Mark–Recapture Estimates of Harp Seal Pup (Phoca groenlandica) Production in the Northwest Atlantic

Pup production of the northwest Atlantic harp seal population (Phoca groenlandica) was estimated using a modified Petersen model corrected for tag loss and nonreporting of recovered tags. Variance estimates were corrected for the additional sources of variation due to tag loss, reporting rate, and the estimation of the number of seals examined for tags. Experiments were conducted in March of 1978, 1979, and 1980 with 9154, 4939, and 6246 pups being tagged in each year, respectively. Estimates from short-term recoveries (within the same year) were unreliable because of failure to satisfy the assumption of uniform mixing of marked and unmarked seals. Pooled estimates from long-term recoveries (1–3 yr) were considered more reliable, with the 1978 estimate of 506 000 ± 77 000 (1 SE) and the 1979 estimate of 489 000 ± 71 000 being most reliable. Based on the results of this study and on the trend in catches of pups and immatures in West Greenland, we conclude that harp seal pup production and hence population size has probably increased since the imposition of catch quotas in 1971.

Download Full-text

Pup Production of Harp Seals, Phoca groenlandica, in the Northwest Atlantic

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f93-267 ◽

1993 ◽

Vol 50 (11) ◽

pp. 2429-2439 ◽

Cited By ~ 18

Author(s):

G. B. Stenson ◽

R. A. Myers ◽

M. O. Hammill ◽

I- H. Ni ◽

W. G. Warren ◽

...

Keyword(s):

Developmental Stages ◽

Harp Seal ◽

Northwest Atlantic ◽

Black And White ◽

Aerial Surveys ◽

Phoca Groenlandica ◽

Best Estimate ◽

Age Related

Northwest Atlantic harp seal, Phoca groenlandica, pup production was estimated from aerial surveys flown off eastern Newfoundland ("Front") and in the Gulf of St. Lawrence ("Gulf") during March 1990. One visual and two independent photographic estimates were obtained at the Front; a single photographic estimate was obtained in the Gulf. Photographic estimates were corrected for misidentified pups by comparing black-and-white photographs with ultraviolet imagery. Estimates were also corrected for pups absent from the ice at the time of the survey using distinct age-related developmental stages. Stage durations in the Gulf appeared consistent with previous studies but were increased by 30% to improve the fit to staging data collected at the Front. The best estimate of pup production at the Front was obtained from the visual surveys. A total of 467 000 (SE = 31 000) pups were born in three whelping concentrations. The photographic estimates were comparable. Pup production estimates for the southern (Magdalen Island) and northern (Mecatina) Gulf whelping patches were 106 000 (SE = 23 000) and 4 400 (SE = 1300), respectively. Thus, total pup production was estimated to be 578 000 (SE = 39 000).

Download Full-text

Mark-recapture estimates of harp seal pup (Phoca groenlandica) production in the northwest Atlantic

Deep Sea Research Part B Oceanographic Literature Review ◽

10.1016/0198-0254(83)96554-8 ◽

1983 ◽

Vol 30 (12) ◽

pp. 929

Keyword(s):

Harp Seal ◽

Northwest Atlantic ◽

Mark Recapture ◽

Phoca Groenlandica

Download Full-text

Estimation of Harp Seal (Phoca groenlandica) Pup Production from Age Samples

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f85-063 ◽

1985 ◽

Vol 42 (3) ◽

pp. 468-473 ◽

Cited By ~ 3

Author(s):

Justin G. Cooke

Keyword(s):

Maximum Likelihood ◽

Mathematical Formulation ◽

Harp Seal ◽

Index Method ◽

Northwest Atlantic ◽

Numerical Example ◽

Phoca Groenlandica ◽

Survival Index ◽

Maximum Likelihood Criterion

A simple numerical example shows that previously used procedures such as the "survival index" method for estimating the pup production in populations of harp seals (Phoca groenlandica) from samples of aged adults are unreliable because of their poor mathematical formulation. A corrected formulation, based on a maximum likelihood criterion, performed well in simulations tests. This was applied to age data from the Northwest Atlantic harp seal stock to obtain revised pup production estimates. A method to correct for the effects of errors in ageing also performed favourably in simulation trials.

Download Full-text

Mandibular dental anomalies of Northwest Atlantic harp seals, Phoca groenlandica

Canadian Journal of Zoology ◽

10.1139/z87-121 ◽

1987 ◽

Vol 65 (3) ◽

pp. 769-771 ◽

Cited By ~ 3

Author(s):

R. E. A. Stewart ◽

B. E. Stewart

Keyword(s):

Genetic Variation ◽

Harp Seal ◽

Dental Anomalies ◽

Supernumerary Teeth ◽

Missing Teeth ◽

Northwest Atlantic ◽

Frequency Distributions ◽

Phoca Groenlandica

We examined 2267 harp seal mandibles to determine the frequency of extra, missing, and malformed teeth; to examine the effect of these anomalies on longevity; and to assess the usefulness of anomalies in identifying stocks of seals. Supernumerary teeth occurred in 1.7% of the seals, 0.5% of the seals were missing teeth (none because of trauma), and 0.6% had morphologically deviant teeth. Only 0.2% of the seals had more than one type of anomaly and none had all three. Average age and age–frequency distributions for anomalous and normal seals were not different. Anomalies were probably too rare and combined too much genetic variation to be useful in stock delineation.

