Report of the Workshop on the Identification of Clupeoid Larvae (WKIDCLUP)

ICES WKIDCLUP REPORT 2014 SCICOM STEERING GROUP ON ECOSYSTEM SURVEYS SCIENCE AND TECHNOLOGY ICES CM 2014/SSGESST:04 Report of the Workshop on the identification of clupeoid larvae (WKIDCLUP) 1-5 September 2014 Hamburg, Germany 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. 2014. Report of the Workshop on the identification of clupeoid larvae (WKIDCLUP), 1-5 September 2014, Hamburg, Germany. ICES CM 2014/SSGESST:04. 36 pp. 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. © 2014 International Council for the Exploration of the Sea ICES WKIDCLUP REPORT 2014 | i Contents Executive summary ................................................................................................................ 1 1 Opening of the meeting ................................................................................................ 2 2 Adoption of the agenda ................................................................................................ 2 3 Clupeid Larvae identification and description ........................................................ 3 3.1 Herring Clupea harengus .................................................................................... 6 3.2 Sprat Sprattus sprattus ....................................................................................... 10 3.3 Sardine Sardine pilchardus ............................................................................... 12 3.4 Anchovy Engraulis encrasicolus....................................................................... 15 3.5 Sardinella Sardinella aurita and S. maderensis .............................................. 17 4 Larvae identification results ...................................................................................... 19 4.1 Methods for larvae identification trials ........................................................... 19 4.2 Results of larvae identification trials ................................................................ 19 4.3 Sources of misidentification of larvae .............................................................. 23 5 Preservation methods of fish larvae ......................................................................... 24 6 References ..................................................................................................................... 28 Annex 1: List of participants............................................................................................... 32 Annex 2: Agenda ................................................................................................................... 34 Annex 3: Recommendations ............................................................................................... 36 ii | ICES WKIDCLUP REPORT 2014 WKIDCLUP in Hamburg, Germany, 1-5 September 2014 Andreis Christophe Makarchouck Matthias Bastian Loots Ineke Enda O’Calla- Birgit Kloppmann Huwer Sakis Maik Pennock ghan Suer Lynette Kroupis Cindy Anne-Marie Tiedemann Dorothee Jérémy Marie Ritchie Elisabete Hen-van Palmén Bratt Moll Denis Leiditz riques Damme ICES WKIDCLUP REPORT 2014 | 1 Executive summary The Workshop on the Identification of Clupeoid larvae (WKIDCLUP) met from 1 to 5 Sep- tember 2014 in Hamburg, Germany, to calibrate clupeoid larvae identification. The meeting was chaired by Cindy van Damme, The Netherlands, and Matthias Kloppmann, Germany. In total 18 persons, representing 11 institutes from nine countries participated in the workshop. The majority of the time at the workshop was spent identifying fish larvae. The results promoted discussion and highlighted specific problem areas. These discussions led to the further development of standard keys and larval identification characteristic tables. There was a slight increase to 56% in the overall agreement in the larval identification. However, there was a decrease in herring larvae agreement, from 68% to 66% from the 1st to the 2nd round. Also for sardine larvae, the percentage agreement decreased, from 37% to 19%. For sprat and anchovy larvae percentage agreement increased, from 62% to 67% and 27% to 51% respectively. However, despite these results, it was encouraging to note that in the 1st round participants were mostly only using myotomes counts and thus confusing all larval species, while in the second round also developmental characteristics at length were taken into account and only herring and sardine were confused. In results of the 2nd round were probably due to the low quality of the available larvae and the rapid deterioration. For sprat, sardine and anchovy only limited numbers of larvae were available for the workshop and most of these were badly preserved. From the results, it became clear that the more experienced clupeoid larvae identifiers showed high agreement with the actual species. Thus, it is crucial for institutes to ensure a continuity of staff and constant training for the larval surveys and identification to guaran- tee and improve the quality of the data derived from these surveys. However, the results from the larval identification trials clearly show that there are still some uncertainties in the identification of clupeoid larvae. For herring larval indices are used for the assessment of the spawning stock. Thus, the cor- rect identification of the clupeoid larvae is important for the management of these stocks. The results of this workshop show that there is still room for improvement in herring larval identification. Clupeoid larval identification workshop should be conducted regularly (i.e. every 5 years) to increase agreement in identification as quality assurance of the larval identification of the surveys used in the assessments. Different preservation methods are available for the preservation of fish larvae. Partici- pants agreed that it is most important that fish larvae are put in preservative immediately after the catch in order to preserve the larval characteristics. Formaldehyde based preserv- atives create lower shrinkage in larvae compared to ethanol solutions. 2 | Report of the Workshop on the identification of clupeoid larvae (WKIDCLUP) 1 Opening of the meeting The meeting started at Monday 1 September 2014. In total, 11 institutes were represented from nine countries (see Table 1.1). In total, 18 participants joined the meeting (Annex 1). Table 1.1. Represented countries and institutes during WKIDFL 2011. COUNTRY INSTITUTE Denmark DTU- Aqua France Ifremer Germany TI (Hamburg and Rostock), IHF Latvia BIOR Netherlands IMARES Portugal IPMA Sweden IMR UK- Northern Ireland AFBI UK- Scotland MS 2 Adoption of the agenda The terms of reference for this meeting were: 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 appearance with ongoing development; c ) Identify sources of misidentification of larvae; d ) Standardize sample processing and data analysis of clupeoid larvae surveys. An agenda was sent round prior to the workshop. The adopted agenda can be found in Annex 2. ICES WKIDCLUP REPORT 2014 | 3 3 Clupeid Larvae identification and description WKIDCLUP compiled an overview of the reference literature used and the characteristics for identification of the different clupeoid larvae. The most used references for identification of fish larvae in the Northeastern Atlantic and Mediterranean are: (Ehrenbaum, 1909; Russell, 1976; Fahay, 1983; Moser et al., 1984; Munk and Nielsen, 2005). Before identification of fish larvae, some background information is needed. To get ac- quainted to major fish larvae description literature, the introduction chapter of Russell (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. In addition, information on the timing of sampling and the area where samples were collected should be available. Based on this, larval identification 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 is the stage between egg and metamorphosis. Larvae are the stage from hatching to attain- ment of characters that allow for identification according to descriptions of adult speci- mens. 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 development of the caudal fin with flexion of the urostyle. The above characteristics can and should 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

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