Last updated on 31 January 2016
The National Institute for Fisheries Research and Development (Instituto National de Investigacion y Desarrollo Pesquero, or INIDEP) is Argentina’s leading fisheries research institution and the official scientific advisor for the Federal Fisheries Council (Consejo Federal Pesquero, or CFP) and the Secretariat for Agriculture, Livestock and Fisheries (Secretaría de Agricultura, Ganadería y Pesca). The institute’s stock assessments and recommendations are based on data from annual surveys, statistics from the Undersecretariat of Fisheries and Aquaculture (Sub-Secretaría de Pesca y Acuicultura, SSPyA), onboard observers’ reports and dockside samplings.
The assessment of hake stocks is carried out by means of the Virtual Population Analysis (VPA) method combined with the Extended Survivors Analysis (XSA) implemented in the Lowestoft VPA program. From the 2009 assessment, nominal catches have been revised with onboard observers’ data to account for under and misreporting; this was motivated by regulations required to enter EU markets but has also resulted in improved confidence in the assessment. As well, FAO statistics data is used to incorporate hake catches by other countries and discards data from target and bycatch fisheries were included to correct catch-at-age estimates to obtain total catch estimates for the assessment model.
The model is calibrated with the abundance by age series obtained during the annual global surveys, Catches per Unit Effort (CPUE) by age from the commercial fleet and recruitment indices from a survey evaluating abundance of juveniles and from bycatch data from the red shrimp (Pleoticus muelleri) fishery (Santos and Villarino, 2015), calculated using data base from on-board observer programs of the different jurisdictions (Chubut, Santa Cruz provinces and Federal waters), which are coordinated under the “Technical Commission of Hake Bycatch in the Patagonian red shrimp fishery” (CFP, 2008).
The global scientific stock survey have had several breaks within 1996-2013, in particular this survey was not conducted between 2008 and 2010, as well as in 2014 and 2015 (Villarino and Santos, 2015), adding uncertainty to the stock assessment.
In the last stock assessment a statistical catch-at-age model using the AD-model builder (ADMB) platform was used in parallel with the traditional model used to assess the stock. Trends of total and spawning biomass are similar between both models, main differences observed in recent years’ estimates. This alternative model considers error in catch at age data and includes specific-age selectivity (Santos and Villarino, 2015). Biomass estimates have been revised downwards compared to last year.
Last updated on 31 January 2016
Stock assessment and Acceptable biological catches (Captura Biológicamente Aceptable, CBA) options for 2016 were estimated using the traditional APV-XSA model. Three recruitment scenarios, ensuring a 90% chance of reaching 600,000 tonnes (Btrp) and 16% or 18% of older mature individuals, in either the short (3 years) or mid-term (7 years) were used for projections. As well, CBAs were calculated with an alternative statistical model (ADMB) using two of the recruitment scenarios.
CBAs from the APV-XSA model ranged between 131 and 240 thousand tonnes for a short-term recovery and between 230 and 285 thousand tonnes for a mid-term recovery. CBAs from the ADMB model ranged between 150 and 301 thousand tonnes for a short-term recovery and between 229 and 323 thousand tonnes for a mid-term recovery. Final Advised TAC was 290,000 tonnes, same as in 2015, closer to those estimated by the alternative model for a short-term recovery and 16% of older mature individuals, or to a mid-term recovery and 18% of older mature individuals, therefore following an intermediate precautionary approach. CBA options were obtained after deducting 10% of misreporting, 15% of discards and a projection of 10.000-19.000 tonnes of bycatch (Santos and Villarino, 2015).
INIDEP advises that additional measures are required to ensure the sustainability of the resource, such as: i) maintenance of current dimensions of the closed area to protect juveniles in the Patagonian area, ii) control the effective utilization of selective devices to diminish bycatch of juveniles both in target and bycatch fisheries and reduce hake discards, iii) increase control of catch and effort declarations to reduce under-reporting, iv) annual adjustment of on-board observers coverage in the hake and shrimp fishery to obtain reliable estimations of biological-fishery variables for the estimation of CBAs, and v) achieve an effective protection of adults during spawning within the spatial closure (Villarino and Santos, 2014; Santos and Villarino, 2015).
As well, INIDEP highlighted that the global hake survey has not been conducted between 2008 and 2010, as well as in 2014 adding uncertainty to the stock assessment results, therefore is highly recommended to ensure that annual research surveys for distribution and abundance estimation are conducted (Santos and Villarino, 2015).
