Timecourse of oocyte development in saithe Pollachius virens
Wild caught North Sea saithe Pollachius virens were monitored for growth, sex steroid profiles and oocyte development pre‐spawning and measured for egg size and group fecundity during the spawning season in the laboratory. Vitellogenesis commenced in late October–early November, at a leading cohort...
Saved in:
Published in | Journal of fish biology Vol. 90; no. 1; pp. 109 - 128 |
---|---|
Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English Norwegian |
Published |
Oxford, UK
Blackwell Publishing Ltd
01.01.2017
Wiley Subscription Services, Inc Academic Press |
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | Wild caught North Sea saithe Pollachius virens were monitored for growth, sex steroid profiles and oocyte development pre‐spawning and measured for egg size and group fecundity during the spawning season in the laboratory. Vitellogenesis commenced in late October–early November, at a leading cohort size (CL) of c. 250 µm, after which oocytes grew rapidly in size until spawning started in February. Notably, a distinct cortical alveoli stage was virtually absent with yolk granules observed in developing oocytes at the very beginning of vitellogenesis. Little atresia was observed pre‐spawning, but atretic re‐absorption of remnant oocytes containing yolk granules was found in all females immediately post‐spawning. As expected, concentrations of sex steroids, oestradiol‐17β (females), testosterone (both sexes) and 11‐ketotestosterone (both sexes), increased pre‐spawning before dropping post‐spawning. The present experiment provides the first validation of sex steroid levels in P. virens. Post‐ovulatory follicles were visible in histological sections from female gonads 9–11 months post‐spawning, but then disappeared. Spawning commenced around a CL of c. 750 µm (700–800 µm). Hydrated oocytes (eggs) measured between 1·04 and 1·31 mm (mean = 1·18 mm) with decreasing sizes towards the end of spawning. The average estimated realized fecundity was c. 0·84 million eggs (median female total length, LT = 60 cm). Spawning lasted from 13 February to 29 March. |
---|---|
Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 NFR/179569 |
ISSN: | 0022-1112 1095-8649 |
DOI: | 10.1111/jfb.13161 |