Garla, Ricardo C.; Gadig, Otto B. F.; Garcia Junior, José; Veras, Leonardo B.; Garrone-Neto, Domingos

doi:10.1590/1982-0224-20160119

person Ricardo C. Garla

schoolDepartamento de Botânica, Ecologia e Zoologia, Universidade Federal do Rio Grande do Norte, 59078-970 Natal, RN, Brazil. rgarla@hotmail.com (corresponding author)schoolLaboratório de Pesquisa de Elasmobrânquios e Nécton Marinho, UNESP - Universidade Estadual Paulista, 11330-900 São Vicente, SP, Brazil. gadig@clp.unesp.br

person Otto B. F. Gadig

schoolLaboratório de Pesquisa de Elasmobrânquios e Nécton Marinho, UNESP - Universidade Estadual Paulista, 11330-900 São Vicente, SP, Brazil. gadig@clp.unesp.br

person José Garcia Junior

schoolRecursos Pesqueiros, Instituto Federal do Rio Grande do Norte, 59500-000 Macau, RN, Brazil. jose_garciajunior@yahoo.com.br

person Leonardo B. Veras

schoolMuseu dos Tubarões, 53990-000 Fernando de Noronha, PE, Brazil. leo@planasub.com.br

person Domingos Garrone-Neto

schoolLaboratório de Pesquisa de Elasmobrânquios e Nécton Marinho, UNESP - Universidade Estadual Paulista, 11330-900 São Vicente, SP, Brazil. gadig@clp.unesp.brschoolCurso de Engenharia de Pesca, UNESP - Universidade Estadual Paulista, 11900-000 Registro, SP, Brazil. garroneneto@registro.unesp.br.

Figuras (5)
Tabelas (2)

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Fig. 1 Fernando de Noronha Archipelago (depicted by the star), 345 km off the Brazilian coast: 1 and 2 indicate sites where juveniles Negaprion brevirostris were observed between 2008 and 2009; 3 and 4 indicates sites where subadult and adult individuals were sighted chasing schools of sardines in 2006, 2012 and 2013.

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Fig. 2 Percentage of occurrence of hunting behaviours of Negaprion brevirostris per a. site, b., c. body size and d. time of the day in Fernando de Noronha Archipelago. I: substrate inspection; SB: sardine blitz; SF: sand fishing; M: morning, A: afternoon; J: juvenile; SA: subadult; A: adult.

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Fig. 3 a. and b. Juvenile Negaprion brevirostris in site 1 seconds before striking a school of sardines.

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Fig. 4 a. Two Negaprion brevirostris (TL > 2 m) patrolling the shoreline near the surf zone of site 03 in January 2012. b. Lemon shark surrounded by a school of sardines displaying “vacuole” behaviour (sensuMagurran, Pitcher 1987). c. The same shark seconds before striking the school of sardines hidden by sand suspension (Photographs by José Carlos Marenga).

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Fig. 5 Three Negaprion brevirostris (TL > 2 m) chasing schools of sardines in waters of the swash zone (0.2-0.5 m depth) during sunrise hours in site 4 in January 2013, and boobies, Sula leucogaster, and black noddies, Anous minutus, in feeding activity (Photograph by Leonardo Veras).

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Tab. 1 Sampling effort per period of the diel cycle in the Fernando de Noronha Archipelago, Brazil. * M = morning (06:00 to 12:00 h); A = afternoon (12:01 to 18:00 h); Wet season (from February to July), Dry season (August to July).

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Tab. 2 Ethogram of snorkeling (S) and cliff-top (C) observed behaviours of Negaprion brevirostris in Fernando de Noronha Archipelago, Brazil (see for location of sites).

Snorkeling censuses (40 min duration each)
	2008			2009
	Apr-May	Jul	Dec	Jan	Jul	Dec
Site 1	89 (48M, 41A)	88 (45M, 43A)	88 (46M, 42A)	93 (48M, 45A)	91 (49M, 42A)	89 (46M, 43A)
Site 2	73 (36M, 37A)	73 (38M, 35A)	75 (40M, 35A)	83 (41M, 42A)	76 (35M, 41A)	83 (40M, 43A)
Total censuses	162	161	163	176	167	172
Cliff-top observation sessions (4 h duration each)
	2006	2007	2008	2011	2012	2013
	Jan-Feb	Jan-Feb	Jan-Feb	Jan-Feb	Jan-Feb	Jan-Feb
Site 3	11 (6M, 5A)	10 (5M, 5A)	10 (5M, 5A)	9 (5M, 4A)	11 (6M, 5A)	12 (6M, 6A)
Site 4	9 (4M, 5A)	10 (5M, 5A)	11 (7M, 4A)	10 (5M, 5A)	10 (5M, 5A)	12 (8M, 4A)
Total sessions	20	20	21	19	21	24

Behaviour category	Size class, sites observed	No., type and duration of observations	Behaviour description	Habitat type/ Depth
Substrate inspection	Juveniles and subadults less than 2 m TL, sites 1 and 2	89 (S), mean duration 8.5 seg (4-15 seg)	A shark approached a hole or crevice poking the substrate with its rostrum. The shark inclined the body forward and introduced its head and/or anterior part of the body in the hole performing abrupt lateral undulations to adjust the anterior part of the body to the hole and keep the body in position.	Reef flat and front reef, 0.5 to 1.5 m
Sardine blitz	Juveniles and subadults less than 2 m TL, sites 1 and 2	47 (S, C), mean duration 15.1 seg (4-30 seg)	One or more sharks approached the sardine schools exhibiting usual “patrolling behaviour” and when at a distance of less than 2 m, suddenly stroked the fishes with short bursts of speed towards a small part of the school.	Reef and rocky flats, sandy bottom with sparse reefs and rocks, 0.5 to 1.5 m
Sand hunting	Subadults larger than 2 TL and adults, sites 3 and 4	12 (C), mean duration 37.7min (17-38min)	Sharks larger than 2 m TL were initially observed performing “patrolling behaviour” at the deeper near-shore section of the beach (~ 1.5 m depth), immediately beyond the surf zone. Similar to the “sardine blitz” described above, but sharks only attacked the schools of sardines in the swash zone (0.3-1 m depth) immediately after the waves have broken.	Sandy beach, 0.3 to 1.5 m

Hunting tactics of the lemon shark, Negaprion brevirostris, in shallow waters of an oceanic insular area in the western equatorial Atlantic

RESUMO