Current and historical information about food habits of bearded seals, Erignurhus burbutus, are p... more Current and historical information about food habits of bearded seals, Erignurhus burbutus, are presented. Shrimps, crabs, and clams are overall the most important prey. Proportions of different prey in the diet vary with age of seals, location, and time of year. Foods of male and female seals are similar. Young seals eat proportionally more shrimps than do older animals. Recently,
Bowhead whales, Salaena mystice-tus, spend the late spring, summer, and early autumn in the Beauf... more Bowhead whales, Salaena mystice-tus, spend the late spring, summer, and early autumn in the Beaufort Sea (Ser-geant and Hoek, 1974). On their north-ward spring migration they usually begin to pass Point Barrow, Alaska, in the latter part of April (Durham, 1979; Braham and ...
Aerial surveys were conducted during late May and early June 1996 - 99 in the central Beaufort Se... more Aerial surveys were conducted during late May and early June 1996 - 99 in the central Beaufort Sea of Alaska, using strip-transect methods. The purpose of these surveys was to quantify and model the effects of environmental covariates on ringe d seal counts and to provide density estimates that would be useful for evaluating trends in seal abundance. Total survey
Twenty eyes from 10 Pacific sleeper sharks Somniosus pacificus, infected with the copepod Ommatok... more Twenty eyes from 10 Pacific sleeper sharks Somniosus pacificus, infected with the copepod Ommatokoita elongata, were collected in Prince William Sound, Alaska, and the eyes of an additional 18 S. pacificus captured in the same area were inspected for copepods. Prevalence of infection by adult female O. elongata was 97% (n = 28); mean intensity of infection was 1.89 (+/-1SD = 0.32) adult female copepods per infected shark and 1.0 (+/- 1SD = 0.0) adult female copepods per infected eye. Five of the 20 collected eyes were infected by O. elongata chalimi, and 9 of 20 eyes had 1 to several remnants of bullae embedded in the cornea. Bullae were each associated with a corneal opacity, and anchoring plugs of chalimi were associated with pinpoint lesions in the cornea or conjunctiva. All eyes exhibited marked edema and erosion of the bulbar conjunctiva, and this torus-shaped lesion corresponded to each O. elongata adult female's presumed feeding and abrasion radius. Histological examinations revealed lesions in the anterior segment of eyes to be generally similar, but graded, in severity, and in all eyes they involved the conjunctiva, cornea, filtration angle, and iris. Epithelial lesions were characterized by corneal ulceration, dysplasia, hyperplasia, and heterophilic keratitis, and by ulcerative conjunctivitis accompanied by epithelial hyperplasia with rete peg formation. Disorganization of fibers, necrosis, mineralization, minimal heterophilic influx, and perilimbic neovascularization were associated with bullae in the corneal stroma. Within the limbus there was diffuse histiocytic and lymphocytic inflammation and marked lymphofollicular hyperplasia. Heterophilic and mononuclear anterior uveitis affecting the filtration angle and anterior surface of the iris was also observed in most eyes. One eye had a partial transcorneal prolapse of a ruptured lens, with degenerative changes in the ruptured lens and severe keratitis associated with the anchoring devices of an adult copepod and several chalimi. Fourteen eyes exhibited 1 to several, randomly distributed, small, round to irregular, corneal opacities or pits that were not associated with copepods, and it is likely that these opacities represented lesions associated with adult female or larval anchoring devices from past infections. The avascular cornea represents a niche that is somewhat shielded from host immune reactions, and this, and the fact that the general body surface of sleeper sharks is covered by tall and sharp placoid scales, may partially explain the corneal attachment of O. elongata adult females. It was concluded that O. elongata infections can lead to severe vision impairment in Pacific sleeper sharks but that these infections do not significantly debilitate hosts because they probably do not need to rely on acute vision for their survival.
A 2-year study was conducted in Bristol Bay, Alaska, to develop and test techniques for marking b... more A 2-year study was conducted in Bristol Bay, Alaska, to develop and test techniques for marking belukha whales with visual and radio tags. Information was also gathered on belukha distribution and abundance, foods and feeding, and rates and causes of mortality. Two types of radio packages were developed: an OAR backpack designed to be bolted through the dorsal ridge, and a Telonics barnacle tag with an umbrella-stake attachment. Testing of tags and attachments revealed that the more-powerful OAR radio could be received at longer distances and lower antenna heights, and the the umbrella-stake attachment penetrated too deeply for reliable use on belukhas.
