Last updated on 1 March 2019
Stock assessment is conducted annually by IFOP (Instituto de Fomento Pesquero; Institute for Fisheries Development). The most recent IFOP’s stock assessment reports are currently available only upon request (here). The assessment model is a statistical catch-at-age model in ADMB incorporating the following sources of information (years included in last assessment are provided in brackets):
- Data from the trawl fishery
- Catches/landings: 1940-2016
- Age structure: 1968-2016
- Weight-at-age: 1968-2016
- Log books: 1983-2016
- Assessment surveys
- Biomass estimates for several years
- Age structure for several years
- Weight-at-age for several years
- CPUE of squid for several years
Catch data are officially recognized as distorted due to high levels of bycatch of the industrial fishery and nonreporting from the artisanal fishery (CCT-RDZCS 2017) (IFOP 2018). Two exploitation scenarios were modeled in 2018. In both of them the exploitation pattern from trawl fishing is assumed to be representative for the whole fishery, but there are differences in the catch data used in the model. In the first one (Case 1) catch data is obtained from official catch records from SERNAPESCA . In the second one (Case 2), official catch records from SERNAPESCA are used for years 1940-1979, whereas catches for the period 1980-2016 are obtained from Arancibia et al., 2017 who standardized catches for that period taking into account bycatch and unreported fishing. Stock assessment assumes a constant value of M=0.33 (IFOP 2018).
The impact of including the corrected catch series for 1980-2016 can be summarized in 1) higher abundance to explain higher catches, 2) higher recruitment, 3) higher fishing mortality and 4) reduced natural mortality due to jumbo squid (IFOP 2018).
Uncertainties in the assessment may be related to the lack of sexual dimorphism in the model and to predation mortality by jumbo flying squid Dosidicus gigas (IFOP 2018).
Last updated on 1 March 2019
Official scientific advice was previously provided annually by IFOP. But under the New General Law on Fisheries and Aquaculture (SUBPESCA 2017) the Scientific and Technical Committee for Demersal Resources of the South-Center Region (Comité Científico Técnico de Recursos Demersales de la Zona Centro-Sur, CCT-RDZCS) – gathering IFOP, INAPESCA, SUBPESCA and several experts from Chilean universities – was created to give scientific support to management decisions (Ministerio de Economia, Fomento y Reconstrucción (MEFR) 2007). Based on IFOP and INPESCA reports, the CCT-RDZCS annually recommends an Acceptable Biological Catch (Captura Biológicamente Aceptable, CBA) range based on the maximum sustainable yield (MSY) approach, where the lower value of the range is 20% below the upper (Subpesca 2015).
The advised acceptable biological catch range for 2018 was 20,000-25,000 tonnes, following the rule of the management plan that states a F=75%*Fmsy when the resource is considered overexploited, as it is the case. However, the decision was controversial as some members of the CCT-RDZS argued that such level of F would be too high to meet the objective of rebuilding the biomass to Bmsy in 7 years counted from the implementation of the management plan. It was also pointed out that the 75%Fmsy rule doesn’t consider unreported and illegal catches that are especially relevant in the artisanal fishery (up to 3-4 times the reported catches); and that as long as illegal and unreported catches are not controlled for, the advice provided by the CCT-RDZS will have limited effectiveness (CCT-RDZCS 2017). Some members of the CCT-RDZCS recommended adopting a more conservative scenario with F=60%*Fmsy but this was not approved (CCT-RDZCS 2017).
In 2017, the advice was also was between 20,000 and 25,000 tonnes but with a formal recommendation of adopting the lower value of the range (20,000 tonnes) (CCT-RDZCS 2016). This recommendation however was not explicit in the 2018 advice (CCT-RDZCS 2017).
In 2013 the CCT-RDZCS advocated the implementation of further management measures such as spatial-temporal closures to protect recruitment and spawning; and advertised the “dangerously high” fishing mortalities in regions VI, VII and VIII (CCT-RDZCS 2013).
The most recent estimation of the reference points for South Pacific hake are (IFOP 2018):
- SSBMSY = 40% of SSB0. In 2018 this was estimated at 239,000 tonnes (Case 1) or 328,000 tonnes (Case 2).
- SSBlim = 20% SSB0. In 2018 it was calculated as 119,500 tonnes (Case 1) or 164,000 tonnes (Case 2).
- FMSY = F 40%SBPR at F=0. In 2018 it was estimated as 0.19/year under both Cases.
The virgin spawning biomass (SSB0) estimate is thus between 597,500 (Case 1) and 820,000 tonnes (Case 2).
Last updated on 1 March 2019
According to Case 1 from the stock assessment model (IFOP 2018), total and spawning biomass in 2017 were 356,000 tonnes and 142,000 tonnes respectively. Results from Case 2 indicate that total and spawning biomass in 2017 were 424,000 tonnes and 174,000 tonnes respectively. The reproductive potential of the stock in 2017 was estimated in 24% of SSB0 in Case 1 and 21% in Case 2, with a probability of 21% and 37% (respectively) that the stock is below the limit value of 20%SSB0 (IFOP 2018). According to these values and the updated reference points, the CCT-RDZS classified the resource as overexploited (CCT-RDZCS 2017).
Biomass in 2017 (as estimated from acoustic surveys) was estimated in 301,330 tonnes (266,919-335,741) which represents an increase of ~24% as compared to 2016 (242,920 tonnes); this increase is mostly related to somatic growth of the individuals as abundance decreased ~10% between 2016 and 2017 (CCT-RDZCS 2017).
In general, catches in 2017 decreased both in the industrial and artisanal fishery as compared to 2016. The CCT-RDZS reported a low percentage of juvenile fish (CCT-RDZCS 2017).
Discards of South Pacific hake are considered low in the artisanal fishery (which however support large levels of unreported catches), and vary among 3-25% in the industrial fishery (Subpesca 2017).
Estimated discard of South Pacific hake in this fishery is 3-4% (IFOP 2016)