report of the workshop on the identification of clupeoid, flatfish, … reports/expert group... ·...

ICES WKIDFL REPORT 2011 STEERING GROUP ON ECOSYSTEM SURVEYS SCIENCE AND TECHNOLOGY

ICES CM 2011/SSGESST:17

REF. SCICOM

Report of the Workshop on the identification of clupeoid, flatfish, gadoids and other fish

larvae (WKIDFL)

5–9 September 2011

Ĳmuiden, The Netherlands

International Council for the Exploration of the Sea Conseil International pour l’Exploration de la Mer

H. C. Andersens Boulevard 44–46 DK-1553 Copenhagen V Denmark Telephone (+45) 33 38 67 00 Telefax (+45) 33 93 42 15 www.ices.dk [email protected]

Recommended format for purposes of citation:

ICES. 2011. Report of the Workshop on the identification of clupeoid, flatfish, gadoids and other fish larvae (WKIDFL), 5–9 September 2011, Ĳmuiden, The Netherlands. ICES CM 2011/SSGESST:17. 27pp.

For permission to reproduce material from this publication, please apply to the Gen-eral Secretary.

The document is a report of an Expert Group under the auspices of the International Council for the Exploration of the Sea and does not necessarily represent the views of the Council.

© 2011 International Council for the Exploration of the Sea

ICES WKIDFL REPORT 2011 | i

Contents

Executive summary ................................................................................................................ 1

1 Opening of the meeting ................................................................................................ 2

2 Adoption of the agenda ................................................................................................ 2

3 Larvae identification keys ............................................................................................ 3

4 Larvae identification ................................................................................................... 11

4.1 Methods for larvae identification trials ........................................................... 11

4.2 Result of larvae identification exercise ............................................................ 11

5 Identify sources of misidentification of larvae ...................................................... 17

6 Preservation methods of fish larvae ......................................................................... 18

7 References ..................................................................................................................... 21

Annex 1: List of participants............................................................................................... 22

Annex 2: Agenda ................................................................................................................... 24

Annex 3: WKIDCL terms of reference for the next meeting ........................................ 26

Annex 4: Recommendations ............................................................................................... 27

ICES WKIDFL REPORT 2011 | 1

Executive summary

The Workshop on the Identification of clupeoid, flatfish, gadoid and other fish larvae (WKIDFL) met from 5 to 9 September 2011 in Ĳmuiden, The Netherlands, to calibrate fish larvae identification. The meeting was chaired by Cindy van Damme, The Neth-erlands, and Matthias Kloppmann, Germany. In total 17 persons representing 10 in-stitutes from 8 countries participated in the workshop.

The majority of the time at the workshop was spent identifying fish larvae. The re-sults promoted discussion and highlighted specific problem areas. These discussions led to the further development of standard keys and larval identification characteris-tic tables. The results were re-assuring as the overall agreement in identification in-creased from 56% in the first round to 63% in the second round. For herring larvae the percentage agreement increased 54% to 74%. For sprat the improvement rose from 55% to 61%. Percentage agreement in sardine increased from 48% to 57%. How-ever, these results in clupeoid identification clearly show that there are still some uncertainties in the identification of clupeoid larvae.

Although overall agreement in larval fish identification increased during the second round and after distinguishing characteristics of major larval fish groups were clari-fied, some difficulties still appeared to occur in correctly identifying particular spe-cies. These difficulties occurred in clupeoids, in the distinction between cod and saithe larvae as well as in distinguishing dab from plaice larvae.

Before the workshop not all institutes counted myotomes to identify the different clupeoid species. However, during the workshop all participants agreed that the main characteristic to identify clupeoid larvae is the number of myotomes in the trunk.

For herring larval indices are used for the assessment of the spawning stock.

Although the agreement in herring larval identification increased in the second round there is still room for improvement. A new larval identification workshop focusing especially on clupeoid identification is proposed to increase agreement in identification.

Different preservation methods are available for the preservation of fish larvae. Par-ticipants agreed that it is most important that fish larvae are put in preservative im-mediately after the catch in order to preserve the larval characteristics. Formaldehyde based preservatives create lower shrinkage in larvae compared to ethanol solutions.

2 | ICES WKIDFL REPORT 2011

1 Opening of the meeting

The meeting started at Monday 5 September 2011. In total, 10 institutes were repre-sented from 8 countries (see Table 1.1). In total, 17 participants joined the meeting (Annex 1).

Table 1.1. Represented countries and institutes during WKIDFL 2011.

COUNTRY INSTITUTE

D e nm a r k D T U- Aq u a

Fr a nc e I f r e m e r

Ge r m a ny vT I

N e the r l a nds I MARE S

N o r wa y I MR

P o r tu ga l I P I MAR

Swe de n I CR

UK - Engl a nd Ce f a s

UK - N o r the r n I r e l a nd AFBI

UK - Sc o t l a nd MSSML

2 Adoption of the agenda

The terms of reference of this meeting were:

a ) Review available information on the identification of fish larvae in the North Sea and adjacent areas, under special consideration of larvae’s ap-pearance with ongoing development, with special emphasis on clupeoid, flatfish and gadoid larvae;

b ) Identify sources of misidentification of larvae; c ) Establish an agreed identification key for clupeoid, flatfish and gadoid lar-

vae; d ) Review methods of proper preservation in fish larvae.

An agenda was sent round prior to the workshop. The adopted agenda can be found in Annex 2.


3 Larvae identification keys

WKIDFL compiled on overview of the reference literature used and the characteris-tics for identification of the different fish larvae. The most used references for identi-fication of fish larvae in the North Sea and adjacent areas are: (Schmidt, 1905, Ehrenbaum, 1909, Russell, 1976, Fahay, 1983, Moser et al., 1984, Munk and Nielsen, 2005).

Before identification of fish larvae some background information is needed. Get ac-quainted to major fish larvae description literature. The introduction chapter of Rus-sell (1976) gives all the background information on larvae characteristics and different development stages and should be read by anyone who wants to identify fish larvae. Also information on the timing of sampling and the area where samples were collected should be available. Based on this information on the possible fish species spawning at the sampling time in the area should be collected.

A fish larva is the active immature form of a fish that differs greatly from the adult and forms the stage between egg and metamorphosis. Larvae are the stage between hatching to attainment of characters that allow for identification according to descrip-tions of adult specimens. The larval stage is characterized by progressive changes throughout its duration

• Organs develop and become functional • Pigmentation changes and becomes stronger • Fins develop and often change position. Most conspicuous is the develop-

ment of the caudal fin with flexion of the urostyle.

The above characteristics can all be used for the species identification of fish larvae.

The characteristics change with the different development stages of the larvae. The yolk-sac stage is the transitional stage between the egg and larval stage. The larvae lack functional eyes and mouth and the fins are not developed. The characteristics known from the eggs are retained during this stage (e.g. yolk segmentation, oil glob-ule). During this stage the characteristic pigmentation develops. Yolk-sac larvae from demersal eggs generally hatch at a further advanced development stage compared to larvae from pelagic eggs.

Most fish larvae live and have to adapt to a completely different environment than their adult conspecifics. They develop typical larval characters that can be used for identification. Several larval characters which need to be utilized for identification are:

• Body shape • Fins and fin fold • Eyes • Spines • Fin rays and fin ray counts • Body proportions • Myotome counts • Pigmentation patterns

Four major groups can be identified from the shape of the body:

• Long, slender and elongated: clupeoids


• Laterally compressed and dorsal-ventrally high: flatfish • More typically fish like forms: gadoids • Some conspicuously aberrant forms: others

Clupeoids

General characteristics:

• Tubular shape of body • Number of myotomes in the trunk • The body proportion changes during development thus the anus moves

forward and the myotome count decreases with age • The difference between clupeoids and sandeel is the position of the anus.

In sandeel the anus is halfway the body, in clupeoids the guts is much longer and the anus is positioned close to the tail.

Primary characteristics of clupeoids (from (Russell, 1976)

Developement stage (tot length) Herring Sprat Pilchard/Sardine Anchovy

Yolk sac Yolk not segmented

Yolk segmented Yolk segmented Yolk segmented, oblong shape

< 10 mm

No. myotomes in trunk

47 37 41–42

10–20 mm


46–47 35–37 41–42

Position pelvic fin Not appaered yet

Appaers at 17.5–20 mm, 4–5 myotomes behind the pylorus

Appaer at 18–20 mm, level with the pylorus

Dorsal fin Rear edge of dorsal fin overlaps with the anal fin

20–40 mm


41–46 31–35 36–41

Position pelvic fin 7–8 myotomes behind the pylorus

4–5 myotomes behind the pylorus

Level with the pylorus

Length of tail from anus to base of caudal fin

Greater than 6 times in total length

Less than 6 times in total length


Secondary characteristics:

Herring is always bigger at any developmental stage compared to the other species. Herring have pigmented eyes at hatching while other species do not gain pigment until later (5mm). Herring attain flexion stage later (17 mm) than other species so larvae at 11–13 mm with flexion will not be herring (Munk and Nielsen, 2005). The head of anchovy is bigger compared to the other species (head measurements are however not very useful to separate the species).

