Overview 10/8/2015. October Pelagic Advice Pelagic AC 7 October 2015

Transcription

1 October Pelagic Advice Pelagic AC 7 October 2015 John Simmonds ICES ACOM Vice Chair Overview WG 1 Blue whiting NSS herring North Sea horse makerel WG 2 Stocks Northeast Atlantic mackerel Western horse mackerel Southern horse mackerel Boarfish Management plans/ strategies NEA Mackerel Special request WG I Blue whiting Blue whiting Blue whiting Recent s to Changes:- A substantial downward revision of the historical SSB and recruitment and a small upward revision of F. Due mostly to low abundance indices from the 2015 acoustic survey for the adult part of this stock. Older age groups were less abundant than expected, based on last year s assessment. Survey was conducted as planned but weather conditions poorer than last 2 years, but the. Overall it was considered that the age structure of the 2015 catch was not in conflict with the survey data. The uncertainty of the assessment and forecast is considered higher than in previous years. The model gave unrealistic very high F and catch values for 2015 in order to fit the low 2015 survey (March April) abundance indices. Overall the chosen may have resulted in a higher than 50% probability of overestimating the stock. 1

2 Blue whiting Catch Basis Outlook catch options 2015 F 2016 SSB (2017) % SSB * % Catch ** framework F = Zero catch 0 F = F = F = F = F = F pa Fpa Status quo catch Catch 2016 = Catch Blue whiting (Summary) Status Fishing mortality (F) has increased from a historical low in 2011 to above F in Spawning-stock biomass (SSB) increased from 2010 to 2014 and is above B trigger. Recent recruitments are estimated above average, but with uncertainty. Additional survey information indicates recruitment above average in 2014 and 2015 and this is taken into account in the short-term forecast. Maximum sustainable yield F F pa, F lim Above Increased risk Advice for 2016: ICES advises that when the is applied, catches in 2016 should be no more than tonnes. B trigger B pa, B lim Above trigger Full reproductive capacity Management plan F MGT Not applicable SSB MGT Not applicable Norwegian spring spawning herring NSS herring NSS herring Recent s to NSS herring Outlook catch options 2015 Catches Basis F w * SSB(2017 ) % SSB % Catch Agreed management plan F MP F (SSB 2016 / B trigger = 0.717) Zero catch^ 0 F = Previous retrospective pattern that overestimates SSB and underestimates F. The revision this year is smaller than in previous years. The 2015 spawning grounds survey in February/March ---first since included. The 2015 Norwegian shelf larvae survey index on the was not included due to poor spatial coverage. 2

3 Value relative to mean Value relative to mean 10/8/2015 NSS herring (Summary) Status The stock is declining and estimated to be below B pa in Year classes are estimated to be small last large year class The 2013 year class is still uncertain -- estimated to be larger than the year classes close to average ( Fishing mortality in 2014 was below F pa and F and the management plan target F. Maximum sustainable yield F F pa Appropriate Harvested sustainably Btrigger B pa, B lim Below Btrigger Increased risk Management plan FMGT Appropriate SSBMGT Below trigger North Sea horse mackerel Advice 2016: ICES advises that when the EU, Faroe Islands, Iceland, Norway, and Russia management plan is applied, catches in 2016 should be no more than tonnes. North Sea horse mackerel Standardised DLN index: HOM 0-19 cm 12 Juvenile indices 3 year averages per. Mov. Avg. 6 (IBTS) 3 per. Mov. Avg. 4 (CGFS) Indices not used directly to calculate the advice Standardised DLN index: HOM 20+ cm 30 Adult indices 3 year averages per. Mov. Avg. 15 (IBTS) 3 per. Mov. Avg. (CGFS) North Sea horse mackerel (Summary) Status The available information, while broadly informative, is insufficient to evaluate 2014 biomass and exploitation status. Both the IBTS Q3 and the CGFS indices of 2+ horse mackerel indicate that the adult stock is relatively stable at a low level. Recruitment has been low with some indications of increases in the last few years. Catches in recent years have been declining slowly with an average around 23 kt ( ), dropping to 13.4 kt in Qualitative evaluation - Unknown - Stable and low Advice for 2016: ICES advises that when the precautionary is applied, catches in 2016 should be no more than tonnes. (Cat 5 advice based on previous catches and previous reductions) WG II North East Atlantic mackerel 3

