Refraction of the Harp Seal, Pagophilus groenlandicus (Erxleben 1777)

Nature ◽  
1970 ◽  
Vol 227 (5253) ◽  
pp. 78-79 ◽  
Author(s):  
DAVID J. PIGGINS
Keyword(s):  
Harp Seal ◽  
Pagophilus Groenlandicus

scholarly journals Estimation of harp seal (Pagophilus groenlandicus) pup production in the North Atlantic completed: results from surveys in the Greenland Sea in 2002

2006 ◽  
Vol 63 (1) ◽  
pp. 95-104 ◽  
Author(s):  
Tore Haug ◽  
Garry B. Stenson ◽  
Peter J. Corkeron ◽  
Kjell T. Nilssen
Keyword(s):  
North Atlantic ◽  
Barents Sea ◽  
Temporal Distribution ◽  
Harp Seal ◽  
Greenland Sea ◽  
The North ◽  
Pagophilus Groenlandicus ◽  
Pack Ice ◽  
Photographic Survey ◽  
Strip Transect

Abstract From 14 March to 6 April 2002 aerial surveys were carried out in the Greenland Sea pack ice (referred to as the “West Ice”), to assess the pup production of the Greenland Sea population of harp seals, Pagophilus groenlandicus. One fixed-wing twin-engined aircraft was used for reconnaissance flights and photographic strip transect surveys of the whelping patches once they had been located and identified. A helicopter assisted in the reconnaissance flights, and was used subsequently to fly visual strip transect surveys over the whelping patches. The helicopter was also used to collect data for estimating the distribution of births over time. Three harp seal breeding patches (A, B, and C) were located and surveyed either visually or photographically. Results from the staging flights suggest that the majority of harp seal females in the Greenland Sea whelped between 16 and 21 March. The calculated temporal distribution of births were used to correct the estimates obtained for Patch B. No correction was considered necessary for Patch A. No staging was performed in Patch C; the estimate obtained for this patch may, therefore, be slightly negatively biased. The total estimate of pup production, including the visual survey of Patch A, both visual and photographic surveys of Patch B, and photographic survey of Patch C, was 98 500 (s.e. = 16 800), giving a coefficient of variation of 17.9% for the survey. Adding the obtained Greenland Sea pup production estimate to recent estimates obtained using similar methods in the Northwest Atlantic (in 1999) and in the Barents Sea/White Sea (in 2002), it appears that the entire North Atlantic harp seal pup production, as determined at the turn of the century, is at least 1.4 million animals per year.

Calling depth and time and frequency attributes of harp (Pagophilus groenlandicus) and Weddell (Leptonychotes weddellii) seal underwater vocalizations

2005 ◽  
Vol 83 (11) ◽  
pp. 1438-1452 ◽  
Author(s):  
Hilary B Moors ◽  
John M Terhune
Keyword(s):  
Light Condition ◽  
Weddell Seal ◽  
Harp Seal ◽  
Vertical Array ◽  
Vocal Cords ◽  
Leptonychotes Weddellii ◽  
Call Duration ◽  
Weddell Seals ◽  
Pagophilus Groenlandicus ◽  
Breeding Seasons

Harp seal (Pagophilus groenlandicus (Erxleben, 1777)) daytime calling depth during the breeding season and Weddell seal (Leptonychotes weddellii (Lesson, 1826)) daytime and nighttime calling depth during the winter and breeding seasons were investigated using a small vertical array with hydrophones placed at depths of 10 and 60 m. Rough calling depth estimates (<35 m, ~35 m, >35 m) and more accurate point depth estimates (±5–10 m in most cases) were obtained. Significantly more calls were produced at depths ≤35 m for both species. The point depth estimates indicated that the calls occurred most frequently at depths >10 m; 60% of harp seal calls and 71% of Weddell seal calls occurred at depths between 10 and 35 m. The seals called predominately within areas of the water column where light would likely penetrate, but still avoided sea-ice interference to some extent. The vocalizations did not change over depth with respect to call type, the number of elements within a call, or total call duration, or with respect to season and light condition for Weddell seals. Frequency (kHz) of calls also did not change with depth, suggesting that harp and Weddell seals control the pitch of their vocalizations with the vocal cords of the larynx.

