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Seasonal Variation in the Accumulation and Loss of 131 I by Tissues of Adult Female Channel Catfish, Ictalurus punctatus (Rafinesque)
Author(s) -
Tarrant Robert M.
Publication year - 1971
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1971)100<237:svitaa>2.0.co;2
Subject(s) - ictalurus , catfish , ovary , fish <actinopterygii> , thyroid , biology , endocrinology , zoology , medicine , fishery
Abstract At bimonthly intervals over a 10‐month period, adult female channel catfish were injected intraperitoneally with a tracer dose of 131 I. Four fish were killed and dissected each day at intervals of 1, 5, 9, and 13 days after injection, and radioactivity in various tissues was determined. The ovary (entire organ) concentrated more 131 I throughout most of the year than even the very active thyroid area, accumulating over 70% of injected 131 I during both January and March. Accumulation of 131 I by the ovary increased from July to March and then decreased in May, although the size of the ovary continued to increase. Concentration of 131 I by the thyroid area throughout most of the year varied inversely with accumulation by the ovary. Accumulation of 131 I by sexually undeveloped fish in May was similar to that of spawned‐out fish in July. Strong similarities were also found between sexually developed fish in May and unspawned fish in July. The maximum amount of 131 I in the ovary within each sampling period occurred on the fifth day after injection, except in July and September when it occurred on the first day. The level of 131 I in the blood was highest on the first day after injection. The concentration of 131 I in the thyroid area expressed as microcuries per gram of tissue much more closely paralleled percentage of injected dose than did the ratio of tissue 131 I to blood 131 I. The only portions of the channel catfish body which consistently accumulated 131 I against a concentration gradient were the thyroid area, ovary, bile, and gut contents. Highest concentrations in the bile and gut contents occurred in May.