Homsir: An international project on horse mackerel stock identification research in the ices area and in the Mediterranean Sea



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Working Document for the ICES Working Group of the Assessment of Mackerel, Horse Mackerel, Sardine and Anchovy. Copenhagen, 14-23 September 2000.
HOMSIR: An international project on horse mackerel stock identification research in the ICES area and in the Mediterranean Sea.

By

Abaunza, P1., Murta, A.2, Teia, A.2, Molloy, J.3, Nascetti, G.4, Mattiucci, S.5, Cimmaruta, R4., Magoulas, A.6, Sanjuan, A.7, MacKenzie, K.8, Iversen, S.9, Dahle, G.9, Gordo, L.10, Zimmermann, C.11, Stransky, C.11, Santamaria, M.T.12, Ramos, P2, Quinta, R.2, Campbell, N.8.



1 Instituto Español de Oceanografía (IEO). P.O. box 240, 39080 Santander, España (Spain).

2 Instituto de Investigação das Pescas e do Mar (IPIMAR). Av. Brasilia, 1400 Lisboa, Portugal.

3 The Fisheries Research Centre (FRC) of the Marine Institute (MI). Fisheries Research Centre, Abbottstown, Dublin 15, Ireland.

4 Tuscia University. Department of Enviromental Sciences (DISA-UNITUS). Department of Environmental Sciences of the Tuscia University, Via S. Camillo de Lellis, I-01100 Viterbo, Italy.

5 Universitá di Roma “La Sapienza”. Istituto di Parassitología. Piazzale Aldo Moro nº5, 00185 Rome, Italy.

6 Institute of Marine Biology of Crete (IMBC) Genetics Department. Main Port, GR 710 013, IRAKLIO, Greece. P.O.box: 2214.

7 Universidade de Vigo. Facultade de Ciencias do Mar e Bioloxía. Department of Bioquemistry, Genetics and Inmunology. Lagoas-Marcosende 36200-Vigo, España (Spain).

8 The University of Aberdeen (UNIABDN). Department of Zoology. Tillydrone Avenue, Aberdeen, AB24 2TZ, UK (United Kingdom).

9 Institute of Marine Research (IMR). P.O. box: 1870 Nordnes, N-5817 Bergen, Norway.

10 Faculdade de Ciências da Universidade de Lisboa (FCUL). Departamento de Zoologia e Antropologia. Bloco C-2, Campo Grande, P-1700 Lisboa, Portugal.

11 Bundesforschungsanstalt für Fischerei (BFA Fi). Institut fur Seefischerei. Palmaille 9, D-22767 Hamburg Germany.

12 Instituto Español de Oceanografía (IEO). Carretera San Andrés s/n , 38120 Santa Cruz de Tenerife, Islas Canarias, España (Spain).

ABSTRACT

The aim of this project is to assess the stock structure of the horse mackerel (Trachurus trachurus), which is an important target species in many north-east Atlantic and Mediterranean fisheries. The project will provide information currently lacking for an effective definition of horse mackerel stock boundaries, and will evaluate the status of the horse mackerel populations. The overall objective will be achieved integrating the results from several techniques such as genetic markers, other biological tags like morphometric studies and the use of parasites, physical tagging and life history traits (growth, reproduction and distribution). The genetic stock assessment will be performed by means of five different genetic approaches comprising the analysis of allozymes, the mitochondiral DNA and the microsatellite DNA. The proposed research will therefore set-up and improved multi-disciplinary tool for fish stock identification, and an exhaustive knowledge of horse mackerel stock structure, in order to allow an enhanced management of horse mackerel resource in European Union waters in short, medium and long term.



INTRODUCTION:
The project “HOMSIR” : A multidisciplinary approach using genetic markers and biological tags in horse mackerel (Trachurus trachurus) stock structure analysis (QLRT-PL1999-01438), was approved last year within the Fifth Framework Programme (1998-2002) for scientific research (European Community), in the area of “Quality of life and management of living resources”. The duration of the project is three years 2000-2002, and the current task is the analysis of the samples collected during 2000.

