Estimation of harp seal pup production in the Greenland Sea using spatial analysis on aerial survey data

Abstract

From 14 March to 6 April 2002 aerial surveys were carried out in the Greenland Sea packice to assess the pup production of the Greenland Sea population of harp seals Pagophilus groenlandicus. One xed-wing twin-engined aircraft was used for reconnaissance rights and photographic strip transect surveys of the whelping patches once they had been located and identifed. A helicopter assisted in the reconnaissance rights, and was used subsequently to by 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 and/or photographically. Using traditional strip-transect analysis, 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 calculated at 98 500 (SE = 16 800), giving a coencient of variation for the survey of 17.9%. A new approach in analysis of this type of data, using a spatial analysis method, has been developed recently. It is the aim of this work to apply this new method to the data obtained in the 2002 photographic surveys (i.e., patches B and C), and to compare the results obtained (both point estimates and variances) with previous results obtained in the traditional strip-transect analysis.