the workshop on guidelines for management strategy ... ices advice oct 2015 js.… · 10/8/2015 1...

10/8/2015

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October Pelagic AdvicePelagic AC

7 October 2015

John SimmondsICES 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 Stock Assessment Blue whiting Recent changes to Stock Assessment

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 approach chosen may have resulted in a higher than 50% probability of overestimating the stock.

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Outlook – catch options 2015Blue whiting

RationaleCatch

(2016)Basis

F

2016SSB (2017)

% SSB

change *

% Catch

change

**

MSY framework 776.391 FMSY = 0.30 0.30 3827.988 6 −40

Zero catch 0 F = 0 0 4569.654 26 −100

F = 0.18 489.605 0.18 4100.934 13 −62

F = 0.20 539.449 0.20 4053.403 12 −59

F = 0.22 588.451 0.22 4006.712 11 −55

F = 0.25 660.414 0.25 3938.210 9 −49

Fpa 0.32 821.443 Fpa 0.32 3785.232 5 −37

Status quo catch1300.00

0

Catch 2016 = Catch

20150.56 3334.140 −8 0

Blue whiting (Summary)

Advice for 2016:

ICES advises that when the MSY approach is applied, catches in 2016 should be no more than 776 391 tonnes.

Status

Fishing mortality (F) has increased from a historical low in 2011 to above FMSY in 2014. Spawning-stock biomass (SSB) increased from 2010 to 2014 and is above MSY Btrigger. 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.

Fishing pressure Stock size

2012 2013 2014 2013 2014 2015

Maximum sustainable yield

FMSY Above MSY

Btrigger Above trigger

Precautionary approach

Fpa, Flim Increased risk Bpa, Blim

Full reproductive

capacity

Management plan FMGT - - - Not applicable SSBMGT - - - Not applicable

Norwegian spring spawning herringNSS herring Stock Assessment

NSS herring Recent changes to Stock Assessment

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 2008 --- included. The 2015 Norwegian shelf larvae survey index on the was not included due to poor spatial coverage.

Outlook – catch options 2015NSS herring

RationaleCatches

(2016)Basis Fw(2016)*

SSB(2017

)

% SSB

change

% Catch

change

Agreed

management plan316876 FMP 0.083 3566000 −1 −3

MSY approach 406787

FMSY ×

(SSB2016/MSY

Btrigger = 0.717)

0.108 3489000 −3 24

Zero catch^ 0 F = 0 0 3836000 7 −100

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NSS herring (Summary)

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 316 876 tonnes.

Status

The stock is declining and estimated to be below Bpa in 2014. Year classes 2005–2012 are estimated to be small last large year class 2004.. The 2013 year class is still uncertain -- estimated to be larger than the 2005–2012 year classes close to average (1988–2012. Fishing mortality in 2014 was below Fpa and FMSY and the management plan target F.

Fishing pressure Stock s ize

2012 2013 2014 2013 2014 2015

Maximum sustainable yield FMSY Appropriate

MSY

Btrigger Below Btrigger

Precautionary approach Fpa

Harvested sustainably

Bpa, Blim Increased risk

Management plan FMGT Appropriate SSBMGT Below trigger

North Sea horse mackerel

North Sea horse mackerel Stock Assessment

0

5

10

15

20

25

30

1990 1995 2000 2005 2010 2015

Valu

e re

lati

ve to

200

6-20

14 m

ean

Standardised DLN index: HOM 20+ cm

3 per. Mov. Avg.

(IBTS)

3 per. Mov. Avg. (CGFS)

0

2

4

6

8

10

12

1990 1995 2000 2005 2010 2015

Valu

e re

lati

ve to

200

6-20

14 m

ean

Standardised DLN index: HOM 0-19 cm

3 per. Mov. Avg. (IBTS)

3 per. Mov. Avg. (CGFS)

Juvenile indices – 3 year averages Adult indices – 3 year averages

Indices not used directly to calculate the advice

North Sea horse mackerel (Summary)

Advice for 2016:

ICES advises that when the precautionary approach is applied, catches in 2016 should be no more than 15 200 tonnes.

(Cat 5 advice based on previous catches and previous reductions)

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 (2011—2013), dropping to 13.4 kt in 2014.


2012 2013 2014 2013 2014 2015

Qualitative evaluation - Unknown - Stable and low

WG II North East Atlantic mackerel

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NEA mackerel Stock Assessment NEA mackerel Recent changes to Stock Assessment

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.

Outlook – catch options 2015NEA mackerel

RationaleCatch

(2016)

F (2016

& 2017)Basis SSB (2016) SSB (2017) SSB change

Catch

change

MSY

Approach667385 0.22 FMSY 3131490 3038633 −3% −46%

Precaution

ary

approach

748576 0.25 Fpa 3116371 2963423 −5% −39%

Zero catch 0 0 F = 0 3245272 3676929 13% −100%

Other

options

469238 0.15 3167133 3224473 2% −62%

527128 0.17 3156896 3169848 0% −57%

612036 0.20 3141621 3090221 −2% −51%

639834 0.21 3136550 3064280 −2% −48%

694691 0.23 3126440 3013277 −4% −44%

721754 0.24 3121400 2988209 −4% −42%

775160 0.26 3111353 2938918 −6% −37%

801509 0.27 3106344 2914690 −6% −35%

827624 0.28 3101346 2890735 −7% −33%

1235608 0.45 catch 2015 3018461 2325691 −23% 0%

NEA mackerel (Summary)

Advice 2016:

ICES advises that when the MSY approach is applied, catches in 2016 should be no more than 667 385 tonnes.ICES further advises that the existing measures to protect the North Sea spawning component should remain in place.

StatusThe Spawning Stock Biomass (SSB) increased since the early 2000s and has been above MSY-Btrigger since 2009. The Fishing Mortality (F) has been declining since the mid-2000s, but remains above Fpa (or Fmsy). 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 2003.


2012 2013 2014 2013 2014 2015

Maximum sustainable yield

FMSY Above MSY

Btrigger Above trigger


Fpa, Flim Increased risk Bpa, Blim

Ful l reproductive

capacity


Western horse mackerelWestern horse mackerel Stock Assessment

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Western horse mackerel Changes in Stock Assessment

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.

Outlook – catch options 2014Western horse mackerel

RationaleCatch

(2016)Basis

F

(2016)

SSB

(2016)

SSB

(2017)

%SSB

change

% TAC

change

MSY

approach 126103

FMSY 0.13 626488 562151 −10 27

Zero catch 0 F = 0 671401 696624 4 −100

Other

options

7944320% TAC

reduction0.08 643386 610367 −5 −20

8440815% TAC

reduction0.08 641676 605358 −6 −15

121571 F2014 0.12 628157 566789 −10 22

99304Advised

TAC(2015)0.1 636148 589371 −7 0

11420015% TAC

increase0.12 630879 574412 −9 15

11916520% TAC

increase0.12 628994 569123 −10 20

ICES MSY advice rule is based on SSB back calculated to Jan 1st .

Western horse mackerel (Summary)

Advice for 2016:


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 2009. In recent years, SSB has been declining and is currently just above MSY Btrigger. Fishing mortality has been increasing since 2007, but remains just below FMSY. Recruitment has been low from 2002 onwards. . Fishing pressure Stock s ize

2012 2013 2014 2013 2014 2015

Maximum sustainable yield FMSY Below

MSY

Btrigger Above


Fpa, Flim Undefined Bpa, Blim Undefined


Southern horse mackerel

Southern horse mackerel Stock Assessment Recent changes to Stock Assessment Southern horse mackerel

Confidence intervals for SSB and recruitment estimates are very wide, indicating high uncertainty in these parameters. F is also uncertain but F is below FMSY. 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.

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Outlook – catch options 2016Southern horse mackerel

Rationale

Catches T.

trachurus

(2016)

BasisF

(2016)

SSB

(2016)*

SSB

(2017)

%SSB

change**

% Catch

change*

**

MSY

approach68583

FMSY 0.11 543572 512309 -6%+136%

Zero catch 0 F2015 = 0 0 548455 579697 +6% -100%

Other

options

27290 F2015 0.044 546572 552747 +1% -7%^

32609 F2015 × 1.2 0.052 546196 547515 0% +12%

43111 F2015 × 1.6 0.070 545445 537206 -2% +48%^

53434 F2015 × 2.0 0.087 544695 527099 -3% +84%

Issue relevant for the adviceThe 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 2011 12% of the catch consisted of the other species.

Currently, fishing mortality is well below FMSY. 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 FMSY

immediately, spreading the yield from the two recent large year classes over a longer period than would be the case when fishing at FMSY, 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 FMSY exploitation, any anticipated discarding should be accounted for in setting the TAC.

Southern horse mackerel (Summary)

Advice for 2016


Stock Status

Fishing mortality (F) has been below FMSY 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 2012. Recruitment (R) in 2013 is estimated to be close to the average of the entire time-series.


2012 2013 2014 2013 2014 2015

Maximum Sustainable Yield FMSY Appropriate

MSY

Btrigger Undefined


Fpa, Flim

Below possible

reference

points

Bpa, Blim Undefined

Management Plan FMGT - - - Not applicable SSBMGT - - - Not applicable

boarfish

Boarfish Stock Assessment Catches

Boarfish Changes from 2013

The basis of advice has changed over the last 5 years. In 2011, the advice was based on average catches in 2008–2010. In 2012, the advice was based on the 2012 acoustic biomass survey estimate and an FMSY proxy. In 2013 the advice was based on the results of a Schaefer surplus production model and followed the MSY approach.

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 approach, using the Schaefer model as an indicator of trends.

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Index A (2014, 2015) 0.623

Index B (2011, 2012, 2013) 1.564

Index ratio (A/B) 0.398

Uncertainty cap Applied 0.8

Recent advised catch for 2015 53296 t

Discard rate (2014) 0.04

Precautionary bufferNot

applied-

Catch advice* 42637 t

Landings corresponding to the

catch advice40932 t

Outlook – catch options 2016Boarfish

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)

Advice for 2016

ICES advises that when the precautionary approach is applied, catches in 2016 should be no more than 42 637 tonnes.

Stock statusThe 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 2010–2013 and is currently close to the 1991 level. Fishing mortality (F) has risen in the last three years.


2012 2013 2014 2013 2014 2015

Qualitative evaluation - Increasing - Stable

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 Fmsy 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 Btrigger, in light of the change from Fmsy as a single reference point to Fmsy 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 2017.

• 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 approach 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 Btrigger.

– 2. Where the SSB is forecast to be below Btrigger, but above Blim, 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 Btrigger.

– 3. Every effort shall be made to maintain a minimum level of SSB greater than Blim. Where the SSB at the start of the TAC year is estimated to be below Blim the TAC shall be set at a level corresponding to a fishing mortality rate consistent with the objective of rebuilding the SSB to above Blim 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 FMSY range for the Northeast Atlantic (NEA) mackerel is Flower = 0.15 and Fupper = 0.24. 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 (MSY). The range is dependent on implementing an MSY Btrigger = 3.0 Mt.

Stock MSY

Flower

FMSY MSY

Fupper

MSY

Btrigger

NEA mackerel 0.15 0.22 0.24 3.0 Mt

0.25 3.2 Mt

0.26 3.5 Mt

0.28 4.0 Mt

0.30 5.0 Mt

Other values of Fupper dependent on the choice of MSY Btrigger Table 9.2.3.3.1.

Higher F and MSY Btrigger values are associated with more variable year-to-year change in catch.Fupper values between 0.24 and 0.30, corresponding to Btrigger values between 3.0 and 5.0 Mt all result in a long-term realized F of 0.23–0.24..

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 change 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 FMSY are based on current biological status derived from the last benchmark. ICES will update these at the next benchmark in 2017. Currently the assessment is more uncertain as the last egg survey data point so ICES does not normally updating values between benchmarks.

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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 Btrigger = 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 changes were caused by an external driver with a continuous trend.

ICES acknowledges that simulations with inclusion of such a scenario would help in mapping the uncertainty related to changes in biological characteristics.

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 change 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

NEAFC questions on blue whiting

the workshop on guidelines for management strategy ... ices advice oct 2015 js.… · 10/8/2015 1...

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