Note: In southern Iberia also the clupeoid Sardinella aurita is found.

It is important that myotome counting is done correctly (i.e. start and end are well identified).

For myotome count in the larvae trunk (from the back of the head to anus), see Fig-ures 3.1 to 3.3. (read also description in Russell, 1976)

Figure 3.1. Myotome counting in clupeoids: Start and endpoint of number of myotomes in the trunk.

Figure 3.2. Myotome counting in clupeoids: The first myotome after the head.


Figure 3.3. Myotome counting in clupeoids: The last myotome at the anus.

Table 3.1. Spawning areas and timing of clupeoids on the Northeast Atlantic Shelf *.

* References:

(Ré and Meneses, 2009), http://www.ices.dk/marineworld/fishmap/ices/pdf/herring.pdf, http://www.ices.dk/marineworld/fishmap/ices/pdf/sprat.pdf,

Unpublished data

Note: not a comprehensive compilation

Area Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecHerring English channel

North SeaN.Sea Variations: Buchan/Shetland

Central North SeaSardine Iberia

Bay of BiscayEnglish ChannelNorth Sea

Sprat Western IberiaNorth Sea

Anchovy CadizWestern IberiaBiscayEnglish Channel

http://www.ices.dk/marineworld/fishmap/ices/pdf/herring.pdf

http://www.ices.dk/marineworld/fishmap/ices/pdf/sprat.pdf


Gadoids


• Typical fish like forms • Anus opens sideways and may be difficult to see • Head mostly rectangular

Gadoid larvae can be divided in two major groups:

A: Well developed pelvic fins in the early stages

Spiny pelvic fins: Rocklings

Blunt pelvic fins: Pelvic fins not reaching anus. Pigments more like big spots than bands. Hake

Pelvic fins reaching longer than anus. Two transversal pigment bands. Ling Pigment bands split laterally

Torsk Pigment bands consistent. Rounded head.

B: Short pelvic fins do not appear until at least 10 mm

With a medio-lateral streak (may be difficult to see in early stages):

Pigments in lines Pollack Pigments in lines, both ventral and dorsal

Pigments in patches Cod The two ventral spots may be bound together, especially in the later stages. Small pigment spots near tail that may be difficult to see, or missing.

Saithe The two ventral spots never together and smaller than the dorsal. Medio-lateral streak appears at smaller size than in cod; first between the poste-rior pigment patches.

Without a medio-lateral streak:

Only ventral pigment line Haddock Ventral pigment line, also pigmen-tation on abdomen and head.

Ventral and dorsal pigment lines Whiting Dorsal line shorter than ventral. Later stages: Pigment pattern not reliable. Haddock always stockier. 1st dorsal fin of whiting longer.

Trisopterus spp. Dorsal and ventral lines al-most equal.

Bib Pigment lines only half-way to the tail.

Poor cod Pigment lines reaches the tail, big melanophores.

Norway pout Ventral line denser than the dorsal, gap in dorsal pigment line.


Flatfish


• Laterally flattened and exhibits asymmetry after metamorphosis • Short, protruding, twisted gut • Rounded head in younger larvae

Bothidae and scophthalmidae are identified by spines on the head and migration of the right eye to left side of head. In pleuronectidae and soleidae the left eye migrates to the right side.

Pleuronectidae

Pleuronectidae have a more slender body form compared to soleidae. The pre-anal area is less than half the total area of the body (Munk and Nielsen, 2005).

Pleuronectidae with ventral pigmentation

Plaice Dab Flounder

Pigmentation Ventral double pigmentation row (less evenly spaced compared to dab)

Very even double row of pigmentation

Scattered pigmentation on ventral surface (Ré and Meneses, 2009)

Other pigmentation

Pigmentation on pectoral fin (Munk and Nielsen, 2005)

Band of pigment midway along post anal part of body (Russell, 1976)

Hatching size 7 mm 3–4 mm 2.25 mm

Size during development

Larger than other pleuronectidae at any development stage

Body shape Long, slender Shorter and stockier compared to plaice

Gut ends closer to the middle of body compared to dab

Head Smaller head Larger head than plaice

Small head and relatively small eyes

Caudal fin rays (Russell, 1976)

19–22 16–18 18

Onset of asymmetry

11–12 mm 10–12 mm < 10 mm

Caudal peduncle longer than broad (Nichols, 1971)

Time and location is important in distinguishing between Plaice and Dab!

Pleuronectidae with bars/bands of melanophores on the primordial fin and body

Asymmetry for long rough dab and lemon sole begins at a larger size (15mm; Munk and Nielsen, 2005).


Long rough dab Lemon sole Halibut Witch

Pigmentation Bands less clearly defined, with pigmentation between bands (Munk and Nielsen, 2005)

More distinct bands compared to long rough dab (Munk and Nielsen, 2005)

Less pigmented and lacks bars on the primordial fin

Body shape Bigger mouth High round body with small head and mouth

Depression above the eyes on a relatively large head

Elongated ap-pearance

Anal fin rays <85 <85 <85 85–102 (Munk and Nielsen, 2005)

Soleidae

Soleidae have a deep abdominal region, a rounded vertical profile of the head and prominent pigmentation (Russell, 1976).

Sole Solenette Thickback sole

Pigmentation Almost unbroken line of pigment along dorsal and ventral body contour

Larger evenly spaced melanophores along body contours

Smaller stellate chromatophores (Nichols, 1976)

Other pigmentation

Pigment on primordial fin bigger and more distinct

Localized pigmention on underside of abdomen

Pigment may be arranged into longitudinal rows

Abdomen Abdomen very prominent especially in earlier stages

Anus just behind body mid point (Russell, 1976)

Hatching size 3 mm (Nichols, 1976) 2 mm 2.5 mm

Scophthalmidae

Triangular mouth and upturned nose.

Early stage rectal and post anal bar of pigment and dense pigmentation

Brill Turbot

Size Larger than turbot at early development stage (Russell, 1976)

In later stages body depth larger than brill

Body shape Longer and more slender at later stages

Short and stout compared to brill

Spines Opercular spines are more strongly developed (Munk and Nielsen, 2005)


Species with bands of pigment at all stages

Topknot Norwegian topknot Megrim

Pigmentation Pigment bands on primordial fin at early stage (Munk and Nielsen, 2005)

Pigment on margin of pectoral fin and row of melanophores along jaw and abdomen

Characteristic rows of pigment along body contour and marginal fin

Spines Otocystic spines Lack of otocystic spines

Two large otocystic spines (Russell, 1976)

Dorsal fin rays 75–94 (Munk and Nielsen, 2005)

85–102 76–84

Bothidae

Rounder head compared to scophthalmidae. Scaldfish have a tentacle on top of the head.


4 Larvae identification

4.1 Methods for larvae identification trials

Trays containing 6 specimens of different fish larvae were used for the fish larvae identification exercise. As each participant moved from microscope to microscope they were asked to provide a species identification for each larva (from a list of 24 species plus an “other” category). During the first trial round there were 2 trays with fish larvae per each of 17 microscopes while during the second trial round only 1 tray per each of 16 microscopes were examined. Because of the different levels of expertise in fish larvae identification only very few participants were able to identify the major part of the larvae during the first trial. Therefore it was decided to reduce the number of specimens during the second round. Participants were allowed to utilize own as well as provided identification literature. Descriptions of the major characteristics of major taxonomic larval fish groups were also provided during an introductory pres-entation.

The results of the first round of larvae identifications were collated and input into spreadsheets. The results were presented and larvae with low agreement in species identification were photographed and displayed on a large screen. Major characteris-tics of those species were thoroughly discussed. Before the second identification trial the results of the subgroups on clupeoid, gadoid and flatfish larval identification characteristics were collated and discussed.

4.2 Result of larvae identification exercise

The original assessment of species identification for each larva, by each participant, was put into a primary result table (not presented here). Once the results were avail-able from every participant two methods of analysis were conducted. The results were initially compared with the predetermined (identifications done by experts from a non-participating institute) or modal species. The second table shows the re-sults for the actual species, which should have been present in the wells of each tray. Both sets of results are presented below. It is possible that some of the differences between these tables can be accounted for by movement of larvae from one well to an-other.

Summaries of the results from the both rounds of fish larval species determination are presented in Tables 4.1 to 4.4. Each of these tables is divided into three sub-tables labelled A-C, where the performance of each participant is judged against the actual species and modal species determination.

Sub-tables A show the number of larvae at each actual or modal species that were assessed by each participant. The numbers at each modal species will therefore be the same for all participants that read all the larvae.

