The Harbor Seal in Washington State

Scheffer, Victor B.; Slipp, John W.

doi:10.2307/2421307

Cited by 78 publications

(54 citation statements)

References 3 publications

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“…Harbor seal abundance increased with increasing proximity to a bathymetric depth of 20 m. This result illustrates that harbor seals selected sites close to deep water, as previously suggested (Scheffer & Slipp 1944, Sullivan 1980). Access to deep water could be advantageous for a couple of reasons.…”

Section: Discussionsupporting

confidence: 80%

“…Some studies have suggested certain factors that could be important in the selection of a haul-out site. Researchers have proposed that harbor seals select sites that are low in disturbance (Schneider & Payne 1983, Thompson 1989, close to available prey (Scheffer & Slipp 1944), protected from wind exposure (Bjørge et al 2002) and with access to deep water (Scheffer & Slipp 1944, Sullivan 1980). Our specific goal, then, was to investigate the importance of these and other factors in the selection of haul-out sites by harbor seals.…”

Section: Introductionmentioning

confidence: 99%

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Spatial modeling of haul-out site use by harbor seals in Cook Inlet, Alaska

Montgomery¹,

Hoef²,

Boveng³

2007

Mar. Ecol. Prog. Ser.

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Harbor seals Phoca vitulina haul out on land to give birth to and rear their pups, rest, escape aquatic predation and molt. The choice of a haul-out site is therefore fundamental to survival and reproduction. Aerial surveys of harbor seals were conducted in Cook Inlet, Alaska, to investigate the seals' selection of various environmental characteristics of haul-out sites. Eight surveys from April, June, August and October were performed to understand how haul-out site use varies seasonally. A GIS database describing all potential haul-out habitats in the study area was created by acquiring separate data sets on bathymetry, sea-bed type, proximity to sources of anthropogenic disturbance, prey availability, biological wave exposure and substrate type. Because harbor seal abundance and several environmental features varied temporally, 4 separate models were developed to account for conditions specific to each survey month. Spatial regression analyses, which allowed data to be spatially autocorrelated, were used to identify the relationships between harbor seal abundance and environmental variables associated with haul-out sites. Harbor seals were found to haul out near available prey and to avoid areas high in anthropogenic disturbance. The seals also selected haul-out sites of rock substrate and those that were near deep water.

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Section: Discussionsupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Spatial modeling of haul-out site use by harbor seals in Cook Inlet, Alaska

Montgomery¹,

Hoef²,

Boveng³

2007

Mar. Ecol. Prog. Ser.

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“…Another phocid seal species, the harbour seal, also gives birth to pups that moult in utero and possess a subcutaneous blubber layer as newborns (Oftedal et al 1991). Harbour seal pups also normally enter the water during their first day of life, often at the first high tide following their birth (Scheffer & Slipp 1944, Venables & Venables 1955, Renouf et al 1983. Hooded seal pups do not enter the water until after weaning, even though they are born with features that can be interpreted as adaptations to an early aquatic debut (Oftedal et al 1991).…”

Section: Physical Characteristics Of Neonates and Pup Energeticsmentioning

confidence: 99%

Behaviour and energetics of ice-breeding, North Atlantic phocid seals during the lactation period

Lydersen¹,

Kovacs²

1999

Mar. Ecol. Prog. Ser.

