Report of the Working Group on Southern Horse Mackerel, Anchovy and Sardine (WGHANSA). 21 - 26 June 2013. Bilbao, Spain
|Ref.||ICES CM 2013/ACOM:16|
|Contributor(s)||Duhamel Erwan, Pawlowski Lionel|
|Sponsor||CIEM / ICES|
|Note||ICES WGHANSA REPORT 2013 ICES ADVISORY COMMITTEE|
|Abstract||The Working Group on Southern Horse Mackerel, Anchovy and Sardine (WGHANSA), met at Bilbao (Spain), 21–26 June 2013, chaired by Andrés Uriarte. There were 11 participants from France, Portugal and Spain (one attending on line). The main task was to assess the status and to provide short term predictions for the stocks of Anchovy in Subarea VIII and in Division IXa, for Sardine in Divisions VIIIc and IXa, and in Divisions VIIIab and subarea VII, and for horse mackerel (T. trachurus) in Division IXa and Jack Marckerel (T. pictoratus) in X (Azores). Most assessments were updated assessments according to the stock annexes, except Jack mackerel in Azores which has a biennial advice.
The Anchovy in Subarea VIII was estimated to be at 56 055 t in May 2013 (within a range 36 220 – 88 925 t), well above Blim, according to the Bayesian modelling of the population. This SSB is perceived to be about 31 % below the 2012 level; Nevertheless the later has been revised upward by 19% as compared with last year assessment. As usual two spring surveys were used as inputs for the Bayesian assessment of the population. After a strong discrepancy of their estimates in 2012, the 2013 estimates of biomass provided by the spring surveys were closer though not coincident (65 909 t the DEPM and 93 854 the acoustic). The decrease in biomass between 2012 and 2013 is related to the relative agreement of both surveys in pointing out that the percentage of age 1 in mass was less than for ages 2 and older, as this imply not a sufficient regeneration of the population in 2013 as to maintain the 2012 biomass. Catch options were provided on the basis of undetermined recruitment in 2014. As in previous years, the WG collected the available data on the fisheries of anchovy in northern areas (Subareas VI, VII and IV), although no assessment is so far required for the anchovy in those regions.
Anchovy in Division IXa, demands separate analysis and advice for the western Iberian Atlantic coasts (i.e. Subdivisions IXa North, Central- North and Central-South) from the southern regions (Algarve and Gulf of Cadiz, i.e. Subdivision IXa South), due to the independent dynamics and genetic differentiation of the populations in these regions. This a data poor stock category for which trend based assessment from surveys is provided. In the western areas catches are generally low, in rare occasion exceeding a thousand tonnes (as in 1995/96). In 2011, after several years of almost null detections, the acoustic PELAGO+PELACUS surveys estimated a Biomass of 27,000 t, in that area, and catches rose up to 3780 t. However in 2013, these surveys estimated a sharp reduction of biomass to rather low normal levels (around 4284 t). This confirms that the outburst episodes of biomass are not sustainable in this North-western region of IXa. In the Subdivision IXa South, where the bulk of the population is usually concentrated and supports a rather stable fishery, the 2013 biomass index from the acoustic PELAGO survey is 49% below the median historic survey results. This estimate was supported by a Spanish recruitment survey in the autumn of 2012which pointed out to a recruitment value below average too. However neither the fishery nor the population indexes (assessed by surveys) show any long trend for the anchovy in IXa south. Exploratory evaluations of current harvest rates in the context of Yield per recruit analysis suggest that current exploitation levels in the IXa seem sustainable. Exploration of length-based reference points also supported this view. There is no information on recruitment that will form the bulk of the catches in the following year.
For the Iberian Sardine, after a gap in survey inputs in 2012, new acoustic surveys in the spring 2013 (PELAGO+PELACUS) allowed an updated analytic assessment of the population. These surveys recorded the lowest historical biomass levels, but at rather similar values as their former estimates of 2011. As such, the assessment based on the Stock Synthesis pointed to a pronounced decline of biomass since 2006 due to the lack of any strong recruitment since 2005. Current biomass of about 192 000 t in 2013, would be around historical minimum, being in 2012 around 64% below the long-term average, while fishing mortality seems to be around the historical average, fluctuating without a clear trend. The stock is expected to decline unless a new strong year class appears. Catch options assuming another low recruitment as in recent years (2008–2012) were provided.
The WG was assessed by the first time the Sardine in Divisions VIIIa,b,d and Subarea VII, by analysing survey trends according to the benchmark carried out in February 2013 (WKPELA). Surveys, restricted to subarea VIII (acoustic –Pelgas- and eggs – Bioman- surveys), show no neat trend in biomass indexes since 2000, though marked fluctuations are recorded. The last big cycle peaked in 2009-2010. Following years were lower but in the middle of the range of biomass for the period 2000-201. Pelgas survey pointed to the highest recruitment in 2013 in subarea VIII. Catch curve analysis on survey and commercial fleets suggest fishing mortality slightly lower than natural mortality, i.e. seemingly sustainable. There is little information from subarea VII: no survey index is available and catches are not monitored for biological sampling, so little can be done in terms of assessing the population and the fishery in this subarea, except assuming trends would be similar to subarea VIII. There is no international TAC for these fisheries. Catch are mainly taken by France and Spain in VIIIa,b,d and by France, Netherlands and United Kingdom in VII.
For the southern Horse mackerel (Division IXa ) a new analytical assessment was carried out following the stock annex, with catches up to 2012 and surveys up to 2011 (as the 2012 survey could not take place). The fishery is shared between Portugal and Spain. The estimated SSB shows some decrease since 2007 but with a wide confidence interval (being estimated around 30% below the long term average). The fishing mortality shows a significant decrease in last two years. Recruitment is estimated to be above average in 2011. No precautionary reference points have been defined for this stock. F35%SPR (0.11) is proposed as a proxy for FMSY. Historical fishing mortalities have on average (0.09) been at or below the candidate FMSY (though actual estimates are very uncertain). Catch options were provided under the assumption of historical geometric mean recruitment.
For the Jack mackerel (Trachurus picturatus) in the waters of the Azores, though the 2012 advice is biennial and valid for 2013 and 2014, the WG continue the collation of data along with some exploratory analysis of that information. The analysis is based on commercial abundance indices from the main fleets, used as an indicator of stock trends. It was noted that catches in 2012 reduced compared to previous years: According to the length and age composition of catches from the purse seine fishery, which target juveniles, this was probably due to a failure of recruits at age 1 in 2012. Although the tuna baitboats do not show a sharp de-crease in cpue as the purse seine fleet for 2012, this could be explained since the bait boats also catch bait offshore when jack mackerel is not available in the coast. As occasional fluctuations of 1 or 2 years have also happened in the past this was not considered to suppose a major warning on the status of the stock or for the fishery.
In addition the WG was asked to report on the advance of the preparation of the benchmarking for Anchovy in Subarea IXa; the WG recommended to delay the benchmarking to 2015, basically due to limited man power and to allow for the new DEPM 2014 survey to be examined by WGACEGGs in Nov2014 and serve as a new input the Benchmark.
Finally the WG proposes in Annex 4 specific actions to be taken to improve the quality and transmission of the data (including improvements in data collection and potential inputs from RACs), as requested to the group.