Full description
Adult reproductive data for redbait is based on collections taken by midwater trawling during the spawning season and includes the biological information - size, sex, reproductive condition (weight and stage).Histological examination of mature ovaries provides information on spawing activity and preserved gonads are examined to determine batch fecundity.
Lineage
Maintenance and Update Frequency: irregular
Statement: Redbait were sub-sampled from mid-water trawl catches taken by the commercial fishing vessel Ellidi off the Tasmanian shelf break, mostly in depths of 100 to 180 m. Adult sampling for the DEPM was paired with plankton sampling in eastern Tasmania in October 2005, and eastern and south-western Tasmania in October 2006. Opportunistic supplementary sampling of commercial fishing operations was conducted during the spawning seasons of 2004, 2005, 2006 and 2007 (September to November inclusive) off eastern and south-western Tasmania.
A random sample of between 100 and 200 fish was frozen from each shot for later examination. These fish were thawed and fork length (FL, ± 1mm), total weight (± 1g), sex, gonad stage and weight (± 0.1g) were recorded. During 2004 and 2005, length and gonad stage were recorded from a further random sample of around 30 females from every shot. The gonads from these fish were removed and preserved in FAACC (10% formalin, 5% glacial acetic acid and 1.3% calcium chloride). During 2006, a random sample of at least 30 mature females was collected from each shot and preserved whole in FAACC (with a slit from vent to ventral cradle to assist preservation). Additional females with hydrated oocytes were also preserved in FAACC but these fish were kept separate from the random samples and used to supplement samples used for fecundity estimation.
For further information on methodology, please consult the FRDC report.
Notes
CreditFisheries Research and Development Corporation (FRDC): 2004/039
Purpose
Determine feasibility of using the daily egg production method to determine spawning biomass of redbait off Tasmania.
Determine feasibility of using the daily egg production method to determine spawning biomass of redbait off Tasmania.
Created: 03 07 2007
text: westlimit=145.0; southlimit=-44.0; eastlimit=149.0; northlimit=-39.0
text: uplimit=200; downlimit=60
Subjects
37 345001 |
Agricultural and Veterinary Sciences |
ANIMALS/VERTEBRATES |
Age |
Aquatic Ecosystem Studies and Stock Assessment |
BIOLOGICAL CLASSIFICATION |
EARTH SCIENCE |
Emmelichthys nitidus |
Fish |
Fisheries Sciences |
Gonad stage |
Gonad weight |
Sex |
Size |
biota |
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Identifiers
- global : 853f16c0-44a1-11dc-8cd0-00188b4c0af8