Age Determinations from Scales of Alosa pseudoharengus (Wilson) and Alosa aestivalis (Mitchill) in Connecticut Waters

Abstract

During 1966 and 1967, scales from 1,125 anadromous alewives, Alosa pseudoharengus, were collected from the Connecticut River and Bride Brook, Lyme, Connecticut. Scales from 722 blueback herring, Alosa aestivalis, were collected from the Connecticut and Thames rivers during the same period. Scales were read and interpreted for total age. Questionable annuli were interpreted by determining the average distance between annuli and the average and range of the number of transverse grooves per annulus. Most scales of both species were found to have zones reflecting habitation of freshwater (freshwater zones). Freshwater zones were broader on blueback scales, and occurred 44% more often than on alewife scales. The relationship between body and scale lengths was calculated for both species and was found to be linear and highly correlated. Alewives reached a maximum age of eight years, while bluebacks reached seven years. Age II and III alewives were never collected. The majority of alewives in the spawning runs in Bride Brook were of age groups V and VI. Forty-seven per cent of the blueback males spawned for the first time at age III and 50% at age IV, while about 75% of the females spawned first at age IV and 16% at age V. Sixty-eight per cent of alewife males spawned for the first time at age IV and 32% at age V, while only 32% of the females spawned first at age IV and 68% at age V. All bluebacks had spawned at least once by age V, and the maximum number of spawnings was considered to be four. All the alewives had spawned at least once and no more than three times by age VI. Females were larger than males in every age group for both species. Mean lengths of alewives, spawning for the first time in Connecticut waters, were compared with other areas. A mean length of 11.8 inches was noted for a Maine study, 10.6 inches for Connecticut waters, and 9.6 inches for a Virginia study.