Current and historical information about food habits of bearded seals, Erignurhus burbutus, are p... more Current and historical information about food habits of bearded seals, Erignurhus burbutus, are presented. Shrimps, crabs, and clams are overall the most important prey. Proportions of different prey in the diet vary with age of seals, location, and time of year. Foods of male and female seals are similar. Young seals eat proportionally more shrimps than do older animals. Recently,
Bowhead whales, Salaena mystice-tus, spend the late spring, summer, and early autumn in the Beauf... more Bowhead whales, Salaena mystice-tus, spend the late spring, summer, and early autumn in the Beaufort Sea (Ser-geant and Hoek, 1974). On their north-ward spring migration they usually begin to pass Point Barrow, Alaska, in the latter part of April (Durham, 1979; Braham and ...
Aerial surveys were conducted during late May and early June 1996 - 99 in the central Beaufort Se... more Aerial surveys were conducted during late May and early June 1996 - 99 in the central Beaufort Sea of Alaska, using strip-transect methods. The purpose of these surveys was to quantify and model the effects of environmental covariates on ringe d seal counts and to provide density estimates that would be useful for evaluating trends in seal abundance. Total survey
Twenty eyes from 10 Pacific sleeper sharks Somniosus pacificus, infected with the copepod Ommatok... more Twenty eyes from 10 Pacific sleeper sharks Somniosus pacificus, infected with the copepod Ommatokoita elongata, were collected in Prince William Sound, Alaska, and the eyes of an additional 18 S. pacificus captured in the same area were inspected for copepods. Prevalence of infection by adult female O. elongata was 97% (n = 28); mean intensity of infection was 1.89 (+/-1SD = 0.32) adult female copepods per infected shark and 1.0 (+/- 1SD = 0.0) adult female copepods per infected eye. Five of the 20 collected eyes were infected by O. elongata chalimi, and 9 of 20 eyes had 1 to several remnants of bullae embedded in the cornea. Bullae were each associated with a corneal opacity, and anchoring plugs of chalimi were associated with pinpoint lesions in the cornea or conjunctiva. All eyes exhibited marked edema and erosion of the bulbar conjunctiva, and this torus-shaped lesion corresponded to each O. elongata adult female's presumed feeding and abrasion radius. Histological examinations revealed lesions in the anterior segment of eyes to be generally similar, but graded, in severity, and in all eyes they involved the conjunctiva, cornea, filtration angle, and iris. Epithelial lesions were characterized by corneal ulceration, dysplasia, hyperplasia, and heterophilic keratitis, and by ulcerative conjunctivitis accompanied by epithelial hyperplasia with rete peg formation. Disorganization of fibers, necrosis, mineralization, minimal heterophilic influx, and perilimbic neovascularization were associated with bullae in the corneal stroma. Within the limbus there was diffuse histiocytic and lymphocytic inflammation and marked lymphofollicular hyperplasia. Heterophilic and mononuclear anterior uveitis affecting the filtration angle and anterior surface of the iris was also observed in most eyes. One eye had a partial transcorneal prolapse of a ruptured lens, with degenerative changes in the ruptured lens and severe keratitis associated with the anchoring devices of an adult copepod and several chalimi. Fourteen eyes exhibited 1 to several, randomly distributed, small, round to irregular, corneal opacities or pits that were not associated with copepods, and it is likely that these opacities represented lesions associated with adult female or larval anchoring devices from past infections. The avascular cornea represents a niche that is somewhat shielded from host immune reactions, and this, and the fact that the general body surface of sleeper sharks is covered by tall and sharp placoid scales, may partially explain the corneal attachment of O. elongata adult females. It was concluded that O. elongata infections can lead to severe vision impairment in Pacific sleeper sharks but that these infections do not significantly debilitate hosts because they probably do not need to rely on acute vision for their survival.
A 2-year study was conducted in Bristol Bay, Alaska, to develop and test techniques for marking b... more A 2-year study was conducted in Bristol Bay, Alaska, to develop and test techniques for marking belukha whales with visual and radio tags. Information was also gathered on belukha distribution and abundance, foods and feeding, and rates and causes of mortality. Two types of radio packages were developed: an OAR backpack designed to be bolted through the dorsal ridge, and a Telonics barnacle tag with an umbrella-stake attachment. Testing of tags and attachments revealed that the more-powerful OAR radio could be received at longer distances and lower antenna heights, and the the umbrella-stake attachment penetrated too deeply for reliable use on belukhas.
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