1983. Validation of age estimation in the harp seal, Phoca groenbandica, using dentinal annuli. Can. J . Fish. Aquat. Sci. 40: 1430-1441. We investigated the validity and accuracy of age estimation in harp seals, Phoca grosra1~ndic.a~ using a sample of 155 known-age teeth from seals age 3 mo to 10 yr. Under transmitted light, transverse sections of harp seal canine teeth showed distinct incremental growth layers (IGLs) in the dentine. The first growth-layer group (GLG). representing1st-year growth, consists of two IGLs: an outer layer sf opaque dentine, bounded by the neonatal Iine, and an inner layer of translucent dentine. Subsequent GLGs. each representing 1 yr of growtla, generally consist of three IGLs: an outer layer of interglobular dentine deposited during the annual molt in April, a middle layer of opaque dentine formed during the northward spring migration (May-June), and an inner layer of translucent dentine formed from July to March. We show that dentinal GLGs can be used to estimate the absolute age of harp seals. The accuracy of the method decreases with age. Only 72.4q0 of estimates of 0-group seals were correct basing only transverse sections. These errors were virtually eliminated (489.0% ~O P P B :~~ age determination) when the tooth root was examined. Based on a single examination of a transverse section, the probabilities of correctly estimating age are 0.983, 0.889, 0.817, and 0.553 at ages I. 2, 3, and 4 + yr, respectively, when clearly inaccurate tag-tooth associations are omitted. The respective probabilities are only slightly higher when age is based on the average of five blind readings, k i n g 1.0, 0.889, 0.833, and 0.625. Beyond age 3 yr, existing data are insufficient to estimate reliably the accuracy of age determined by counting GLGs.

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Stomachs from 58 harp seals (Phoca groenlandica) from the northern part of the Barents Sea were collected between August 20 and September 5, 1987. Fifty-six of the stomachs contained identifiable remains. The amphipod Parathemisto libellula was the most common food item, found in 98% of the seal stomachs and constituting 57.9% of the total volume. Fish were the second most important prey group, with Arctic cod (Boreogadus saida) as the dominant species followed by Nybelin's sculpin (Triglops nybelini) and Greenland halibut (Reinhardtius hippoglossoides). Decapods, mainly Pandalus borealis, were also common as prey of harp seals. No sex- or age-related differences in choice of food were found. From knowledge of the depths at locations where seals were collected and the presence of fresh benthic fishes in the seal stomachs, it is assumed that harp seals could forage at depths below 300 m.

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