Stock identification research:
The catches of Trachurus trachurus in the Notheast Atlantic and in the Mediterranean area rise up over the 500,000 t, representing an important source of income for local economies (FAO 1998). There is a stock characteristic in carangidae that make them very suitable for developing sustainable fisheries, in contrast with the clupeids. This is their natural pattern of variation characterized by the “steady situation”, that means without large variation in catches year after year (Caddy & Gulland, 1983; Bas, 1995). However, this property could change if the pattern of fishing changes as can be observed in the historical development of the “western stock” in the Northeast Atlantic horse mackerel (ICES, 2000). To assess the fishing pattern and the state of the resource a comprehensive knowledge of the stock structure is required (Gulland, 1971; Hilborn & Walters, 1992). In the ICES area the stocks are defined mainly according to the eggs distribution, resulting in: The western stock (North-east continental shelf of Europe, from France to Norway); the North sea stock (North Sea area) and the Southern stock (Atlantic waters of the Iberian península). Special attention has been focused on the current stock definition, recognizing the uncertainties in the distribution limits and the lack of biological information to support such stock units (ICES,1992, 2000) . There are just a few papers about the stock structure in the ICES area and they cover only a small part of the stock distribution, or the information is so scarce that it is not possible to conclude the delineation of subpopulations. In the Mediterranean area and in the North-African waters, the biological information is also scarce and even though there is no specific mention of Trachurus trachurus (only Trachurus spp.) in some revision work on fisheries statistics (FAO, 1997).

The concept of stock can be considered under two points of view: the genetic approach and the operational approach (Tyler & Gallucci, 1980; Booke, 1981; Carvalho & Hauser, 1994). In essence, the stock concept describes the characteristics of the units assumed homogeneus for particular management purpose (Begg and Waldman, 1999).

Fish stocks are identified on the basis of differences in characteristics between stocks. Investigation of any single characteristic will not necessarily reveal stock differences even when “true” stock differences exist (Type I error). To overcome this difficulty an holistic approach of fish stock identification, involving a broad spectrum of techniques, appears to be pertinent (Begg & Waldman, 1999). In this project, we apply the following techniques to the same data set: Genetic identification by using diferent molecular genetic markers; Parasitological surveys on horse mackerel samples, morphometric studies based on body and otolith shape analysis; physical tagging and life history traits analysis.
OBJECTIVES:
The overall objective of this proposal is the biological stock identification of the horse mackerel (Trachurus trachurus) throughout its whole geographical distribution range, from North-eastern Atlantic to Mediterranean Sea.

To achieve the overall objective, the following complementary goals will be pursued:



  • Identification of horse mackerel populations and stocks from the Mediterranean Sea and North-east Atlantic using different molecular genetic markers (allozyme electrophoresis, mitochondrial DNA sequencing, DNA microsatellite, SSPC).

  • Evaluation of the levels of genetic variability in the identified populations.

  • Estimation of the genetic divergence and assessment of the genetic relationships among stock units.

  • Estimation of gene flow between populations and stocks by means of indirect methodologies based on genetic data, in order to highlight the degree of population subdivision.

  • Evaluation of parasitic infection levels by means of epizootiological parameters (prevalence, mean intensity and/or abundance of metazoan infection) in the horse mackerel samples.

  • Interpretation of the parasitology results in terms of host population biology (e.g.: migration routes, feeding and spawning areas).

  • Application of the geometric morphometrics on the horse mackerel body and otoliths, as a tool for the identification of intraspecific variation.

  • Testing of body and otolith shape differences among areas, by applying multivariate statistical techniques.

  • Evaluation of the viability in the application of internal and external tags in the horse mackerel.

  • Use of physical tagging in selected areas to infer patterns of movement and degree of mixing among horse mackerel stocks or populations.

  • Examination of the different population parameters: growth rate, maturity ogive, fecundity, age structure, distribution and abundance, to identify horse mackerel management units.

  • Assessment of the effects of the extrinsic factors (fishing pressure), the space and time, in the population parameters observed.

  • Correlation between host population biologicaly data, tagging results, genetic data and parasitic fauna composition in the identified horse mackerel units.

  • Guidelines drawn from the obtained results for the management of horse mackerel, aimed at maintaining genetic diversity and demographic structure of the resource in EU waters.



Short description of the work:
The operative structure of the project is articulated in various workpackages that include tasks regarding the different approaches to be taken.

A first task is the sampling of horse mackerel in the whole study area: Northeast Atlantic and Mediterranean Sea (Fig.1). To carry out this task, 20 sampling sites have been selected in the horse mackerel distribution area from which a total of 200 specimens will be caught (100 each year in two years of sampling). All the techniques will be applied on the same fish. The horse mackerel will be frozen and will be sent to the responsibles by the reproductive (part of the life history traits) and parasitological analysis. Tissue samples will be taken previously, following the protocols, and sent to the responsible scientists for genetic analysis. Basic biological data will be recorded from all the individuals, from all the selected sites, and sent to responsible scientists for their analysis.