4 NEA mackerel NEA mackerel Recent s to The assessment is unstable, which is a source of concern. One major source of concern is the short time series for the IESSNS survey. The assessment this year is more uncertain than last year, because it is now two years after the last triennial eggs survey data point. NEA mackerel Catch F (2016 & 2017) Outlook catch options 2015 Basis SSB SSB (2017) SSB Catch Approach F % 46% Precaution ary F pa % 39% Zero catch 0 0 F = % 100% Other % 62% options % 57% % 51% % 48% % 44% % 42% % 37% % 35% % 33% catch % 0% NEA mackerel (Summary) Status The Spawning Stock Biomass (SSB) increased since the early 2000s and has been above -B trigger since The Fishing Mortality (F) has been declining since the mid-2000s, but remains above F pa (or F msy ). The Recruitment (R) shows an increasing trend since the late 1990s with two large year classes (2002 and 2006). The 2011 year class is estimated to be well above average (third in magnitude since 1990), in contrast recruitment for 2013 appears to be the lowest since Maximum sustainable yield F Fpa, F lim Above Increased risk Advice 2016: ICES advises that when the is applied, catches in 2016 should be no more than tonnes. ICES further advises that the existing measures to protect the North Sea spawning component should remain in place. Btrigger Bpa, Blim Above trigger Full reproductive capacity Management plan F MGT Not applicable SSB MGT Not applicable Western horse mackerel Western horse mackerel 4

5 Western horse mackerel Changes in Western horse mackerel Outlook catch options 2014 Catch Basis F SSB SSB (2017) %SSB % TAC The assessment relies on the triennial egg survey. There is large uncertainty in the absolute estimates of SSB. The landings fraction sampled to estimate biological parameters has increased for 2013; As in previous years, and despite the data sampling regulations for EU countries, some countries with major catches have not conducted biological sampling programs. Work is ongoing with the development of a fisheries-independent abundance or recruitment index through combining a number of international bottom trawl surveys F Zero catch 0 F = Other options % TAC reduction % TAC reduction F Advised TAC(2015) % TAC increase % TAC increase ICES advice rule is based on SSB back calculated to Jan 1 st. Western horse mackerel (Summary) Stock status The stock and the fishery are very dependent on occasional high recruitments. The very high 1982 recruitment gave a peak in SSB in 1988, and the relatively high one in 2001 gave a moderate increase in SSB up to In recent years, SSB has been declining and is currently just above B trigger. Fishing mortality has been increasing since 2007, but remains just below F. Recruitment has been low from 2002 onwards.. Southern horse mackerel Maximum sustainable yield F Below Btrigger Above Fpa, Flim Undefined Bpa, Blim Undefined Management plan FMGT Not applicable SSBMGT Not applicable Advice for 2016: ICES advises that when the is applied, catches in 2016 should be no more than tonnes. Southern horse mackerel Southern horse mackerel Recent s to Confidence intervals for SSB and recruitment estimates are very wide, indicating high uncertainty in these parameters. F is also uncertain but F is below F. The strong recruitments in 2011 and 2012 first estimated last year were confirmed by this year assessment. The historic SSB has been relativity stable but has been consistently underestimated, seen again this year. In this year s data the weight-at-age in the catch in 2014 was observed to be unusually high relative to the time-series. The reason for this could not be determined and weight-at-age for that year was estimated as the arithmetic mean of the three previous years. 5

