THE BIOLOGY OF THE LESSER SAND-EEL AMMODYTES-TOBIANUS L IN THE GALWAY-BAY AREA

Two separate spawning components of a population of Ammodytes tobianus (Pisces, Ammodytidae) were recorded on the west coast of Ireland. The two groups were distinguished principally by differences in the size of the opaque centre of the otoliths. There was also a significant dif ference between the mean vertebral number of the spring- and autumn-sp awned fish. A sample of 219 spring-spawned and 574 autumn-spawned fish were examined during the period November 1987 to August 1989. The spr ing spawning period was December to February and the first influx of s pring-spawned juveniles occurred in June. The autumn spawning period w as in August and September and autumn-spawned juveniles were captured in January. The most recent year-classes dominated the age structure o f the population. Peak feeding intensity for both groups coincided wit h a peak growing period in April. All guts were empty from mid-Decembe r to early March. Copepods, mainly planktonic, formed the major food i tems but mysids were more important in July and August.