The Age and Growth of Gasterosteus aculeatus, Pygosteus pungitius and Spinachia vulgaris, as Shown by their Otoliths

Abstract

The literature on the age and growth of sticklebacks and on the use of otoliths in detn. of the age of fishes is reviewed. Technics for removal, treatment and interpretation of the otoliths of sticklebacks are descr. It is shown that in G. aculeatus and P. pungitius a transparent ring is laid down in the otolith in June or July, followed by an opaque zone laid down between July and the following June. In some otoliths the opaque zone is not visible until Sept. These 2 spp. live for a max. of under 3.5 yrs., most of them becoming sexually mature during their 1st yr. of life. Both spp. grow rapidly during their 1st yr., P. pungitius growing more rapidly than G. aculeatus. After the 1st yr. the rate of growth falls, and growth seems almost to stop in P. pungitius. This results in considerable overlap in size of the different yr. groups. Variations in mean and max. size in different populations of G. aculeatus are shown to be due to different growth rates and not to differences in span of life. It is suggested that the same applies to P. pungitius, S. vulgaris is shown to form no transparent rings in the otolith. This supports statements by several workers that it is an annual fish.