Environmental Biology of Fishes

, Volume 73, Issue 4, pp 379–389

Intra-specific variations of egg size, clutch size and larval survival relatedto maternal size in amphidromous Rhinogobius goby

Article

DOI: 10.1007/s10641-005-2230-8

Cite this article as:
Tamada, K. & Iwata, K. Environ Biol Fish (2005) 73: 379. doi:10.1007/s10641-005-2230-8

Synopsis

Newly hatched amphidromous Rhinogobius sp. CB (cross band type) larvae drift downstream to the sea to grow and develop before returning upstream as juveniles. Since larger and older individuals usually inhabit the upper reaches of rivers, larvae from larger females are more likely to suffer higher risks of starvation or predation during their longer migration to the sea. We examined the relationship between reproductive parameters (egg volume and clutch size) and maternal length. We collected adult Rhinogobius sp. CB along the course of the Aizu River (Wakayama Prefecture, Japan) and spawned them under laboratory conditions. We measured egg volumes and clutch sizes, as well as larval starvation tolerance. Both egg volume and clutch size increased with standard length or age of the maternal fish, while egg density in these clusters did not correlate with standard length. Gonad-somatic index (GSI) also tended to increase with maternal standard length. There was a significant positive correlation between egg size and the 72-h survival rate of unfed hatchlings. Intra-specific variation of egg volumes and clutch sizes in this species seems to be an adaptation for enhancing offspring survivorship during migration to the sea. Some females spawned a second time. Second spawned egg sizes were smaller than first spawned egg sizes, although there was no difference in clutch size between the two. Egg size variation between subsequent spawns may be an adjustment to the changes in seasonal environmental conditions.

Key words

reproductionlarval starvation tolerancematernal sizeintra-specific variation

Copyright information

© Springer 2005

Authors and Affiliations

  1. 1.Biological laboratory, Faculty of EducationWakayama UniversityJapan
  2. 2.Takao Public Junior High SchoolTanabeJapan