSTRACTEcologists and managers require accurate population estimates of marine mammals to assess potential anthropogenic threats to these animals. We present estimates of in‐water density and abundance of a distinct stock of harbor seals (Phoca vitulina richardii) in Hood Canal, Washington, USA. We used aerial line‐transect survey data collected from 2013 to 2016 to directly estimate harbor seal density and abundance in the waters of Hood Canal, a deep‐water fjord in the Salish Sea. We estimated a correction factor for trackline detection probability from dive and surface time data gathered from regional seal tagging studies, and applied this factor to correct for seals missed on the trackline during surveys. We applied conventional and multiple covariate line‐transect approaches in the analysis. The resulting best estimate of in‐water density of harbor seals in the Hood Canal study region was 5.80 seals/km2, with an estimated abundance of 2,009 seals. We did not derive a correction factor to account for the number of seals on land (i.e., hauled out). Therefore, these estimates do not reflect total stock size but provide a starting point to evaluate potential influences of anthropogenic activities, particularly those involving underwater noise, on this marine mammal stock. © 2021 The Wildlife Society.

Regional, seasonal and age class blubber fatty acid signature analysis of harbour seals in Alaska from 1997 to 2010.

Alaskan harbour seal populations are currently listed as a species of special concern. Although there is evidence of recent stabilization or even partial recovery of harbour seal numbers in areas of historic decline, most populations have not made substantial recoveries. To date, few data exist regarding spatial and seasonal changes in blubber fatty acids (FAs) for Alaskan harbour seal populations. The purpose of this study was to qualitatively investigate harbour seal blubber FA profiles for regional, seasonal and age class differences. Blubber FA concentrations were analysed using MANOVA and linear discriminant analysis (LDA) from 760 individual harbour seals across Bristol Bay, Kodiak, Prince William Sound and Southeast Alaska from 1997 to 2010. Our results suggest spatial and seasonal differences are largely driven by monounsaturated FAs, most notably 14:1n-5, 16:1n-7 and 18:1n-7. In addition, our data revealed a progression in blubber FAs from pups to adults, with a shift from saturated FAs and short-chained monounsaturated FAs in the pup blubber to more long-chain monounsaturated FAs and polyunsaturated FAs in adults. Lastly, harbour seals pups had elevated saturated FA 16:0 concentrations when compared to other age classes, regardless of location or period. With this vast spatial and seasonal FA information, we believe future sampling of blubber FAs from Alaskan harbour seal populations could be a useful tool in assessing the response of this species and its ecosystem to changes associated with natural and anthropogenic pressures.

Selenium volatilization from tundra soils in maritime Antarctica

Maritime Antarctica harbors a large number of penguins and seals that provide considerable input of selenium (Se) originating as guano into terrestrial ecosystems. Subsequent Se emissions via biomethylation and volatilization from these sources of Se have not been studied. Here, penguin colony soils (PCS) and adjacent tundra marsh soils (TMS), seal colony soils (SCS) and adjacent tundra soils (STS), and normal upland tundra soils (NTS) were collected in maritime Antarctica. For the first time, Se volatilization and speciation were investigated in these soils through incubation experiments using chemo-trapping method. The Se contents in PCS, SCS, STS and TMS were highly enriched compared with NTS, with organic matter-bound Se accounting for 70%-80%. Laboratory incubations yielded the greatest Se volatilization rates (VRSe) in PCS (0.20 ± 0.01 μg kg−1 d−1), followed by SCS (0.14 ± 0.01 μg kg−1 d−1) at low temperature (4 °C). Soil frozen-thawing induced 1–4 fold increase in VRSe, and the VRSe continuously increased until the soils fully thawed. The VRSe showed a significant positive correlation (R2 = 0.96, p < 0.01) with soil temperature. Methylated Se species were dominated by dimethylselenide (DMSe) in PCS and dimethyldiselenide (DMDSe) in SCS. Our results imply that the combination of climate warming, frozen-thawing processes, and high-Se inputs from sea animals will significantly increase tundra soil Se volatilization in maritime Antarctica. High VRSe from penguin colony soils, and significantly elevated Se levels in the mosses close to penguin colony, suggest that volatilization of Se from penguin colony soils play an important role in the mobilization and regional biogeochemical cycling of Se in maritime Antarctica.

