Stock Assessment Form

Sardine in GSAs 01 and 03

Reference Year: 2016

Reporting Year: 2017

-

Data from landings and surveys of sardine from the GSA01 and GSA03 have been pooled to

assess a stock of this species in the Alboran sea. This assessment was done in the framework

of the CopeMed Working Group on small pelagic species. The meeting held on the 9-11

October in Malaga was attended by experts from Morocco, Spain and Algeria. Data from 2006

in GSA01 and GSA03 have been pooled for running XSA. The stock of sardine is probably in

overexploitation in GSA03 and GSA01 combined.

Stock Assessment Form version 1.0 (November

2014) Sardine GSA01 and 03

Stock assessment form

Sommario 1 Basic Identification Data ............................................................................................................. 3

2 Stock identification and biological information ......................................................................... 4

2.1 Stock unit ......................................................................................................................... 4

2.2 Growth and maturity ....................................................................................................... 5

3 Fisheries information ............................................................................................................... 7

3.1 Description of the fleet ................................................................................................... 7

3.2 Historical trends ............................................................................................................. 11

Spain ..................................................................................................................................... 11

3.3 Management regulations .............................................................................................. 14

4 Fisheries independent information .......................................................................................... 15

4.1 Acoustic survey .............................................................................................................. 15

4.1.1 Brief description of the method .......................................................................................... 15

4.1.2 Spatial distribution of the resources ................................................................................. 17

5 Stock Assessment ..................................................................................................................... 18

5.1 {Extended Survivor analysis (XSA) using surveys as tuning data} .................................. 18

5.1.1 Model assumptions ............................................................................................................. 18

5.1.2 Scripts .................................................................................................................................. 18

5.1.3 Input data and Parameters ................................................................................................. 19

5.1.4 Tuning data .......................................................................................................................... 19

5.1.5 Results ................................................................................................................................. 19

5.1.6 Robustness analysis ............................................................................................................. 20

5.1.7 Retrospective analysis, comparison between model runs, sensitivity ............................... 20

5.1.8 Reference points ................................................................................................................. 23

6 Draft scientific advice ................................................................................................................ 25

6.1 Explanation of codes ....................................................................................................... 26

1 Basic Identification Data

Scientific name: Common name: ISCAAP Group:

Sardina pilchardus sardine 35

1st Geographical sub-area: 2nd Geographical sub-area: 3rd Geographical sub-area:

1 3

1st Country 2nd Country 3rd Country

Spain Morocco

Stock assessment method: (direct, indirect, combined, none)

Indirect: Extended Survivor analysis (XSA) model in FLR, BioDyn and VIT

Authors:

M.H. Idrissi1, A. Giráldez2, S. EL Arraf3, S. Ben smail4 , P. Torres2, M. Serghini5, P. Hernández6 and

M. Vasconcellos6

Affiliation: 1INRH. Institut National de Recherche Halieutique, Nador, Morocco 2IEO. Instituto Español de Oceanografía at Fuengirola, Spain 3INRH. Institut National de Recherche Halieutique, Tanger, Morocco 4CNRDPA. Centre National de Recherche et de Développement de la Pêche et de l’Aquaculture,

Algeria 5INRH. Institut National de Recherche Halieutique, Casablanca, Morocco 6FAO FIAF-CopeMed II Project

2 Stock identification and biological information

2.1 Stock unit

Within the framework of Copemed II five joint assessments for sardine between Spain

and Morocco have been carried out: (in 2012, 2015 ,2016 and 2017, the current one).

All of them have been submitted to the GFCM WGs and were validated for the last

two years. However, the contradictory results between the status in GSA 01 and in

GSA 03 and in the joint (GSAs 01 and 03) potentially reflect regional differences thus

stressing that the issue of stock boundaries is problematic in the Alboran Sea. The SAC

WGs in 2015 and 2016 recommended an in-depth analysis on stock boundaries and to

continue investigating the pertinence of joining GSAs 1 and 3 for the assessment of

sardine.

