Reproduction and induced spawning of trochus, Trochus niloticus (Linnaeus)

  • Ricky Gimin

    Student thesis: Masters by Research - CDU

    Abstract

    The reproductive cycle of trochus, Trochus niloticus Linn., from Mermaid Island and Sunday Island in King Sound, Western Australia, was studied as part of the trochus research program carried out at the Northern Territory University, Darwin. The reproductive cycle was established using gonad indices (gonad index, GI, and gonad bulk index, GBI) and histological examinations by sacrificing 15 females and 10 males with basal diameter >60 mm on a monthly basis for one year starting from May 1995. The sex ratio of the trochus population based on the monthly sampling was not significantly different from an expected ratio of 1 male : 1 female (p>0.05) for mature individuals of all size classes. Spearman correlation showed that there was significant correlation (p0.05) in terms of latency period and spawning rate compared with control animals (minus chemicals). Preliminary studies were carried out to determine the roles of males or male sexual products in inducing females to spawn. Sperm did not induce spawning in females. Spawning also did not occur if females were separated from males. Artificial fertilisation with sperm of ammonium hydroxide (NH4OH) treated-eggs from excised ovary also failed. The effect of different salinities on early development (from egg stage to metamorphosis and from post-larvae (P/L) to 2 month-old juveniles) was determined. Until metamorphosis, the best growth and survival rates occurred at salinity 35 ppt. After settling, the P/L grew well at 30 or 35 ppt salinities reflecting an increased tolerance to salinity. Three kinds of substrata (fibreglass plate = FRP, shell grits = SG and coral pieces = CP) was inoculated with the same diatoms and used to grow juveniles for 72 days. The juveniles reared in natural substrata (SG and CP) grew significantly faster (p
    Date of Award1997
    LanguageEnglish
    Awarding Institution

    Cite this

    Reproduction and induced spawning of trochus, Trochus niloticus (Linnaeus)
    Gimin, R. (Author). 1997

    Student thesis: Masters by Research - CDU