Doctoral Programme on Marine Ecosystem Health and Conservation
 The MARES Researchers and their Research
Population and sub-population structure of albacore tuna in the North Atlantic and Mediterranean.
PhD Code: MARES_12_11:
  • Host institute 1: P4 - Galway Mayo Institute of Technology (GMIT)
  • Host institute 2: P18 - AZTI-Tecnalia
  • Host institute 3: University of Bologna
Research fields:
  • T4 - Natural Resources: overexploitation, fisheries and aquaculture
  • Brophy Deirdre
  • Arrizabalaga Haritz
  • Fausto Tinti (University of Bologna -
Contact Person and email: Deirdre Brophy -

Subject description
The albacore tuna (Thunnus alalunga) is a widely distributed and highly migratory species occurring in all tropical and temperate oceans. Albacore distribution in the North Atlantic is not well described although spawning is thought to occur in tropical and subtropical regions off the coast of North Africa and in the Sargasso Sea (Beardsley, 1969; Pinccinetti et al., 1973). In the north Atlantic, young albacore migrate to temperate waters in late summer and autumn where they are commercially targeted (Bard, 1981). In the Mediterranean Sea the distribution of albacore is discontinuous with the highest concentrations occurring in the Tyrrhenian, Ionian, Adriatic and Aegean Sea (Megalofonou, 2000). Fish migrate between feeding areas in the north, where the commercial fishery is concentrated and localised spawning areas in the south (Marano et al., 1999).
Albacore support commercially important fisheries in the Northeast Atlantic and Mediterranean. From June-September, aggregations of juveniles and young adults are targeted by baitboat, trolling and pelagic trawling vessels from Spain, France and Ireland in the Bay of Biscay and surrounding waters (ICCAT, 2008).  In the Mediterranean, albacore are commercially exploited primarily by longlines and trolling, and are valuable for recreational fishing (Baez et al., 2011).
Tagging studies report a low rate of albacore migration between the Atlantic and Mediterranean (Arrizabalaga et al., 2004) and the two stocks are genetically distinct (Davies et al., 2011b; Montes et al., In press; Nakadate et al., 2005; Vinas et al., 2004), justifying their separate management. There is some evidence to suggest that independent subpopulations may also exist within the Northeast Atlantic (Davies et al., 2011b) and in the Mediterranean (Davies et al., 2011b; Montes et al., In press), however stock boundaries are not well defined and are not considered in the stock assessment. Failure to account for the existence of multiple  components within a management unit can lead to the potential collapse of the less productive component and a loss of resilience to environmental change (Carvalho and Hauser, 1994; Hutchinson, 2008). Improving current understanding of albacore stock structure is crucial to ensure that the stock assessment and management of the species is appropriately designed and robust to uncertainties.
Otoliths are calcium carbonate and protein based structures located in the inner ears of teleost fish which function in hearing and balance. They grow incrementally throughout a fish’s life at a rate that is proportional to somatic growth and their constituents are not resorbed; consequently they provide a permanent record of the fish’s life history (Secor et al., 1995). The chemical composition (Campana, 1999; Mei-Yu and Geffen, In press) and morphology (Cardinale et al., 2004) of the otolith are at least partly influenced by the surrounding environment. Fish that occupy different environments for part or all of their lives often show variation in otolith composition and structure. Measurements of otolith shape, incremental patterns and chemical composition are used to characterise fish from different geographic locations and elucidate stock structure (e.g.(Brophy and Danilowicz, 2002; Cadrin et al., 2010; Ferguson et al., 2011).
The proposed project aims to elucidate heterogeneity within the North Atlantic and Mediterranean albacore populations using otolith composition and morphometrics, growth and life history parameters. The information obtained will be used within a simulation modelling framework to investigate the consequences of the observed structuring for the overall productivity of the stock under various management scenarios. The project builds on previously completed research by the proposers (Arrizabalaga, 2003; Arrizabalaga et al., 2004; Arrizabalaga et al., 2007; Brophy et al., 2008; Davies et al., 2011a; Davies et al., 2011b) and also complements ongoing projects in which they are involved (Goñi et al., 2011; Montes et al., In press; Velado et al., 2011).