Following these recommendations, the Project CopeMed II, organized a “Technical

workshop for the identification of stock units in the Alborán Sea” from 3-6 April 2017

in Alicante, Spain. Experts from Algeria, Italy, Morocco Spain and Tunisia presented

and discussed current methodologies for the delimitation of stocks and agreed on a

medium-term research program to identify stocks distribution of sardine, hake and

blackspot seabream in the Alborán sea (GSAs 1, 2, 3,4 and adjacent waters). The

Program will have a minimum duration of two years and will follow a multidisciplinary

approach i.e.: hydrodynamics modelling, genetics techniques, parasites, life history

traits, elemental composition, morphometry and fishery patterns. Sampling of

individuals will be designed from the beginning of the study with this purpose, taking

advantage of the current surveys in place. This proposal has been approved by the 10th

meeting of the Coordination Committee last 31st October. The outcomes will be shared

with the GFCM WGs and the SAC in the coming years.

The present document reports joint assessments of sardine in GSA 01, and GSA 03. A

preliminary assessment was also tried by adding data from the Alboran part of GSA

04, which is represented by the ports of Ghazauet and Beni Saf. The results of this

preliminary assessment are presented in a different Stock Assessment Form.

2.2 Growth and maturity

Table 2.2-1: Maximum size, size at first maturity and size at

recruitment.

Spanish data

Somatic magnitude measured

(LT, LC, etc) LT Units cm

Sex Fem Mal Combined Reproduction

season Autumn-Winter

Maximum

size

observed

22.6 (2016)

25 (2004-2015)

Recruitment

season

Spring-summer

Size at first

maturity

12.24 (2016)

12.95 (2003-

2015)

Spawning

area

All the coast

Recruitment

size to the

fishery

11.5 (2015)

Nursery area

Bays

Moroccan data

Somatic magnitude measured (LT, LC, etc)

LT Units cm

Sex Fem Mal Combined Reproduction

season Autumn-Winter

Maximum

size

observed

20.4 (2016)

Recruitment

season

Spring-summer

Size at first

maturity 12.11 (2016) Spawning

area All the coast

Algerian data

Somatic magnitude measured

(LT, LC, etc) LT Units cm

Sex Fem Mal Combined Reproduction

season Winter

Maximum

size

observed

21.8

19.5

21.8

Recruitment

season

Spring-summer

Size at first

maturity 12.4 (2016) Spawning

area Bays and gulfs

Table 2-2.2: M vector and proportion of matures by size or age. Calculated with Gislasson method for the

two GSAs (0 and 03) in 2014

Size/Age Natural mortality Proportion of matures

Age 0 1.79 0.42

Age 1 1.01 0.80

Age 2 0.79 0.99

Age 3 0.70 1

Age 4 0.65 1

Age 5+ 0.62 1

Spanish

data

Sex

Units female male Combined Years

Growth model

L∞ cm 22.3 2014

K Year-1 0.47 2014

t0 year -1.48 2014

Data source IEO 2014

Length weight

relationship a 0.0030 2014

b 3.3260 2014

Moroccan

data

Sex

Units female male Combined Years

Growth model

L∞ cm 21.12 2016

K Year-1 0.49 2016

t0 year -0.64 2016

Data source INRH 2016

Length weight

relationship a 0.0084 2016

b 2.9720 2016

M (scalar)

sex ratio (% females/total)

55%

3 Fisheries information

3.1 Description of the fleet

Spain

The current fleet in GSA 01 the Northern Alboran Sea is composed by 87 units,

characterised by small vessels, average TJB 24.7. 16% of them are smaller than 12 m

(operational Unit 1), 84% > 12 m (operational Unit 2), and no one bigger than 24m.

The purse seine fleet has been continuously decreasing in the last two decades, from

more than 230 vessels in 1980 to 87 in 2016. A strong reduction of larger vessels

occurred from 1985 onwards, possibly linked to a decreasing in anchovy catches in

Northern Morocco, where a part of that fleet fished under agreement between the

countries. Subsequently the fleet continued to decline but more slowly.

Although sardine has a lower price than anchovy is an important support to the

fishery as it is the most fished species. Catches in the period 1990-2015 has been

highly variable, with a minimum of 3000 tons in 1997. Higher catches occurred in

1992 (11000 tons). All period average is about 6000 tons.

