scholarly journals Historical trend in harbour seal (Phoca vitulina) abundance in Iceland back to the year 1912

2010 ◽  
Vol 8 ◽  
pp. 147 ◽  
Author(s):  
Erlingur Hauksson ◽  
Sólmundur T Einarsson
Keyword(s):  
Population Decline ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
Early 20Th Century ◽  
Fishing Gear ◽  
Early 19Th Century ◽  
Harvest Rate ◽  
Aerial Surveys ◽  
Seal Population ◽  
By Catch

The harbour seal (Phoca vitulina) is Iceland’s most abundant seal and has likely been exploited since the settlement of the country. Detailed information on skin exports is available as far back as 1912, and suggests that the catch, consisting mainly of pups, was far higher in the early 20th century than now. Assuming that skin exports were proportional to catches, these data were used to back-calculate the size of the Icelandic harbour seal population to the year 1912. The results indicate that the harbour seal population was considerably larger in the early 19th century than at present, about 60,000 (90% CI:40-100) animals. Aerial surveys conducted since 1980 indicate that the population has declined from 33,000 (90% CI:26,000-44,000) animals in 1980 to about 12,000 (90% CI:9,000-16,000) animals in 2006. The population time series suggests thatthe stock began to decline rapidly around 1960 and continued to decrease until 2003. In the period 1980 - 2003, the population declined even though reported catches were relatively low. Harvest rate had probably been about 10% before 1960. Between 1960 and 1980 the reported harvest rate increased to about 13%, but unknown numbers of adult seals were also taken as by-catch and shot in defence of salmon rivers. Since 2003, total removals have decreased and the population decline appears to have ceased. Entanglements in fishing gear and other incidental unreported hunting could increase again in the future. Therefore, the population must be monitored on a regular basis, and better information on by-catch and other unreported harvest is needed.

scholarly journals Review on utilization and research on harbour seal (Phoca vitulina) in Iceland

2010 ◽  
Vol 8 ◽  
pp. 341 ◽  
Author(s):  
Erlingur Hauksson ◽  
Sólmundur T Einarsson
Keyword(s):  
Phoca Vitulina ◽  
Economic Resources ◽  
Harbour Seal ◽  
Legal Rights ◽  
Large Dataset ◽  
Harbour Seals ◽  
Seal Population ◽  
By Catch ◽  
Catch Statistics ◽  
Anisakid Nematodes

Harbour seals (Phoca vitulina) have been harvested in Iceland since the first settlers arrived in the 9th century. Pups were generally netted, clubbed and harpooned until 1875 when general use of guns for hunting began. Seal-hunting has been traditional amongst the farms legal rights. Seal hunting was an important supplement to other economic resources. Harbour seal skins, salted ordried, were exported and large dataset of catch statistics is available from trading logbooks since the late 19th century. In the early 20th century catch was about 6,000. In the ‘bounty’ period 1982 – 1989, maximum catches were of 4,000 animals with about 350 hunters participated; in 2006 catches were only about 100 animals with 18 hunters. After 1989 the population continued to decline even though catches decreased markedly. Unreported by-catch in fishing gear, hunt for local consumption and shooting of seals swimming in salmon rivers estuaries may have kept the total removal from the stock above sustainable levels. A considerable Icelandic knowledge base had been compiled about the biology of the harbour seal since the late 16th century, with the first written reference in 1588-1589. In the last decades, research on various aspects of its biology and monitoring have been intensified, with focus on abundance, distribution, diet and nematode infestation. The main results show that the Icelandic harbour seal population - has declined annually about 5% in the period 1980-2006, - was most abundant on the NW-coast, - feeds mainly on sand-eels and gadoids, - and was less infected with anisakid nematodes than grey seals. Seal watching, as a low-consumptive indirect utilization, may represent a new economical opportunity if properly regulated.

scholarly journals Vulnerability of harbour seals, Phoca vitulina, to transient industrial activities in the Strait of Dover

2005 ◽  
Vol 85 (4) ◽  
pp. 1015-1016 ◽  
Author(s):  
Laurent J.J. Seuront ◽  
Perrine Prinzivalli
Keyword(s):  
Interannual Variability ◽  
Industrial Wastewater ◽  
Anthropogenic Activities ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
Industrial Activities ◽  
Dramatic Decline ◽  
Harbour Seals ◽  
Seal Population ◽  
Number Of Individuals

The abundance of the harbour seal (Phoca vitulina) was recorded on a tidal bar in the Dover Strait off Calais, over a six-year period between 1999 and 2004. Despite clear seasonal and interannual variability in the number of individuals hauled out on the bar, underwater activities devoted to the installation of industrial wastewater pipes conducted during seven weeks 1 km away from the bar led to a dramatic decline in the number of seals hauling out. A full 19 months after the end of the operations the harbour seal population had not recovered their initial abundance. The results of this study have critical consequences on the conservation of P. vitulina in areas impacted by anthropogenic activities.

scholarly journals Monitoring trends in the abundance of harbour seals (Phoca vitulina) in Icelandic waters