Preliminary Underwater Observations of the Breeding Behavior of the Harp Seal (Pagophilus groenlandicus)

1978 ◽  
Vol 59 (1) ◽  
pp. 181-185 ◽  
Author(s):  
B. R. Merdsoy ◽  
W. R. Curtsinger ◽  
D. Renouf
Keyword(s):  
Harp Seal ◽  
Breeding Behavior ◽  
Pagophilus Groenlandicus

Influence of vessel noises on underwater vocal activity of harp seals

1979 ◽  
Vol 57 (6) ◽  
pp. 1337-1338 ◽  
Author(s):  
J. M. Terhune ◽  
R. E. A. Stewart ◽  
K. Ronald
Keyword(s):  
Marked Decrease ◽  
Harp Seal ◽  
Pagophilus Groenlandicus ◽  
Vocal Activity

Recordings of harp seal (Pagophilus groenlandicus) underwater vocalizations were obtained on whelping patches in the Gulf of St. Lawrence, Canada. The seals vocalized throughout the day and night. A marked decrease in seal vocalizations occurred following the arrival of a vessel. The relatively loud motor noises of the vessel completely masked the seal calls (within a 2-km or more radius) except during the night when the vessel's motors were shut down. The decreased seal vocalizations may reflect a change in the seal's behaviour and (or) movement of some seals away from the area of the vessel.

scholarly journals A Neurological Comparative Study of the Harp Seal (Pagophilus groenlandicus) and Harbor Porpoise (Phocoena phocoena) Brain

2010 ◽  
Vol 293 (12) ◽  
pp. 2129-2135 ◽  
Author(s):  
Solveig Walløe ◽  
Nina Eriksen ◽  
Torben Dabelsteen ◽  
Bente Pakkenberg
Keyword(s):  
Comparative Study ◽  
Harp Seal ◽  
Phocoena Phocoena ◽  
Harbor Porpoise ◽  
Pagophilus Groenlandicus

Population and density of the bipolar ganglion cells in the cochlea of the harp seal (Pagophilus groenlandicus Erxleben, 1777)

1976 ◽  
Vol 54 (11) ◽  
pp. 1918-1926 ◽  
Author(s):  
F. Ramprashad
Keyword(s):  
Hair Cells ◽  
Ganglion Cells ◽  
Spiral Ganglion ◽  
Harp Seal ◽  
Nerve Cell Body ◽  
Continuous Ring ◽  
Average Value ◽  
Pagophilus Groenlandicus ◽  
Sensory Hair Cells ◽  
Two Peaks

The population and density of the bipolar ganglion cells were determined from serial horizontal sections and graphic reconstructions of the cochleas of five captive harp seals. The [Formula: see text]-turn spiral ganglion forms a continuous ring throughout its course except at the extreme basal end where it is narrowest. The nerve cell body is 25 μm long (16.1–38.8 μm) and 16 μm wide (10–24 μm). The average number of ganglion cells present was 57 185 (46 389 – 70 952), with a corrected total number of 52 000 ganglion cells. Two peaks are present in the density curve of the ganglion cells. The first was at 1–1.5 mm and the second at 20 mm, where 2620 cells/mm2 and 2250 cells/mm2 respectively are present.The ratio of total ganglion cells to total sensory hair cells was about 3:1. This ratio was not uniform throughout the length of the cochlea; it was 6:1 at 2–3 mm from the basal end and declined gradually to 3:1 at the apical end. The average total of ganglion cells in the harp seal exceeded the average value in humans, but did not exceed the values found in dolphins.

The harp seal, Pagophilus groenlandicus (Erxleben, 1777). VII. A histophysiological study of certain skeletal muscles

1971 ◽  
Vol 49 (1) ◽  
pp. 25-30 ◽  
Author(s):  
J. C. George ◽  
N. V. Vallyathan ◽  
K. Ronald
Keyword(s):  
Skeletal Muscles ◽  
Biochemical Properties ◽  
Histochemical Demonstration ◽  
Harp Seal ◽  
Activity Levels ◽  
Sodium Pentobarbital ◽  
Pagophilus Groenlandicus

A quantitative and histochemical study of Ms. pectoralis, gluteus, psoas, diaphragma (dorsal, lateral, and ventral parts separately) of the harp seal was carried out. Myoglobin and iron contents of all the muscles were high, highest being of M. psoas. Fat and glycogen were low in all muscles. The low glycogen value was possibly due to rapid glycolysis during struggle in capture and while the animal was under an overdose of sodium pentobarbital that was administered for killing it. Phosphorylase and succinate dehydrogenase (SDH) activity levels were also low. Lipase (tributyrinase) activity was high, that of M. diaphragma being higher than the other muscles studied. The histochemical investigation revealed some of the morphological and biochemical properties of the component fibers. Two types of fiber, the red (type 1) and white (type 2), comparable to those of other skeletal muscles were distinguished in all muscles except in the case of M. pectoralis where an intermediate type was also seen in sections treated for the histochemical demonstration of SDH activity.The low levels of fat and SDH in the muscles indicate that fat is not a favored metabolite for muscular energy. The significance of the high lipase (tributyrinase) activity is doubtful. It is suggested that the role of this enzyme is to clear the fat so as to prevent the accumulation of fat in the muscles which are, by and large, geared for a glycolytic metabolism as an adaptation for the animal's diving habit. The high myoglobin content of the muscles, however, should provide the oxygen necessary for the oxidation of glucose during the initial part of the dive.

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