Behaviors of Grey Seals (Halichoerus Grypus) Addressed Towards Human Swimmers During Experimental Open Water Encounters Off Heligoland (German Bight, North Sea)

Risks arising for humans during swim encounters with seals are poorly understood. This study was initiated to examine behaviors of unhabituated grey seals addressed towards humans during experimental, noncommercial seal-swim activities off Heligoland. In total, 26 in-water encounters were conducted. Behavioral classes and the number of seals simultaneously approaching swimmers were time sampled. A set of risky and nonrisky interactive behaviors was continuously sampled. Seals spent approximately the same amount of time interacting with swimmers (53%) as they did ignoring them (47%). Seals displayed higher rates of nonrisky behaviors than risky ones, but risky behaviors occurred during 73% of all seal-swims. Seals remained ≤20 m near swimmers for 51% and ≤1 m for 13% of the time. A mean number of 0.65 and 0.18 seals approached swimmers per minute within a range of ≤20 m and ≤1 m, respectively. Behavioral classes, interactive behaviors, and the number of seals approaching ≤20 m did not vary significantly throughout seal-swims but the number of seals approaching ≤1 m moderately decreased. Due to high rates of risky behaviors, it is recommended to promote public awareness on site and to regulate seal-swims before commercial operations emerge.

The ebb and flow of adaptive co-management: A longitudinal evaluation of a conservation conflict

Adaptive co-management (ACM) is an emerging approach to the governance of social-ecological systems, but there are few long-term assessments of its efficacy. This is especially true in conservation conflicts, where ACM can mitigate disputes between polarised stakeholders. We evaluated ACM that emerged in 2005 to address conflict between seal conservation and fisheries interests in the Moray Firth, Scotland. We interviewed 20 stakeholders in 2015, repeating a survey carried out in 2011 which applied an indicator framework to measure outcomes and pre-conditions for ACM to continue. In 2015, all but one of the 12 outcome indicators were positive, the exception being the conservation status of salmon. However, pre-conditions for ACM’s continuation had weakened, with declines between 2005, 2011 and 2015. These were most marked for three indicators: leaders prepared to champion the process, presence of a bridging organisation or individual, and participation of all impacted stakeholders. The results show that ACM in this conservation conflict is dynamic. Perceived declines in salmon abundance and increases in seal numbers have renewed tensions amongst stakeholders, triggering a ‘revival’ phase of ACM initiated by fishery interests. Our study provides empirical evidence of ACM’s fluid nature, and how resource crises can reignite ACM. We suggest that participatory evaluation is a potentially important early-warning mechanism that can identify remedial action and galvanise stakeholders to respond to the re-emergence of conflict.

Seasonal distribution and some biological parameters of the Caspian seal (Pusa caspica) in the southeastern region of the Caspian Sea.

The Caspian seal (Pusa caspica) from Phocidae family is the only living mammal that exclusively inhabits the landlocked Caspian Sea. This study was first of its kind conducted on the Caspian seals in the southeastern region of the Caspian Sea from 2010 to 2016. Seasonal observations, gender, maturity, biometric parameters and condition index of each observed Caspian seal were studied. Totally 74 live Caspian seals including 42 males and 32 females were observed in this study. The Caspian seals observed in autumn were significantly greater in number than in the other seasons (p 0.05), however, the number of juvenile seals were significantly more than adults (p 0.05). A significant difference was observed between adult and juvenile seals in biometric parameters (p 0.05). Since Caspian seals are listed as endangered species in the IUCN Red List, further research is required to understand the status of this population and conserve the only mammals of the Caspian Sea.

Computational analysis for scallop seals with sickle grooves, part I: Leakage performance

Reducing of leakage rate of annular seals is an important objective of sealing technology. A number of noncontact seals are used for hermetic sealing of centrifugal compressors shafts such as: annular, labyrinth, honeycomb, hole pattern, pocket and scallop seals. In the art, scallop seals are of great interest in terms of reducing costs and time of manufacture. This paper presents results of calculation of leakage rate characteristics of scallop seals with sickle grooves (SSSG) depending on seal geometry. The Computational Fluid Dynamics (CFD) technique is used for calculation of hydrodynamic characteristics of seal. The Design of Experiment (DOE) technique is used for analysis of influence of scallop depth and width, rib width and number of scallops in circumferential direction on sealing performance of scallop seal. Such a comprehensive approach to the calculation using computational methods allows improving and further optimizing the existing designs of scallop seals.