2010 ◽  
Vol 8 ◽  
pp. 227 ◽  
Author(s):  
Erlingur Hauksson
Keyword(s):  
Coastal Area ◽  
East Coast ◽  
Aerial Survey ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
Northwest Coast ◽  
Coastal Regions ◽  
Harbour Seals ◽  
Seal Population ◽  
Icelandic Waters

Harbour seal (Phoca vitulina) numbers along the coast of Iceland were monitored by aerial survey in the period 1980-2006. Trends in the abundance of the harbour seal population on the whole coast and in coastal regions of Iceland waters were estimated using ANCOVA on the survey counts, corrected for the influence of several covariates. Harbour seals were found in every coastal area, but were most abundant in Faxaflói, Breiðafjörður and on the northwest coast inthe beginning of this study. Harbour seal numbers declined significantly at a rate of rest = -0.04 (SE 0.005) yr-1 during this period. Decline was highest in Faxaflói and at the south coast (≅7%), while the east coast experienced a significant but lesser (≅1%) decline. Other coastal areas did not show significant trends. The northwest coast was the richest harbour seal area in Iceland in 2006. In Icelandic waters seals are commercially harvested, and unreported but probably high numbers of harbour seals are killed intentionally by shooting and accidentally in fishing geareach year. These factors likely contributed to the overall observed decline in seal numbers.

Vitamin A physiology in the precocious harbour seal (Phoca vitulina): a tissue-based biomarker approach

2002 ◽  
Vol 80 (9) ◽  
pp. 1511-1519 ◽  
Author(s):  
Lizzy Mos ◽  
Peter S Ross
Keyword(s):  
Vitamin A ◽  
Marine Mammals ◽  
Relevant Information ◽  
Phoca Vitulina ◽  
Retinyl Palmitate ◽  
Harbour Seal ◽  
Natural Processes ◽  
Reproductive Endocrine ◽  
Positive Correlations ◽  
Free Ranging

Vitamin A is a nutrient essential to all mammals for growth and development, as well as for the maintenance of reproductive, endocrine, and immune systems. Environmental contaminant-related disruption of vitamin A has been observed in many wildlife species and can therefore be used as a biomarker of toxic effects. However, the natural processes regulating vitamin A uptake, storage, and distribution among compartments are poorly understood in marine mammals. In this study, 20 young healthy harbour seals (Phoca vitulina) were captured to establish a compartment-based model providing a foundation for a mechanistic understanding of vitamin A physiology and disruption. Vitamin A (retinol, retinyl palmitate, and (or) retinoic acid) was quantified in blood plasma and in biopsy samples of liver, blubber, and skin. Although the highest concentrations of vitamin A were found in liver, blubber represents a more important storage depot, with an estimated 66% of the total retinoid content of the compartments measured. We suggest that vitamin A physiology in the precocious harbour seal has evolved to deal with high vitamin A availability during a short nursing period and to sustain growth during the postweaning fast. Positive correlations in vitamin A concentrations among liver, blubber, and skin support the use of less invasive biopsy sampling of just blubber or skin, which can provide physiologically relevant information in biomarker studies of free-ranging marine mammals.

scholarly journals Pengaruh ekstrak minyak cumi pada umpan bubu terhadap hasil tangkapan kepiting bakau dan rajungan di Perairan Malise Kecamatan Tabukan Tengah

2016 ◽  
Vol 2 (3) ◽  
Author(s):  
Maichel Arvan Pananggung ◽  
Ivor L. Labaro ◽  
Emil Reppie
Keyword(s):  
Coastal Waters ◽  
Scylla Serrata ◽  
Fishing Gear ◽  
Swimming Crab ◽  
Portunus Pelagicus ◽  
Mangrove Crab ◽  
Gill Net ◽  
Oil Extract ◽  
Mangrove Crabs ◽  
By Catch

