Tolotti et al.: Vertical movements of oceanic whitetip sharks ( Carcharhinus longimanus ) 
381 
the scientific community recently has undertaken sig- 
nificant research to fill these wide gaps in scientific in- 
formation. These studies include work on age, growth, 
and reproductive biology (Tambourgi et al., 2013; Joung 
et al., 2016), feeding (Madigan et al., 2015), genetics 
(Camargo et al., 2016; Li et ah, 2016), fisheries (Rice 
and Harley 1 ; Tolotti et al., 2013; Piovano and Gilman, 
2016), and movement patterns and behavior (Musyl 
et al., 2011; Howey-Jordan et al., 2013; Tolotti et al., 
2015b; Howey et al., 2016). 
Data from satellite archival tags, together with fish- 
ery-dependent data, revealed valuable information con- 
cerning horizontal movements, depth preferences, and 
temperature ranges of the oceanic whitetip shark. Pre- 
vious studies have shown that this wide-ranging species 
has a high degree of site fidelity and exhibits philopatric 
behavior (Howey-Jordan et al., 2013; Madigan et al., 
2015; Tolotti et al., 2015b). They also have documented 
the epipelagic nature of this species and its high degree 
of vulnerability to open-ocean fisheries. These findings 
are new and have conservation applications, but sev- 
eral aspects of the behavior of this shark still need to 
be addressed. Detailed information on vertical move- 
ments within the epipelagic environment still need to 
be studied; most of the published research concerning 
this species has not explored vertical movements, and 
only general summaries have been provided. 
Within the general framework of ecosystem-based 
fisheries management, it is essential to improve our 
knowledge of bycatch species (particularly for threat- 
ened species), including our knowledge of their be- 
havior and vertical movement patterns (Pikitch et 
al., 2004; Garcia and Cochrane, 2005). The aim of this 
study was to analyze the vertical movements of the 
oceanic whitetip shark in order to extend our knowl- 
edge beyond the existing knowledge that this is an epi- 
pelagic species. The main objectives were 1) to investi- 
gate diel patterns and behavior types and 2) to analyze 
the influence of environmental factors on the vertical 
behavior of this shark. 
Materials and methods 
Time series of depth data for 6 oceanic whitetip sharks 
were analyzed. All data were obtained from pop-up 
satellite archival tags deployed in the Atlantic Ocean 
(n= 5) and Indian Ocean (n= 1) in 2011 and 2012 (Ta- 
ble 1). Deployment periods varied from 100 to 178 d. 
Summarized results, based on the data from the 5 tags 
deployed in the Atlantic Ocean, were previously pre- 
sented in Tolotti et al. (2015b). The sharks in the At- 
lantic Ocean were tagged close to the equator on the 
western side of the Atlantic Ocean during commercial 
longline operations. The sharks were brought onboard 
1 Rice, J., and S. Harley. 2012. Stock assessment of oceanic 
whitetip sharks in the western and central Pacific Ocean. 
West. Cent. Pacific Fish. Comm. WCPFC-SC8-2012/SA- 
WP-06, rev. 1, 53 p. [Available from website.] 
for the tagging procedure, and tags were attached at 
the base of the first dorsal fin with a loop of polyamide 
monofilament. In addition to the vertical movements 
reported here, horizontal movements were observed 
for the sharks. After tagging, all individuals made ex- 
tensive horizontal movements but remained mostly 
in the equatorial zone (Tolotti et al., 2015b). Only 1 
shark migrated south. The shark tagged in the Indian 
Ocean was caught with a hand line during a research 
cruise in the Mozambique Channel. For the tagging 
procedure, this shark was brought on board and placed 
in a tagging cradle. The tag was attached intramuscu- 
larly under the first dorsal fin with a stainless steel 
tether and large Wilton anchors (Wildlife Computers 
Inc., 2 Redmond, WA). From its tagging location in the 
Mozambique Channel, this individual migrated north, 
following the African coast to Somalia. The estimated 
tracks of all 6 tagged individuals are provided in Sup- 
plementary Figure 1 (online only). 
Data description 
Pop-up satellite archival tags typically record the am- 
bient depth (pressure), water temperature, and light 
level at a high temporal resolution (for our study, the 
resolution was 10 s). This information is then used to 
generate different data products that are transmit- 
ted by satellite after the tags detach from the animal. 
Transmitted data products will depend on tag model 
and user-defined settings. Two models of pop-up satel- 
lite archival tags, manufactured by Wildlife Computers 
Inc., were used in this study, 5 MiniPATs and 1 PAT- 
MklO. The MiniPATs were programmed to transmit 
depth data with a resolution of 5 min. The PAT-MklO 
does not transmit data as a time series, only as an 
aggregated summary of its records. However, this lat- 
ter tag was physically recovered from Crystal Beach, 
Texas, after drifting at sea for about 1 year after its 
release from the shark. The recovery of this tag al- 
lowed the download of the complete depth and tem- 
perature time series with a 10-s resolution. The Mini- 
PATs were not recovered. Although MiniPATs were 
not programmed to transmit temperature time-series 
data, other data produced and transmitted by the tags 
provided information on the surrounding environment. 
These products included a daily analysis of the surface 
mixed layer and sea-surface temperature (SST), as well 
as a summary of temperature at depth profiles. These 
data were also available from the recovered PAT-MklO. 
Data analysis 
Vertical movement patterns The periods of the day were 
classified according to local times of sunrise and sun- 
set, by following the procedure described in Tolotti et 
al. (2015b). In summary, the local times were based 
2 Mention of trade names or commercial companies is for iden- 
tification purposes only and does not imply endorsement by 
the National Marine Fisheries Service, NOAA. 
