The assessment model used by IFOP (Instituto de Fomento Pesquero) and INPESCA (Instituto de Investigación Pesquera) is a statistical catch-at-age model in ADMB incorporating catch, length, age, weight and logbook data from commercial fisheries, and biomass, catch-at-age and age-weight estimates, and squid abundance, from trawl sampling, direct acoustic and geostatistical methods employed in a regular survey (CCT-RDZCS, 2015). IFOP’s stock assessment reports are currently available only upon request. 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) evaluates the IFOP report and publishes its evaluation of the status of the stock, and its advice on biological reference points and on catch limits (CCT-RDZCS, 2015). Two exploitation scenarios were modeled in 2015, either distinguishing the artisanal and industrial fleets (scenario 2) or, in the base case, assuming the artisanal fisheries (longline and gillnet) have the same exploitation pattern as the industrial trawl fisheries (scenario 1).
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 (Tascheri et al, 2015). The presence of this predator has been identified as an important factor in understanding and monitoring the resource dynamics (IFOP, 2013; Subpesca, 2013; Subpesca, 2013b). Overall, the uncertainty in the assessment of stock status is considered to be relatively low (Tascheri et al., 2015).
Official scientific advice was previously provided annually by IFOP. But under the New General Law on Fisheries and Aquaculture (Ley General de Pesca y Acuicultura 18.892, LGPA) the CCT-RDZCS – gathering IFOP, INPESCA, Subpesca and several experts from Chilean universities – was created to give scientific support to management decisions (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, 2015a). Given the poor condition of the stock, the CBA for 2016 is advised between 18,400 and 23,000 tons, as it was for 2015. For 2015 the Committee had recommended that, considering uncertainties in the assessment, the catch limit should preferably be set close to the lower limit of the range (CCT-RDZCS, 2014; Subpesca, 2014). For 2016, no preference was expressed by the Committee but it noted that if no increase should occur in the biomass in 2016, the TAC should be reduced given the uncertainty around the stock response considering the significant levels of illegal and unreported fishing (CCT-RDZCS, 2015).
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 (Subpesca, 2013; Subpesca, 2013b).
An official discussion about a Recovery Plan for this fishery was initiated in 2012 and it was expected to imply a significant decrease in fishing levels if implemented. Given the stock condition, in 2014 the CCT-RDZCS reiterated the need for the development and implementation of a recovery plan (CCT-RDZCS, 2014), with positive outcomes.
In 2015, Subpesca formally adopted new definitions of reference points for the stock (Subpesca, 2015b), in accordance with the recommendations of IFOP and INPESCA (CCT-RDZCS, 2014; Subpesca, 2014) and based on MSY targets as foreseen under the LGPA. Values of reference points are re-estimated in the assessment so vary from year to year:
- Biomass at Maximum Sustainable Yield, BMSY = 40% of SSB0. In 2015 this was estimated as 249.9 thousand tons (scenario 1) or 378.8 thousand tons (scenario 2)
- Biomass Limit Reference point, Blim = 20% SSB0. In 2015 it was calculated as 129.5 thousand tons (scenario 1) or 189.5 thousand tons (Scenario 2)
- FMSY = F 40%SPR at F=0. In 2015 it was estimated as 0.27/year (scenario 1) or 0.20/year (scenario 2; Tascheri et al., 2015), or 0.53 /year under scenario 2 according to CCT-RDZS (2015).
The virgin spawning biomass (SSB0) estimate is thus between 620,000 and 950,000 tons.
The spawning stock biomass is estimated to be between 93,000 and 119,000 tons (scenario 2 and scenario 1 median points, respectively; Tascheri et al., 2015), at 12 to 20% (Tascheri et al., 2015) or 11 or 19% (CCT-RDZS, 2015) of the virgin biomass level. It is unclear where the differences in these ranges result from. According to CCT-RDZS the stock is collapsed, below both Blim and BMSY, and is now thought to have been in a collapsed state for 11 years, showing no signs of recovery in either biomass or size structure. The situation is considered to be of high risk to its conservation (Subpesca, 2015a). IFOP considers the stock to be at the least overexploited, but the probability of it being collapsed is between 0.5 or 1, depending on the scenario considered (Taschei et al., 2015) The size structure of the population shows no significant changes from its deteriorated state. The fecundity index had been on a decreasing trend but shows an apparent uptick in 2015 that needs to be confirmed (CCT-RDZCS, 2015). Average total length from industrial catches also showed a small increase in 2014, albeit remaining below the reference size, and potentially caused by fishing close to spawning aggregations. Artisanal fisheries showed similar slight increases in 2014 relative to 2013 (Tascheri et al., 2015). Overall, the fishery shows no signs of recovery throughout its extent (CCT-RDZCS, 2015). Although fishing mortality was recently considered to be below FMSY (Subpesca, 2014), concerns have been raised as to the uncertainty introduced in F by illegal and unreported fishing (Subpesca, 2015a).
The fishery started in the 1930s and a period of full exploitation occurred between 1953 and 1961 with annual landings around 80 thousand tons. The stock suffered a sharp decrease after reaching the maximum historical landings level at around 130,000 tons in 1968, and landings stabilized at around 30,000 tons up to the 1980s, coinciding with hake’s decreased use in fishmeal production, and low domestic demand for human consumption. As the stock recovered and exports increased another landings peak of around 120,000 tons was hit in the early 2000s. Since then, the stock’s biomass and landings have been decreasing, and the stock’s age structure has become dependent on juvenile fish (Tascheri et al., 2015). TACs have been being gradually reduced – in 2014 another TAC reduction was enforced and artisanal fisheries were to receive a compensation to mitigate quota reductions (CONFEPACH website).
The spawning biomass, which remains below the biomass reference limit B20% since 2004, increased slightly from 2007-2012 but decreased again in 2013. In recent years, F had been below FMSY. The exploitation rates observed during 2001-2013, and the additional causes of mortality (e.g., predation by jumbo flying squid and other species), have prevented the stock’s recovery from its over-exploited (now collapsed) condition (IFOP, 2013; Subpesca, 2013; Subpesca, 2013b). 26% to 34% of the stock was estimated to be removed in 2003 and 2004 by predation by jumbo flying squid (IFOP, 2013). However, it’s now noted that mortality due to discarding and under-reporting of landings has been underestimated, so historical estimates of predation by squid will likely be reduced accordingly (Tascheri et al., 2015).