Seasonal Variation in Protein Content of Bluegill Pituitary Glands
Percy W. Laarman
Abstract.-Seasonal variations in the protein content of pituitary glands of the bluegill, Lepomis macrochirus Rafinesque were measured. Collections were made from March to October 1969, inclusive. The acetone-dried pituitary glands represented 14.5% of the wet weight. Seventy-six percent of the annual fish growth occurred between 1 May and 1 August. Per cent protein in the acetone-dried glands increased from 25% in early spring to 56% in August. The pituitary gland was large and active before growth and reproduction began, and became smaller with a higher percentage protein content, after growth and spawning were completed. Care should be taken in evaluating experiments in which fish metabolism is a factor since the response of the fish may vary significantly during different times of the year.