Last updated on 18 July 2019
Morocco consistently conducts acoustic surveys in the central region (FAO 2016; FAO 2018; FAO 2018; FAO 2019). There is also a biological sampling program in Moroccan ports; sampling intensity is typically higher in Zone A than in Zone B and in the Southern Zone (Zone C).
Annual stock assessments are conducted separately by the FAO’s Working Group on the Assessment of Small Pelagic Fish off Northwest Africa, and Morocco’s Institut National de Recherche Halieutique, (INRH). Publication timing is somewhat variable. The latest published reports assess the stock’s status using data through 2017 (INRH 2018; FAO 2019).
Approaches used to assess the stock in 2017 were consistent with prior years, with both the INRH and the FAO working group using forms of the Schaefer (Schaefer 1954) global production model. The INRH applied two versions of the model: 1) a biomass dynamic (BIODYN) model developed by CECAF, and 2) a Stock-Production Model Incorporating Covariates (ASPIC) model, known for its integration of variability and uncertainty (INRH 201; INRH 2018). Their methods adjust total catches by abundance indices from acoustic surveys and fisheries, though the ASPIC model is statistically more reliant on catches (INRH 2016). They also carried out a third approach, a virtual population method known as “extended survivors analysis” (XSA). Meanwhile, the FAO Working Group also implemented a dynamic version of the Schaefer model, with total catches adjusted from survey abundance indices, and the model was fit using Excel non-linear optimization software (FAO 2019). A length cohort analysis (LCA) model applied by the FAO working group, gave inconclusive results.
Last updated on 18 July 2019
Since 2001, scientific advice for small pelagic resources in NW Africa has been provided annually by an international working group under the FAO's Fishery Committee for the Eastern Central Atlantic (CECAF) (Garcia et al. 2012; FAO 2018; FAO 2019). In line with CECAF's overarching mission (FAO 2019), the group of scientists is tasked with assessing stock status and recommending management options geared towards optimal and sustainable exploitation for the benefit of coastal countries. Reports are usually released with a significant time-lag. The INRH, meanwhile, includes general management recommendations in their stock assessment reports, but does not offer specific catch advice (INRH 2018).
Relative biological reference points are used for the stock due to the uncertainty in estimating absolute values (FAO 2006; INRH 2018; FAO 2019). 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.
The publication timing of the FAO working group's catch advice typically has a two-year gap. In the latest assessment (based on 2017 stock status and published in June of 2019), the working group recommended catch limit of 550,000 tonnes, the same amount they recommended in the preceding several years (FAO 2019). The working group also maintained that while the stock could likely sustain an increase in catches, a precautionary approach is necessary in light of the stock’s sensitivity to hydroclimatic dynamics. Based on similar concerns, the INRH, in their recent assessment, likewise advocated for a vigilant and adaptive management approach (INRH 2018). Noting the pattern of rising catches during a period of static biomass levels, they further advised that measures to reduce mortality are needed for small pelagic stocks in order to assure exploitation levels continue to be sustainable.
The FAO working group has also made a number of recommendations related to improving stock assessments for sardines in the northwest African region (general to all zones), including: relaunching coordinated regional surveys to estimate abundance throughout the species' distribution, undertaking recruitment surveys along the species' range, strengthening of age reading and validation methods, continuation of size frequency analysis, and improvements to fishing effort series and biosampling programs (FAO 2019). An analysis of catch data series and fishing effort for all fleets relative to climate indices was also recommended.
Last updated on 18 July 2019
Considering the 2018 assessment results collectively, the INRH interpreted the stock status of the Central pilchard stock in 2017 to be non-fully exploited, and the FAO Working Group concluded the same based on their Schaefer dynamic production model.
Acoustic survey indices show the biomass of small pelagics in the North, Central and South Atlantic coasts (66% of which is comprised of sardine) to have increased by 4.3% from 2016-2017 (INRH 2018). Though, a slight decrease was observed in the acoustic abundance index for sardine in the Central Zone (FAO 2019).
Dynamic production model assessments by INRH and the FAO produced very similar target and limit reference point estimates, indicating a stock in good condition and not fully exploited (INRH: B2017/B0.1=1.40, B2017/BMSY=1.54, F2017/F0.1=0.55, and F2017/FMSY=0.50; FAO: B2017/B0.1=1.39, and B2017/BMSY = 1.53, F2017/F0.1= 0.56, and F2017/FMSY=0.51) (INRH 2018; FAO 2019). Both the INRH and the FAO working group reported that their applications of these models produced a satisfactory fit.
The INRH’s ASPIC results (using two different adjustments) were far less optimistic, both indicating a state of over exploitation in terms of biomass (B2017/B0.1=0.53 and 0.73; B2017/BMSY=0.58 and 0.80). The INRH’s XSA model showed biomass to be at similar level to pre-2003 biomass, and lower than a period of higher abundance between 2005-2007. With respect to fishing pressure, the ASPIC model results portray a state of overexploitation (CPUE model) and full exploitation (Biomass model). Respectively, results from the two approaches (CPUE and Biomass adjusted) were: F2017/F0.1 = 2.17 and F2017/FMSY = 1.95; and F2017/F0.1 = 1.13 and F2017/FMSY = 1.02. The INRH’s XSA model estimated the exploitation rate on the stock to be 0.51 – slightly above 0.4, a rate considered to be an appropriate limit reference point for small pelagic species based on the work of (Patterson 1992). Meanwhile, F was estimated to be well over F0.1, but well under Fmsy.
While the different models applied to the stock by the INRH continue to yield mixed results, they are consistent in pattern with previous years, with the Biodyn model producing an optimistic assessment and both ASPIC models producing more troubling results. Comparing the assessment of the stock in 2017 to that in 2016, estimates of biomass are similar for the Biodyn model, lower for the ASPIC CPUE model, and higher for the ASPIC Biomass model. Estimates of fishing pressure are higher in 2017 from the Biodyn and ASPIC CPUE models (considerably higher in the latter case) than in 2016, and stable from the ASPIC Biomass model. The INRHs XSA model showed an inverse trend in F in comparison to SSB, with F increasing continuously during 2015-2017.