Electronic Tagging of Atlantic Bluefin Tuna (Thunnus thynnus, L.) Reveals Habitat Use and Behaviors in the Mediterranean Sea

Abstract

We analyzed the movements of Atlantic tuna (Thunnus thynnus L.) in the Mediterranean Sea using data from 2 archival tags and 37 pop-up satellite archival tags (PAT). Bluefin tuna ranging in size from 12 to 248 kg were tagged on board recreational boats in the western Mediterranean and the Adriatic Sea between May and September during two different periods (2000 to 2001 and 2008 to 2012). Although tuna migrations between the Mediterranean Sea and the Atlantic Ocean have been well reported, our results indicate that part of the bluefin tuna population remains in the Mediterranean basin for much of the year, revealing a more complex population structure. In this study we demonstrate links between the western Mediterranean, the Adriatic and the Gulf of Sidra (Libya) using over 4336 recorded days of location and behavior data from tagged bluefin tuna with a maximum track length of 394 days. We described the oceanographic preferences and horizontal behaviors during the spawning season for 4 adult bluefin tuna. We also analyzed the time series data that reveals the vertical behavior of one pop-up satellite tag recovered, which was attached to a 43.9 kg tuna. This fish displayed a unique diving pattern within 16 days of the spawning season, suggesting a use of the thermocline as a thermoregulatory mechanism compatible with spawning. The results obtained hereby confirm that the Mediterranean is clearly an important habitat for this species, not only as spawning ground, but also as an overwintering foraging ground.

Migrations and movements of Atlantic tarpon revealed by two decades of satellite tagging

“…Partial migration results from individual differences in behaviour, that is, a kind of animal personality (Nilsson, Bronmark, Hansson, & Chapman, ). Partial migrations have been observed for many satellite‐tagged species, for example yellowfin tuna ( Thunnus albacares , Scombridae (Hoolihan et al, )); bluefin tuna ( Thunnus thynnus , Scombridae (Block et al, ; Cermeño et al, ; Wilson et al, ); sailfish ( Istiophorus platypterus , Istiophoridae (Hoolihan, Luo, Goodyear, Luo, Goodyear, Orbesen, & Prince, )); blue marlin ( Makaira nigricans , Istiophoridae (Goodyear et al, )); white marlin ( Kajikia albida , Istiophoridae (Hoolihan et al, )); swordfish ( Xiphias gladius , Xiphiidae (Dewar et al, )); tiger shark ( Galeocerdo cuvier , Carcharhinidae (Hammerschlag, Gallagher, Gallagher, Wester, Luo, & Ault, )); and acoustically tracked common snook ( Centropomus undecimalis , Centropomidae; Trotter, Blewett, Taylor, & Stevens, ). Partial migration is one of the major factors that could potentially account for spatial and temporal variations in population abundance and, hence, is a powerful force shaping ecosystem dynamics and trophic effects (Chapman, Brönmark, Nilsson, & Hansson, ; Chapman, Hulthén, et al, ).…”

Otolith shape variation provides a marker of stock origin for north Atlantic bluefin tuna (Thunnus thynnus)

“…Differences between locations could be explained by variation in the environments experienced by fish from different year-classes, as has been observed in other species (Campana and Casselman 1993;Bolles and Begg 2000) or could occur if contingents within a single spawning stock pursued divergent migration pathways. It has been suggested, based on evidence from electronic tagging, that the eastern stock of bluefin tuna comprises a resident component that spends prolonged periods foraging in the Mediterranean and a more migratory component that crosses the Straits of Gibraltar to feed in the Atlantic Ocean (Fromentin and Lopuszanski 2013;Cermeño et al 2015). Such heterogeneity in life histories could contribute to the differences in otolith shape observed between fish from the Bay of Biscay and the Adriatic Sea, for example.…”

Motes enhance data recovery from satellite-relayed biologgers and can facilitate collaborative research into marine habitat utilization

“…Also, for heavily exploited fish species, fish-borne archiving tags can be recovered in moderate numbers [7,29]. However, in general (and especially for real and near-real time applications), archived data from fishes and marine mammals have to be acquired via transmissions picked up and relayed by orbiting satellites.…”