Please Note:

The Open Access Repository has moved to a new authentication system as of the 1st of November.

Account holders will now be able to login using their University of Tasmania credentials.
If you have trouble logging in please email us on E.Prints@utas.edu.au so we can assist you.

Public users can still access the records in this repository as normal

Open Access Repository

The reproductive biology and movement patterns of the draughtboard shark, (Cephaloscyllium laticeps): implications for bycatch management

Downloads

Downloads per month over past year

Awruch, CA (2007) The reproductive biology and movement patterns of the draughtboard shark, (Cephaloscyllium laticeps): implications for bycatch management. PhD thesis, University of Tasmania.

[img]
Preview
PDF (Front Matter)
Thesis_front.pdf | Download (166kB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (Introduction & Chapter 1)
Intro._&_Ch_1.pdf | Download (206kB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (Chapter 2)
chap2.pdf | Download (1MB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (Chapter 3)
chap3.pdf | Download (221kB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (Chapter 4)
chap4.pdf | Download (624kB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (Conclusion & Bibliography)
Conc_&_Bib.pdf | Download (153kB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (Whole thesis)
Thesis final.pdf | Download (5MB)
Available under University of Tasmania Standard License.

| Preview

Abstract

The draughtboard shark (Cephaloscyllium laticeps) is the most common shark on
temperate reefs in southeastern Australia. In order to implement adequate management
plans its reproductive biology and movement patterns were studied.
Females developed a single external-type ovary with a maximum follicle diameter of 35
mm. Vitellogenesis commenced at 10 mm follicle diameter. The male reproductive tract
consisted of paired testis with spermatocysts undergoing diametric development.
The hormones testosterone, 17-β estradiol, progesterone and 11-ketotestosterone
(males only) were examined to determine their role in reproduction. Testosterone and
estradiol showed major changes during follicle development. Estradiol increased as the
follicle developed before declining as the follicle reached maturity. Testosterone
remained low during the first stages of follicular development and increased as the
follicle reached maturity. Progesterone showed a peak just prior to ovulation.
Testosterone was the only hormone that varied with maturity in males and no levels of
11-ketotestosteorne were detected.
Females were able to store sperm for at least 15 months and eggs were laid in pairs at
monthly intervals. Juveniles hatched after 12 months.
The size at maturity and seasonality of reproduction were estimated using reproductive
parameters obtained from dissected animals and from steroid hormones. The sizes at
onset of sexual maturity by both methods were similar. Females laid eggs throughout
the year with a peak in deposition between January and June. Elevated values of
testosterone and progesterone coincide with this period of egg deposition. Males
showed no seasonal pattern in reproduction although both testosterone and the amount
of sperm in the seminal vesicle were marginally higher in the first semester of the year.
Movement studies were undertaken using conventional and acoustic tagging. The area
of study included a marine reserve and the adjacent bays of southeast Tasmania. Both methods demonstrate that the majority of sharks remained in the same region in which
they were tagged, although a few sharks moved large distances. Sharks were active
throughout the day and night with peak activity during dawn and dusk. This species
could remain stationary on the bottom for periods up to five days. No correlation was
found between activity and lunar patterns and both sexes showed similar activity
patterns
This study has provided the first information on reproduction and movement of
draughtboard shark and demonstrated the potential for hormones to provide
reproductive information necessary for management without the need to sacrifice the
shark.

Item Type: Thesis (PhD)
Date Deposited: 26 Jan 2009 23:22
Last Modified: 11 Mar 2016 05:53
Item Statistics: View statistics for this item

Actions (login required)

Item Control Page Item Control Page
TOP