ABSTRACT Mangrove crab (Scylla serrata) and swimming crab (Portunus pelagicus) are economically important marine commodities produced from the coastal waters of Sangihe Islands Regency. But those marine commodity products are usually only caught accidentally with a bottom gill net. There has been a special trap fishing gear for that resources, but not known well by local fishermen. Addition of squid oil extraction baits could increase the fishing power of mangrove crab and swimming crab traps. This research aims to study the effect of squid oil extract on traps bait to catch mangrove crab and swimming crab; and identify the types of biota captured. This research was done in coastal waters of Malise village, Tabukan Tengah District of Sangihe Islands Regency for 2 weeks September 2015; based on experimental method. Six unit traps were operated ten trips where three units of them used scad mackerel bait that injected with squid oil extract, and tree other units just used scad mackerel bait without extract; and the capture data were analyzed using t test. The catch was 142 individuals (135 mangrove crabs and 7 swimming crab); where 86 crabs was caught by scad mackerel bait with squid oil extract, and 56 crabs caught with bait without squid oil extract. The analysis showed that the use of squid oil extracts on trap baits increased the catch. Keywords: mangrove crab, swimming crab,trap baits, squid oil extract, Sangihe   ABSTRAK[1] Kepiting bakau (Scylla serrata) dan rajungan (Portunus pelagicus) merupakan komoditi hasil laut ekonomis penting yang dihasilkan dari perairan pantai Kabupaten Kepulauan Sangihe. Tetapi komoditi hasil laut tersebut biasanya hanya tertangkap tanpa sengaja (by catch) dengan jaring insang dasar. Sebenarnya telah ada alat tangkap bubu khusus untuk kepiting bakau dan rajungan, tetapi belum dikenal oleh nelayan lokal. Pemberian ekstrak minyak cumi pada umpan, diduga dapat meningkatkan kemampuan tangkap dari bubu kepiting bakau dan rajungan. Penelitian ini bertujuan untuk mempelajari pengaruh ekstrak minyak cumi pada umpan bubu terhadap hasil tangkapan kepiting bakau dan rajungan, dan mengidentifikasi jenis-jenis biota yang tertangkap. Penelitian ini dilakukan di perairan Malise Kecamatan Tabukan Tengah, Kabupaten Kepulauan Sangihe; selama 2 minggu pada bulan September 2015; yang didasarkan pada metode eksperimental. Enam unit bubu dioperasikan selama sepuluh trip untuk mengumpulkan data; di mana tiga unit menggunakan umpan ikan layang yang disuntikan ekstrak minyak cumi, dan tiga unit lainnya hanya menggunakan umpan ikan laying tanpa ekstrak; dan data dianalisis dengan uji t. Tangkapan total berjumlah 142 ekor (135 ekor kepiting bakau dan 7 ekor rajungan); di mana 86 ekor tertangkap dengan umpan layang yang diberi ekstrak minyak cumi, dan 56 ekor tertangkap dengan umpan tanpa ekstrak. Hasil analisis menunjukkan bahwa penggunaan ekstrak minyak cumi pada umpan bubu, memberikan hasil tangkapan yang sangat berbeda dibandingkan dengan umpan tanpa ekstrak minyak cumi. Kata-kata kunci: kepiting bakau, rajungan, umpan bubu, ekstrak minyak cumi, Sangihe  

scholarly journals Trace metal accumulation in hair and skin of the harbour seal, Phoca vitulina

1993 ◽  
Vol 26 (3) ◽  
pp. 152-155 ◽  
Author(s):  
C. Wenzel ◽  
D. Adelung ◽  
H. Kruse ◽  
O. Wassermann
Keyword(s):  
Trace Metal ◽  
Metal Accumulation ◽  
Phoca Vitulina ◽  
Harbour Seal

scholarly journals Deiminated proteins and extracellular vesicles as novel biomarkers in pinnipeds: Grey seal (Halichoerus gryptus) and harbour seal (Phoca vitulina)

Biochimie ◽  
2020 ◽  
Vol 171-172 ◽  
pp. 79-90 ◽  
Author(s):  
Bergljót Magnadóttir ◽  
Pinar Uysal-Onganer ◽  
Igor Kraev ◽  
Vilhjálmur Svansson ◽  
Karl Skírnisson ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
Grey Seal ◽  
Novel Biomarkers

Repetition enhances hearing detection thresholds in a harbour seal (Phoca vitulina)

1993 ◽  
Vol 71 (5) ◽  
pp. 926-932 ◽  
Author(s):  
S. D. Turnbull ◽  
J. M. Terhune
Keyword(s):  
White Noise ◽  
Background Noise ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
Detection Thresholds ◽  
Noise Masking ◽  
Phoca Groenlandica ◽  
Hearing Thresholds ◽  
Lower Detection ◽  
Pinniped Species

Pure-tone hearing thresholds of a harbour seal (Phoca vitulina) were measured in air and underwater using behavioural psychophysical techniques. A 50-ms sinusoidal pulse was presented in both white-noise masked and unmasked situations at pulse repetition rates of 1, 2, 4, and 10/s. Test frequencies were 0.5, 1.0, 2.0, 4.0, and 8.0 kHz in air and 2.0, 4.0, 8.0, and 16.0 kHz underwater. Relative to 1 pulse/s, mean threshold shifts were −1, −3, and −5 dB at 2, 4, and 10 pulses/s, respectively. The threshold shifts from 1 to 10 pulses/s were significant (F = 12.457, df = 2,36, p < 0.001) and there was no difference in the threshold shifts between the masked and unmasked situations (F = 2.585; df = 1,50; p > 0.10). Broadband masking caused by meteorological or industrial sources will closely resemble the white-noise situation. At high calling rates, the numerous overlapping calls of some species (e.g., harp seal, Phoca groenlandica) present virtually continous "background noise" which also resembles the broadband white-noise masking situation. An implication of lower detection thresholds is that if a seal regularly repeats short vocalizations, the communication range of that call could be increased significantly (80% at 10 pulses/s). This could have important implications during the breeding season should storms or shipping noises occur or when some pinniped species become increasingly vocal and the background noise of conspecifics increases.

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