Otoliths and biological data will be obtained from albacore collected in the North Atlantic over two years; young fish will be sourced from commercial fishing operations in the Bay of Biscay and surrounding waters while mature albacore will be obtained from AZTI on board observers in the tropical tuna purse seiners unloading in Dakar (Senegal), as well as from scientific colleagues from the ICCAT Albacore working group.
Albacore from commercial fishing operations in the eastern and western Mediterranean will be sampled over two years. Efforts will be made to obtain collections of both feeding (the primary target commercial fishing efforts) and spawning fish (concentrated in the south).Material collected for use in previous projects will be available to the project. Stock composition of the fished aggregations may vary during the season due to temporal migrations of sub-units (Davies et al., 2011b). Efforts will be spread across the season to ensure that representative samples are collected, facilitating detailed temporal investigation of stock composition.
Otoliths will be photographed for shape analysis of the outline using fourier descriptors and shape indices. One of each pair will be prepared for analysis of chemical composition using ICP-MS (using analytically clean techniques) while the second will be prepared for measurement of daily increments at the larval core. Spatial and temporal variation in the measured parameters will be used to characterise albacore from the different areas.
Alternative albacore management strategies will be tested using simulation modelling(Kell et al., 2009; Kerr et al., 2010; Secor et al., 2009). This will include (i) an operational model to reflect alternative plausible stock structures (based on new knowledge generated in the project), an (ii) observation model that describes how pseudo-data are generated from the operating model, and (iii) a stock assessment and management model to derive estimates of stock status.  This framework will inform the choice of management strategies that are robust to stock structure uncertainties.
The student will divide their time between the Marine and Freshwater Centre at GMIT, Ireland (partner 1) and the Marine Research Division at AZTI-Tecnalia, Basque Country (partner 2) under the joint supervision of Dr Deirdre Brophy (GMIT) and Dr HaritzArrizabalaga (AZTI).  During years 1 and 2, the student will spend time in Ireland and Spain (depending on the pattern of the fishery) to ensure maximum spatial coverage in their sampling. Outside of the sampling period, in years 1 and 2 the student will be based at GMIT working on the stock identification aspects of the project. The student will spend 6-9 months at AZTI working on stock-simulation (end year 2, start year 3).
Dr Brophy has 10 years of experience in teaching, research project management and postgraduate supervision (4 MSc and 6 PhD students supervised to completion). Her research supports the sustainable management of fisheries within an ecosystem context, with emphasis on fish population biology, stock structure, and early life history processes. She has extensive experience in the analysis of fish age and growth and the application of advanced otolith techniques (e.g. shape analysis and chemical composition) to questions of life history and stock structure. She has over 30 publications in the peer-reviewed literature and has secured over €1.7 million in research funding since 2004. Her students have a strong track record of publishing, presenting at international conferences and securing relevant employment.
Haritz Arrizabalaga holds a PhD in Marine Science (“An holistic approach to albacore population structure”). He currently works as a Principal Investigator at AZTI Tecnalia, leading research projects about albacore and bluefin tuna fisheries and population dynamics. He has participated in over 20 national and international research projects, and has been an active member of the Standing Committee for Research and Statistics (SCRS) of the International Commission for the Conservation of Atlantic Tuna since 2002. He chaired the SCRS Subcommittee on Ecosystems between 2006 and 2010, and chairs the albacore working group since 2011. He participated in the Scientific Committee of the Indian Ocean Tuna Commission (IOTC) from 2000-2002. His main research areas include tuna population structure, stock assessment, environmental influence on population dynamics, habitat use, migrations and ecology. He regularly supervises master and PhD students and has published 18 peer reviewed papers, coedited one book and contributed over 35 working documents in both ICCAT and IOTC. He has lead several research projects involving biological sampling and analysis of albacore and bluefin tuna
  • Arrizabalaga, H., 2003. Estructura poblacional del atún blanco (Thunnus alalunga Bonn. 1788): una aproximación multidisciplinary. Universidade de Vigo, p. 161.