Sub-tables B show the numbers of larvae of each species as actually assessed by each participant.

Sub-tables C show the percentage agreement in species identification between the assessment of each participant and the actual or modal species.

Tables 4.1 and 4.2 show differences in the results from the first round of analysis, where determined species of larvae were used (Table 4.1) and where modal species (Table 4.2) were used to compare with participants’ assessment of species. The differ-ences between these tables probably partly reflect the extent to which some larvae


were unintentionally moved between cells during the first round of analysis. This is apparent when comparing the results in sub-tables C (Tables 4.1 and 4.2) and is par-ticularly highlighted by the difference between ‘determined’ and ‘modal’ species determinations for some species. If participants are judged against ‘determined’ spe-cies they appear to have a lower overall agreement among each other than when judged against ‘modal species’.

The results of both rounds of analysis also show differences between the use of ‘de-termined’ or ‘modal’ species determination (Tables 4.1 to 4.4). If participants are judged against ‘determined’ species they appear to score a lower level of overall agreement in species determination than with ‘modal’ species determination.

The results show significant improvements in the allocation of larvae to the correct determined species, from the first to the second round of analysis. However, they also highlight the difficulties in being able to positively identify larvae where there are few distinguishing features other than the pigmentations patterns or myotome counts. After the first round of analysis there was some discussion on the features which aid fish larvae identification. Some references and criteria were produced (see section 3) to help with the identification of selected fish larvae groups (clupeoids, gadoids and flatfish). These discussions and criteria helped to improve the mean percentage agreement between participants' identification of fish larvae to species (Tables 4.1C, 4.2C, 4.3C and 4.4C). For herring larvae the percentage agreement in-creased from 56% to 78% with determined species and from 54% to 74% with modal species. For sprat the improvement rose from 47% to 63% for determined species and from 55% to 61% for the modal species. Percentage agreement in sardine increased from 33% to 45% in determined and from 48% to 57% in modal species evaluation. However, these differences in clupeoid identification between determined and modal species clearly show that there are still some uncertainties in the identification of clupeoid larvae. Overall, the percentage agreement rose from 49.5% (‘determined’ spp.) and 56.3% (modal spp.) in the first round to 58.7% and 62.8% in the second round of analysis. These results were very re-assuring particularly as most of the microscopes were of differing quality standards with some lacking eyepiece graticules to enable measurement of larvae.


Table 4.1. Species identification first determination. The species compositions based on actual species reflecting the best estimates based on only those larvae that were used for species identi-fication by the participant (A), the species compositions as obtained per participant (B) and the percentages agreement with modal species or actual species (C) are shown per species by partici-pant and for the whole group that took part in the species identification exercise on fish larvae. A weighted mean percent agreement is given by person and all persons combined.

A

Reader 1 Reader 2 Reader 3 Reader 4 Reader 5 Reader 6 Reader 7 Reader 8 Reader 9 Reader 10 Reader 11 Reader 12 Reader 13 Reader 14 Reader 15 TOTALHer r ing 1 8 11 4 5 17 10 7 4 5 9 3 8 17 13 6 127

Sprat 2 7 13 3 4 16 12 5 5 5 6 1 8 17 13 4 119Sardine 3 8 13 2 4 15 11 5 2 5 5 2 10 16 11 3 112

Anchovy 4 5 10 2 3 10 7 3 3 3 4 1 4 9 9 4 77Cod 5 7 12 2 3 13 7 3 - 2 6 2 7 13 11 3 91

Haddock 6 1 4 2 - 7 5 1 - 2 2 2 2 7 7 1 43Whiting 7 3 7 2 3 10 8 4 - 2 4 2 6 11 7 2 71

Hake 8 - - - - - - - - - - - - - - - -Rock ling 9 4 12 2 3 15 13 7 3 3 7 4 6 15 7 4 105

Plaice 10 3 9 - 2 10 7 3 2 2 4 2 6 9 6 3 68Dab 11 6 8 3 1 9 8 6 - 3 4 2 4 10 6 1 71

Flounder 12 5 8 4 1 8 7 3 - 3 3 1 5 8 6 - 62L emon Sole 13 1 6 2 2 7 5 3 3 2 4 1 3 8 6 1 54L ong R Dab 14 3 3 2 1 3 3 2 - 2 1 - 3 4 1 - 28

Sole 15 4 9 1 1 9 7 3 3 1 4 1 3 8 6 2 62Solenette 16 3 6 3 2 7 7 5 1 4 2 - 2 8 3 2 55

Gobies 17 1 3 2 1 3 2 1 2 1 2 - 2 3 3 - 26Chrystal Goby 18 2 3 1 1 3 1 1 1 - 2 1 2 2 3 1 24

Dragonette 19 2 4 1 1 4 4 1 1 1 - 1 3 3 3 1 30Mackerel 20 3 3 1 1 4 2 1 1 1 2 1 1 4 2 - 27

Horse Mack 21 2 3 - 1 3 1 - - 1 1 - 2 3 3 - 20Maurolicus 22 1 - 1 - 2 1 - 1 - 1 - 1 2 2 - 12

Sandeel 23 - - 1 1 - 1 1 - 1 - - 1 1 - - -Other species 24 3 7 1 1 7 4 1 1 2 3 1 5 8 6 2 52

Saithe 25 4 5 2 1 6 4 2 - 2 3 1 2 6 4 - 42Total 1-25 86 159 44 43 188 137 68 33 53 79 29 96 192 138 40 1385

B

Species Reader 1 Reader 2 Reader 3 Reader 4 Reader 5 Reader 6 Reader 7 Reader 8 Reader 9 Reader 10 Reader 11 Reader 12 Reader 13 Reader 14 Reader 15 TOTALHer r ing 1 9 13 7 8 30 10 4 3 11 9 3 5 16 10 6 144

Sprat 2 10 16 2 - 6 13 5 5 3 8 4 9 22 15 3 121Sardine 3 4 10 1 2 14 7 8 5 2 1 - 11 7 10 2 84

Anchovy 4 2 9 1 1 8 7 3 1 - 7 - 5 9 5 2 60Cod 5 7 7 4 4 3 5 6 - 5 7 2 6 17 3 4 80

Haddock 6 - 4 5 1 8 6 1 - - 3 - 3 9 10 1 51Whiting 7 1 3 3 2 8 4 8 - 9 2 4 7 10 16 2 79

Hake 8 - - - 1 1 - - - - 1 1 - 2 3 1 10Rock ling 9 5 18 - 1 9 10 9 4 2 3 6 5 8 8 3 91

Plaice 10 - 8 1 - 8 7 1 1 1 7 - 5 - - 1 40Dab 11 10 13 2 7 19 15 3 - 4 6 1 8 34 1 - 123

Flounder 12 4 7 4 1 6 8 - - - - - 4 5 1 - 40L emon Sole 13 1 10 2 3 10 6 3 4 4 4 1 3 10 4 1 66L ong R Dab 14 2 1 1 - 3 2 - - - 1 - 2 1 - - 13

Sole 15 5 10 1 3 8 5 - 1 1 4 1 2 2 6 2 51Solenette 16 3 4 3 2 6 7 4 2 6 2 1 3 17 2 - 62

Gobies 17 3 4 2 1 5 1 2 3 1 3 - 2 4 4 - 35Chrystal Goby 18 1 2 - 1 - 1 2 - - 2 1 3 1 1 - 15

Dragonette 19 1 4 1 - - 1 - - 1 - - 3 3 4 3 21Mackerel 20 3 4 1 - 10 6 1 1 - 7 4 2 - 2 1 42

Horse Mack 21 4 2 - - 5 2 1 - - 2 - 3 - 7 2 28Maurolicus 22 3 - 1 - 2 2 1 - - - - - 2 1 - 12

Sandeel 23 - - 2 5 2 3 5 1 3 - - 1 6 10 4 42Other species 24 3 6 - - 4 3 - 2 - - - 2 7 - 2 29

Saithe 25 5 4 - - 13 6 1 - - - - 2 - 15 - 46Total 1-25 81 155 44 43 175 131 67 33 53 79 29 94 192 123 40 1339

C

Reader 1 Reader 2 Reader 3 Reader 4 Reader 5 Reader 6 Reader 7 Reader 8 Reader 9 Reader 10 Reader 11 Reader 12 Reader 13 Reader 14 Reader 15 ALLHer r ing 1 75% 82% 75% 80% 71% 50% 29% 75% 100% 56% 100% 38% 41% 8% 50% 56%

Sprat 2 86% 92% 0% 0% 6% 50% 20% 80% 20% 67% 100% 75% 53% 38% 0% 47%Sardine 3 38% 62% 0% 50% 27% 18% 80% 50% 40% 0% 0% 50% 13% 45% 33% 35%

Anchovy 4 40% 90% 50% 0% 60% 71% 67% 33% 0% 75% 0% 100% 22% 11% 25% 48%Cod 5 71% 50% 100% 100% 0% 43% 33% - 50% 67% 100% 86% 69% 18% 33% 49%