The two operational units fish the same species, there are no major differences,

sardine is the most fished species by both of them. Although there is a slight difference

in the percentage of mackerel catches, as bigger ships are able to fish species with

more swimming ability.

Species with a lower economic value are also captured, sometimes representing a high

percentage of landings: horse mackerel (Trachurus spp.), mackerel (Scomber spp.),

and gilt sardine (Sardinella aurita). The interest about some of these species has been

increasing because there is a new market for them; gilt sardine and mackerel,

especially the first, are sold for tuna farming. A requirement for such sales is a high

yield by fishing day, due to its low economic value. In the case of mackerel it is

exported to Portugal.

Data used in the assessment correspond to EU-Data Collection Framework. Unit of

effort has been effective fishing night by species. Series of CPUE shows a very similar

profile to catches.

Morocco

The moroccan purse seiner fletes targeting sardine last year in GSA 03 (Moroccan

Mediterranean sea was composed by 110 vessels, characterized by small vessels,

average TJB is 50 tx and 252 horse power. 7% of them are smaller than 12 m

(operational Unit 1), 86% of them are between 12 m and 24 m (operational Unit 2),

and 7% are bigger than 24m (operational Unit 3).

This fleet is based mainly in 4 important ports M'diq, Nador, Al Hoceima and Ras

Kebdana with high mobility of seiners between ports following the abundance of

resources. In addition there are around one hundred of small scale boats fishing in

coastal areas that are not considered in this study due to the lack of reliable statistics

from this segment.

Landings of small pelagic in the Mediterranean are composed by sardine, sardinella,

anchovy, horse mackerel, chub mackerel and others. Sardine and anchovy are the

target species of seiners: sardine for its abundance and anchovy for its high

commercial value.

On the last decade, the total production of sardines in the Mediterranean Moroccan

sea, fluctuates between 7000 and 15300 tons/year. Between the years 2007 and 2016,

the annual average production of sardines is about 11312 tons. Fig 3.2.1

Landings of sardine showed an increase from 2008 to a maximum in 2009. Since then

landings have decreased, reaching the lowest value in 2011. From that year onwards.

it showed an increasing trend setting an highest in 2014 (catches represented 13286

tons), when landings started to decrease again.

The analysis of the evolution of fishing effort (expressed in effective fishing days)

exerted on the sardine stock between 2007 and 2016 shows that fishing effort has the

same trend of catches.

CPUE has a maximum peak in 2007 (2273 kg/day), with a little recovery between 2012

and 2013 but after that CPUE is decreasing. The general evolution signals a decreasing

trend. Fig 3.2.2

Table 3-1: Description of operational units exploiting the stock

Country

GSA

Fleet Segment

Fishing Gear

Class Group of Target

Species

Species

Operational Unit

1*

Spain

1

G-Purse Seine

(6-12 m)

02-Seine

Nets

31- Small gregarious

pelagic

PIL

Operational Unit 2

Spain

1

H-Purse Seine

(>12)

02-Seine

Nets

31- Small gregarious

pelagic

PIL

Operational Unit 1

Morocco

3

G-Purse Seine

(6-12 m)

02-Seine

Nets 31- Small gregarious

pelagic

PIL

Operational Unit 2

Morocco

3

H-Purse Seine

(12-24 m)

02-Seine

Nets 31- Small gregarious

pelagic

PIL

Table 3.1-2: Catch, bycatch, discards and effort by operational unit in the reference year

Operational Units*

Fleet

(n° of

boats)*

Catch (T or

kg of the

species

assessed)

Tons

Other species

caught (names and

weight )

Tons

Discards

(species

assessed)

Discards

(other

species

caught)

Effort

(units)

ESP 01 G 02 31-PIL

14

342

Anchovy: 70 Trachurus spp: 300 Scomber spp: 133

Sardinella: 93

Otros: 161

negligible

negligible

Effective

fishing

day for

species

ESP 01 H 02 31-PIL

73

3829

Anchovy: 1108 Trachurus spp:

1376 Scomber spp: 815

Sardinella: 895

Otros: 988

negligible

negligible

Effective

fishing

day for

species

Total 87 4171 5939

Operational Units*

Fleet

(n° of

boats)*

Catch (T or

kg of the

species

assessed)

