380 
National Marine 
Fisheries Service 
NOAA 
Abstract — Time series of depth 
data, obtained for 6 oceanic whitetip 
sharks ( Carcharhinus longimanus) 
tagged with pop-up satellite archi- 
val tags, were analyzed in detail. 
The aim was to improve our knowl- 
edge of the vertical behavior of this 
species. Individuals were tagged in 
the Atlantic Ocean (rc= 5) and In- 
dian Ocean (n=l) between 2011 and 
2012. Deployment periods for these 
tags varied from 100 to 178 d. The 
sharks spent most of their time in 
the mixed layer, displaying the typi- 
cal behavior of an epipelagic species. 
However, analyses revealed complex 
vertical movement patterns, includ- 
ing marked diel changes that reflect 
3 different types of behavior. Results 
of the generalized additive models 
indicate that vertical movements 
were strongly correlated with varia- 
tions in the depth of the mixed layer. 
A correlation between vertical move- 
ments and sea-surface temperature 
(SST) was also observed. When SST 
was above average, oceanic whitetip 
sharks increased their vertical am- 
plitude, disregarding the reduction 
of the mixed layer. Thermoregula- 
tion likely allows this type of verti- 
cal movement. 
Manuscript submitted 7 September 2016. 
Manuscript accepted 15 May 2017. 
Fish. Bull. 115:380-395 (2017). 
Online publication date: 14 June 2017. 
doi: 10.7755/FB. 115.3.8 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Fishery Bulletin 
«%• established in 1881 •<§> 
Spencer F. Baird 
First U.S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Fine-scale vertical movements of oceanic 
whitetip sharks ( Carcharhinus longimanus ) 
Mariana Tolotti (contact author ) 1 ' 2 
Robert Bauer 1 
Fabien Forget 1 
Pascal Bach 1 
Laurent Dagorn 1 
Paulo Travassos 3 
Email address for contact author: mariana.travassos@ird.fr 
1 Unite Mixte de Recherche (UMR) Marine Biodiversity, Exploitation, and Conservation 
(MARBEC) 
Institut de Recherche pour le Developpement 
Avenue Jean Monnet CS 30171 
34203 Sete Cedex, France 
2 Departamento de Oceanografia 
Universidade Federal de Pernambuco 
Avenida Professor Moraes Rego, 1235-Cidade Universitaria 
50670-901 Recife, Brazil 
3 Departamento de Pesca e Aquicultura 
Universidade Federal Rural de Pernambuco 
Rua Dom Manoel de Medeiros s/n-Dois Irmaos 
52171-900 Recife, Brazil 
The oceanic whitetip shark ( Car- 
charhinus longimanus) is a pelagic 
predator threatened across the tropi- 
cal oceans of the world (Bonfil et al., 
2008). This species is a common by- 
catch of pelagic fisheries that target 
tuna ( Thunnus spp.), swordfish (Xi- 
phias gladius ), and other tuna-like 
species (Beerkircher et al., 2002; Hall 
and Roman, 2013; Gallagher et al., 
2014; Fredou et al., 2015; Oliver et 
al., 2015). The oceanic whitetip shark 
acquired its status of vulnerable 
globally and critically endangered in 
the northwest and western central 
Atlantic Ocean on the IUCN Red List 
of Threatened Species because of the 
increasing fishing pressure through- 
out its range and because of a lack 
of information regarding its biology 
and ecology (Baum et al., 2015). As 
a precautionary approach, a series of 
management measures that banned 
the landing, storing, and selling of 
oceanic whitetip sharks were imple- 
mented recently by management or- 
ganizations of all regional tuna fish- 
eries (Tolotti et al., 2015a). To date, 
this species is the only pelagic shark 
protected in the Atlantic, Pacific, and 
Indian oceans. The Convention on 
International Trade in Endangered 
Species of Wild Fauna and Flora has 
also included the oceanic whitetip 
shark in its Appendix II (CoP16 Prop. 
42), which includes species for which 
trade must be closely controlled. 
The lack of information regarding 
the biology and ecology of the oceanic 
whitetip shark is partly due to it be- 
ing captured as bycatch — a situation 
that has historically resulted in few 
incentives for research and conserva- 
tion (Barker and Schluessel, 2005). 
In light of the ocean-wide population 
declines observed for this species and 
because of the increasing interest in 
the conservation of bycatch species, 
