South Pacific hake

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). 

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%*F_msy 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 B_msy in 7 years counted from the implementation of the management plan. It was also pointed out that the 75%F_msy 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%*F_msy 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):

• SSB_MSY = 40% of SSB₀. In 2018 this was estimated at 239,000 tonnes (Case 1) or 328,000 tonnes (Case 2).
• SSB_lim = 20% SSB₀. In 2018 it was calculated as 119,500 tonnes (Case 1) or 164,000 tonnes (Case 2).
• F_MSY = 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).

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).

Historically, reported landings only occasionally exceeded TACs, and have not done so since 2000. In 2016 and 2017, reported landings were 9-13% below the set TACs. However, official landing records provided by SERNAPESCA are likely underestimating real catch. A recent report estimated that the real catches of South Pacific hake in Chile doubled the reported catches for the period 1980-2015 (Arancibia et al. 2017). 

Unreported landings and discards must be accounted for according to IFOP and CCT-RDZS (CCT-RDZCS 2017) in order to reliably estimate fishing mortality rates and adequately determine stock status, as was done in the last stock assessment analysis (IFOP 2018) (Case 2).

The “Plan for the Reduction of Bycatch and Incidental Catch in the artisanal and industrial fishery of South Pacific Hake” implements the obligation to install onboard cameras to monitor discarding activities from 2018 for the industrial fleet and 2020 for the artisanal fleet. The plan also incorporates the obligation to carry on board observers in all fishing vessels (artisanal and industrial) by the end of 2018.

There is very good compliance with regulations on the size and characteristics of the fishing gears (IFOP 2018).

In January 2019, a new law that strengthens the inspection body in Chile (SERNAPESCA) was published (MEFT 2019).

Chile is a member of the Agreement of the Conservation of Albatrosses and Petrels and as such it is committed to achieve and maintain a favorable conservation status of albatrosses and petrels. The list of species to which the agreement applies includes 22 species of albatross and 9 species of petrels (ACAP 2018).  

In 2012 the Government of Chile promulgated the Bycatch Law (MEFT 2012) which established a program of research projects aimed at investigating the bycatch in the main Chilean fisheries in order to eventually design and implement Bycatch Reduction Plans for those fisheries. Those research programs would rely on fisheries observers on board and data provided directly by the vessels. The South Pacific hake fishery was amongst the first to join the program and included both the industrial and the artisanal fisheries. Results from this program (IFOP 2016) were used to elaborate the “Plan for the Reduction of Bycatch and Incidental Catch in the artisanal and industrial fishery of South Pacific Hake” (Subpesca 2017). This Plan bans any type of discard of main species (including the target species) except if it is allowed according to the conditions established by article 7B of the General Law for Fisheries and Aquaculture. In those cases the individuals need to be sorted by species, biomass estimated, and discarded with methods compatible with the capacity of detection and quantification of on-board cameras (which are mandatory under the mentioned Plan). Discards and incidental catch must be reported to the authorities. 

There is a very good knowledge of the bottom habitats along the Chilean coast especially where the main national fisheries take place. The information is available in the Final Report of the Project “Characterization of the seabed between the III and X Regions” (Melo et al. 2007). Among other information, the Report includes: 

• An exhaustive review of previous works addressing many aspects of the bottom habitats of the Chilean continental shelf
• A list of descriptors of the abiotic and biotic characteristics of the seabed
• A characterization of the seabed using the descriptors described in the Report
• Maps with bathymetry, salinity, oxygen and bottom habitats
• Maps with granulometry and organic matter content
• Information on the presence of corals at each sampling station
• Information on the presence of fish and macrobenthos at each sampling station
• Description of the bentho-demersal community including predator-prey relationships and an ecotrophic model

In Chile, there are five marine reserves: La Rinconada in Region II, Isla Chañaral in Region III, Isla Choros-Damas in Region IV, Putemún and Pullinque in Region X. The main objective of these reserves is to conserve natural banks of northern scallop Argopecten purpuratus, Chilean oyster Tiostrea chilensis and giant mussel Choromytilus chorus among others and also to protect aquatic vertebrates such as dolphins and penguins (Ministerio del Medio Ambiente (MMA) 2008), spawning areas and productive zones. Additionally, four Marine Parks are declared in order to protect units of ecological interest, and associated diversity and habitats (Subpesca 2004).

Also, since the enactment of the General Law on Fisheries and Aquaculture in 1991 (SUBPESCA 2017), a Reserve Zone for Artisanal Fishing has been established by law. It extends over 5 nautical miles measured from the coast from Region I to 41º28,6’S (located in the first third of Region X) and from south of 41°28,6’ up to 5 nm west of the straight baselines. This regulation is also in force around the oceanic islands and in inland waters. This measure, besides justifying the development and promotion of the artisanal fishing activity, prevents the industrial fleet from entering the coastal zone to carry out extractive fishing operations. It has also become a conservation measure for the bulk of fishery resources that spawn near the coast and inland waters.

A number of studies described the ecosystem and trophic relationship of the bentho-demersal community of central and southern Chile (Cubillos et al. 2003)(Neira and Arancibia 2007). M. gayi gayi exhibits a key trophic role in the ecosystem of Central Chile, with consistent predation on small pelagic fish (mainly common sardine Strangomera bentiincki, myctophid fish and crustaceans). In turn M. gayi gayi is an important prey for sea lions (Otaria flavenscens) and jumbo squid (Dosidicus gigas). Moreover M. gayi gayi is highly cannibalistic, preying on juveniles age 0-2 years (Gatica et al. 2015). 

However, the most complete analysis of the whole ecosystem and habitats is the Final Report of the Project “Characterization of the seabed between the III and X Regions” (Melo et al. 2007). It includes a detailed analysis of the prey-predator relationships and an ecotrophic model using Ecopath. The model concluded that M. gayi gayi was the dominant species of the bentho-demersal community and was estimated to have the highest trophic level of all the marine resources in the Chilean continental shelf (Melo et al. 2007). This information suggests that the South Pacific hake is a keystone species in the bentho-demersal ecosystem of central and southern Chile, and therefore its removal is likely to have profound consequences. Specifically the Ecopath model predicted positive trophic impacts by M. gayi gayi on seabirds, jumbo squid and macrobenthos; and a negative impact on conger eels, palm ruff (Seriolella violacea), the southern rays bream (Brama australis), the Patagonian grenadier (Macruronus magellanicus), the South Pacific hake (cannibalism), the squat lobster (Cervimunida johni) and the bigeye flounder (Hippoglossina macrops).

At present the management of the South Pacific Hake (through the Management Plan) is not following an ecosystem approach. Actually, the need for such an approach is highlighted in the Management Plan and other studies as a future need that will complement the current Management measures (Gomez et al. 2017) (Subpesca 2016).

The recently approved Bycatch Reduction Plan may help to protect the whole bentho-demersal ecosystem as this fishery (specially the industrial component) is characterized for a high bycatch diversity with high trophic fluxes and high biomass (Melo et al. 2007). Besides, the analysis of the impact of jumbo squid on Chilean hake in the stock assessment (IFOP 2018) is a good example on how to take into account food web-mediated mechanisms to explain stock fluctuations (Gomez et al. 2017).