Tons

Other species

caught (names and

weight )

Tons

Discards

(species

assessed)

Discards

(other

species

caught)

Effort

(units)

MAR 03 G 02 31- PIL

6

221

Anchovy: 1 Trachurus spp: 113

Scomber spp: 34 Sardinella: 51

Autres: 16

negligible

negligible

Effective

fishing

day for

species

MAR 03 H 02 31- PIL

100

9927

Anchovy: 113 Trachurus spp:

1139 Scomber spp: 1533

Sardinella: 106

Autres : 1

negligible

negligible

Effective

fishing

day for

species

MAR 03 I 02 31-PIL

4

755

Anchovy: 4 Trachurus spp: 69 Scomber spp: 104

Sardinella: 38 Autres

: 0

negligible

negligible

Effective

fishing

day for

species

Total 110 10903 3913

Table 3.1-3: Evolution of Catches 2003-2016.

Spain (sardine seiners)

YEAR

Catch (tons)

CPUE Kg/fishing day

2003 8087 1189 2004 3957 792 2005 7516 1272 2006 9971 1478 2007 6139 1116 2008 4468 1069 2009 5972 1313 2010 7328 1270

2011 6293 1139 2012 6214 1112 2013 4983 956 2014 5174 932 2015 5248 977 2016 4171 911

Average 6109 1067

Morocco (total catch)

YEAR

CATCH (tons)

CPUE (Kg/fishing day)

2006 15293 1953

2007 13824 2273

2008 7937 1587

2009 14982 1487

2010 12179 1238

2011 6981 1014

2012 9247 1321

2013 14158 1334

2014 14395 1164

2015 11824 1105

2016 7593 895

Average 11674 1397

3.2 Historical trends

Spain

Fig.

3.2-

1:

Trend in sardine landing and CPUEs, years 1990-2016.

(Spain)

Morocco

Fig. 3.2-2: Trend in sardine landing and effort (2007-2016 Morocco)

EFFORT total catch sardine Catch seiners

2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 0 0

2000

4000 2000

4000 6000

6000 8000

8000

12000 10000

10000 14000

12000 16000

Fig. 3.2-3: Trend in seiners effort on sardine CPUE, years 2007-2016 (Morocco)

Fig. 3.2-4: Trend in total catch sardine and CPUE, years 2007-2016. (Morocco)

CPUE EFFORT

2007 2008 2009 2010 2011 2012 2013 2014 2015

2016

0 0

500

4000 2000

1000

6000

1500 8000

2000 10000

2500 12000

Fig. 3.2-5: Landings of sardine in GSA 01 and 03

Figure 3.2-6 : Trend in sardine CPUEs in GSA 01 and 03

Figure 3.2-7: Landings and biomass indices of sardine obtained from acoustic surveys in GSA 01 and 03

Fig. 3.2.8. Trend in sardine landing in GSA01_03 and 04, years 2005-2016

3.3 Management regulations

Regulations in Spanish Mediterranean Sea

Regulated by Fishery European regulations REGULATION (EC) Nº 1967/2006 of

December 21, 2006, with a more restrictive Spanish regulations.

Features gear: Minimum aperture of 14 mm mesh, The height of the purse seine shall

not exceed 82 m and the use of purse seines is not allowed at a depth less than 70

percent of the net length, Length net will not exceed more than 300 m except for

Alboran Sea which may be up to 450 m. Characteristics of vessels: No less than 9 m

long, maximum power 450 hp, only one auxiliary boat and there is a Regulating for its

power lights. Fishing areas: prohibited fishing less than 35 m deep, although at a

distance of 300 m offshore it is permitted at a lower depth than 50m. There are

forbidden fishing areas to keep safe anchovy recruitment. Fishing effort: No fishing on

weekend restricted fishing areas and seasonal closures in some regions. Minimum

sizes: Minimum legal landing size 11 cm. List of species authorized to be fished by the

gear. Margin of 2% of others species.

Regulations in Moroccan Mediterranean Sea

Features gear: Minimum mesh size of 11 mm. Characteristics of vessels: No less than

3 tjb; only one auxiliary boat. Fishing areas: prohibited fishing less than 0.5 nautical

mile (1 nM in some regions). There are forbidden areas to safe sardine recruitment.