141

122

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ABSTRACT. This review presents a comparative analysis of the behaviour and energetics of the icebreeding phocid seals of the North Atlantic in relation to their habitat(s). In very broad terms, it suggests that the term 'ice-breeding' is too simplistic and may lead to misconceptions about the actual degree of variability that exists in the breeding habitats of seals that do not give birth on land The variation that exists within ice habitats is quite remarkable in terms of: temporal and structural stability of the pupping platform; the degree to which animals have access to the water; the nsk of predation; and perhaps also the local availability of food. These factors all appear to influence the behaviour of mothers and pups and the allocation of energy during the lactation period of the species studied. Two basically different nursing strategies can be identified that may have evolved, at least in part, as a consequence of variation in these variables. The pattern displayed by grey (Halichoerus grypus), harp (Phoca groenlandica) and hooded (Cystophora crjstata) seals involves a short lactation period, during which a large amount of energy is transferred from the mother to the pup through extremely-energy-rich milk. Pups of these species are very inactive and consequently a very high proportion of the received energy can be stored as body tissue, mainly in the form of subcutaneous blubber. The mothers generally feed little or not at all during the nursing period and the pups are weaned abruptly, having not yet entered the water in most cases. The other strategy, found in bearded (Erignathus barbatus) and ringed (Phoca I~ispida) seals, involves a longer lactation penod, where less-energy-rich milk is transferred to very active pups These pups learn to swim and dive during the nursing period, and are weaned with body compositions that are similar to those of adults The mothers feed during lactation and weaning is less abrupt, with pups feeding independently, while still receiving milk from their mothers.

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“…Adult harbor seals have about 40 vibrissae next to either nostril. Their lengths vary, but can reach up to about 125 mm long [117], making them among the largest known animal structures that could serve as flow sensors.…”

Section: Why They Might Be Importantmentioning

confidence: 99%

Passive wake detection using seal whisker-inspired sensing

Beem¹

2015

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This thesis is motivated by a series of biological experiments that display the harbor seal's extraordinary ability to track the wake of an object several seconds after it has swum by. They do so despite having auditory and visual cues blocked, pointing to use of their whiskers as sensors of minute water movements. In this work, I elucidate the basic fluid mechanisms that seals may employ to accomplish this detection. Key are the unique flow-induced vibration properties resulting from the geometry of the harbor seal whisker, which is undulatory and elliptical in cross-section.First, the vortex-induced vibration (VIV) characteristics of the whisker geometry are tested. Direct force measurements and flow visualizations on a rigid whisker model undergoing a range of 1-D imposed oscillations show that the geometry passively reduces VIV (factor of > 10), despite contributions from effective added mass and damping. Next, a biomimetic whisker sensor is designed and fabricated. The rigid whisker model is mounted on a four-armed flexure, allowing it to freely vibrate in both in-line and crossflow directions. Strain gauges on the flexure measure deflections at the base. Finally, this device is tested in a simplified version of the fish wake -seal whisker interaction scenario. The whisker is towed behind an upstream cylinder with larger diameter. Whereas in open water the whisker exhibits very low vibration when its long axis is aligned with the incoming flow, once it enters the wake it oscillates with large amplitude and its frequency coincides with the Strouhal frequency of the upstream cylinder. This makes the detection of an upstream wake as well as an estimation of the size of the wake-generating body possible. A slaloming motion among the wake vortices causes the whisker to oscillate in this manner. The same mechanism has been previously observed in energy-extracting foils and trout actively swimming behind bluff cylinders in a stream. Dave, Jason, Gabe, Pablo, Remi, and Yahya were postdocs when we first met.Thank you for being approachable and sharing much needed advice all along the way.Your love of science has inspired me to be more inquisitive.Brandon, Chris, Matthew, and Patrick were undergrads or high school students who spent their summers working in the Tow Tank with me. Thanks for giving me the chance to practice being a mentor, moving this research forward a lot faster than I could do on my own, and helping me lift the mega-whisker in and out of the tank! May you all keep on building and exploring.Thanks to Kathy Streeter and the New England Aquarium staff for helping me understand more about real harbor seals. They graciously collected shed whisker specimens and allowed me to take many close-up pictures of their seals.Thanks to all the people who helped me prepare for and make it through research cruises: Eric Hayden, Terry Hammar, and Hanu Singh for contributing their expertise 5 to help me make my first ocean-ready sensor, all parties involved in the first UNOLS Chief Scientist Training Cruise se...

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The Harbor Seal in Washington State

Cited by 78 publications

References 3 publications

Spatial modeling of haul-out site use by harbor seals in Cook Inlet, Alaska

Spatial modeling of haul-out site use by harbor seals in Cook Inlet, Alaska

Behaviour and energetics of ice-breeding, North Atlantic phocid seals during the lactation period

Passive wake detection using seal whisker-inspired sensing

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