  • Arrizabalaga, H., Costas, E., Juste, J., González-Garcés, A., Nieto, B., Victoria, L.-R., 2004. Population structure of albacore Thunnus alalunga inferred from blood groups and tag-recapture analyses. Marine Ecology Progress Series 282, 245-252.
  • Arrizabalaga, H., Lopez-Rodas, V., Costas, E., Gonzalez-Garces, A., 2007. Use of genetic data to assess the uncertainty in stock assessments due to the assumed stock structure: the case of albacore (Thunnus alalunga) from the Atlantic Ocean. Fishery Bulletin 105, 140-146.
  • Baez, J.C., de Urbina, J.M.O., Real, R., Macias, D., 2011. Cumulative effect of the North Atlantic Oscillation on age-class abundance of albacore (Thunnus alalunga). Journal of Applied Ichthyology 27, 1356-1359.
  • Bard, F.X., 1981. Le thon germon (Thunnus alalunga Bonnaterre 1788) de l’Ocean Atlantique. De la dynamique des populations à la strategie demographique. Université de Paris, France.
  • Beardsley, G.L., 1969. Proposed migrations of albacore, Thunnus alalunga, in the Atlantic Ocean. Transactions of the American Fisheries Society 98, 589-&.
  • Brophy, D., Danilowicz, B.S., 2002. Tracing populations of Atlantic herring (Clupea harengus L.) in the Irish and Celtic Seas using otolith microstructure. Ices Journal of Marine Science 59, 1305-1313.
  • Brophy, D., Gosling, E., Cosgrove, R., Davies, C.A., Mirimin, L., 2008. Stock structure and migration patterns in Atlantic albacore tuna—providing essential data for sustainable development and management of a valuable fishery., Report to BIM (Irish Sea Fisheries Board) under the Irish National Development Plan, Project No. 05.SM.T1.16.1.
  • Cadrin, S.X., Bernreuther, M., Danielsdottir, A.K., Hjorleifsson, E., Johansen, T., Kerr, L., Kristinsson, K., Mariani, S., Nedreaas, K., Pampoulie, C., Planque, B., Reinert, J., Saborido-Rey, F., Sigurosson, T., Stransky, C., 2010. Population structure of beaked redfish, Sebastes mentella: evidence of divergence associated with different habitats. ICES Journal of Marine Science 67, 1617-1630.
  • Campana, S.E., 1999. Chemistry and composition of fish otoliths: pathways, mechanisms and applications. Marine Ecology-Progress Series 188, 263-297.
  • Cardinale, M., Doering-Arjes, P., Kastowsky, M., Mosegaard, H., 2004. Effects of sex, stock, and environment on the shape of known- age Atlantic cod (Gadus morhua) otoliths. Canadian Journal of Fisheries and Aquatic Sciences 61, 158-167.
  • Carvalho, G.R., Hauser, L., 1994. Molecular-Genetics and the Stock Concept in Fisheries.  4, 326-350.
  • Davies, C.A., Brophy, D., Jeffries, T., Gosling, E., 2011a. Trace elements in the otoliths and dorsal spines of albacore tuna (Thunnus alalunga, Bonnaterre, 1788): An assessment of the effectiveness of cleaning procedures at removing postmortem contamination. Journal of Experimental Marine Biology and Ecology 396, 162-170.
  • Davies, C.A., Gosling, E.M., Was, A., Brophy, D., Tysklind, N., 2011b. Microsatellite analysis of albacore tuna (Thunnus alalunga): population genetic structure in the North-East Atlantic Ocean and Mediterranean Sea. Marine Biology 158, 2727-2740.
  • Ferguson, G.J., Ward, T.M., Gillanders, B.M., 2011. Otolith shape and elemental composition: Complementary tools for stock discrimination of mulloway (Argyrosomus japonicus) in southern Australia. Fisheries Research 110, 75-83.
  • Goñi, N., Fraile, I., Arregi, I., Santiago, J., Laconcha, U., Arrizabalaga, H., Estonba, A., 2011. Ongoing albacore research in the Bay of Biscay (Northeast Atlantic): the “Hegaluze 2010” Project, ICCAT Collective Volume Of Scientific Papers.