Fishing effort: No fishing on Friday, restricted fishing areas and seasonal closures in

some regions. Minimum sizes: 45 individuals/kg for sardine. List of species authorized

to be fished by the gear. Margin of 3% of others species except Boops boops 10%.

4 Fisheries independent information

4.1 Acoustic survey

Direct methods: acoustics

4.1.1 Brief description of the method

Table 4.1-1: Acoustic cruise information.

Date 1. MEDIAS: June-July; ECOMED: November-December (SPAIN)

2. ACOUMED : 2 surveys/year (April-may; September) (MOROCCO)

3. ALPEL: February -March (ALGERIA)

Cruise 1. MEDIAS (Spain)

2. ACOUMED (Morocco)

3. Algerian Coast (from

Algerian-Moroccan border

to the Algerian-Tunisian

border)

R/V 1. Miguel Oliver

2. Charif al idrissi

3. Belkacem GRINE

Target species 1. Anchovy and sardine

2. Small pelagics

3. Sardina pilchardus, Sardinella aurita, Engraulis

encrasicolus, Trachurus trachurus, Trachurus

mediterraneus, Trachurus picturatus, Boops

Boops, Scomber scombrus

Sampling strategy 1. 66 tracks normal to the coast. Inter-transect

distance: 4 or 8 nautical miles

2. Inter-transect distance: 5 nautical miles

3. Inter-transect distance: 8 nautical miles

Sampling season 1. MEDIAS: June-July; ECOMED: November- December (Spain)

2. ACOUMED: (April-may; September) (Morocco) 3. ALPEL: Winter (Algeria)

Investigated depth range (m) 1. 30-200 m depth (Spain)

2. 20-400 m depth (Morocco)

3. 20.200 m depth (Algeria)

Echo-sounder 1. Scientific Echo-sounder EK60 equipped with 5

frequencies (18, 38, 70, 120 & 200 kHz)

2. Echo-sounder EK60 (38- 120-200 kHz)- scrutinizing

by BI500

3. Echo-sounder EK60 equipped with 3 frequencies

(38- 120-200 kHz)

Fish sampler 1. Pelagic trawls with 10, 16 & 18 m vertical opening

2. Japanese Pelagic trawl, with gear: type O.B (Al),

1.44 m² (216.4 kg).

3. Pelagic trawls with 18m vertical opening (Algeria)

Cod –end mesh size as opening (mm) 20 mm

ESDU (i.e. 1 nautical mile) Elementary Distance Sampling Unit: 1 nautical mile

TS (Target Strength)/species 1. 72.6 dB for anchovy and sardine

2. 72 dB for sardine

3.

(Sardina pilchardus, Engraulis encrasicolus and

Sardinella aurita : -72.6) ; (Trachurus. Trachurus,

Trachurus. mediterraneus T. picturatus and

Scomber japonicus : -68.7) ; Boops boops: -67;

Scomber scombrus: -84.9) ALGERIA

Software used in the post-processing 1. SonarData Echoview, PESMA (Visual Basic)

2. BI500 and Echoview

3.

Echoview

Samples (gear used) 1. Pelagic trawl

2. Japanese Pelagic trawl

3.

Pelagic trawl

Biological data obtained 1.

Length-weight relationship, age, sex, maturity

2. Length-weight relationship, age, sex, maturity

3.

Length-weight relationship, age, sex, maturity,

otoliths

Age slicing method Otolith

Maturity ogive used 3. (ALPEL) Six stage WKSPMAT

4.1.2 Spatial distribution of the resources

Figure 4.1.1. Densities distribution of sardine Spain 2015

Figure 4.1.2. Densities distribution of sardine (saison automne 2015). Morocco.

5 Stock Assessment

5.1 {Extended Survivor analysis (XSA) using surveys as tuning data}

Ad hoc methods for tuning single species VPA's to fleet catch per unit effort (CPUE)

data are sensitive to observation errors in the final year because they make the

assumption that the data for that year are exact. In addition, the methods fail to utilize

all of the year class strength information contained within the catches taken from a

cohort by the tuning fleets.