Site use and connectivity of female grey seals (Halichoerus grypus) around Wales

Grey seals (Halichoerus grypus) are a qualifying feature of three special areas of conservation (SACs) in Wales, yet relatively little is known of their site use along this coastline. Since 1992, many individuals and organisations have contributed to a grey seal photographic identification database held by Natural Resources Wales, which is one of the largest and oldest of its kind, providing key information from grey seal haul-out sites around the Celtic and Irish Seas. Here, we investigated spatial connectivity of haul-out sites and fidelity of adult females to breeding sites. The minimum number of adult female grey seals using the area between 1992 and 2016 was 2688. Individual capture histories and relative spatial transition probabilities (Pij) between pairs of location groups were calculated. Adjacent locations were highly connected (e.g. Lleyn Peninsula and Bardsey, Pij = 0.7) but connections spanned the entire region, up to 230 km apart (e.g. Skomer and Dee Estuary, Pij = 0.004). Resights were recorded within SACs (e.g. Lleyn Peninsula and Bardsey [Lleyn Peninsula and the Sarnau SAC], Pij = 0.7), between SACs (e.g. Bardsey and Skomer [Pembrokeshire Marine], Pij = 0.03), between SACs and non-designated areas (e.g. Skerries and Bardsey, Pij = 0.09) and between sites outside any protected area (e.g. Dee Estuary and Anglesey, Pij = 0.5). While inter-annual fidelity to breeding sites was high (Pij = 0.82–1), individual female grey seals moved throughout the region. This evidence of extensive site use beyond protected areas is important for the management and conservation of grey seals around Wales.

Insight into the Release Agents/PVD Coatings Interaction for Plastic Mold Technology

In polymer processing, the formation of undesired fouling hinders the plastic manufacturing processes. Hence, the use of emulsions as releasing agents is mandatory and their affinity to the mold substrates plays a crucial role. Therefore, this research work has been focused on the wetting properties of commercial water-based release agents (namely Marbocote® W2140, EP, EV-333) towards different Physical Vapor Deposition (PVD) nitride coatings (AlTiN, NbN, ZrN and TiN), usually adopted in the industrial manufacture of Hydrogenated Nitrile Butadiene Rubber (HNBR). The investigated solid substrates were characterized by means of profilometry, SEM/EDX and Surface Free Energy (SFE) analyses, whereas, tensiometric determinations were acquired on the commercial pure and diluted emulsions. The release agents/mold substrates wettability features were studied by means of the work of adhesion and the spreading coefficient. Finally, nitride-coated mold seals were directly tested in an industrial plant with the most performing release agent in terms of adhesive features; for the first time, a deep correlation between the service life, in terms of number of molded seals, and surface (contact angles, work of adhesion and spreading coefficient)/electrochemical (OCP) features was drawn.

Identification of causes of death of Baikal seal (Pusasibirica Gmelin, 1788)

The Baikal seal is the only endemic mammal of Lake Baikal. In late October 2017, 132 dead Baikal seals were found on the shore of the lake. To identify causes of death, postmortem necropsy, virological, chemical toxicological, microbiological, and parasitological studies were carried out. Several hypotheses for explaining the causes of the deaths were put forward. The most probable causes are heart failure and asphyxia due to echo sounders (sonar). The causes were confirmed by the results of histological examination of the hearts and lungs of a large number of dead seals found on the southern shore of Lake Baikal (a center for the fishing industry).

Population trends of harbour and grey seals in the Greater Thames Estuary

In this paper, results from two decades of seal population data for the Greater Thames Estuary between 2003 to 2019 are presented, together with the results of two harbour seal pup surveys conducted in 2011 and 2018. Counts of hauled out harbour and grey seals were conducted during aerial surveys and these have been scaled up to estimate population sizes. Most recent population estimates suggest ~900 harbour and ~3,200 grey seals reside in the Greater Thames Estuary. Both species have shown an upward population trend since surveys began in 2003. The wide distribution and growing number of seals across the Greater Thames Estuary over the last two decades shows the importance of this region for both species. It also highlights the value of long-term monitoring data to compliment seal surveys taking place elsewhere in the UK.

Re-examination of population structure in Arctic ringed seals using DArTseq genotyping

Although Arctic ringed sealsPhoca hispida hispidaare currently abundant and broadly distributed, their numbers are projected to decline substantially by the year 2100 due to climate warming. While understanding population structure could provide insight into the impact of environmental changes on this subspecies, detecting demographically important levels of exchange can be difficult in taxa with high abundance. We used a next-generation sequencing approach (DArTseq) to genotype ~5700 single nucleotide polymorphisms in 79 seals from 4 Pacific Arctic regions. Comparison of the 2 most geographically separated strata (eastern Bering vs. northeastern Chukchi-Beaufort Seas) revealed a statistically significant level of genetic differentiation (FST= 0.001, p = 0.005) that, while small, was 1 to 2 orders of magnitude greater than expected based on divergence estimated for similarly sized populations connected by low (1% yr-1) dispersal. A relatively high proportion (72 to 88%) of individuals within these strata could be genetically assigned to their stratum of origin. These results indicate that demographically important structure may be present among Arctic ringed seals breeding in different areas, increasing the risk that declines in the number of seals breeding in areas most negatively affected by environmental warming could occur.

