Last updated on 2 May 2017
Stock assessments have typically been performed by the FAO’s working group on the assessment of small pelagic fish off Northwest Africa; but Morocco’s Institut National de Recherche Halieutique, (INRH) has also been publishing stock status reports in recent years (Indrajaya 2015)(INRH 2015)(INRH 2016)(INRH 2016). Publication timing is quite variable. The latest published reports by both the FAO and the INRH assess the stock’s status using data through 2016 (INRH 2016)(FAO 2018). The INRH applied two Schaefer (Schaefer 1954) global production model approaches in its most recent assessment of the central stock: 1) a biomass dynamic (BIODYN) model developed by CECAF, and 2) A Stock-Production Model Incorporating Covariates (ASPIC) model, known by its integration of variability and uncertainty (INRH 2016) . Their methods adjust total catches by abundance indices from acoustic surveys and fisheries. The INRH’s BIODYN treatment included the addition of a qualitative environmental variable. While the BIODYN assessments indicated good stock status relative to target and limit reference points (B2016/B0.1=1.43, and B2016/BMSY=1.57 respectively), the ASPIC results (using two different adjustments) were far less optimistic (B2016/B0.1=0.63 and 0.64; B2016/BMSY=0.69 and 0.70), indicating a state of overexploitation. The BIODYN result was reported to produce a satisfactory fit. Meanwhile, the FAO Working Group on the Assessment of Small Pelagics off Northwest Africa also applied a BIODYN type model using catches fit with two series of abundance data (FAO 2018c). Results were similar to the INRH BIODYN result (B2016/B0.1=1.38, and B2016/BMSY = 1.52), and the FAO Working Group interpreted the stock status to be non-fully exploited. The INRH, carried out a third method, “extended survivors analysis” (XSA) which showed biomass to be in a trend of gradual increase between 2010-2016, and indicated the stock status to be fully exploited.
Results with respect to fishing mortality were also varied. The INRH’s CECAF and XSA approaches (INRH 2016) both indicated the stock is not fully exploited relative both the target (F2016/F0.1 estimated to be 44% and 74% by the two methods respectively) and limit (F2016/FMSY estimated to be 0.4 by both methods) reference points. The FAO results by the CECAF method gave the same result as for the INRH’s (F2016/F0.1= 44% and F2016/FMSY=0.4). Conversely, both ASPIC model approaches indicated fishing pressure is excessive – results from the two aproaches (Biomass and CPUE adjusted) were: F2016/F0.1 = 114% and F2016/FMSY = 103%; and F2016/F0.1 = 160% and F2016/FMSY = 144%. While the ASPIC models are somewhat limited in that they do not account for environmental effects on stock size, the results are nonetheless considered by the INRH.
Morocco consistently conducts acoustic surveys in the central region (FAO 2016)(FAO 2018)(FAO 2018). There is also a biological sampling program in Moroccan ports, though sampling intensity is typically lower in the Central Zone ports than for ports in the Northern and Southern zones.
Last updated on 2 May 2017
Since 2001, scientific advice has been provided annually by a FAO working group of scientists who assess the status of small pelagic resources in NW Africa, under the Committee for the Eastern Central Atlantic Fisheries (CECAF), who assess the status of small pelagic resources in NW Africa, and recommend management options geared towards their optimal and sustainable exploitation (Garcia et al. 2012)(FAO 2018). Reports are usually released with a significant time-lag.
Relative biological reference points are used for the stock due to the uncertainty in estimating absolute values (FAO 2006)(INRH 2016)(FAO 2018). Advice is given in relation to agreed target reference points – e.g. B/B0.1 and F/F0.1. Maximum sustainable yield (MSY) indices F/FMSY and B/BMSY are used as the relative limit reference points.
Stock assessments reports published by the INRH (Indrajaya 2015)(INRH 2015)(INRH 2016)(INRH 2016) present results from multiple models, and make general recommendations, but do not offer specific catch advice. The usual practice of the FAO working group, meanwhile, is to publish and make specific recommendations based on a single modeling approach (FAO 2018). While the FAO interpreted stock status in 2016 to be still not fully exploited, and likely able to sustain an increase in catches, they advised that the stocks sensitivity to hydroclimatic changes requires the adoption of a precautionary approach. As in past years, the FAO also advised that a catch limit be adopted; and for 2017, they recommended maintaining catches at 550,000 tonnes, the same as for 2016.
Last updated on 2 May 2017
The condition of the central sardine stock is uncertain based on the mixed results obtained by the FAO and INRH stock assessments. While the FAO working group interpreted the stock to be "not fully exploited", as indicated based on their BIODYN type model result (FAO 2018), the INRH did not reject or accept any one result presented from their different approaches, which indicated a range of different stock conditions from "not fully exploited" to "overexploited" (INRH 2016). However, there was general consistency with results obtained by respective similar models in the prior year (categorically speaking - e.g. "not fully exploited", "fully exploited" or "overexploited"), indicating the stock in 2016 was in a similar condition as in 2015. All of the INRH and FAO models indicated slightly higher biomass with respect to reference points (with the exception of one ASPIC result), and a decreasing, stable or increasing fishing mortality trend depending on the model (significantly increasing based on the ASPIC models; stable or decreasing based on BIODYN results). The INRH's new XSA approach also indicated a trend of increasing biomass.
Sardine dominate small pelagic catches in the NW Africa subregion. In the Central Zone in 2016, catches were 440,485 tonnes (FAO 2018), comprising 79% of the multispecies harvest (INRH 2016). The amount was an increase from 2015 when catches were 366,894 tonnes, and significantly down from the record 745,000 tonnes attained in 2001 (FAO 2018). Since 2011, catches have fluctuated within a smaller range, between approximately 350,000 and 440,000 tonnes, except for in 2014 when catches reached over 570,000 tonnes. Spatio-temporal closures and marine mammal (bottlenose dolphin) interaction with (i.e. dolphin "attacks on") purse seiners were considered potential influences resulting in reduced catches in the Central Zone in 2015 (INRH 2016). The vast majority of the catch in the Central Zone occurs in Zone B (FAO 2018).
Catch per unit effort (CPUE) for Moroccan purse seiners has fluctuated in a relatively stable range over the long term, between approximately 10 and 20 tonnes per trip, since 1983, with the exception of an unusually high value recorded for 2001 (FAO 2018). A gradual decrease from 2010, to the long-term low CPUE recorded in 2015, was followed by a slight increase in 2016.