Extended Survivors Analysis (XSA), (Shepherd, 1992,1999), an extension of Survivors

Analysis (Doubleday, 1981), is an alternative approach which overcomes these

deficiencies. In general, the algorithms used within the ad hoc tuning procedures,

exploit the relationship between fishing effort and fishing mortality.

XSA focuses on the relationship between catch per unit effort and population

abundance, allowing the use of a more complicated model for the relationship

between CPUE and year class strength at the youngest ages. (Darby and Flatman,

1994).

5.1.1 Model assumptions

Input Parameters

• Landings time series 2006-2016 (official landings, Spain & Morocco; GSAs 1&3).

• Catch-at-Length data converted to Catch-at-Age data using LFDA.

• Growth Parameters, average between IEO 2015 and INRH 2016 .

• M vector by age using Gislason spreadsheet, average between IEO 2015 and

INRH 2016.

• Tuning data Moroccan survey ACOUMED from 2006 to 2016.

Main Settings

• Ages 0 to 4+ for catches and ages 0 to 3+ for surveys

• Fbar has been set 1-3

5.1.2 Scripts

The script has been provided to the sharepoint.

5.1.3 Input data and Parameters

Catch numbers at length was transformed in age by LFDA software and summed for

the two regions GSA1 and GSA3.

Table 5.1. Catch numbers at age (in thousands) Age/years 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

0 21614 27967 3717 17492 18364 25080 83366 85925 61035 40313 41282 1 299474 85062 296662 274955 401599 200034 356911 238065 317071 407016 265135 2 374151 202503 65331 151564 182538 109577 147109 172585 248758 159526 132701 3 84865 149208 42524 101225 84512 61866 66162 84598 54106 66182 42325 4 13969 33612 18657 36630 23649 19151 19889 20583 18944 15519 8383 5+ 3156 10314 8052 17742 12016 9702 7942 10256 5282 4768 3871

5.1.4 Tuning data

As tuning data, we used the abundance index from acoustic survey for GSA03 from

2006 to 2015.

Table 5. 2. Abundances index from Morocco survey (in thousands). Age/years 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

0 144473 44688 115040 NA NA 146274 166634 NA 269957 1481000 1 573066 358933 927581 NA NA 169871 2370882 NA 3221092 977000 2 1736985 1117295 2322584 NA NA 816019 154403 NA 2918385 1176000 3 58160 18178 417935 NA NA 107199 18837 NA 1064 12000 4 0 0 0 NA NA 1183 616 NA 0 0 5+ 0 0 0 NA NA 0 0 NA 0 0

5.1.5 Results

Fig. 5.1.: Age structure of sardine in GSA01&03 in GSAs 01 and 03, the exploited stock is mostly

composed by ages 1 and 2.

Fig. 5.2: Consistency in catches (in the left) and in surveys (in the right)

5.1.6 Robustness analysis

5.1.7 Retrospective analysis, comparison between model runs, sensitivity

Fig.5.3: sensitivity on r-gae et q-age

We used the three best combinations of rage, qage

and shrink.ages r=1 q=3 shkages=2 r=0 q=3

shkages=1 r=-1 q=3 shkages=1

r=1 q=3

shkages=2

Fse0.5

Fse1.0

Fse2.0 Fse3.0

Fse2.5 Fse1.5

r=0 q=3

shkages=1

Sh0.5

Sh2.0 Sh3.0

Sh2.5 Sh1.5

Sh1.0

Fig. 5.4: Retrospective analysis on different stock parameters.

According to the retrospective analysis, two values of fse: 0.5 and 2.0 were

considered good and for which we will calculate the reference points.

5.1.8 Reference points

The reference points for the different combinations of parameters selected as good

are given in the table 5.3.

Table 5.3: Reference points resulting from different combination of parameters in XSA, in the last

column, the resul obtained in a previous assessment done in 2016.

