Aquatic Environment and Biodiversity Annual Review 2012

AEBAR 2012: Non-protected bycatch
Figure 6.17: Percentage of the total catch contributed by the main bycatch species (those representing 1%
or more of the total catch) in the observed portion of the scampi fishery, and the percentage discarded.
The “Other” category is the sum of all other bycatch species (fish and invertebrates) representing less
than 1% of the total catch.
Total annual bycatch since 1990–91 ranged from about 2100 t to 9200 t and, although highly variable,
showed a significant decline over the past 20 years – driven mainly by a decline in the bycatch of
QMS species (Figure 6.18). Annual bycatch has generally been an even mixture of QMS and non-
QMS species, with invertebrate species (although showing a significant increase over time)
accounting for only about 7% of the total bycatch for the whole period. Rattails (split evenly between
javelinfish and all other species combined) accounted for 30–80% of the annual non-QMS bycatch.
Comparison of bycatch rates with relative biomass estimates from trawl surveys to test for similarity of
trends over time was possible for the Chatham Rise and Auckland Islands fishery areas, but these were
inconclusive.
Total annual discards ranged from 6790 t in 1995–96 to 1430 t in 2005–06 and, although showing a
general decrease since 2001–02, there was no significant trend in overall discard levels since 1990–91
(Figure 6.19). Discards were dominated by non-QMS species (overall about 75%) followed by QMS
species (16%) and invertebrates (9%). Rattail species accounted for nearly 60% of the non-QMS
discards and about 45% of all discards.
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