Last updated on 31 Jan 2016
Since 2010, the Spawning Biomass Limit (Blim) for this stock has been defined as 450,000 tonnes (Villarino et al., 2012). As for the biomass target reference point (Btrp), the recent increase in SSB has led scientists to consider 600,000 tonnes as current Btrp (replacing the previous Btrp of 550,000 tonnes). Coupled with these biomass reference points, is the objective that the percentage of older spawners (ages 5+) should be at or above 16% or 18% (Santos and Villarino, 2015).
There is neither a target reference point for fishing mortality in place nor a harvest control rule for managing the fishery.
Last updated on 31 January 2016
Total biomass for 2014 was estimated in 904,400 tonnes, 2% lower than the previous year, but an 8% increase in spawning stock biomass (SSB) was estimated for 2014 in comparison to 2013, due to the 2010 and 2011 strong year classes reaching maturity. SSB for 2014 was estimated at 580,000 tonnes. Despite the increasing trend observed in SSB since 2012 (likely related to management measures for protecting juveniles), total biomass and SSB estimates have been revised downwards compared to last year, and SSB is now estimated at slightly below its target reference point (Btrp = 600,000 tonnes).
Fishing mortality (of totally recruited ages F3-6) in 2014 was estimated at 0.48, the lowest in the time series, however fishing mortality for age 2 group indicates increasing exploitation over this group in the last two years. Recruitment (age 2) since 2005 has been high, although due to the lack of global surveys in 2014 and 2015 it was not possible to follow these cohorts strength.
Discards levels and fishing mortality by the Argentine red shrimp showed a slight increase in 2014 (28,000 tonnes); hake discards by the hake fishery are higher than those caused by the shrimp fishery and have increased significantly in recent years; from 36,000 tonnes in 2012, to 46,500 tonnes in 2013 and 62,600 tonnes in 2014 (Santos and Villarino, 2015).
Proportion of older spawners was estimated at 11% in 2013 and 2014, well below the target levels for the proportion of older mature individuals (ages 5 to 7+), set at 16 and 18%. INIDEP observed that despite high recruitment levels, most fish do not survive to become older spawners, therefore the current strategy is not allowing recovery to a balanced age structure population, due to high fishing pressure exerted in the past (Santos and Villarino, 2013; 2015).
Last updated on 31 Jan 2016
National landings have been corrected with estimates of IUU fishing and discard rates, allowing improved estimates for total catches. Up to 1996 they gradually increased reaching around 640,000 tonnes. Discards are also estimated to have peaked around this period, at around 140 – 160 thousand tonnes annually. A sharp fall was then registered, bottoming out in 2000 at 237,000 tonnes, followed by an increase to around 500,000 tonnes in 2004. A decreasing trend had been recorded until 2008, since then corrected national landings have stabilized at around 270,000 tonnes. Total estimated catches are in average 30% higher than corrected national landings, considering the complete time-series.
Fishing mortality (F) increased in the mid-1990s, remaining at close to 0.9. From then large oscillations have occurred, with F peaking at 1.02 in 2004. Since 2007, F shows a decreasing trend with F2014 being the lowest of the time series (Santos and Villarino, 2015).
Between 1990 and 1997, spawning biomass was stable at levels between 552,000 and 620,000 tonnes. A gradual decrease was observed since then, reaching a time series low of 323,000 tonnes in 2002, followed by a significant increment up to 2006, and a decrease trend once again. Since 2008, reproductive biomass shows an increasing trend until present, over-passing Blim (450,000 tonnes) in 2013, and slightly lower than Btrp (600,000 tonnes) in 2014. Recruitment doubled from 1991 to 1994 and remained high until 1997, when SSB was around 600,000 tonnes. A sharp fall was observed from 1998 to 1999 to the lowest rates in the series, followed by a gradual positive trend and achieved the maximum value of the decade in 2004. Then large oscillations have occurred, and in general from 2000-2012 recruitment has been on average 21% lower than those observed in the 1990s. Recruitment indexes are not very reliable, since the global scientific stock survey was not conducted in 2014 nor in 2015, increasing uncertainty to the stock assessment and projections (Villarino and Santos, 2014; Santos and Villarino, 2015).
Before 1990 landings at age structure registered percentages of older mature individuals (ages 5+) higher than 20%, while between 1996 and 2013 the proportion ranged from 11% to 19%. The proportion of older mature individuals (ages 5 to 7+) has not achieved the target (%18); it was estimated at 15.2 % in 2011 and 17.7% in 2012, but significantly lower in 2013 and 2014, at 11% (Villarino and Santos, 2014; Santos and Villarino, 2015).