Reference points for the Iberian sardine stock (ICES areas VIIIc and IXa)

Three Yield-Per-Recruit/stock-recruitment approaches (deterministic, stochastic with plotMSY and stochastic with HCS) were used to explore reference points for the management of the Iberian sardine. The sensitivity of reference points was evaluated in relation to alternative scenarios of productivity, growth and selectivity. Growth and selectivity scenarios had a small impact on stock projections whereas productivity scenarios were very influential. The three approaches gave coherent results, but the approach using HCS, assuming uncertainty in stock biology and recruitment dynamics, was preferred to derive reference points for sardine. In this approach, the risks of the stock fa lling below some low biomass level can also be taken into account. This possibility was considered to be useful in the case of the sardine for which exploitation at maximum YPR or F0.1 resulted in values above historical exploitation and higher than Floss, therefore unsuitable as precautionary management targets. Bloss (306 thousand t) is proposed as a proxy for Blim but given no indication that recruitment is impaired below this biomass level, the group considers that the level of risk of falling below this candidate for Blim acceptable in the evaluation of a management plan should be higher than the standard ICES value (5%).The stock productivity has declined over time; therefore a scenario of low productivity was assumed (recruitment in the period 1993-2010). Under this productivity scenario, the Fmsy value for the sardine stock is 0.34, a value associated with a high probability (45%) of the biomass falling below the proposed Blim and therefore, incompatible with precautionary considerations. The WG proposes an F= 0.27, corresponding to a Prob(B<Blim)<15% under equilibrium, as the best available candidate for an F management target (proxy for Fmsy) assuming the low productivity scenario (since 1993) will continue in the future. This F provides high yield conditional to a low probability that the biomass falls below Blim=Bloss in equilibrium, thus incorporating precautionary considerations

ICES. 2019. Working Group on Southern Horse Mackerel, Anchovy and Sardine (WGHANSA).

The Working Group on Southern Horse Mackerel, Anchovy and Sardine (WGHANSA1) met by correspondence from 3 to 7 June 2019, and in Madrid from the 25 to the 28 of November 2019, and was chaired by Alexandra Silva (Portugal). There were 13 participants from France, Portugal, Spain and UK. The main task of WGHANSA was to assess the status the stocks of sardine in the Celtic Seas and English Channel (pil.27.7), sardine in the Bay of Biscay (pil.27.8abd), sardine in the Cantabrian Sea and Atlantic Iberian waters (pil.27.8c9a), anchovy in the Bay of Biscay (ane.27.8), anchovy in Atlantic Iberian waters (ane.27.9a; components west and south), horse mackerel in Atlantic Iberian waters (hom.27.9a) and jack mackerel in the Azores (jaa.27.10). Assessments and short-term forecasts were updated according to the stock annexes. There is no assessment method adopted for pil.27.7 due to the lack of data. The stock of pil.27.8abd was assessed as category 1 for the first time, following an interbenchmark. Recruitment has been above the average, the spawning–stock biomass declined and fishing mortality steeply increased in 2010–2012. SSB is fluctuating above MSY Btrigger and F2018 is above FMSY and below Fpa. This year, the DEPM datapoint for 2017 was included in the pil.27.9a assessment for the first time, following a revision of the survey data. The stock has decreased since 2006 and stabilized to a historical low since 2012. The biomass of age 1 and older fish has been decreasing since 2006 and reached the lowest historical value in 2015. It has since increased slightly but is below Blim since 2011. Recruitment has been below the time-series average since 2005. Recruitment in 2018 was around the geometric mean of the last five years. Fishing mortality has been decreasing from a peak in 2011. In 2018, it was the lowest in the time-series and below Fpa and Flim. The stock size indicator for anchovy in 9a.west decreased 90% from 2018 to 2019 (4129 t), after a period of an increasing trend since 2014. The harvest rate decreased 67% from management year 2017 to 2018 being below the median of the historical time-series.The relative spawning–stock biomass of the south component of the anchovy 9.a stock has fluctuated without a trend over the time-series, with most of the values above Bpa. From 2018 to 2019, the relative SSB decreased 5% but is still well above Bpa. Relative Fishing mortality (F) has fluctuated with no clear trend. From management year 2017 to 2018, relative F decreased 93%. The SSB of horse mackerel in Division 9.a fluctuated from 1992, the beginning of the assessment period, to 2012–2013 and afterwards increased continuously to a historical maximum, in 2018. The consistently high recruitment since 2011 has contributed to the SSB increase. Fishing mortality was 0.029 year -1 in 2018, showing a 29% decrease compared to 2017. Fishing mortality has been below FMSY over the whole time-series. The spawning–stock biomass has been above MSY Btrigger over the whole time-series. The exploration of data on anchovy abundance-at-age from juvenile surveys IBERAS-JUVESAR and ECOCADIZ-RECLUTAS indicated the series are still short to conclude about their future incorporation into the assessments. The analyses of internal consistency of the indices and of their consistency with spring acoustic surveys showed promising results for ECOCADIZ-RECLUTAS and pointed out the need to revisit the results of some of the surveys, particularly the IBERAS_JUVESAR series. For sardine, 0-group abundance from IBERAS-JUVESAR (2013–2019) combined with data from an earlier autumn survey, SAR-PT-AUT (discontinued in 2008) covering the northwestern Iberian waters, showed a significant correlation with the abundance of age 1 individuals in surveys carried out in the following spring