Haddock 6 0% 100% 100% - 57% 40% 0% - 0% 100% 0% 100% 29% 29% 0% 47%Whiting 7 33% 29% 100% 33% 20% 25% 100% - 100% 25% 50% 67% 27% 29% 0% 38%

Hake 8 - - - - - - - - - - - - - - - -Rock ling 9 100% 100% 0% 33% 60% 77% 100% 100% 67% 43% 100% 83% 53% 57% 75% 71%

Plaice 10 0% 56% - 0% 20% 71% 0% 50% 0% 50% 0% 50% 0% 0% 33% 28%Dab 11 100% 88% 67% 0% 67% 88% 17% - 0% 50% 0% 100% 90% 0% 0% 62%

Flounder 12 80% 88% 100% 0% 38% 100% 0% - 0% 0% 0% 60% 50% 0% - 52%L emon Sole 13 100% 100% 100% 100% 100% 100% 100% 100% 100% 75% 100% 67% 88% 67% 100% 91%L ong R Dab 14 33% 33% 50% 0% 33% 33% 0% - 0% 0% - 33% 25% 0% - 25%

Sole 15 75% 100% 100% 100% 78% 71% 0% 33% 0% 50% 0% 67% 0% 83% 0% 58%Solenette 16 67% 50% 100% 50% 71% 100% 80% 100% 100% 0% - 100% 88% 67% 0% 75%

Gobies 17 100% 67% 50% 0% 100% 50% 0% 100% 0% 100% - 50% 33% 0% - 54%Chrystal Goby 18 50% 33% 0% 100% 0% 100% 100% 0% - 100% 100% 100% 0% 0% 0% 42%

Dragonette 19 0% 100% 100% 0% 0% 25% 0% 0% 0% - 0% 67% 0% 33% 100% 33%Mackerel 20 100% 100% 100% 0% 100% 100% 100% 100% 0% 100% 0% 100% 0% 50% - 70%

Horse Mack 21 100% 67% - 0% 33% 100% - - 0% 0% - 0% 0% 33% - 35%Maurolicus 22 100% - 100% - 50% 100% - 0% - 0% - 0% 100% 50% - 58%

Sandeel 23 - - 100% 0% - 0% 100% - 100% - - 100% 100% - - -Other species 24 33% 86% 0% 0% 29% 50% 0% 100% 0% 0% 0% 40% 25% 0% 0% 31%

Saithe 25 50% 60% 0% 0% 100% 50% 50% - 0% 0% 0% 100% 0% 75% - 45%1-25 61.6% 74.2% 63.6% 37.2% 42.6% 59.1% 47.1% 66.7% 37.7% 46.8% 44.8% 63.5% 39.6% 26.8% 30.0%

RANKING 5 1 3 13 10 6 7 2 12 8 9 4 11 15 14Weighted mean 49.5%

Species compositions as estimated per participant and whole group

Modal oractual species

Percentage agreement in species identification per species

Species compositions using modal/actual species (second last column input table)Modal or

actual species


Table 4.2. Species identification first determination. The species compositions based on modal species reflecting the best estimates based on only those larvae that were used for species identi-fication by the participant (A), the species compositions as obtained per participant (B) and the percentages agreement with modal species or actual species (C) are shown per species by partici-pant and for the whole group that took part in the species identification exercise on fish larvae. A weighted mean percent agreement is given by person and all persons combined.

A


Sprat 2 10 14 3 4 17 13 6 4 4 5 1 11 19 14 4 129Sardine 3 4 7 1 2 8 6 2 1 3 2 1 4 8 6 1 56

Anchovy 4 4 8 1 2 9 7 2 2 2 4 1 5 8 8 4 67Cod 5 9 11 3 4 13 7 4 - 4 5 1 7 13 9 2 92

Haddock 6 1 5 3 - 9 7 2 - 2 3 2 2 9 7 1 53Whiting 7 4 7 2 3 11 7 4 - 4 6 3 7 13 8 4 83

Hake 8 - - - - - - - - - - - - - - - -Rock ling 9 4 11 1 2 12 10 5 3 2 6 4 6 12 7 4 89

Plaice 10 - 2 - - 2 2 2 - - 1 - 1 2 - 1 -Dab 11 10 20 4 4 21 18 8 2 5 8 4 12 21 16 3 156

Flounder 12 5 7 4 1 7 6 3 - 3 3 1 4 7 5 - 56L emon Sole 13 3 8 4 3 9 8 5 3 4 4 1 5 11 7 1 76L ong R Dab 14 1 1 - - 1 - - - - 1 - 1 1 - - 6

Sole 15 4 9 1 1 9 7 3 3 1 4 1 3 8 6 2 62Solenette 16 3 6 3 2 7 7 5 1 4 2 - 2 8 3 2 55

Gobies 17 2 4 1 - 4 1 - 2 - 3 1 2 3 4 1 28Chrystal Goby 18 1 2 1 1 2 1 1 1 - 1 - 1 1 2 - 15

Dragonette 19 1 2 1 2 3 3 1 1 2 - - 1 3 2 1 23Mackerel 20 3 4 1 1 5 3 1 1 1 2 2 2 5 3 - 34

Horse Mack 21 2 5 - 1 5 4 1 - 1 1 1 4 4 4 1 34Maurolicus 22 1 - 1 - 2 1 - 1 - 1 - 1 2 2 - 12

Sandeel 23 - - 2 2 - 2 2 - 2 - - 2 2 - - -Other species 24 2 4 - - 4 1 - 1 - 1 - 2 4 3 - 22

Saithe 25 2 4 1 - 4 2 1 - - 3 1 1 4 4 - 27Total 1-25 86 159 44 43 188 137 68 33 53 79 29 96 192 138 40 1385

B


Sprat 2 10 16 2 - 6 13 5 5 3 8 4 9 22 15 3 121Sardine 3 4 10 1 2 14 7 8 5 2 1 - 11 7 10 2 84

Anchovy 4 2 9 1 1 8 7 3 1 - 7 - 5 9 5 2 60Cod 5 7 7 4 4 3 5 6 - 5 7 2 6 17 3 4 80

Haddock 6 - 4 5 1 8 6 1 - - 3 - 3 9 10 1 51Whiting 7 1 3 3 2 8 4 8 - 9 2 4 7 10 16 2 79

Hake 8 - - - 1 1 - - - - 1 1 - 2 3 1 10Rock ling 9 5 18 - 1 9 10 9 4 2 3 6 5 8 8 3 91

Plaice 10 - 8 1 - 8 7 1 1 1 7 - 5 - - 1 40Dab 11 10 13 2 7 19 15 3 - 4 6 1 8 34 1 - 123

Flounder 12 4 7 4 1 6 8 - - - - - 4 5 1 - 40L emon Sole 13 1 10 2 3 10 6 3 4 4 4 1 3 10 4 1 66L ong R Dab 14 2 1 1 - 3 2 - - - 1 - 2 1 - - 13

Sole 15 5 10 1 3 8 5 - 1 1 4 1 2 2 6 2 51Solenette 16 3 4 3 2 6 7 4 2 6 2 1 3 17 2 - 62

Gobies 17 3 4 2 1 5 1 2 3 1 3 - 2 4 4 - 35Chrystal Goby 18 1 2 - 1 - 1 2 - - 2 1 3 1 1 - 15

Dragonette 19 1 4 1 - - 1 - - 1 - - 3 3 4 3 21Mackerel 20 3 4 1 - 10 6 1 1 - 7 4 2 - 2 1 42

Horse Mack 21 4 2 - - 5 2 1 - - 2 - 3 - 7 2 28Maurolicus 22 3 - 1 - 2 2 1 - - - - - 2 1 - 12

Sandeel 23 - - 2 5 2 3 5 1 3 - - 1 6 10 4 42Other species 24 3 6 - - 4 3 - 2 - - - 2 7 - 2 29

Saithe 25 5 4 - - 13 6 1 - - - - 2 - 15 - 46Total 1-25 81 155 44 43 175 131 67 33 53 79 29 94 192 123 40 1339

C


Sprat 2 70% 93% 33% 0% 18% 54% 33% 100% 25% 100% 100% 73% 74% 36% 0% 55%Sardine 3 50% 86% 0% 50% 50% 17% 100% 100% 67% 0% 0% 75% 13% 50% 100% 48%

Anchovy 4 50% 100% 100% 0% 67% 71% 100% 50% 0% 75% 0% 100% 38% 13% 25% 57%Cod 5 78% 45% 100% 100% 0% 43% 50% - 75% 80% 100% 86% 85% 22% 50% 57%

Haddock 6 0% 80% 100% - 44% 57% 0% - 0% 100% 0% 100% 33% 29% 0% 47%Whiting 7 25% 43% 100% 67% 36% 43% 100% - 100% 17% 67% 71% 31% 50% 25% 48%

