Investigating the movements and behaviour of Patagonian toothfish (Dissostichus eleginoides Smitt, 1898) around the Falkland Islands using satellite linked archival tags Judith Brown a, c, d, ⁎, Paul Brickle b, c, d , Beth E. Scott c a St. Helena Government, Essex House, Jamestown STHL 1ZZ, Saint Helena b South Atlantic Environment Research Institute, P.O. Box 609, Stanley FIQQ 1ZZ, Falkland Islands c University of Aberdeen, School of Biological Sciences (Zoology), Tillydrone Ave., Aberdeen AB24 2TZ, UK d Falkland Islands Fisheries Department, P.O. Box 598, Stanley FIQQ 1ZZ, Falkland Islands abstract article info Article history: Received 22 April 2012 Received in revised form 12 February 2013 Accepted 13 February 2013 Available online 19 March 2013 Keywords: Archival pop-up tags Falkland Islands Feeding behaviour Patagonian toothfish Spawning migration Knowledge of the seasonal movements of Patagonian toothfish is an essential component for understanding their ecology and fisheries management. As only one demersal longline vessel participates in this fishery in Falkland's waters, over a vast slope area, the use of conventional tags to provide data on migration or stock assessment is not viable. In contrast, archival pop-up tags have enabled the examination of toothfish movements without having to recapture tagged individuals with reasonably high success rates. Patagonian toothfish (n = 30, >127 cm L T ) were tagged with pop-up satellite tags between 19/09/2007 and 7/07/2010 in the South Atlantic close to the Falkland Islands. The data from 16 tags that successfully released and uploaded data (plus one recaptured fish) revealed strong site fidelity, with eleven toothfish moving less than 50 km from their release po- sition over a 6 month period. Furthermore, depth data inferred three behavioural patterns showing seasonal bathymetric movements, foraging and spawning activities. Coinciding with the reported spawning months of July–August, spawning movements were recorded with fish moving repeatedly into shallower waters of 900– 1200 m. Foraging behaviours were also evident with differences in the scale of foraging movement related to fish size, possibly linked to a shift in diet with size. Fish were found to move deeper during December and these are potentially post-spawning movements allowing the fish to take advantage of different prey availability. © 2013 Elsevier B.V. All rights reserved. 1. Introduction The Patagonian toothfish (Dissostichus eleginoides) is a deepwater long lived notothenid (Collins et al., 2010) which has been exploited commer- cially around the Falkland Islands since 1994 (Laptikhovsky and Brickle, 2005). Due to its longevity and growing commercial value gathering in- formation on the movements of Patagonian toothfish and understanding their ecology and behaviour are essential components of their fisheries management. Advances in technology in recent years have seen the de- velopment of archival pop-up tags which allow for the examination of mi- gratory movements of fish and sharks (Pade et al., 2009), as well as giving insights into behaviour (Seitz et al., 2005; Stevens et al., 2010), without requiring retrieval of the tagged animal. With only one demersal longliner operating in Falkland's waters and a vast slope area (approximately 150,000 km 2 ), the use of conventional (T-bar) tags would not be viable for studying toothfish as a huge number of fish would need to be tagged to guarantee returns which would be uneconomic commercially. Hence, archival tags provide a fishery-independent means of studying toothfish around the Falklands in their natural environment. Fish often migrate to find favourable conditions for spawning and development of their young (e.g. Atlantic salmon, Salmo salar; eels, Anguilla anguilla) however, the energetic investment in large distance fish migration is high (Crossin et al., 2004). A triangular migration pat- tern was suggested by Harden Jones (1968) to occur in many species with adults swimming ‘up current’ to spawn, then the young are car- ried to good feeding areas by the currents and then once the young grow to become larger active swimmers they move to adult feeding grounds. In the case of Patagonian toothfish, juveniles are known to migrate from the shelf and slope (at depths of 150–400 m) into deeper water (400–>2000 m) as they become adults and they also change their diet (Arkhipkin et al., 2003). From examination of toothfish maturity, Laptikhovsky et al. (2006) reported toothfish to migrate from the Burdwood Bank after spawning, northward to 40– 45°, westwards to Chilean waters and eastwards to the Scotia ridge. In other areas toothfish are reported as non-migratory (DeWitt et al., 1990; Williams et al., 2002). Previous tagging experiments on Patagonian toothfish (using con- ventional t-bar tags) have provided data on the dispersal of fish, growth during deployment time and for use in stock assessment (via mark Journal of Experimental Marine Biology and Ecology 443 (2013) 65–74 ⁎ Corresponding author at: St. Helena Government, essex House, Jamestown STHL 1ZZ Saint Helena. Tel.: +290 2270. E-mail address: jude@dicksonandbrown.com (J. Brown). 0022-0981/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jembe.2013.02.029 Contents lists available at SciVerse ScienceDirect Journal of Experimental Marine Biology and Ecology journal homepage: www.elsevier.com/locate/jembe