PLASMA PROGESTERONE CONCENTRATIONS MEASURED USING AN ENZYME-LINKED-IMMUNOSORBENT-ASSAY USEFUL FOR DIAGNOSING PREGNANCY IN HARBOR SEALS (PHOCA-VITULINA)

Wild-caught female harbor seals (Phoca vitulina) were classified as se xually mature or immature on the basis of standard body length (< 125 cm immature, > 125 cm mature) and plasma progesterone concentrations m easured using an enzyme-linked immunosorbent assay (ELISA), a techniqu e usable in the field. Sexually mature females were classified as preg nant or non-pregnant on the basis of their plasma progesterone concent rations. Of 28 wild mature female harbor seals caught in the Moray Fir th, N.E. Scotland, between the end of February and the end of May, 79% had plasma progesterone concentrations greater than 60 nmol liter(-1) , the lowest plasma progesterone concentration measured in one of eigh t females later observed with a pup, and were diagnosed as pregnant. A linear discriminant function, calculated to provide a method of disti nguishing pregnant and non-pregnant females, predicted 100% of non-pre gnant females and 95.8% of pregnant females using plasma progesterone concentration, standard length, and month of capture as parameters. Pl asma progesterone concentrations were less than 30 nmol liter(-1) in a ll mature and immature males and immature females. In mature females p lasma progesterone concentrations ranged from 0-318 nmol liter(-1).