Untitled

Abstract

Histological studies of the blue bream (Ballerus ballerus L., 1758) (Actinopterygii, Cypriniformes, Cyprinidae) gonad maturation have not been conducted to date. The aim of this study was to analyse the annual gonad development cycle of the blue bream from the Oder River and Lake Dąbie in north-western Poland.The spawning period of the blue bream, a single-portion spawner, was short, lasted approximately two weeks and occurred in the first half of April in Lake Dąbie, and in the second half of April in the Oder River. The blue bream male gonads reached maturity stage IV before the winter and remained at this stage until early spring. The gonads contained cells at all spermatogenetic stages and the tubule lumen was filled with numerous spermatozoa. The males from Lake Dąbie finalized their spermatogenesis in April slightly faster than those from the Oder River. Some individuals had gonad filled with large amounts of spermatozoa even in May and June.

Reproductive Potential of Stone Moroko (Pseudorasbora parva, Temminck et Schlegel, 1846) (Teleostei: Cypriniformes: Gobionidae) Inhabiting Central Europe

“…Similarly, to other cyprinids, during the peak of reproduction, gonads of male stone moroko are at stage IV, when the successive formation of new sperm cells occurs as a result of maturation of propagating new cells of the spermatogenesis process. Similarly, to other cyprinid species, stone moroko males maintained the ability to spawn for a longer period than females [35,49,71]. In the case of stone moroko, about 10% of males retained reproduction capability for a month longer than females.…”

“…The sex ratio was rarely equal to 0.99:1 [27] or with female predominance [34]. In other cyprinids, fish females were mostly predominant [35,[45][46][47][48][49][50], although equal proportions of the sexes or domination of males were recorded [51][52][53][54][55][56][57].…”

“…Males of studied stone moroko were ready to spawn at the end of April, at the same moment as the females. In other cyprinid species, males became ready for reproduction earlier than females [35,49,71]; only a few species are ripe at the same moment as females [50]. Similarly, to other cyprinids, during the peak of reproduction, gonads of male stone moroko are at stage IV, when the successive formation of new sperm cells occurs as a result of maturation of propagating new cells of the spermatogenesis process.…”

“…In the Polish population, spermatocytes were first observed as late as January, and propagation of B spermatogonia was only observed in autumn and winter (stage II L ). During autumn and early winter, gonads in other cyprinids are also at the II L stage; only in blue bream during winter do gonads attain stage IV containing even spermatozoa [35,49,50,71,72]. In the latter species, stage II is short, and spawning commences at the earliest time among cyprinids, i.e., from the beginning of April.…”

Artificial Reproduction of Blue Bream (Ballerus ballerus L.) as a Conservative Method under Controlled Conditions

“…The spawning period can shift to late May if the water does not become warm enough due to low spring air temperatures [5]. The blue bream's annual reproductive cycle description is based on gonad morphology, GSI fluctuations [5] and the gonad histology in fish of both sexes in the annual development cycle [8,9]. This species' reproduction under controlled conditions has not yet been conducted.…”