Catch, Effort and CPUE
Bluethroat and Purple Wrasse have a long history of commercial fishing in Tasmania, but the two species have only been separated in fishery returns data since 2007/08. Previous stock assessment reports show estimates of Wrasse catches prior to 2007/08 (Fraser et al. 2021).
Purple Wrasse catches have generally been lower than Bluethroat Wrasse catches, showing a declining trend from 2008/09, an increase to 21.4 t in 2017/18, and a steep decline in 2019/20 and 2020/21 (Figure below). Purple Wrasse catch in 2020/21 was only 7.3 t. Steep declines in catches of both species in 2019/20 and 2020/21 are likely due to the impact of the COVID-19 pandemic on live fish markets, with widespread restaurant closures and restricted air freight.
Lower catches of both species since the late 2000s were accompanied by a decline in the use of fish traps that resulted from the prohibition of abalone gut usage as bait. This prohibition was a response to the appearance of the abalone viral ganglioneuritis in Victoria and forced fishers to seek alternative, but less effective baits.
Catch and effort for fish traps have been at low and declining levels for over a decade (Figure above). Fish trap CPUE has fluctuated during this period, showing a general increasing trend for both species (Figure above). Handline catch, effort, and CPUE for both species have been relatively stable or slightly increasing over the last decade.
Wrasse traded dead and used as bait in rock lobster pots have been historically under reported. These data are not included in the catch data described above.
With Bluethroat Wrasse being more susceptible to line fishing methods and Purple Wrasse more vulnerable to trap capture, Bluethroat Wrasse are now taken in larger quantities in the live fishery. Gillnets account for the bulk of the remaining catch, but because survival in nets is poor, gillnet caught Wrasse are rarely marketed live.
In recreational survey data, the two Wrasse species have not been distinguished. However, given Bluethroat Wrasse represent ~70% of commercial catch and Purple Wrasse ~30%, it can be assumed for rough approximation that the species’ relative proportion in recreational catches is similar. Combined recreational Wrasse catches have typically represented about 10% of total Wrasse catch (Lyle 2005; Lyle et al. 2009; Lyle et al. 2014b; Lyle et al. 2019) – see the 2019/20 Scalefish Fishery Assessment report for trends (Fraser et al. 2021). Thus, neither Wrasse species is considered to be an important recreational target species. Bluethroat Wrasse are a reasonably common by-catch species of recreational gillnet fishers, with research showing that this species has a moderate to low post-release survival,
particularly when gillnets are deployed for more than 4 hours (Lyle et al. 2014a).
Wrasse are reef-associated species and it is important to note that state-wide analyses are insensitive to changes in abundance at the level of individual reefs at which the fishery might impact stocks. Regional shifts in effort over the years may have masked localised depletions, with fishers moving to new lightly fished areas to maintain catches and CPUE.
The full 2020/21 Scalefish Assessment, released Dec 2022, can be found at the link: