The first capture report on histological observation of largemouth bass, Micropterus salmoides, ovary in Hokkaido [Japan]
2004
Teranishi, T. (Hokkaido. Fish Hatchery, Eniwa (Japan)) | Ohhama, H.
Largemouth bass (HB) was caught for the first time in a small lake in Hokkaido on July 2001. The ovary of HB was observed histologically to see whether the largemouth bass spawned or not. The ovaries of the largemouth bass (YB) caught in Yamanashi Prefecture was compared with HB. The GSI value of the HB was 2.42%. The GSI values of the YB in July showed a range of 2.5% to 5.6%. The ovary of HB contained mainly atretic oocytes at the pre-matured stage (the yolk globule stage and the migratory nucleus stage) and the follicle atresia. Post-ovulatory follicles were not present in the ovary of the HB. In July ovary samples of the YB indicated levels were equal to GSI values of the HB. The YB also contained oocytes from pre-mature through to the ripe oocyte stage. These results suggest that the oocytes of the HB developed on the eve of finishing the vitellogenesis but degenerated without spawning.
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