Age Determination and Longevity in Fishes

Abstract

It is possible to determine the age of fishes with reasonable accuracy by reading the ‘growth rings’ (annuli) in hard parts (scale, otolith, opercular bone, vertebra and cross-section of dorsal or pectoral spine and fin rays). Primary growth increments in ‘otoliths’ can also be used as an alternative method of age determination. The traditional methods could be supplemented with more reliable fmorochrome and microradio-graphic techniques. The suitability of the use of hard parts and the techniques may vary among the species. It is essential that the ‘true rings’ be distinguished from other types of rings, such as false rings, larval rings and spawning rings through repeated examination of samples to avoid confusion and inaccuracy in age determination. The causes and the periodicity of ring formation may vary from species to species. The growth history of fishes could be traced by back calculation of length attained at different ages. Among the different types of growth equations, the Von Bertalanffy’s model appears to be the most suitable for fishes of both temperate and tropical regions. With slight modification, the same model may also serve to estimate the maximum theoretical calculated age (longevity) of fishes. The longevity of fishes show wide variations. The life-span may be short, intermediate and long. Whereas the lowest range of life-span (1-2 years) is exhibited by some species of lampreys and teleosts, there are species of dogfishes, sturgeons, paddlefishes, rockfishes and eels which have the life-span (70-152 years) in the highest range. A number of factors (size, sex, temperature, diet, reproduction, age at maturity and genetic composition) are believed to influence the longevity of fishes.

Age and growth of three coastal-pelagic tunas (Actinopterygii: Perciformes: Scombridae) in the Florida Straits, USA: blackfin tuna, Thunnus atlanticus, little tunny, Euthynnus alletteratus, and skipjack tuna, Katsuwonus pelamis

“…Spawning intensity for all three species has been found to increase during the spring (Collette andNauen 1983, Hare et al 2001), which could explain the second band. Though some environmental factors, such as water temperature, feeding opportunity, and spawning stress, have been attributed to periodic band formation, it is believed that an undefined physiological rhythm, possibly caused by factors such as pituitary secretions or genetics, is primarily responsible for the bands (Das 1994). Comparison aging studies between hard structures have found that otoliths are oftentimes simply the most reliable, accurate, and time efficient method for ageing fish (Prince et al 1986, Lowerre-Barbieri et al 1994, Ihde and Chittenden 2002, Sipe and Chittenden 2002, Isermann et al 2003, Li et al 2006).…”

“…The MIR was plotted against calendar quarter as well as month to determine the time of band formation (Das 1994). The MIR was also plotted against South Florida seasons, where winter included December, January, and February; spring included March, April, and May; summer included June, July, and August; and autumn included September, October, and November.…”

Relationships between fish length and otolith size for five cyprinid speciesfrom Lake Ladik, Samsun, Turkey

“…There are three pairs of otoliths, the sagitta, asteriscus, and lapillus (Das, 1994). Otoliths show differences in size and shape.…”

Morphological and Biometrical Characteristics on Otolith of Barbus tauricus Kessler, 1877 on Light and Scanning Electron Microscope

“…There are three pairs of otoliths named as sagitta, asteriscus and lapillus (Das, 1994). Otoliths show the differences in size and shape.…”