Points de référence

Serie 2006-2016 assessment last

year 1;3;2;0.5 0;3;1;0.5 -1;3;1;0.5 1;3;2;2 0;3;1;2 -1;3;1;2 0;1;1;3

F0.1 0.64 0.608 0.608 0.759 0.69 0.64 0.79 FCUR 0.48 0.73 0.71 0.15 0.10 0.05 0.71 F/F0.1 0.76 1.21 1.17 0.2 0.14 0.07 0.9

E 0.48 0.58 0.57 0.21 0.15 0.08 0.52

r= - 1 q=3

shkages

=1

Sh0.5 Sh2.0

Sh1.5

Sh3.0

Sh2.5 Sh1.0

Figure 5.5. Trends of the four indicators as estimated by XSA for each set of parameters of table

5.3 The stock is mainly driven by catches in GSA3. Current model is unstable, so that

different parametrizations would give different perspectives of the stock (from low

exploitation to overexploitation). Under a precautionary approach, the exploitation

rate in the worse scenario is E=0.58.

The stock is assessed as possibly in overexploitation.

Management advice: Reduce fishing mortality.

1 ;3; 2;0.5 0 ;3; 1;0.5 - 1 ;3; 1;0.5

1 ;3;2; 2 0 ;3;1; 2 -

1 ;3;1; 2

6 Draft scientific advice

Based on Indicator Analytic al

reference

point

(name

and value)

Current

value from

the analysis

(name and

value)

Empirical

reference value

(name and

value)

Trend

(time

period)

Status

Fishing

mortality

GSAs 01&03

(XSA)

E=0.58 E=0.4 (Patterson

threshold)

IO

Stock

abundance

Biomass

SSB

Recruitmen

t

Final Diagnosis Based on XSA, the stock is probably in overexploitation

6.1 Explanation of codes

Trend categories

1) N - No trend

2) I - Increasing

3) D – Decreasing

4) C - Cyclic

Stock Status Based on Fishing mortality related indicators

1) N - Not known or uncertain – Not much information is available to make a

judgment;

2) U - undeveloped or new fishery - Believed to have a significant potential for

expansion in total production;

3) S - Sustainable exploitation- fishing mortality or effort below an agreed fishing

mortality or effort based Reference Point;

4) IO –In Overfishing status– fishing mortality or effort above the value of the

agreed fishing mortality or effort based Reference Point. An agreed range of

overfishing levels is provided;

Range of Overfishing levels based on fishery reference points

In order to assess the level of overfishing status when F0.1 from a Y/R

model is used as LRP, the following operational approach is proposed:

• If Fc*/F0.1 is below or equal to 1.33 the stock is in (OL): Low

overfishing

• If the Fc/F0.1 is between 1.33 and 1.66 the stock is in (OI):

Intermediate overfishing

• If the Fc/F0.1 is equal or above to 1.66 the stock is in (OH): High

overfishing

*Fc is current level of F

5) C- Collapsed- no or very few catches;

Based on Stock related indicators

1) N - Not known or uncertain: Not much information is available to make a

judgment

2) S - Sustainably exploited: Standing stock above an agreed biomass based

Reference Point;

3) O - Overexploited: Standing stock below the value of the agreed biomass

based Reference Point. An agreed range of overexploited status is provided;

Empirical Reference framework for the relative level of stock biomass index

• Relative low biomass: Values lower than or equal to 33rd

percentile of biomass index in the time series (OL)

• Relative intermediate biomass:Values falling within this limit

and 66th percentile (OI)

• Relative high biomass:Values higher than the 66th percentile

(OH)

4) D–Depleted: Standing stock is at lowest historical levels, irrespective of the

amount of fishing effort exerted;

5) R –Recovering: Biomass are increasing after having been depleted from a

previous period;

Agreed definitions as per SAC Glossary

Overfished (or overexploited) - A stock is considered to be overfished when its

abundance is below an agreed biomass based reference target point, like B0.1 or

BMSY. To apply this denomination, it should be assumed that the current state of the

stock (in biomass) arises from the application of excessive fishing pressure in previous

years. This classification is independent of the current level of fishing mortality.

Stock subjected to overfishing (or overexploitation) - A stock is subjected to

overfishing if the fishing mortality applied to it exceeds the one it can sustainably

stand, for a longer period. In other words, the current fishing mortality exceeds the

fishing mortality that, if applied during a long period, under stable conditions, would

lead the stock abundance to the reference point of the target abundance (either in

terms of biomass or numbers).