Trajectory of tuna with tag ID # 10P0398

<p>(A) June 16 to June 20 (pink dot and triangle, respectively) and (B) July 6 to July 10 (pink dot and triangle, respectively) plotted with the mean Sea Surface Salinity (SSS) and the mean geostrophic velocity (UV) for those specific days.</p

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

<div><p>We analyzed the movements of Atlantic tuna (<i>Thunnus thynnus</i> 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.</p></div

Mean values, maximums, minimums and standard deviation for cluster 2 and 3 for all months when present.

<p>Mean values, maximums, minimums and standard deviation for cluster 2 and 3 for all months when present.</p

Locations of bluefin tuna fishing operations between April and August in the Mediterranean Sea from 1989 to 2012 (n = 6031) (different color dots), and spatial distribution of the Japanese longliners’ total bluefin tuna catches in Algeria from 2000 to 2007 (based on Abdelhadi <i>et al</i>.,[69]) (red dotted line).

<p>PS = Purse seiners, LL = Longliners and BB = Bait boats.</p

Summary information on the deployments of electronic tags (>22 days on fish)—from 2000–2012 on western Mediterranean and Adriatic Sea bluefin tuna, analyzed in this study.

<p>Summary information on the deployments of electronic tags (>22 days on fish)—from 2000–2012 on western Mediterranean and Adriatic Sea bluefin tuna, analyzed in this study.</p

Dendrogram for tag #10P0648 determined from clustering analysis of differences in diving patterns Each column represents a 24-hours depth histogram (n = 175 days) and the color is the fraction of time.

<p>The density variable is expressed as a fraction of each day spent in depth bins defined along the y-axis.</p

Trajectory of tuna with tag ID # 10P0398

<p>(A) June 16 to June 20 (pink dot and triangle, respectively) and (B) July 6 to July 10 (pink dot and triangle, respectively) plotted with the mean Sea Surface Salinity (SSS) and the mean geostrophic velocity (UV) for those specific days.</p

Daily positions for the 38 tuna analyzed in this study.

<p>Orange circles represent the internally tagged fish, while the white circles are the positions of the tunas tagged with pop-up satellite tags in both basins.</p

Mean values, maximums, minimums and standard deviation for the clusters obtained.

<p>Mean values, maximums, minimums and standard deviation for the clusters obtained.</p

Longitude for internal tag #0890152 by year.

<p>Longitude for internal tag #0890152 by year.</p