Genetics:With the aim to identify the boundaries and the genetic status of the various stocks, different molecular approaches will be used, in order to magnify their resolution power and to validate the results obtained with each single technique: multilocus allozyme electrophoresis (MAE), microsatellite DNA (msDNA), mitochondrial DNA sequencing (mtDNA) and single-strand conformation polymorphism (SSCP).

Parasites: The use of parasites as biological tags requires the identification of the species by applying morphological criteria and molecular techniques (i.e. MAE analysis). The latter is specially necessary to identify anisakid nematods. The analysis of infestation levels allows us to identify parasite tags and to interpretate parasites distribution in terms of horse mackerel population biology.

Morphometry: Horse mackerel specimens from each location will be analysed to find body and otolith shape differences among areas or samples.

Tagging: Experiments in artificial tanks provide useful information on the viability of the artificial tagging, in order to carry out a preliminary tagging operation limited to a selected area, for migration studies.

Life history traits: Growth, reproduction and distribution are the resultant in space and time of the population dynamic characteristics. The analysis of these factors will allow the identification of production units or stocks.

Finally all the data will be integrated to assess the status and the structure of horse mackerel stocks.







Innovative aspects:
The real definition and delimitation of stocks for a pelagic fish species, such as horse mackerel, is only possible when the whole distribution area of the species is included in the study. This project will provide the opportunity to carry out, for the first time, such an extensive study using the most advanced techniques on horse mackerel sampled in selected sites of North-east Atlantic and Mediterranean waters, covering its whole range. In particular, a firm background on horse mackerel population genetics will provide quick and reliable tools to identify and assess the status of fish stocks. In paticular, well planned population genetic studies require the analysis of a significant number of individuals with multiple genetic markers applied. All the genetic techniques that will be employed in this research project are simple, rapid, safe and relatively inexpensive. They will allow to investigate horse mackerel samples from the whole range of the species with different genetic markers (MAE, mtDNA sequences, msDNA and SSCP) simultaneously. This will increase the resolution power and the accuracy of the results obtained concerning genetic diversity, the differentiation and gene flow of the horse mackerel from the Atlantic and Mediterranean seas.

Another innovative aspect of the project is represented by the integration of genetic and biological data. Genetics, other biological tags and tagging (morphometry, parasitic composition analysis, physical tagging) have never been compared in this species. Moreover studies carried out using a large number of different approaches, as proposed here, have been rarely accomplished on pelagic fish species. The results expected will provide both the detection and the identification of biologically defined horse mackerel stocks in the North-east Atlantic Ocean and Mediterranean Sea, and the scientific base to plan a sustainable management of this fisheries resource in European waters.

Finally, the multi‑disciplinary approach used here will constitute a scientific reference for the assessment of exploited fish stocks and for a sustainable management and conservation of fisheries resources.

REFERENCES
Bas, C. 1995 . Ecological structures: expansion and replacement . Sci. Mar., 59(3-4): 373-380.

Begg, G.A., Waldman, J.R. 1999. An holistic approach to fish stock identification. Fish. Res. 43: 35-44.

Booke, H.E. 1981. The conondrum of the stock concept – Are nature and nurture definable in fishery science?. Can. J. Fish. Aquat. Sci. 38: 1479-1480.

Caddy, J.F., Gulland, J.A. 1983. Historical patterns of fish stocks. Marine Policy, nº Oct. 1983: 267-278.

Carvalho, G. R. & T. J. Hauser, 1994. Molecular genetics and the stock concept in fisheries. Rev. Fish Biol. Fish., 4: 326-350.

FAO. 1997. Long- and short-term trends of Mediterranean fishery resources. FAO Studies and Reviews, Nº 69., 71 pp.

FAO. 1998. Yearbook of fishery statistics. Capture production. FAO Fisheries Series No. 50. (or FAO Statistics Series No 140).

Gulland, J. A. 1971. Ecological aspects of fishery research. Adv. Ecol. Res., 7: 115-176

Hilborn, R., Walters, C.J. 1992. Quantitative fisheries stock assessment. Choice, dynamics & uncertainty. Chapman & Hall. New York, 570 pp.

ICES, 1992. Report of the Study Group on the Stock Identity of Mackerel and Horse Mackerel. ICES C.M. 1992/ H:4.



ICES, 2000. Report of the Working Group on the Assessment of Mackerel, Horse Mackerel, Sardine and Anchovy. ICES C.M. 2000/ACFM:5.

Tyler, A.V., Gallucci, V.F. 1980. Dynamics of fished stocks. In: R.T. Lackey and L.A. Nielsen (eds): Fisheries Management. pp: 111-147. Blackwell Scientific Publications.

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