Reducing the short-term mortality of juvenile school prawns ('Metapenaeus macleayi') discarded during trawling

Title
Reducing the short-term mortality of juvenile school prawns ('Metapenaeus macleayi') discarded during trawling
Publication Date
2006
Author(s)
Macbeth, William G
Broadhurst, MK
Paterson, BD
Wooden, Michael Edward
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
Oxford University Press
Place of publication
United Kingdom
DOI
10.1016/j.icesjms.2006.03.008
UNE publication id
une:1341
Abstract
A field experiment was carried out in southeastern Australia to assess the short-term mortalityand stress incurred by juvenile school prawns ('Metapenaeus macleayi') discarded froman estuarine trawler. Some 35% of the prawns died up to 72 h after being caught in a trawl,exposed to air during sorting and separation from the retained catch (as per normal commercialprocedures), then discarded into replicate cages. Total mortality was partitioned intothat caused by trawling (about 16% of mortalities), and by subsequent sorting and grading(about 19%). Assuming that the majority of the non-penaeid bycatch is excluded fromtrawls (by the use of bycatch reduction devices), the latter mortalities could be almost eliminatedby sorting and separating unwanted school prawns in water-filled compartments.Emersion stress was measured as concentrations of L-lactate in the haemolymph, whichwere elevated for at least 40 min following capture, but similar among all trawled treatments.L-lactate levels decreased within the first 24 h post-capture, then remained constantover at least the next 48 h, and were greater than baseline levels. The potential benefits associatedwith subtle changes to handling practices onboard estuarine trawlers are discussed.
Link
Citation
ICES Journal of Marine Science, 63(5), p. 831-839
ISSN
1095-9289
1054-3139
Start page
831
End page
839

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