Hake 8 - - - - - - - - - - - - - - - -Rock ling 9 100% 100% 0% 50% 75% 100% 100% 100% 100% 50% 100% 83% 67% 57% 75% 81%

Plaice 10 - 100% - - 50% 50% 0% - - 100% - 100% 0% - 100% -Dab 11 100% 65% 50% 100% 71% 67% 13% 0% 40% 50% 25% 58% 81% 0% 0% 56%

Flounder 12 80% 100% 100% 0% 43% 100% 0% - 0% 0% 0% 75% 57% 0% - 55%L emon Sole 13 33% 100% 50% 100% 89% 75% 60% 100% 100% 75% 100% 60% 73% 57% 100% 76%L ong R Dab 14 100% 100% - - 100% - - - - 0% - 0% 0% - - 50%

Sole 15 75% 100% 100% 100% 78% 71% 0% 33% 0% 50% 0% 67% 0% 83% 0% 58%Solenette 16 67% 50% 100% 50% 71% 100% 80% 100% 100% 0% - 100% 88% 67% 0% 75%

Gobies 17 100% 75% 100% - 100% 100% - 100% - 67% 0% 0% 67% 25% 0% 64%Chrystal Goby 18 100% 50% 0% 100% 0% 100% 100% 0% - 100% - 100% 0% 0% - 47%

Dragonette 19 0% 100% 100% 0% 0% 33% 0% 0% 50% - - 100% 33% 50% 100% 39%Mackerel 20 100% 100% 100% 0% 100% 100% 100% 100% 0% 100% 0% 50% 0% 33% - 65%

Horse Mack 21 100% 40% - 0% 40% 25% 100% - 0% 0% 0% 50% 0% 50% 100% 38%Maurolicus 22 100% - 100% - 50% 100% - 0% - 0% - 0% 100% 50% - 58%

Sandeel 23 - - 100% 50% - 0% 100% - 100% - - 50% 50% - - -Other species 24 50% 100% - - 50% 100% - 100% - 0% - 50% 50% 0% - 55%

Saithe 25 100% 50% 0% - 75% 50% 100% - - 0% 0% 100% 0% 75% - 48%1-25 72.1% 76.1% 75.0% 58.1% 53.2% 63.5% 47.1% 63.6% 64.2% 50.6% 44.8% 65.6% 50.5% 29.7% 37.5%

RANKING 3 1 2 8 9 7 12 6 5 10 13 4 11 15 14

Percentage agreement in species identification per speciesModal or

actual species

Weighted mean 56.6%


actual species



Table 4.3. Species identification second determination. The species compositions based on actual species reflecting the best estimates based on only those larvae that were used for species identification by the participant (A), the species compositions as obtained per participant (B) and the percentages agreement with modal species or actual species (C) are shown per species by participant and for the whole group that took part in the species identification exercise on fish larvae. A weighted mean percent agreement is given by person and all persons combined.

A


Sprat 2 8 8 7 7 8 8 7 8 7 8 6 8 8 7 7 112Sardine 3 10 9 9 10 10 10 10 10 10 10 10 10 10 10 10 148

Anchovy 4 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 30Cod 5 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 60

Haddock 6 5 5 5 5 5 5 5 5 5 5 4 5 5 5 4 73W hiting 7 7 7 7 7 7 7 6 6 7 7 7 7 7 7 7 103

Hake 8 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15Rock ling 9 6 5 5 5 6 5 6 5 6 6 6 6 6 6 4 83

Plaice 10 2 2 2 - 2 2 2 2 2 2 2 2 2 2 2 28Dab 11 4 4 4 3 4 4 4 4 4 4 3 4 4 4 4 58

Flounder 12 6 6 6 5 6 6 6 6 6 6 6 6 6 6 5 88L emon Sole 13 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 75L ong R Dab 14 1 1 1 1 1 1 1 1 1 1 1 - 1 1 - 13

Sole 15 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 30Solenette 16 6 5 6 6 6 6 5 5 6 6 5 6 6 6 6 86

Gobies 17 2 2 2 2 2 2 2 1 2 2 2 2 2 2 2 29Chrystal Goby 18 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 45

Dragonette 19 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 30Mackerel 20 2 2 2 2 2 2 2 2 2 2 2 2 2 2 1 29

Horse Mack 21 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15Maurolicus 22 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 45

Sandeel 23 - - - - - - - - - - - - - - - -Other species 24 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 45

Saithe 25 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 75Total 1-25 95 91 92 90 96 94 92 91 95 96 90 95 96 95 88 1396

B


Sprat 2 10 10 10 2 1 7 4 13 9 9 9 13 12 6 11 126Sardine 3 8 6 5 4 10 9 13 6 5 5 7 4 4 10 8 104

Anchovy 4 1 2 1 2 3 2 1 2 1 2 3 3 - 1 1 25Cod 5 5 4 5 5 4 2 2 3 4 3 2 3 5 2 3 52

Haddock 6 6 6 6 5 6 4 6 8 9 8 3 4 6 4 5 86W hiting 7 7 7 7 4 4 4 5 7 8 4 16 7 8 7 5 100

Hake 8 1 1 1 1 1 1 1 1 1 3 2 1 1 - 1 17Rock ling 9 3 4 3 4 2 2 4 4 2 - 5 4 3 1 2 43

Plaice 10 2 5 5 - 2 6 2 4 2 5 3 5 - 4 6 51Dab 11 5 1 1 8 7 5 4 1 7 3 1 1 7 1 3 55

Flounder 12 6 6 6 2 6 7 5 6 - 8 - 7 7 2 1 69L emon Sole 13 6 5 5 7 5 4 7 6 6 4 4 4 4 4 2 73L ong R Dab 14 - 1 1 3 1 2 - - - 1 - 1 2 - 3 15

Sole 15 1 2 4 4 4 2 2 2 - 4 2 1 3 7 - 38Solenette 16 7 5 4 3 4 3 6 5 8 3 2 6 5 13 5 79

Gobies 17 2 - 3 1 4 6 2 1 1 3 1 2 1 2 5 34Chrystal Goby 18 3 5 2 3 - - 4 3 4 5 3 3 2 1 2 40

Dragonette 19 2 2 2 2 1 2 1 2 1 1 2 1 - - 4 23Mackerel 20 2 2 2 - 3 3 2 1 - 3 5 5 2 - 4 34

Horse Mack 21 1 1 - 3 3 2 3 - 2 2 4 2 - 2 1 26Maurolicus 22 3 3 3 4 1 3 3 3 3 - - 3 3 2 3 37

Sandeel 23 - - - - 1 - - - - - - - 1 2 - 4Other species 24 5 3 5 1 3 5 3 3 4 3 2 3 6 8 5 59

Saithe 25 3 5 4 6 8 7 6 6 8 7 9 6 5 8 5 93Total 1-25 92 86 88 84 88 87 86 85 87 89 81 89 91 87 83 1303

C


Sprat 2 100% 100% 86% 0% 13% 75% 29% 100% 71% 63% 33% 88% 88% 14% 71% 63%Sardine 3 70% 67% 44% 0% 40% 70% 70% 50% 40% 40% 30% 20% 40% 50% 50% 45%

Anchovy 4 50% 100% 50% 50% 100% 100% 50% 100% 50% 100% 50% 100% 0% 0% 50% 63%Cod 5 100% 75% 50% 0% 25% 25% 25% 50% 50% 50% 0% 50% 50% 25% 0% 38%

Haddock 6 100% 100% 100% 60% 60% 60% 80% 100% 80% 80% 0% 80% 80% 40% 75% 74%W hiting 7 100% 100% 100% 29% 57% 57% 67% 100% 100% 43% 71% 100% 100% 86% 43% 77%

Hake 8 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 0% 100% 93%Rock ling 9 50% 80% 60% 60% 33% 40% 67% 80% 33% 0% 83% 67% 50% 17% 50% 51%

Plaice 10 50% 50% 50% - 100% 100% 50% 50% 0% 100% 0% 50% 0% 50% 50% 50%Dab 11 75% 0% 0% 100% 100% 75% 75% 25% 75% 25% 0% 0% 100% 0% 25% 45%

Flounder 12 100% 100% 100% 40% 100% 100% 83% 100% 0% 100% 0% 100% 100% 0% 20% 70%L emon Sole 13 100% 100% 100% 100% 100% 80% 100% 100% 80% 80% 80% 80% 80% 80% 40% 87%L ong R Dab 14 0% 100% 100% 100% 100% 100% 0% 0% 0% 0% 0% - 100% 0% - 46%

Sole 15 0% 50% 50% 50% 0% 100% 0% 100% 0% 100% 100% 0% 50% 50% 0% 43%Solenette 16 83% 80% 50% 33% 33% 50% 60% 100% 83% 50% 40% 67% 67% 67% 17% 58%