6 Southern horse mackerel Catches T. trachurus Basis F Outlook catch options 2016 SSB * SSB (2017) %SSB ** % Catch * ** F % % Zero catch 0 F 2015 = % -100% F % -7%^ Other F % +12% options F % +48%^ F % +84% Issue relevant for the advice The advice pertains to T. trachurus, while the TAC is set for all Part of the catches consist of other horse mackerel; the fraction varies, in % of the catch consisted of the other species. Currently, fishing mortality is well below F. The advice implies increasing current fishing mortality by a factor of 2.6. Sporadic events of exceptionally strong recruitment have been observed in this species, such as 1996 and 2011/2012 for this stock giving rapid periodic increases in SSB followed by long periods with lower recruitment. If managers wish to maximize catch stability following such recruitment events it may be preferable not to increase F to F immediately, spreading the yield from the two recent large year classes over a longer period than would be the case when fishing at F, given the long lifespan and the low natural mortality for this species. Discards are considered negligible. Under the EU landing obligation, a de minimus exemption for discarding horse mackerel has been granted for a part of the fishery. ICES information on current discarding suggests it is negligible. Discarding under the de minimus exemption should be monitored closely to ensure that catches of horse mackerel do not increase above the ICES advised catch. To achieve F exploitation, any anticipated discarding should be accounted for in setting the TAC. Southern horse mackerel (Summary) Stock Status Fishing mortality (F) has been below F over the whole time-series and the spawning stock biomass (SSB) has been relatively stable, showing a recent increase resulting from the strong recruitments in 2011 and Recruitment (R) in 2013 is estimated to be close to the average of the entire time-series. boarfish Maximum Sustainable Yield F Appropriate Btrigger Undefined F pa, Flim Below possible reference points Bpa, Blim Undefined Management Plan FMGT Not applicable SSBMGT Not applicable Advice for 2016 ICES advises that when the is applied, catches in 2016 should be no more than tonnes. Boarfish Catches Boarfish Changes from 2013 The basis of advice has d over the last 5 years. In 2011, the advice was based on average catches in In 2012, the advice was based on the 2012 acoustic biomass survey estimate and an F proxy. In 2013 the advice was based on the results of a Schaefer surplus production model and followed the. The Model is not considered suitable for category 1 advice, because uncertainty is not handled consistently with a rapid increase in the last two years as the model follows the acoustic survey too closely. While the Schaefer surplus production model provides indications of trends, these are not considered reliable enough to form the basis for assessment. Therefore the 2014/2015 ICES advice is based on the data-limited, using the Schaefer model as an indicator of trends. 6

