Food habits, selectivity, and foraging modes of the school shark Galeorhinus galeus

The foraging ecology of the school shark Galeorhinus galeus was studied in Anegada Bay, Argentina, during the seasonal occurrence of this species in Argentinean waters (October to April) from 1998 to 2001. Of the 408 individuals examined, 168 (41.2%) had food remains in their stomachs. The proportio...

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Autores principales: Lucifora, Luis O., García, Verónica B., Menni, Roberto Carlos, Escalante, Alicia H.
Formato: Articulo
Lenguaje:Inglés
Publicado: 2006
Materias:
Ciencias Naturales
Chondrichthyes
Diet
Elasmobranch
Galeorhinus galeus
Gape limitation
Piscivory
Predation
School shark
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/83095
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-83095
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Naturales
Chondrichthyes
Diet
Elasmobranch
Galeorhinus galeus
Gape limitation
Piscivory
Predation
School shark
spellingShingle Ciencias Naturales
Chondrichthyes
Diet
Elasmobranch
Galeorhinus galeus
Gape limitation
Piscivory
Predation
School shark
Lucifora, Luis O.
García, Verónica B.
Menni, Roberto Carlos
Escalante, Alicia H.
Food habits, selectivity, and foraging modes of the school shark Galeorhinus galeus
topic_facet Ciencias Naturales
Chondrichthyes
Diet
Elasmobranch
Galeorhinus galeus
Gape limitation
Piscivory
Predation
School shark
description The foraging ecology of the school shark Galeorhinus galeus was studied in Anegada Bay, Argentina, during the seasonal occurrence of this species in Argentinean waters (October to April) from 1998 to 2001. Of the 408 individuals examined, 168 (41.2%) had food remains in their stomachs. The proportion of individuals with food remains was negatively correlated with total length. In general, the diet was composed mainly of teleosts (98.5% IRI [index of relative importance]), with invertebrates and chondrichthyans as minor prey. The diet varied ontogenetically and seasonally. Juveniles and adults differed in their consumption of invertebrates, with juveniles preying more on benthic invertebrates, mainly the octopus Octopus tehuelchus, and adults on squid. From December to February, adults preyed mainly on benthic teleosts (almost exclusively the Atlantic midshipman Porichthys porosissimus), while from March to April the consumption of squid increased. A comparison of numbers of prey in stomachs with abundance of prey in the environment in March and April showed that, in these months, juveniles selected invertebrates and demersal teleosts and avoided pelagic teleosts and chondricthyan prey, and adults selected squid and avoided pelagic teleosts. This indicates that, during this period, G. galeus is not an opportunistic predator. The mean size of prey increased with increasing shark length, but even large sharks consumed small prey. All shark sizes consumed prey fragments that were significantly larger than other prey consumed whole. This indicates that G. galeus is able to overcome gape limitation by mutilating prey, and that the ontogenetic diet shift was not due to a change in the ability to seize prey.
format Articulo
Articulo
author Lucifora, Luis O.
García, Verónica B.
Menni, Roberto Carlos
Escalante, Alicia H.
author_facet Lucifora, Luis O.
García, Verónica B.
Menni, Roberto Carlos
Escalante, Alicia H.
author_sort Lucifora, Luis O.
title Food habits, selectivity, and foraging modes of the school shark Galeorhinus galeus
title_short Food habits, selectivity, and foraging modes of the school shark Galeorhinus galeus
title_full Food habits, selectivity, and foraging modes of the school shark Galeorhinus galeus
title_fullStr Food habits, selectivity, and foraging modes of the school shark Galeorhinus galeus
title_full_unstemmed Food habits, selectivity, and foraging modes of the school shark Galeorhinus galeus
title_sort food habits, selectivity, and foraging modes of the school shark galeorhinus galeus
publishDate 2006
url http://sedici.unlp.edu.ar/handle/10915/83095
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