  • Hutchinson, W.F., 2008. The dangers of ignoring stock complexity in fishery management: the case of the North Sea cod. Biology Letters 4, 693-695.
  • ICCAT, 2008. Report of the 2007 ICCAT albacore stock assessment session (Madrid, Spain, July 5 to 12, 2007). Collected Volume of Scientific Papers  ICCAT, pp. 697–815.
  • Kell, L.T., Dickey-Collas, M., Hintzen, N.T., Nash, R.D.M., Pilling, G.M., Roel, B.A., 2009. Lumpers or splitters? Evaluating recovery and management plans for metapopulations of herring. Ices Journal of Marine Science 66, 1776-1783.
  • Kerr, L.A., Cadrin, S.X., Secor, D.H., 2010. Simulation modelling as a tool for examining the consequences of spatial structure and connectivity on local and regional population dynamics. Ices Journal of Marine Science 67, 1631-1639.
  • Marano, G., De Zio, V., Pastorelli, A.M., Rositani, L., Ungaro, N., Vlora, A., 1999. Synopsis on the biology and fisheries on Thunnus alalunga (Bonnaterre, 1788). Biology Marine Mediterranean 6, 192–214.
  • Megalofonou, P., 2000. Age and growth of Mediterranean albacore. Journal of Fish Biology 57, 700-715.
  • Mei-Yu, C., Geffen, A.J., In press. Taxonomic and geographic influences onfish otolith microchemistry. Fish and Fisheries In press.
  • Montes, I., Iriondo, M., Manzano, C., Arrizabalaga, H., M.A., P., Goñi, N., Davies, C.A., Estonba, A., In press. Worldwide genetic structure in albacore (Thunnus alalunga) through microsatellite DNA markers. Marine Ecology Progress Series.
  • Nakadate, M., Vinas, J., Corriero, A., Clarke, S., Suzuki, N., Chow, S., 2005. Genetic isolation between Atlantic and Mediterranean albacore populations inferred from mitochondrial and nuclear DNA markers. Journal of Fish Biology 66, 1545-1557.
  • Pinccinetti, C., Pinccinetti, M.G., Lalami, Y., Tellai, S., Barrois, J.M., 1973. Note sur presence dans les eauxalgeriennesd'unelarve de thon ougermon Thunnus alalunga (Bonn.). Pelagos IV, 66-72.
  • Secor, D.H., Dean, J.M., Campana, S.E.E., 1995. Recent Developments in Fish Otolith Research. University of South Carolina Press, Columbia, S.C.
  • Secor, D.H., Kerr, L.A., Cadrin, S.X., 2009. Connectivity effects on productivity, stability, and persistence in a herring metapopulation model. ICES Journal of Marine Science 66, 1726-1732.
  • Velado, I., Laconcha, U., Zarraonaindia, I., Iriondo, M., Manzano, C., Arrizabalaga, H., Pardo, M.A., Goñi, N., Heinisch, G., Lutcavage, M., Estonba, A., 2011. SNP discovery in Thunnus alalunga and T. thynnus for genetic diversity and population structure analyses., ICCAT COLLECTIVE VOLUME OF SCIENTIFIC PAPERs.
  • Vinas, J., Bremer, J.R.A., Pla, C., 2004. Inter-oceanic genetic differentiation among albacore (Thunnus alalunga) populations. Marine Biology 145, 225-232.
Employment Details
The candidate will be employed at GMIT on a researcher contract. They will be paid approximately 2000€ a month.

Expected outcomes
  • At least 3 peer reviewed publications focused on the following topics:
    • Defining stock boundaries for albacore in the Northeast Atlantic using otolith chemical composition and morphology and life history dynamics
    • Temporal variability in the distribution of stock components of the Northeast Atlantic albacore fishery.
    • Evaluation of management strategies for albacore tuna in light of underlying stock structure
  • Scientific advice to support albacore stock assessment and management
    • Identification of stock components within the main management units of the Northeast Atlantic and Mediterranean Sea
    • Development of a simulation modelling framework for evaluating the consequences of observed stock structure for management

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