Publication Date:
2021-06-27
Description:
The potential for changes to onboard handling practices in order to improve the fate of juvenile school prawns (Metapenaeus macleayi) discarded during trawling were investigated in two Australian rivers (Clarence and Hunter) by comparing a purpose-built, water-filled sorting tray against a conventional dry tray across various conditions, including the range of typical delays before the start of sorting the catch (2 min vs. 15 min). Juvenile school prawns(n= 5760), caught during 32 and 16 deployments in each river, were caged and sacrificed at four times: immediately(T0), and at 24 (T24), 72 (T72), and 120 (T12 0) hours after having been discarded. In both rivers, mostmortalities occurred between T0 and T24 and, after adjusting for control deaths (〈12%), were greatest for the15-min conventional treatment (up to 41% at T120). Mixed-effects logistic models revealed that in addition to the sampling time, method of sorting, and delay in sorting, the weight of the catch, salinity, and percentage cloud cover were significant predictors of mortality. Although trawlingcaused some mortalities and comparable stress (measured as L -lactate) in all school prawns, use of the water tray lessened the negative impacts of some of the above factors across both the 2-min and 15-min delays in sorting so that the overall discard mortality was reduced by more than athird. When used in conjunction with selective trawls, widespread application of the water tray should help toimprove the sustainability of trawling for school prawns.
Keywords:
Biology
;
Ecology
;
Fisheries
Repository Name:
AquaDocs
Type:
article
,
TRUE
Format:
application/pdf
Format:
application/pdf
Format:
286-297
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