FIRST INSTRUMENTAL AERIAL SURVEY OF RINGED SEALS (PUSA HISPIDA) AND BEARDED SEALS (ERIGNATHUS BARBATUS) IN THE RUSSIAN ZONE OF THE CHUKCHI AND EAST-SIBERIAN SEAS IN SPRING 2016

An instrumental aerial survey was conducted in the Russian part of the Chukchi Sea and the eastern East-Siberian Sea in the spring of 2016 to investigate new technical capabilities for estimating abundance and distribution of ringed and bearded seals on the spring ice. Density of both species decreased with distance to the mainland; the largest concentrations of ringed seals were detected in coastal waters, including the Koluchinskaya and Chaunskaya Bays. Taking into account the portion of seals in the water (on average 32 %) and the portion of seals that were disturbed by the aircraft engine noise and dove (on average 30.2 % of ringed seals and 5.9 % of bearded seals), the number of ringed seals in the surveyed area was estimated as 50,839 (СI 95 %: 25,400–73,859; CV = 23.8 %), and the number of bearded seals as 14,590 (CI 95 %: 6,404–24,560; CV = 31.1 %). These estimates are considered to be biased low, primarily due to asynchronic collapse of the ringed seal snow lairs in different parts of the surveyed area, which caused a highly variable detection probability of this species that was difficult to account for.

Re‐evaluating the population size of South American fur seals and conservation implications

Abstract South American fur seals (Arctocephalus australis) are widely distributed, yet surprisingly little is known about their ecology. In particular, population data are sparse and outdated for many breeding locations, including the Falkland Islands. Data deficiency impedes the development of coherent conservation and management strategies. To address knowledge gaps, for the first time since 1965 an archipelago‐wide census of South American fur seals breeding at the Falkland Islands was undertaken, which provided the first pup abundance estimate since 1926 – data that are critical for assessing population trends. In total, 36,425 South American fur seal pups were counted at the Falkland Islands in 2018, a greater than four‐fold increase since the last census, and far greater than the 7,990 pups counted in Uruguay, which was presumed to be the largest South American fur seal population in the world. Hence, based on pup abundance, the Falkland Islands is presently the largest population of South American fur seals, even when considering a correction factor of 3.9 that was applied to pup counts in Uruguay, which yielded an estimated 31,160 pups. The results redefine South American fur seal abundance, the contribution of breeding locations (Falkland Islands, Uruguay, Argentina, Chile) and the distribution of breeding colonies at the Falkland Islands, which has far reaching implications for conservation and management. In particular, the present study has effectively doubled the Atlantic population size of the species, which is now estimated to comprise about 76,000 pups, of which the Falkland Islands accounts for 48% and Uruguay 41%. Accordingly, changes in the number of South American fur seals breeding at the Falkland Islands will influence the global population trends and conservation status of the species. Monitoring South American fur seals breeding at the Falkland Islands is therefore crucial to understand the impacts of anthropogenic pressures, such as fisheries, and to inform management and conservation policy. The results provide a baseline from which to measure changes in abundance.

Effect of multiple use and sterilization on sealing performance of bipolar vessel sealing devices.

BackgroundAdvanced bipolar vessel sealing devices are widely used in human and veterinary medicine to reduce the operation time and intraoperative blood loss. Because most devices are made for a single use, their application is cost intensive. The aim of this study was to investigate the influence of multiple uses and sterilization on the performance of bipolar vessel sealing devices.MethodsThe burst pressure of sealed porcine renal arteries was compared between the disposable devices „LigaSure”(Valleylab) and „Caiman“(Braun Vetcare) and the reuseable device „MarSeal”(KLS Martin). Additionally, the influence of the sterilization process was investigated, and the sealing time, number of cutting activations and tissue sticking were noted.ResultsThe disposable devices showed reliable performances over multiple activations and sterilization cycles, except for one Caiman device. Seals created with all devices achieved supra-physiologic burst pressures, with the highest pressure measured in a cycle using a MarSeal device.DiscussionDuring 25 activations with and without intermittent sterilization, no correlation was found between increasing seal numbers and decreasing burst pressure. However, the number of cycles in our study was limited to five.ConclusionFor limited numbers of cycles and sterilization procedures, seals created with the disposable vessel sealing devices LigaSure and Caiman achieved burst pressures comparaable to those produced with the reuseable MarSeal.

