Description of the stages and scale of maturity for gonads of female pollock

• Published in: Izvestiâ Tihookeanskogo naučno-issledovatelʹskogo rybohozâjstvennogo centra Vol. 190; pp. 33 - 48
• Main Author: Ponomarev, S.S.
• Format: Journal Article
• Language: English
• Published: Vladivostok TINRO-Center 2017
• Subjects: Biological development; Gadus chalcogrammus; Growth; Hermaphroditism; Hydration; Marine; Marine fishes; Oocytes; Sexual maturity; INW, Russia
• ISSN: 1606-9919; 2658-5510
• DOI: 10.26428/1606-9919-2017-190-33-48

Walleye pollock maturing, its gonads changes and the oocytes development are considered, in particular the structure of filiform gonads, gonads of hermaphrodites, and atretic phenomena. Determining of the maturity stages is discussed, with some recommendations. The first stages (I, II) are usually determined without any problem. Gonad color is recommended to be accounted for correct determining of the stage II-III, it becomes more saturated and reddish at this stage. The stages III and III-IV could be combined, so far as they have no any cardinal difference. Special stage VI-III is proposed for re-spawning fish because of more viable eggs. Distinctive features between the stages IV-V and V are described. Deviations in gonad development are noted, as resorrption, filiform gonads, or hermaphroditism that are important bioindicators of the populations state and their living conditions. Year-to-year variability of these deviations frequency is shown. Three types of the filiform gonads are defined, containing whether male or female germ cells or connective tissue. The true synchronous type of hermaphroditism is determined for pollock.