Growth and Relative Size of Calcified Structures of Fish
Casselman, John M.; Casselman, John M.; Ontario Ministry of Natural Resources, Fisheries Research, Glenora Fisheries Station
Журнал:
Transactions of the American Fisheries Society
Дата:
1990
Аннотация:
AbstractThe relationship between size of calcified structures and the body of fish has been used widely in fisheries science to estimate body size at a younger age by “back-calculation.” I labeled the calcified tissue of northern pike Esox lucius with tetracycline to examine the concurrent linear growth of calcified structures and the body. I also conducted comparisons of the sizes of one or more calcified structures with body sizes of northern pike, lake trout Salvelinus namaycush, and muskellunge Esox masquinongy. Over a broad size and age range (juveniles and older), growth of scales, cleithra, and otoliths is only transitorily isometric in relation to body growth. Although scale growth is more strongly allometric than bone growth, allometry in both structures is positive during rapid growth and negative during slow growth. Slower-growing individuals have relatively smaller scales and cleithra. Calcified structure-body relations indicate that in older fish, growth of the scales virtually ceases while body growth continues, albeit at a greatly reduced rate as size approaches an asymptotic length. Cleithral growth in these fish, although greatly reduced, continues at a relatively greater rate than that of the scales. In contrast to scales and bones, otoliths grow relatively slower than the body during rapid growth and relatively faster than the body during slow growth. In slow-growing or old fish, otoliths grow more rapidly than the other structures and continue to record cyclic seasonal growth and age, whereas scales of these fish fail to grow in a regular fashion and can even resorb or erode and fail to provide an accurate record of age. Nutritional status, as indicated by prey availability, influences the size relations between calcified structures and the body. When more prey are available, northern pike have relatively larger cleithra. Hence, the relative size of calcified structures provides a sensitive indicator of growth and reflects subtle changes in growth rate and nutritional status.
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