Small Finds, Big Values: Cylinder Seals and Coins from Iraq and Syria on the Online Market

Abstract:Discussions about looted antiquities often focus on large, culturally and monetarily valuable items. Nevertheless, it is clear that mundane small finds, which sell for relatively small amounts, account for a large portion of the global market in antiquities. This article highlights two types of small artifacts—namely, cylinder seals and coins, presumed to come from Syria and Iraq and offered for sale by online vendors. We argue that the number of cylinder seals and coins sold on the Internet has increased steadily since 2011, reaching a peak in 2016–17. This shows that the trade in Iraqi and Syrian antiquities has shifted from big-ticket items sold in traditional brick-and-mortar shops to small items readily available on the Internet for modest prices. The continuing growth of the online market in antiquities is having a devastating effect on the archaeological sites in Iraq and Syria as increasing demand fuels further looting in the region.

Diet and isotopic niche overlap elucidate competition potential between seasonally sympatric phocids in the Canadian Arctic

Interspecific interactions may be altered as a result of poleward species range shifts caused by climate change. In recent decades, Cumberland Sound, Nunavut, in the Canadian Arctic, has undergone concurrent increases in the availability of the forage fish capelin (Mallotus villosus) and the number of migratory harp seals (Pagophilus groenlandicus) during the open-water period; however, the impacts of these changes on endemic Arctic species, such as ringed seals (Pusa hispida), have received little attention. We coupled stomach contents with stable isotope analysis (δ13C and δ15N) of muscle and liver to determine the extent of potential competition between ringed seals (n = 91) and harp seals (n = 39) in Cumberland Sound. Isotopic niche breadth was greater for ringed seals (95% ellipse: 10.08‰2) than for harp seals (95% ellipse: 8.00‰2), and harp seal isotopic niche overlapped more with ringed seal isotopic niche than vice versa, suggesting asymmetrical competition potential. Although there was high overlap in isotopic niche breadth (range 50.3–91.0%) and prey species consumed (Schoener’s Index 0.60), stomach content analysis revealed differences in prey species proportions and size composition, thereby reducing the degree of realized niche overlap. Harp seals consumed a higher biomass of fish (66.7%) than did ringed seals (31.9%), and harp seals also consumed larger capelin (64–200 mm), polar cod (Boreogadus saida; 28–194 mm), and Liparidae (55–115 mm) than ringed seals (63–154 mm, 20–189 mm, and 16–128 mm, respectively). With climate change and range shifts predicted to continue into the future, our results provide an important baseline for future studies examining interspecific interactions.

Predation of Harp Seals, &lt;i&gt;Pagophilus groenlandicus&lt;/i&gt;, by Polar Bears, &lt;i&gt;Ursus maritimus&lt;/i&gt;, in Svalbard

Harp seals (Pagophilus groenlandicus) that breed in February and March in the White Sea migrate to open water around Svalbard and Franz Josef Land in the Barents Sea, feeding pelagically while following the receding ice edge northward to the edge of the polar pack. Although harp seals are present throughout the area during the summer, they are primarily pelagic and do not appear to be extensively preyed upon by polar bears (Ursus maritimus). However, occasionally, large numbers of harp seals may haul out and rest on the pack ice or feed in the water below the ice and surface to breathe between the floes. When approached by a polar bear while on the ice, harp seals do not exhibit the instant flight response characteristic of the polar bear’s primary prey species, ringed (Pusa hispida) and bearded seals (Erignathus barbatus). In this situation, polar bears may make multiple kills without either consuming their own prey or scavenging seals killed by other bears. This behavior appears not to frighten other nearby harp seals, whether hauled out on the ice or in the water below the floes. These unusual concentrations of harp seals hauled out on sea ice may be related to the distribution and abundance of fish or other epontic prey. Their lack of an escape response to predators on the surface of the sea ice is probably a result of briefly hauling out in large numbers in spring while whelping on the sea ice in areas where the consequences of potential polar bear predation are insignificant. The rare events of harp seal mortality from bears killing them on the surface of pack ice during the summer do not appear to have a significant impact at the population level of either species.