Download Full-text

Further Analysis of Population Trends in the Northwest Atlantic Harp Seal (Phoca groenlandica) from 1967 to 1985

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f86-066 ◽

1986 ◽

Vol 43 (3) ◽

pp. 553-564 ◽

Cited By ~ 12

Author(s):

Derek Roff ◽

W. Don Bowen

Keyword(s):

Simulation Model ◽

Age Structure ◽

Population Trends ◽

Harp Seal ◽

Population Increase ◽

Northwest Atlantic ◽

Phoca Groenlandica ◽

Precise Estimation ◽

Rate Of Increase ◽

Minimum Estimate

We examined changes in the age structure of the northwest Atlantic harp seal (Phoca groenlandica) population from 1967 to 1983. Through this period there has been a statistically significant population increase in the proportion of seals aged 2–6 yr. Precise estimation of the rate of increase is hindered by a tendency for immature seals to be overrepresented in samples of molting males. Two methods were developed to correct for this bias; these provide a minimum estimate of the proportion of seals aged 2–6 yr present in 1967. Utilizing a simulation model, we showed that the unadjusted and adjusted age distributions are both extremes and that the correct distribution probably lies between them. In both cases the data are more consistent with an increasing than a decreasing population, given the level of catch experienced by this population up to 1982. Recent total catches of 75 000 or less in 1983 and 1984 are substantially below the most conservative estimates of replacement yield in 1985 and will result in a further, more rapid population increase.

Download Full-text

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

Behavioral and Brain Sciences ◽

10.1017/s0140525x15000928 ◽

2016 ◽

Vol 39 ◽

Author(s):

Mary C. Potter

Keyword(s):

Working Memory ◽

Rapid Serial Visual Presentation ◽

Language Comprehension ◽

Short Term Memory ◽

Visual Presentation ◽

Long Term Memory ◽

Short Term ◽

Term Memory ◽

Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Download Full-text

Ultrastructural investigations of MDL 19,660-induced effects on the canine platelet and megakaryocyte

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100159412 ◽

1990 ◽

Vol 48 (3) ◽

pp. 374-375

Author(s):

D.E. Loudy ◽

J. Sprinkle-Cavallo ◽

J.T. Yarrington ◽

F.Y. Thompson ◽

J.P. Gibson

Keyword(s):

Antidepressant Drug ◽

Beagle Dogs ◽

Long Term Effects ◽

Short Term ◽

Platelet Counts ◽

Toxicological Studies ◽

Induced Aggregation ◽

Internal Architecture

Previous short term toxicological studies of one to two weeks duration have demonstrated that MDL 19,660 (5-(4-chlorophenyl)-2,4-dihydro-2,4-dimethyl-3Hl, 2,4-triazole-3-thione), an antidepressant drug, causes a dose-related thrombocytopenia in dogs. Platelet counts started to decline after two days of dosing with 30 mg/kg/day and continued to decrease to their lowest levels by 5-7 days. The loss in platelets was primarily of the small discoid subpopulation. In vitro studies have also indicated that MDL 19,660: does not spontaneously aggregate canine platelets and has moderate antiaggregating properties by inhibiting ADP-induced aggregation. The objectives of the present investigation of MDL 19,660 were to evaluate ultrastructurally long term effects on platelet internal architecture and changes in subpopulations of platelets and megakaryocytes.Nine male and nine female beagle dogs were divided equally into three groups and were administered orally 0, 15, or 30 mg/kg/day of MDL 19,660 for three months. Compared to a control platelet range of 353,000- 452,000/μl, a doserelated thrombocytopenia reached a maximum severity of an average of 135,000/μl for the 15 mg/kg/day dogs after two weeks and 81,000/μl for the 30 mg/kg/day dogs after one week.

Download Full-text

Comparison of Auditory, Language, Memory, and Attention Abilities in Children With and Without Listening Difficulties

American Journal of Audiology ◽

10.1044/2020_aja-20-00018 ◽

2020 ◽

Vol 29 (4) ◽

pp. 710-727

Author(s):

Beula M. Magimairaj ◽

Naveen K. Nagaraj ◽

Alexander V. Sergeev ◽

Natalie J. Benafield

Keyword(s):

Auditory Processing ◽

Short Term Memory ◽

Group Differences ◽

Long Term Memory ◽

Short Term ◽

Significant Group ◽

Term Memory ◽

Memory And Attention ◽

Speed And Accuracy

Objectives School-age children with and without parent-reported listening difficulties (LiD) were compared on auditory processing, language, memory, and attention abilities. The objective was to extend what is known so far in the literature about children with LiD by using multiple measures and selective novel measures across the above areas. Design Twenty-six children who were reported by their parents as having LiD and 26 age-matched typically developing children completed clinical tests of auditory processing and multiple measures of language, attention, and memory. All children had normal-range pure-tone hearing thresholds bilaterally. Group differences were examined. Results In addition to significantly poorer speech-perception-in-noise scores, children with LiD had reduced speed and accuracy of word retrieval from long-term memory, poorer short-term memory, sentence recall, and inferencing ability. Statistically significant group differences were of moderate effect size; however, standard test scores of children with LiD were not clinically poor. No statistically significant group differences were observed in attention, working memory capacity, vocabulary, and nonverbal IQ. Conclusions Mild signal-to-noise ratio loss, as reflected by the group mean of children with LiD, supported the children's functional listening problems. In addition, children's relative weakness in select areas of language performance, short-term memory, and long-term memory lexical retrieval speed and accuracy added to previous research on evidence-based areas that need to be evaluated in children with LiD who almost always have heterogenous profiles. Importantly, the functional difficulties faced by children with LiD in relation to their test results indicated, to some extent, that commonly used assessments may not be adequately capturing the children's listening challenges. Supplemental Material https://doi.org/10.23641/asha.12808607

Download Full-text