7 Boarfish Outlook catch options 2016 Index A (2014, 2015) Index B (2011, 2012, 2013) Index ratio (A/B) Uncertainty cap Applied 0.8 Recent advised catch for t Discard rate (2014) 0.04 buffer Not applied - Catch advice* t Landings corresponding to the catch advice t A management strategy has been proposed by the Pelagic AC. ICES is providing advice for this stock following the standard procedures which conforms to the proposed strategy from the Pelagic AC. Boarfish (Summary) Stock status The stock status relative to reference points is currently unknown. Survey indices and an exploratory assessment indicate that the stock has declined sharply since the peak in and is currently close to the 1991 level. Fishing mortality (F) has risen in the last three years. Qualitative evaluation Advice for Increasing - Stable ICES advises that when the precautionary is applied, catches in 2016 should be no more than tonnes. Coastal States special request NEA mackerel The Coastal States are preparing a new long-term management strategy for the stock of mackerel in the North East Atlantic. This strategy would include target fishing mortalities expressed as a range rather than a single reference point. ICES is requested to provide a plausible range of values around F msy for the mackerel stock in the North East Atlantic, based on the stock biology (including possible density-dependent growth), fishery characteristics and environmental conditions. ICES is also requested to update other reference points, including B trigger, in light of the from F msy as a single reference point to F msy as a range. Given the uncertainty in stock level, growth patterns and recruitment, and taking into account the growing time series on tagging information (RFID), ICES is requested to perform the next (intermediate) benchmark in The Coastal States would also like to inform ICES that they no longer consider that the existing management plan is appropriate, and that ICES should therefore give its advice based on the following objectives and timelines until a new management strategy is in place: 1.The Parties agree to limit their fishing on the basis of a TAC corresponding to a fishing mortality rate within the range of fishing mortalities defined by ICES as being consistent with fishing at maximum sustainable yield, provided that the SSB at the end of the TAC year is forecast to be above the value of B trigger. 2. Where the SSB is forecast to be below B trigger, but above B lim, the Parties agree to reduce the upper and lower bounds of the range of fishing mortality referred to in paragraph 1 by the proportion of SSB at the start of the TAC year to B trigger. 3. Every effort shall be made to maintain a minimum level of SSB greater than B lim. Where the SSB at the start of the TAC year is estimated to be below B lim the TAC shall be set at a level corresponding to a fishing mortality rate consistent with the objective of rebuilding the SSB to above B lim the following year. The Parties may also take additional management measures that are deemed necessary in order to achieve this objective. ICES advises that the precautionary F range for the Northeast Atlantic (NEA) mackerel is F lower = 0.15 and F upper = The range reflects the target F values that are expected to result in high long-term yield deviating at maximum -5% from the maximum sustainable yield (). The range is dependent on implementing an B trigger = 3.0 Mt. Other values of F upper dependent on the choice of B trigger Table F Stock F lower F upper B trigger NEA mackerel Mt Mt Mt Mt Mt Higher F and B trigger values are associated with more variable year-to-year in catch. F upper values between 0.24 and 0.30, corresponding to B trigger values between 3.0 and 5.0 Mt all result in a long-term realized F of The Northeast Atlantic (NEA) mackerel stock is currently characterized by: low weight-at-age, late maturity, and early spawning compared to the historical mean. There is no firm scientific basis yet to indicate whether this situation should be considered permanent or transient (either returning to the previous state or continuing to in the same direction). However, recent scientific publications have indicated that the growth of mackerel could be dependent on a number of factors, including the size of the mackerel stock and the size of the Norwegian spring-spawning herring stock (Jansen and Burns, 2015; Olafsdottir et al., 2015). In accordance with standard practice ICES uses current weights, maturities etc. for advice. Current values of F are based on current biological status derived from the last benchmark. ICES will update these at the next benchmark in Currently the assessment is more uncertain as the last egg survey data point so ICES does not normally updating values between benchmarks. 7

8 Reflecting the uncertainty in the temporal dynamics of the biological characteristics of the NEA mackerel stock, ICES has also evaluated a scenario where the biological characteristics gradually return to the historical mean (ICES, 2015c). It is worth noting that even though the parameterization of this scenario does not assume any relationship between stock size and growth, the consequences in the short term are similar to those resulting from density-dependent growth, i.e. a decrease in stock size and an increase in growth rate. This scenario allows for a higher level of fishing mortality, leading to short-term differences in terms of higher yield; however, the difference in long-term yield is expected to be small (+3% with B trigger = 3.0 Mt). To cover a more complete range of potential biological scenarios, an alternative one with a continuing trend in the biological characteristics should also be investigated. This alternative scenario could be envisioned if the s were caused by an external driver with a continuous trend. Management in a scenario that explicitly assigns the return to faster growth only to the stock size is based on a more demanding assumption than present management. Preliminary simulations indicate that with density-dependent growth taken into account in a management rule, fishing mortality could be slightly (about 10%) higher (ICES, 2015c). (ie, a from 0.22 to 0.24) This scale of difference is within the F Ranges advised by ICES F lower = 0.15 to Fupper =0.24 This compares with F 2013 = 0.30 F 2014 = 0.34 and projected F in 2015 = 0.37 and Flim = 0.36 ICES acknowledges that simulations with inclusion of such a scenario would help in mapping the uncertainty related to s in biological characteristics. NEAFC questions on blue whiting 8