Gobies 17 100% 0% 100% 0% 50% 100% 50% 0% 50% 0% 0% 0% 0% 100% 100% 45%Chrystal Goby 18 100% 100% 67% 100% 0% 0% 100% 67% 100% 100% 67% 33% 67% 33% 33% 64%

Dragonette 19 100% 100% 100% 100% 50% 0% 50% 100% 50% 50% 100% 50% 0% 0% 50% 60%Mackerel 20 100% 100% 100% 0% 50% 50% 100% 50% 0% 0% 0% 100% 0% 0% 100% 48%

Horse Mack 21 100% 100% 0% 100% 100% 0% 0% 0% 100% 0% 0% 100% 0% 100% 0% 47%Maurolicus 22 100% 100% 100% 100% 33% 100% 100% 100% 100% 0% 0% 100% 100% 67% 100% 80%

Sandeel 23 - - - - - - - - - - - - - - - -Other species 24 100% 100% 100% 0% 100% 100% 67% 100% 33% 33% 67% 100% 100% 100% 67% 78%

Saithe 25 60% 80% 40% 60% 80% 80% 80% 80% 80% 80% 100% 80% 60% 80% 60% 73%1-25 81.1% 79.1% 69.6% 40.0% 54.2% 63.8% 62.0% 74.7% 56.8% 51.0% 37.8% 63.2% 64.6% 38.9% 43.2%

RANKING 1 2 4 13 10 6 8 3 9 11 15 7 5 14 12Weighted mean

58.7%


Modal oractual species

Percentage agreement in species identification per species


actual species


Table 4.4. Species identification second determination. The species compositions based on modal species reflecting the best estimates based on only those larvae that were used for species identification by the participant (A), the species compositions as obtained per participant (B) and the percentages agreement with modal species or actual species (C) are shown per species by participant and for the whole group that took part in the species identification exercise on fish larvae. A weighted mean percent agreement is given by person and all persons combined.

A


Sprat 2 10 10 9 9 10 10 9 10 9 10 8 10 10 9 9 142Sardine 3 7 6 6 7 7 7 7 7 7 7 7 7 7 7 7 103

Anchovy 4 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 30Cod 5 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 45

Haddock 6 7 6 6 7 7 6 7 6 7 7 6 7 7 7 4 97Whiting 7 7 7 7 7 7 7 6 6 7 7 7 7 7 7 7 103

Hake 8 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15Rock ling 9 4 4 4 3 4 4 4 4 4 4 4 4 4 4 4 59

Plaice 10 3 3 3 1 3 3 3 3 3 3 2 3 3 3 3 42Dab 11 3 3 3 2 3 3 3 3 3 3 3 3 3 3 3 44

Flounder 12 6 6 6 5 6 6 6 6 6 6 6 6 6 6 5 88L emon Sole 13 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 75L ong R Dab 14 1 1 1 1 1 1 1 1 1 1 1 - 1 1 - 13

Sole 15 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15Solenette 16 7 6 7 7 7 7 6 6 7 7 6 7 7 7 7 101

Gobies 17 1 1 1 1 1 1 1 - 1 1 1 1 1 1 1 14Chrystal Goby 18 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 60

Dragonette 19 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 30Mackerel 20 2 2 2 2 2 2 2 2 2 2 2 2 2 2 1 29

Horse Mack 21 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15Maurolicus 22 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 45

Sandeel 23 - - - - - - - - - - - - - - - -Other species 24 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 45

Saithe 25 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 90Total 1-25 95 91 92 90 96 94 92 91 95 96 90 95 96 95 88 1396

B


Sprat 2 10 10 10 2 1 7 4 13 9 9 9 13 12 6 11 126Sardine 3 8 6 5 4 10 9 13 6 5 5 7 4 4 10 8 104

Anchovy 4 1 2 1 2 3 2 1 2 1 2 3 3 - 1 1 25Cod 5 5 4 5 5 4 2 2 3 4 3 2 3 5 2 3 52

Haddock 6 6 6 6 5 6 4 6 8 9 8 3 4 6 4 5 86Whiting 7 7 7 7 4 4 4 5 7 8 4 16 7 8 7 5 100

Hake 8 1 1 1 1 1 1 1 1 1 3 2 1 1 - 1 17Rock ling 9 3 4 3 4 2 2 4 4 2 - 5 4 3 1 2 43

Plaice 10 2 5 5 - 2 6 2 4 2 5 3 5 - 4 6 51Dab 11 5 1 1 8 7 5 4 1 7 3 1 1 7 1 3 55

Flounder 12 6 6 6 2 6 7 5 6 - 8 - 7 7 2 1 69L emon Sole 13 6 5 5 7 5 4 7 6 6 4 4 4 4 4 2 73L ong R Dab 14 - 1 1 3 1 2 - - - 1 - 1 2 - 3 15

Sole 15 1 2 4 4 4 2 2 2 - 4 2 1 3 7 - 38Solenette 16 7 5 4 3 4 3 6 5 8 3 2 6 5 13 5 79

Gobies 17 2 - 3 1 4 6 2 1 1 3 1 2 1 2 5 34Chrystal Goby 18 3 5 2 3 - - 4 3 4 5 3 3 2 1 2 40

Dragonette 19 2 2 2 2 1 2 1 2 1 1 2 1 - - 4 23Mackerel 20 2 2 2 - 3 3 2 1 - 3 5 5 2 - 4 34

Horse Mack 21 1 1 - 3 3 2 3 - 2 2 4 2 - 2 1 26Maurolicus 22 3 3 3 4 1 3 3 3 3 - - 3 3 2 3 37

Sandeel 23 - - - - 1 - - - - - - - 1 2 - 4Other species 24 5 3 5 1 3 5 3 3 4 3 2 3 6 8 5 59

Saithe 25 3 5 4 6 8 7 6 6 8 7 9 6 5 8 5 93Total 1-25 92 86 88 84 88 87 86 85 87 89 81 89 91 87 83 1303

C


Sprat 2 90% 80% 100% 11% 10% 70% 33% 100% 67% 50% 38% 100% 70% 11% 78% 61%Sardine 3 86% 67% 67% 14% 43% 100% 100% 57% 43% 43% 43% 43% 43% 43% 71% 57%

Anchovy 4 50% 100% 50% 50% 100% 100% 50% 100% 50% 100% 50% 100% 0% 0% 50% 63%Cod 5 100% 100% 100% 0% 33% 67% 0% 67% 100% 100% 0% 100% 100% 67% 0% 62%

Haddock 6 86% 100% 100% 43% 57% 50% 86% 100% 71% 86% 0% 57% 71% 43% 75% 68%Whiting 7 100% 100% 100% 29% 57% 57% 67% 100% 100% 43% 71% 100% 100% 86% 43% 77%

Hake 8 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 0% 100% 93%Rock ling 9 75% 100% 75% 100% 50% 50% 100% 100% 50% 0% 100% 75% 75% 25% 50% 68%

Plaice 10 67% 100% 100% 0% 33% 67% 33% 100% 0% 100% 0% 100% 0% 33% 100% 60%Dab 11 100% 33% 33% 100% 67% 67% 67% 33% 67% 33% 0% 33% 100% 0% 67% 52%

Flounder 12 100% 100% 100% 40% 100% 100% 83% 100% 0% 100% 0% 100% 100% 0% 20% 70%L emon Sole 13 100% 100% 100% 100% 100% 80% 100% 100% 80% 80% 80% 80% 80% 80% 40% 87%L ong R Dab 14 0% 100% 100% 100% 100% 100% 0% 0% 0% 0% 0% - 100% 0% - 46%

Sole 15 0% 100% 100% 100% 0% 100% 0% 100% 0% 100% 100% 0% 100% 100% 0% 60%Solenette 16 86% 83% 57% 43% 43% 43% 67% 83% 71% 43% 33% 71% 71% 71% 29% 59%

Gobies 17 100% 0% 100% 0% 0% 100% 100% - 100% 0% 0% 0% 0% 100% 100% 50%Chrystal Goby 18 75% 100% 50% 75% 0% 0% 100% 75% 100% 100% 75% 50% 50% 25% 25% 60%

Dragonette 19 100% 100% 100% 100% 50% 0% 50% 100% 50% 50% 100% 50% 0% 0% 50% 60%Mackerel 20 100% 100% 100% 0% 50% 50% 100% 50% 0% 0% 0% 100% 0% 0% 100% 48%

Horse Mack 21 100% 100% 0% 100% 100% 0% 0% 0% 100% 0% 0% 100% 0% 100% 0% 47%Maurolicus 22 100% 100% 100% 100% 33% 100% 100% 100% 100% 0% 0% 100% 100% 67% 100% 80%

Sandeel 23 - - - - - - - - - - - - - - - -Other species 24 100% 100% 100% 0% 100% 100% 67% 100% 33% 33% 67% 100% 100% 100% 67% 78%

Saithe 25 50% 83% 67% 83% 83% 100% 67% 83% 100% 100% 100% 100% 83% 100% 67% 84%1-25 83.2% 84.6% 79.3% 43.3% 51.0% 63.8% 66.3% 79.1% 60.0% 55.2% 37.8% 73.7% 66.7% 38.9% 48.9%

RANKING 2 1 3 13 11 8 7 4 9 10 15 5 6 14 12



actual species

Percentage agreement in species identification per speciesModal or

actual species

Weighted mean62.2%


5 Identify sources of misidentification of larvae

Although overall agreement in larval fish identification increased during the second round and after distinguishing characteristics of major larval fish groups were clari-fied, some difficulties still appeared to occur in correctly identifying particular spe-cies. These difficulties occurred in clupeoid, in the distinction between cod and saithe larvae as well as in distinguishing dab from plaice larvae. In clupeoid the major source of misidentification lies in the difficulties to count myotomes, particularly in determining where to start and to end counting. Furthermore, without the aid of polarization equipment it is often difficult to clearly identify single myotomes close to the head as well as in small larvae in general. Larvae handling with needles and tweezers (needed for positioning of the individual larvae for myotome counting) produced damage that introduced some counting errors towards the end of the mi-croscopic analyses.

