Open AccessThyroid Hormones and Their Influences on Larval Performance and Incidence of Cannibalism in Walleye Stizostedion vitreum 1
Author(s) -
Hey Jane,
Farrar Eugenia,
Bristow Brian T.,
Stettner Craig,
Summerfelt Robert C.
Publication year - 1996
Publication title -
journal of the world aquaculture society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.655
H-Index - 60
eISSN - 1749-7345
pISSN - 0893-8849
DOI - 10.1111/j.1749-7345.1996.tb00592.x
Subject(s) - stizostedion , biology , cannibalism , larva , hormone , thyroid hormones , zoology , thyroid , incidence (geometry) , endocrinology , fishery , medicine , ecology , fish <actinopterygii> , physics , optics
Thyroid hormones, 3,5,3′,5′‐ tetraiodothyronine (T 4 ) and 3,5,3′‐ triiodothyronine (T 3 ) have been found in the eggs of several teleost species and are potential regulators of larval development, growth, and survival. The purpose of the present study was to determine whether natural variation of T 3 and T 4 in the eggs of six stocks of walleye, five wild stocks from Kansas, Iowa, Wisconsin, Minnesota, and North Dakota, and a semi‐domesticated stock from an Ohio fish hatchery, have an effect on larval performance in mass culture. Immersion studies were conducted with samples of larvae from four of the same stocks at exposure concentrations of 0.01, 0.05, and 0.1 ppm of T 3 and T 4 . Natural egg concentrations of T 3 (range from 0.70 to 1.5 ng/g wet weight of egg) were not significantly different among stocks. Although means of T 4 concentration among stocks were significantly different (range 0.53–9.27 ng/g), the difference was caused by the exceptionally high concentration for the Wisconsin stock (9.27 ng/g ± 2.20). Performance measures of the Wisconsin stock (Mississippi River), were not related to T 4 concentration in that stock. In spite of similarity in concentrations of T 4 and T 3 in the eggs, there were significant performance differences among the stocks (survival to 21 d, gas bladder inflation, viability, cannibalism, and growth). The immersion studies, however, revealed a significant difference in incidence of cannibalism and temperature units (TU) to 50% mortality (i.e., survival) between the control groups and treatment groups exposed to 0.01 to 0.1 ppm T 3 and T 4 . Survival was extended more than 2‐fold longer in larvae immersed in T 3 compared with T 4 . The immersion study indicated that thyroid hormones are potentially regulators of walleye development, but further investigations are needed to determine reasons for differences in larval performance based on natural concentrations in the egg and artificial exposure (immersion).