ICES. 2020. Working Group on Acoustic and Egg Surveys for Sardine and Anchovy in ICES areas 7, 8 and 9

he Working Group on Acoustic and Egg Surveys (WGACEGG) coordinates pelagic surveys for a number of stocks and provides monitoring for the two major sardine and anchovy stocks in ICES areas 6, 7, 8, and 9. The group evaluated small pelagic fish biomass indices derived from acoustic and Daily Egg Production Method (DEPM) surveys in ICES areas 6, 7, 8 and 9. These indices have been provided to the ICES Working Group on Southern Horse Mackerel, Anchovy and Sardine (WGHANSA), the Working Group on Widely Distributed Stocks (WGWIDE) and the Herring Assessment Working Group for the Area South of 62ºN (HAWG) stock assessment group, to serve as fishery-independent input for analytical assessment purposes. DEPM and acoustic indices were derived based on data collected using independent methods. Acoustic- and DEPM-derived biomass indices from quasi-synoptic surveys conducted in the Bay of Biscay in spring were compared, to assess the presence of potential bias and to improve the precision of fish stock biomass estimates. The DEPM-based anchovy biomass index was 22% higher than the acoustic index in 2019. Unusual concentrations of anchovy in Eastern Cantabrian Sea, an area not covered by the acoustic survey, and the presence near the sea surface of actively spawning individuals possibly under-sampled by acoustics in central Bay of Bay had been postulated as potential causes of this discrepancy. No significant difference was found between sardine biomass indices derived from DEPM and acoustics in 2019. The group has updated its database of standard gridded maps covering the European Atlantic area. This initiative continues to inform on the spatial dynamics of various parameters collected during the surveys coordinated under the auspices of the group (fish acoustic densities, anchovy and sardine egg abundance, surface temperature and salinity). Results of an analysis of the time series of gridded maps (anchovy and sardine acoustic density, surface salinity and temperature) showed quantitative changes in the spatial and temporal distribution of anchovy and sardine over the last 15 years, and further define their habitats in European Atlantic waters in spring. The timing and spatial coverage of DEPM and acoustic surveys that will be conducted by group members in 2020 were planned to optimise the monitoring of anchovy and sardine populations and their pelagic environment in the European Atlantic area. The synoptic nature of the survey components has been assessed for each target species. A manual describing the protocols used during the DEPM surveys coordinated by the WGACEGG group was reviewed, and writing of a manual of WGACEGG acoustic surveys continued. Both manuals will be available in 2020. The final results of the 2017 sardine DEPM assessment were endorsed by the group

Preliminary results from the ECOCADIZ 2020-07 Spanish acoustic survey (01 – 14 August 2020)

The present working document summarises a part of the main results obtained from the Spanish (pelagic ecosystem-) acoustic survey conducted by IEO between 01st and 14th August 2020 in the Portuguese and Spanish shelf waters (20-200 m isobaths) off the Gulf of Cadiz (GoC) onboard the R/V Miguel Oliver. The 21 foreseen acoustic transects were sampled. A total of 26 valid fishing hauls were carried out for echo-trace ground-truthing purposes. Four additional night trawls were conducted to collect anchovy hydrated females (DEPM). This working document only provides abundance and biomass estimates for anchovy, sardine and chub mackerel, which are presented without age structure. The distribution of all the mid-sized and small pelagic fish species susceptible of being acoustically assessed is also shown from the mapping of their back-scattering energies. GoC anchovy acoustic estimates in summer 2020 were of 5153 million fish and 44 877 tones, with the bulk of the population occurring in the Spanish waters. The current biomass estimate becomes in the second historical maximum within the time-series. The estimates of sardine abundance and biomass in summer 2020 were 1923 million fish and 50 721 t, estimates close to the historical average, but lower than the values estimated last year and the most recent maxima reached in 2018. A total of 32 854 t and 448 million fish were estimated for Chub mackerel, estimates similar to the most recent ones and very close to the time-series average

