Catch, Effort and CPUE

In Tasmania, Blue Warehou are primarily taken using gillnet gear (Figure below). A variety of methods are used by Commonwealth fisheries, including other gillnet categories (e.g., shark gillnets), Danish seine, and trawl.

Due to the low availability of Blue Warehou since the early 2000s, the species has been rarely targeted. Catch dropped to 10.9 t in 2010/11, and remained below 10 t until 2017/18, when it reached 12.6 t (Figure above). In the most recent three seasons, catch has been less than 2 t, with only 1.1 t landed in 2020/21. Peak Tasmanian landings were 317.6 t in 1991/92, which corresponded with the peak of Australia-wide landings of almost 3,000 t (AFMA 2014). Commonwealth commercial landings have also been down in recent years, with 10.1 t harvested in 2019/20 and 2.4 t harvested in 2020/21 (Patterson et al. 2021).

Two stocks of Blue Warehou are believed to occur in southern Australian waters, the east and the west Bass Strait stocks (Bruce et al. 2001), which has led to the species being managed by AFMA as two stocks. The Tasmanian fishery is now mainly centred off the southeast coast, and thus probably targets the eastern stock. Historically, catches have also been taken off the north and northwest coasts, which are presumably harvested from the western stock.

In Tasmania, Blue Warehou are also targeted by recreational fishers using gillnets, and to a lesser extent, line fishing. Historically, recreational catches have been lower than commercial catches (Figure above). However, in 2012/13, the recreational catch of Blue Warehou was almost double the commercial catch (Lyle et al. 2014b). In 2017/18, recreational catch declined again, representing approximately 6% of total catch (Lyle et al. 2019).

Following an increase in commercial gillnet effort and CPUE on the southeast and east coasts between 1995/96 and 1998/99 that resulted in an increase in landings, effort has fallen to substantially lower levels ever since (Figure above). This situation is influenced by the limited availability of Blue Warehou in Tasmanian waters. After an initial increase and substantial drop, CPUE has stabilised since 2000/01, showing notable fluctuations around the refence value, with an historical low CPUE value in 2020/21 (Figure above).