Small cod and saithe larvae often show similar pigmentation in the mid-tail area, the only distinguishing feature remaining is the tiny pigment spot at the tip of the tail in cod. These spots are often overlooked and the specimen then erroneously identified as saithe.

Major distinguishing character for dab and plaice is the double row of pigmentation along the ventral side of the tail. While in dab the spacing in the spots is more regular than in plaice, this is in some cases very hard to decide upon. The secondary charac-teristic that dab are smaller at any developmental stage than plaice can only be con-sulted if comparative material of the respective other species is available.


6 Preservation methods of fish larvae

It is important that fish larvae are preserved in a fixative as soon as possible after catching. Shrinkage of fish larvae, causing distortion of the vertebral column (Figure 7.1) occurs quickly after catching even in larvae that are kept in cool conditions or on ice. For best preservation fish larvae should be put in a preservative fluid immedi-ately after catch.

Figure 7.1. Distorted vertebral column in a fish larva which was sorted in a cool environment from the catch before preservation in 4% buffered formaldehyde.

Different methods of preservation are available for fish larvae (e.g. (Steedman, 1976)). Fixation in 4% formaldehyde solutions is a widely used preservative. The formalde-hyde solution needs to be buffered at pH 7. Alkaline or acidic formaldehyde solu-tions cause loss of pigmentation or of calceus structure, respectively, in the larvae. Borax and sodiumacetate-trihydrate are often used to buffer the formaldehyde solu-tions. Sodiumacetate-trihydrate is a more stable buffer compared to Borax and Borax is also likely to produce a too high, alkaline pH. Formaldehyde causes some shrink-age of the fish larvae (Fox, 1996, Santos et al., 2009), but larvae characteristics are well preserved, though some of the pigmentation is lost (Figure 7.2).

Figure 7.2. Fish larvae immediately after catching preserved in 4% buffered formaldehyde. Notice the undistorted vertebral column.


Due to the health hazards of formaldehyde other fixatives such as ethanol are used for preservation. Ethanol also has the advantage that larvae can be used for DNA analysis, and otoliths from the larvae can still be used for analysis. However, shrink-age in ethanol preserved larvae is much larger compared to formaldehyde preserved larvae (Santos et al., 2009, Fox, 1996) and pigmentation is lost in ethanol.

Pigmentation of the larvae, especially the yellow and red pigments, disappear in both formaldehyde and ethanol solutions due to pigment oxidation. (Mastail and Bataglia, 1978, Bigot, 1979) developed a solution, Bataglia sauce, in which the pigmentation on the larvae is better preserved.

Recipe for Bataglia sauce (10 litre)

Ingredient Quantity CAS number

Formaldehyde 36% (39% w/v), HCHO, MW: 30.03 g/mol

4 litre 50–00–0

Propanediol-1,2, CH3-CHOH-CH2OH, MW: 76,1 g/mol

2 litre 57–55–6

Distilled water 4 litre

EDTA: Ethylene Diamine Tetra acetic Acid disodium salt dehydrate, MW: 372.24 g/mol

40 g 6381–92–6, white crystals

BHA: Butyl Hydroxyl Anisole C11H16O2, 2-tert-Butyl-4-methoxyphenol

16 g 121–00–6,

orange-brown crystals

L(+) Ascorbic acid (vitamin C) 4 g 50–81–7, yellow crystals

Sodium glycerophosphate hydrate (glyc-erol), C3H5(OH)2PO4,xH2O, MW: 216.04 g/mol

120 to 300 g 5507, white crystals, 3–41–1


Preparation of Bataglia sauce (note: the dilution of the chemicals takes a long time!)

1 ) Dissolve 40 g EDTA in 1 litre distilled water with magnetic stirrer. Buffer to pH 7 with glycerol.

2 ) Dissolve 16 g BHA in 1 litre propanediol and stir with magnetic stirrer. 3 ) Mix into a 10 litre beaker with a magnetic stirrer 4 litre formaldehyde

with 40 to 100 gr glycerol and buffer to pH 7. 4 ) Add EDTA dissolved in distilled water. Stir well! 5 ) Add BHA dissolved in propanediol. Stir well! 6 ) Add the remaining 1 litre of propanediol. Stir well! 7 ) Add ascorbic acid. Stir well! 8 ) Buffer to pH 7 with 20 to 50 gr glycerol. 9 ) Add remaining 3 litre distilled water. The mixture may become whitish for

a moment. 10 ) Buffer to pH 7 with 20 to 50 gr glycerol. Let it stir for about 30 minutes. 11 ) For storage, use a bottle with a double-seal, leak-resistant closure. 12 ) Wait for 10 days before using. Keep the solution at >15°C (not in the

fridge!). A thermal shock may induce polymerisation of formalin. This does not affect the solution’s properties. Filter the solution (but it is not easy!) or depolymerise with sodium carbonate (it is not easy too!).

13 ) Finally, the samples are preserved in seawater using 6% of the Bataglia so-lution (which is enough when plankton account for ¼ of the sample vol-ume). The resulting concentration of formalin in the sample is less than 1%.

Lugol iodine solutions (Steedman, 1976) can be used for preservation of fish larvae. However due to the iodine the larvae are stained yellow-orange. Before species iden-tification, the stain needs to be removed by putting the larvae in another chemical.

DNA analysis of larvae can be done on ethanol preserved samples. Some methods have been developed to carry out DNA analysis on formaldehyde or Bataglia sauce fixed larvae as well (Goodsir et al., 2008, Lelievre et al., 2010). However, the DNA analysis on formaldehyde fixed larvae is more expensive compared to the ethanol fixed analysis.

After preservation in 4% buffered formaldehyde or Bataglia sauce the larvae samples can be analysed in Steedman solution containing propylene phenoxetol and propane-1,2-diol (Steedman, 1976). These chemicals also fix most of the formaldehyde fumes from the fixed larvae. The larvae can be kept in this solution for up to 10 years at room temperature before deteriorating (Steedman, 1976). For long-term storage Steedman solution with the addition of 2% buffered formaldehyde is recommended.

Long-term storage of fish larvae samples should be done in dark and cooled storage rooms to prevent deterioration and loss of pigmentation. The pH should be kept at 7 and needs to be checked regularly.


7 References

Bigot, J. L. 1979. Identification des zoés de tourteau (Cancer pagurus L.) et d’étrille (Macropipus puber L.). Comparaison avec d’autres zoés de morphologie très voisine. ICES CM1979/L:17.

Ehrenbaum, E. 1909. Eier und Larven von Fischen, Lipsius & Tischer, Kiel und Leipzig.

Fahay, M. P. 1983. Guide to the early stages of marine fishes occuring in the western North Atlantic Ocean, Cape Hateras to the southern Scotian Shelf. J. Northw. Alt. Fish. Sci., 4: 423.

Fox, C. J. 1996. Length changes in herring (Clupea harengus) larvae: Effects of capture and storage in formaldehyde and alcohol. Journal of Plankton Research, 18: 483–493.

Goodsir, F., Armstrong, M. J., Witthames, P. R., Maxwell, D. L., and Fox, C. J. 2008. The use of species-specific TaqMan probes for identifying early stage gadoid eggs following formaldehyde fixation. ICES Journal of Marine Science, 65: 1573–1577.

Lelievre, S., Verrez-Bagnis, V., Jerome, M., and Vaz, S. 2010. PCR-RFLP analyses of formalin-fixed fish eggs for the mapping of spawning areas in the Eastern Channel and Southern North Sea. Journal of Plankton Research, 32: 1527–1539.