Uncertainty estimation and model selection in stock assessment models with non-parametric effects on fishing mortality

Uncertainty coming from assessment models leads to risk in decision making and ignoring or misestimating it can result in an erroneous management action. Some parameters, such as selectivity or survey catchabilities, can present a wide range of shapes and the introduction of smooth functions, which up to now have not been widely used in assessment models, allows for more flexibility to capture underlying nonlinear structures. In this work a simulation study emulating a sardine population is carried out to compare 3 different methods for uncertainty estimation: multivariate normal distribution, bootstrap (without and with bias correction) and Markov chain Monte Carlo (MCMC). In order to study their performance depending on the model complexity, five different scenarios are defined depending on the shape of the smooth function of the fishing mortality. From 100 simulated data sets, performance is measured in terms of point estimation, coefficients of variation, bias, skewness, coverage probabilities and correlation. In all approaches model fitting is carried out using the a4a framework. All three methods result in very similar performance. The main differences are found for observation variance parameters where the bootstrap and the multivariate normal approach result in underestimation of these parameters. In general MCMC is considered to have better performance, being able to detect skewness in posterior distributions, showing small bias and reaching expected coverage probabilities. It is also more efficient in terms of time consumption in comparison with bootstrapping.JRC.D.2-Water and Marine Resource

Assessing natural mortality of anchovy from surveys' population and biomass estimates

In ordinary catch at age models, natural mortality conditions and determines the catchabilities at age obtained for the surveys which tune the assessments. For the same reason, inferring the Natural mortality of a fish stock from surveys’ estimates, require some assumption of the survey catchabilities at age. The anchovy fishery in the Bay of Biscay has been closed since 2005 up to 2010, due to low biomass levels. In the mean time, and since 1989, the population has been directly monitored by two independent surveys, acoustic and egg (DEPM) surveys, which supplied the basic information for the assessment of this stock carried out by ICES. The closure of the fishery supposes a major contrast on total mortality levels affecting the population in comparison with the former period of exploitation, suitable to get estimates of Natural and Fishing mortalities, under the assumption of no major changes in M occurring between both periods. Log linear models and a seasonal integrate catch at age analysis were tuned to the fishery and two series of surveys under the assumption of constant catchabilities across ages for the two surveys’ population estimates. An analysis of the period 1987-2009, searching for a single and constant natural mortality at age, results in minimum residual SSQ for an M around 0.8. But a better result is obtained when a pattern of increasing natural mortality at age is allowed, a possibility suggested since a long time for this type of short living species. Keywords: Anchovy; Natural mortality, M at age, Integrate assessment

A maximum likelihood method for obtaining incubation temperature of eggs of synchronous spawning fishes

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WORKSHOP ON THE IBERIAN SARDINE MANAGEMENT AND RECOVERY PLAN (WKSARMP)

The Workshop on the Iberian Sardine Management and Recovery Plan, chaired by Manuela Azevedo (Portugal), met in Lisbon, Portugal, 1–5 April 2019 to evaluate if the management and recovery strategies jointly proposed by the Portuguese and Spanish administration meet the client´s objective and are precautionary according to ICES precautionary criterion. The request also asked for the re-examination of the Biological Reference Points (BRPs) for the Iberian sardine stock. The working group decided to keep the current BRPs, Blim of 337.4 thousand tonnes and FMSY of 0.12year-1, corresponding to the scenario of medium stock productivity, because the updated estimates as well as the estimates from the analysis of the effect on the BRPs of the assessment retrospective showed that both were within confidence bounds (95%) of the current adopted reference points. The working group also estimated BRPs considering the recent low stock productivity to be in the period 2006–2017 as specified in the request. Blim_low was estimated to be 196.3 thousand tonnes and FMSY_low was estimated to be 0.032year-1, corresponding to the scenario of low stock productivity. The estimated BRPs were used to set the biomass and fishing mortality reference levels of the catch rules and also, following the ICES guidelines for the evaluation of management plans, the basis to compute performance statistics of the management strategy evaluation under each operating model