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Habitat use patterns of franciscana dolphins (Pontoporia blinavillei) of southern Brazil in relation to water depth

Habitat use patterns of franciscana dolphins (Pontoporia blinavillei) of southern Brazil in relation to water depth
Habitat use patterns of franciscana dolphins (Pontoporia blinavillei) of southern Brazil in relation to water depth
The patterns of habitat use by the franciscana dolphins (Pontoporia blainvillei) along its distribution are poorly known. This study investigates the patterns of habitat use with respect to depth for 181 individuals of different age, size, gender and reproductive condition off Rio Grande do Sul, southern Brazil. The results reveal that franciscanas are very homogeneously distributed according to depth. Individuals from all lengths utilize nearly the entire range of depths of the surveyed area. Larger or older animals do not use deeper waters than younger animals, indicating that body size and age are not limiting factors for franciscanas that occupy deeper or offshore waters. Gestation seems to not cause a change in the distribution of females. Although the sex-ratio of the overall data did not vary from 1:1 in different depth intervals, a small-scale comparison between the northern and southern coast demonstrated the existence of some kind of sexual segregation. Franciscana by-catch in Rio Grande do Sul is not sustainable and it is agreed that management procedures are needed. Nevertheless, the available data on species distribution do not allow the designing of a protected area in order to minimize the by-catches of a particular sex/reproductive class.

0025-3154
943-949
Danilewizc, Daniel
60265313-7cad-4b39-92cb-a2ac921a370f
Secchi, Eduardo R.
4b11331a-8943-45e9-a969-980e1f560028
Ott, Paulo H.
df4c7de4-ad13-41b6-8cee-241885bff789
Moreno, Ignacio B.
63e154dc-f658-470c-84a2-f7ba788b1696
Bassoi, Manuela
65ced820-d7f5-487c-8afb-cc06385fd55a
Borges-Martins, Marcio
7298b33b-47cd-4f6e-adcc-5a58972ac923
Danilewizc, Daniel
60265313-7cad-4b39-92cb-a2ac921a370f
Secchi, Eduardo R.
4b11331a-8943-45e9-a969-980e1f560028
Ott, Paulo H.
df4c7de4-ad13-41b6-8cee-241885bff789
Moreno, Ignacio B.
63e154dc-f658-470c-84a2-f7ba788b1696
Bassoi, Manuela
65ced820-d7f5-487c-8afb-cc06385fd55a
Borges-Martins, Marcio
7298b33b-47cd-4f6e-adcc-5a58972ac923

Danilewizc, Daniel, Secchi, Eduardo R., Ott, Paulo H., Moreno, Ignacio B., Bassoi, Manuela and Borges-Martins, Marcio (2009) Habitat use patterns of franciscana dolphins (Pontoporia blinavillei) of southern Brazil in relation to water depth. Journal of the Marine Biological Association of the United Kingdom, 89 (5), 943-949. (doi:10.1017/S002531540900054X).

Record type: Article

Abstract

The patterns of habitat use by the franciscana dolphins (Pontoporia blainvillei) along its distribution are poorly known. This study investigates the patterns of habitat use with respect to depth for 181 individuals of different age, size, gender and reproductive condition off Rio Grande do Sul, southern Brazil. The results reveal that franciscanas are very homogeneously distributed according to depth. Individuals from all lengths utilize nearly the entire range of depths of the surveyed area. Larger or older animals do not use deeper waters than younger animals, indicating that body size and age are not limiting factors for franciscanas that occupy deeper or offshore waters. Gestation seems to not cause a change in the distribution of females. Although the sex-ratio of the overall data did not vary from 1:1 in different depth intervals, a small-scale comparison between the northern and southern coast demonstrated the existence of some kind of sexual segregation. Franciscana by-catch in Rio Grande do Sul is not sustainable and it is agreed that management procedures are needed. Nevertheless, the available data on species distribution do not allow the designing of a protected area in order to minimize the by-catches of a particular sex/reproductive class.

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More information

Published date: August 2009

Identifiers

Local EPrints ID: 71775
URI: http://eprints.soton.ac.uk/id/eprint/71775
ISSN: 0025-3154
PURE UUID: 37d6a3c7-b1e0-46e2-abc8-c15650227da0

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Date deposited: 22 Dec 2009
Last modified: 13 Mar 2024 20:42

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Contributors

Author: Daniel Danilewizc
Author: Eduardo R. Secchi
Author: Paulo H. Ott
Author: Ignacio B. Moreno
Author: Manuela Bassoi
Author: Marcio Borges-Martins

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