Mastail, M., and Bataglia, A. 1978. Amelioration de la conservation des pigments du zooplancton. ICES C.M.1978/ L:20: 5.

Moser, H. G., Richards, W. J., Cohen, D. M., Fahay, M. P., Kendall, A. W. J., and Richardson, S. L. 1984. Ontogeny and Systematics of Fishes.

Munk, P., and Nielsen, J. G. 2005. Eggs and larvae of North Sea fishes, Biofolia, Frederiksberg, Denmark.

Nichols, J. H. 1971. Pleuronectidae. Fiches Ident. Oeufs Larves Poissons. 4–6. 18 pp.

Nichols, J. H. 1976. Soleidae. Fiches Ident. Oeufs Larves Poissons. 150/151. 10 pp.

Ré, P., and Meneses, I. 2009. Early stages of marine fishes occuring in the Iberian peninsula. 283 pp.

Russell, F. S. 1976. The eggs and planktonic stages of British marine fishes, Academic Press, London.

Santos, J. N. S., Araujo, F. G., and Silva, D. S. 2009. Length correction for early-juvenile Brazilian herring Sardinella janeiro (Eigenmann, 1894) after preservation in formalin, ethanol and freezing. Neotropical Ichthyology, 7: 87–92.

Schmidt, J. 1905. The pelagic post-larval stages of the Atlantic species of Gadus. A monograph with 3 plates and 16 figures in the text. Meddr Komn Danm Fisk- og Havunders Ser Fisk-eri l, 4: 1–77.

Steedman, H. F. 1976. Zooplankton fixation and preservation, Unesco press, Paris.


Annex 1: List of participants

Name Address Phone/Fax E-mail

Maria Manuel Angélico

IPIMAR, Av Brasilia, Lisboa, Portugal

+351213027000 [email protected]

Elvire Antajan Ifremer, 150 Quai Gambetta. 62200 Boulogne sur Mer France


Paul Bouch Cefas Laboratories, Pakefield Road, Lowestoft NR33 0HT UK


Cindy van Damme (Chair)

IMARES, Haringkade 1, 1976 CP Ĳmuiden, The Netherlands

+31317487078/+31317487326

[email protected]

Denise Doran Cefas Laboratories, Pakefield Road, Lowestoft NR33 0HT UK


Ruben Hoek IMARES, Haringkade 1, 1976 CP Ĳmuiden, The Netherlands


Hannes Höffle DTU Aqua National Institute of Aquatic Resources Kavalergården 6 DK-2920 Charlottelund Denmark

004535883481/004535883333

[email protected]

Matthias Kloppmann (Chair)

vTI-SF, Palmaille 9, 22767 Hamburg, Germany


Christophe Loots Ifremer, 150 Quai Gambetta. 62200 Boulogne sur Mer France


Hildegunn Mjanger

Institute of Marine Research Postbox 1870 Nordnes 5817 Bergen Norway

+4755238500/8661

[email protected]

Enda O'Callaghan AFBI, 18 Newforge Lane, Belfast, BT9 5PX, Northern Ireland

02890255449 [email protected]

Ineke Pennock IMARES, Haringkade 1, 1976 CP Ĳmuiden, The Netherlands


mailto:[email protected]





Name Address Phone/Fax E-mail

Lynette Ritchie MSS, 375 Victoria Rd, Aberdeen UK


Ann-Christin Rudolphi

Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Marine Research, Box 4, SE-453 21 Lysekil, Sweden

+46104784044 +46761268035

[email protected]

Jan Henrik Simonsen

Institute of Marine Research Nye Flodevigvei 20, 4817 His Norway

+4737059025/ +4798626755

[email protected]

Lisbet Solbakken Institute of Marine Research Postbox 1870 Nordnes 5817 Bergen Norway

+4755238500/8665

[email protected]

Birgit Suer vTI, Institut für Seefischerei, Palmaille 9, 22767 Hamburg Germany






Annex 2: Agenda

Monday 5 September

13:30 Start Workshop

13:30 Welcome and general announcements

13:40 Introduction round

13:50 Introduction to larvae identification and available information on fish larvae identification (presentation Matthias)

15:00 Break

15:15 1st individual larvae identification trial

17:30 End of the day

Tuesday 6 September

9:00 Continue 1st individual larvae identification trial

12:30 Lunch

13:30 Discuss results of the first individual larvae identification trial. Identify sources of misidentification

15:00 Break

15:15 Review available information on larvae identification (break out in groups)


Wednesday 7 September

9:00 Review available information on larvae identification (presentations of the break out in groups)

11:00 Break

11:15 Second individual larvae identification trial

12:30 Lunch

13:30 Continue the second individual larvae identification trial


19:00 Workshop diner in Haarlem

Thursday 8 September

9:00 Discuss results of the second individual larvae identification trial

11:00 Break

11:15 Review available information on larvae identification (break out in groups)

12:30 Lunch

13:30 Establish and agree on larvae identification keys (presentations of the break out groups)

15:00 Break


15:15 Compile overview of methods of larvae preservation used and agree on an overview of suggested future methods for different survey demands


Friday 9 September

9:00 Report writing: discussion conclusions, recommendations and future

11:00 Break

11:15 Report writing: discussion conclusions, recommendations and future

12:00 Final discussions

12:30 End of the workshop


Annex 3: WKIDCL terms of reference for the next meeting

The Workshop on the identification of clupeoid larvae (WKIDCL), chaired by Cindy van Damme*, the Netherlands, and Matthias Kloppmann*, Germany, will meet in Hamburg, Germany, 2–6 September 2013 to:

a ) Carry out comparative larvae identification trials following the pattern of trial – analysis – retrial;

b ) Review available information on the identification of clupeoid larvae on the Northeast Atlantic Shelf, under special consideration of larvae’s ap-pearance with ongoing development;

c ) Identify sources of misidentification of larvae; d ) Standardize sample processing and data analysis of clupeoid larvae sur-

veys.

WKIDFL will report by 15 October 2013 (via SSGESST) for the attention of the SCI-COM.

Supporting information Priority Different clupeoid larvae surveys, e.g. herring larvae and MIK are carried

out on the Northeast Atlantic Shelf and provide essential data for the assessment of fish stocks in the North Sea, the Irish Sea and the Baltic.

Scientific Justification Larvae surveys are currently carried out by different countries and the result of these surveys are of direct importance for the assessment. Since larvae can easily be mixed up, effective quality control and proper larvae identification is essential to the survey results. The overall agreement on clupeoid larvae identification between participants at the 2011 WKIDFL workshop was 59%. Another workshop is required to increase correct larvae identification, to establish a reliable identification key and to exchange experience of all involved participants.

Relation to Strategic Plan

Directly relevant to the advice on herring and sprat fisheries.

Resource Requirements

No specific resource requirements beyond the need for members to prepare for and participate in the meeting

Participants Scientists and technicians of the involved laboratories; at minimum eight participants.

Secretariat Facilities None

Financial No financial implications

Linkages to Advisory Committees

The survey data are prime inputs to the assessments which provide ACOM with information required for responding to requests for advice/information from NEAFC and EC DG MARE.

Linkages to other Committees or Groups

HAWG, SSGESST, IBTSWG, WGIPS, WGACEGG

Linkages to other Organizations

None

Cost Share


Annex 4: Recommendations

Recommendation Adressed to

1. WKIDFL recommends that workshops on general fish larvae identification are held regularly (every 5 years) to exchange knowledge and to increase agreement on sample processing and identification of fish larvae. Especially when conducting ecosystem wide surveys it is important to standardize methods and larvae identification.

SSGESST, SCICOM

2. WKIDFL recommends a workshop on the identification of clupeoid larvae in 2013 to increase the agreement of clupeoid larvae identification in the dedicated surveys

SSGESST, WGIPS, IBTSWG, HAWG

3. WKIDFL recommends to use validated larvae for future clupeoid larvae identification workshops, collected from incubation of eggs.

WGACEGG, WGIPS

4. Based on the experiences at the workshop it is recommended that a binocular microscope should have the following features: Options for a black or white stage plate for use with incident (top) light. A transparent stage plate for transmitted (bottom) light. Dark field illumination for contrast. Adjustable brightness. Magnification with click stops. Magnification should be at least 1.6x. A choice of 10x and 20x eyepieces. Adjustable binocular head and ergonomic design to allow flexibility of movement. Adjustable focus on all eyepieces. Calibrated eyepiece graticules. Double (fibre optic) cold light source, with adjustable focus, to avoid shadows. Polarization equipment. Mechanical stages to position samples easily in the field of view and to hold the samples firmly.

All participants, Chairs of future larvae identification workshops

5. It is recommended that a discussion sharepoint is kept open for all participants to upload pictures of difficult fish larvae and discuss the identification with the other participants

ICES secretariat

report of the workshop on the identification of clupeoid, flatfish, … reports/expert group... ·...

Documents