This is a common species (Nielsen
et al. 1999). It occurs in two main widely-separated areas that presumably have negligible mixing between them: South America (Chile/Argentina) and Australia/New Zealand. Based on a comparison of historical landings data and biomass estimates, and for the purposes of estimating population percent decline on a global level for this Red List assessment, the proportion that each of these subpopulations represent is 50%. Furthermore, within South America, Chile and Argentina represent about 50% each, or 25% each of the global population. In Australia/New Zealand, catches are significantly lower on average in Australia compared to New Zealand, and therefore, New Zealand was assumed to represent 45% of the global population with 5% assigned to Australia. Across these subpopulations, and by applying a weighted decline depending on the assumed proportion of each stock, biomass declined by an average of 39% since 1970, or over the past ~54 years.
Argentina: During the 1980s, catches of this species in Argentina were less than 10,000 tons annually and subsequently increased to a peak of 34,775 t in 1990 and averaged more than 20,000 t annually during the 1990s (Belleggia
et al. 2023). In recent years (~2020), average annual catch declined to less than 4,000 t (Belleggia
et al. 2023), which represents an 80% decline over about the past 30 years; although, this decline is partly attributed to a reduction in fishing effort during 2012–2020 (Di Marco 2022). From 1980 to 2021, biomass in Argentina declined overall and has been stable at a relatively low level since 2014 and the fishery stock has not recovered despite reducing fishing effort since 2012 (Di Marco 2022). Total biomass and spawning stock biomass declined by 68 and 77%, respectively, between 1980 and 2020, and as of 2021, the stock was at about 12% of the virgin stock biomass (Di Marco 2022). It is considered overfished and at risk for recruitment overfishing (Di Marco 2022).
Catches in the Malvinas/Falkland Islands have represented approximately 13% of the Falkland Islands and Argentina combined annual catch on average from 1987 to 2021. In the Malvinas/Falkland Islands, catch per unit effort (CPUE) increased from 1990 to 2013 and then declined from 2014 through 2021 by about 18% (Ramos and Winter 2022). A high proportion of the catch is comprised of immature individuals, and this may cause growth overfishing (Ramos and Winter 2022).
Chile: According to otolith shape analysis, there are at least two separate stocks in Chilean Patagonia (Wiff et al. 2020). This species has been harvested by industrial trawlers since about 1978, catches increased during the mid 1980s and it was considered 'fully exploited' by 1992 (Baker
et al. 2014, Wiff
et al. 2020). Both stocks of this species in Chile are overfished and the spawning biomass declined by 32% (northern stock) and 36% (southern stock) from 1997–2021, or over the past ~30 years (Tascheri 2022).
Australia: The population of this species in Australia is managed as a single stock as no genetic difference has been detected between the east and west sectors, though separate eastern and western assessments are still conducted during the stock assessment process based on biological differences such as body size (Bessell-Browne
et al. 2021, Horn 2022). This species has been commercially exploited in Australia since the 1970s (Bessell-Browne
et al. 2021). According to the most recent stock assessment conducted in 2018, both the eastern and western stocks are considered 'sustainable' and overfishing is not occurring, nor are they overfished (Bessell-Browne
et al. 2021). CPUE in the eastern stock from 1986–2019 was variable from 1986 to 1995, declined from 1998 to 2005 by about 50% and has had a relatively flat trend over the 2001–2019 period (Cordue 2018, Bessell-Browne
et al. 2021). CPUE in the western stock from 1986–2019 declined from 1997 to 2005 by about 57% and has had an increasing trend from 2006–2019 (Cordue 2018, Bessell-Browne
et al. 2021). The overall decline in CPUE from 1986 to 2019, or over the past 30–35 years, is less than 10% and has been increasing or stable since the lowest value in the time series which occurred in 2005 (Cordue 2018, Bessell-Browne
et al. 2021).
New Zealand: This species has been commercially exploited in New Zealand since at least the 1930s, but substantial catches were not taken until the 1970s (FNZ 2023). There are at least five biological stocks in New Zealand (Horn 2022, Mormede
et al. 2023) and overfishing is not likely to be occurring in any of these stocks (FNZ 2023). Based on a comparison of historical landings data and biomass estimates, the largest stocks are LIN 3&4 and LIN 5&6, with both combined assumed to represent 75% of the New Zealand subpopulation. Across these stocks and by applying a weighted decline depending on the assumed proportion of each stock, biomass declined by an average of 32% since 1970, or over the past ~50 years, overfishing is not occurring and the fishery is certified sustainable.
- Between the 1970s and 1980s, the stock on the Chatham Rise significantly declined due to fishing, followed by a recovery to 1990 and further decline to the early 2000s and has been stable or increasing since then. Biomass estimates for the Chatham Rise LIN 3&4 stock declined by about 44% from 1970 to 2022, or over the past ~50 years and it declined by about 30% from the peak in 1990 to the early 2020s, or over about the past 30 years (FNZ 2023). However, biomass has been increasing or stable since the early 2000s though recruitment has been generally low (Mormede et al. 2023). According to an assessment conducted in 2022, overfishing is very unlikely to be occurring in the LIN 3&4 stock (FNZ 2023, Mormede et al. 2023).
- Biomass estimates for the Sub-Antarctic LIN 5&6 stock declined through the 1990s but have been stable since the early 2000s, it declined by about 29% from 1970 to 2021, or over the past ~50 years and it declined from the peak in the early 1990s to the early 2020s by about 25% (FNZ 2023). According to an assessment conducted in 2021, overfishing is exceptionally unlikely to be occurring in the LIN 5&6 stock (FNZ 2023).
- Biomass in the west coast South Island LIN 7WC stock has slowly declined since 2012, and overall by about 49% from 1971 to 2022, or over the past ~50 years and it declined by about 15% from 1991 to 2023, or over the past ~30 years (FNZ 2023). According to an assessment conducted in 2023, overfishing is unlikely to be occurring in the LIN 7WC stock (FNZ 2023).
- Biomass of the Bounty Plateau LIN 6B stock declined by about 39% between 1980 to 2006 (FNZ 2023). According to the most recent assessment conducted in 2006, the overfishing status is unknown and fishing pressure in general has been low and erratic since 1980 on the LIN 6B stock and annual catches have fluctuated widely over time (FNZ 2023).
- The Cook Strait LIN 7CK stock biomass declined overall by about 46% from 1970 to 2010 with a steep decline from 1999 to 2010, and according to the most recent stock assessment conducted in 2010, overfishing is very unlikely to be occurring (FNZ 2023).