Oral Presentation Australian Society of Fish Biology and Oceania Chondrichthyan Society Conference 2016

Sperm storage in deep-sea holocephalans (#27)

Brit Finucci 1 , Matthew R Dunn 1 , Emma Jones 2 , Jane Anderson 3
  1. Victoria University of Wellington, Wellington, New Zealand
  2. National Institute of Water and Atmospheric Research (NIWA), Auckland, New Zealand
  3. Department of Pathology and Molecular Medicine, University of Otago, Wellington, New Zealand

Chimaeras are a globally distributed and yet relatively unknown subclass of fish within the Chondrichthyes. Many chimaeras are deep-sea, and are presumed to have reproductive parameters similar to other chondrichthyans that are characteristic of low productivity. Sperm storage has been reported in many chondrichthyans. The ability to store sperm is thought to be advantageous for deep-sea species, increasing reproductive efficiency in a resource-limited environment where sexual segregation is often present. To date, sperm storage has only been confirmed in the inshore chimaera (Callorhinchus milli) and based on this observation, is presumed to be widespread across the holocephalans. Specimens of longnose spookfish (Harriotta raleighana), Pacific spookfish (Rhinochimaera pacifica), and brown chimaera (Chimaera carophila) were collected from research trawl surveys and commercial vessels around New Zealand at depths between 400 and 1300 m. Using histological techniques and transmission electron microscopy, sperm storage tubules (SSTs) and sperm bundles were identified in the terminal zone of the oviducal gland of mature individuals. SSTs were identified in both macroscopically active and resting stages. A large, gelatinous mass, consistent with a sperm plug, was also found in the accessory genital gland of mature H. raleighana and R. pacifica. These results contribute to the ecological understanding of a relatively unknown and unique group of deep-sea animals.