Body and otolith shape analyses of the Brazilian sardine, Sardinella brasiliensis, to differentiate population-units in the purse seine fishery off Brazil
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1
Centro Interdisciplinar de Investigação Marinha e Ambiental. Terminal de Cruzeiros do Porto de Leixões, Avenida General Norton de Matos S/N, 4550-208, Portugal
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2
Laboratório de Ecossistemas Aquáticos e Pesqueiros, Departamento de Oceanografia, Universidade do Vale do Itajaí, R. Uruguai 458, Centro 88302-901, Brazil
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3
Faculdade de Ciências da Saúde da Universidade Fernando Pessoa. Rua Carlos da Maia 296 4200-150, Portugal
The description of the size structure and size at first maturity (L50) of the Brazilian sardine, Sardinella brasiliensis, in the SE brazil, evidenced distinct fishing areas composed of individuals with distinct biological attributes: one off Santa Catarina State (SC) and another off Rio de Janeiro (RJ) State, suggesting a two population-unit scenario. This hypothesis was evaluated hereby using fish body and otolith shape morphometry of S. brasiliensis caught off Southern Brazil. Fish were obtained from the commercial purse seine fishery off southern Brazil in May and September of 2018. For each fishing area, the same number of sardines was selected at all length intervals available in order to remove the confounding effect of size. Body shape was defined from the positioning of twelve pre-established landmarks. Otolith morphometry was described from otolith measurements (length, width, area, and perimeter), shape indexes (form-factor, aspect ratio, roundness, rectangularity, ellipticity and circularity) and Elliptic Wavelet Descriptors. Data was evaluated through univariate and multivariate statistics. A linear discriminant function analysis was applied and the accuracy of re-classification for each sample was evaluated through the jack-knifed (leave-one out) cross-validation matrix. Body shape analysis confirmed the difference between the two hypothesized populations. Otolith morphometry analysis also showed significant differences in both univariate and multivariate tests. Elliptic Wavelet Descriptors clearly separated geographical populations and the overall reclassification rate was 95%. The association of body and otolith shape with the geographical position of the catch showed that RJ sardines separate from SC conspecifics by a more rectangular otolith shape. Sardines captured off RJ presented a larger and wider body shape against a thinner and slender form of SC sardines. Differences observed in body and otoliths of sardines captured off RJ seemed to be a function of their development in waters more often enriched by upwelling event of the South Atlantic Central Water. Further studies using other complimentary methodologies (e.g. elemental and isotopic otolith signatures) are however need to unravel the S. sardinella population structure in the Brazilian coast.
Acknowledgements
Sincere thanks to the industrial fish processing industries whose partnership made this study possible. The Coordination for the Improvement of Higher Education Personnel (CAPES) for the granting of a PhD scholarship, the National Research Council (CNPq) under the Projeto Sardinha: Apoio Técnico-Científico ao Plano de Gestão para o Uso Sustentável da Sardinha-Verdadeira no Sudeste do Brasil and the Brazilian Fund for Biodiversity (FUNBIO) for financial support.
Keywords:
Sardinella brasiliensis,
Geometric morphometric,
Elliptical Wavelet Descriptors,
population structure,
stock identification
Conference:
XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019.
Presentation Type:
Poster
Topic:
OTOLITHS AS A TOOL TO STUDY FISH LIFE CYCLES
Citation:
Schroeder
R,
Schwingel
PR and
Correia
AT
(2019). Body and otolith shape analyses of the Brazilian sardine, Sardinella brasiliensis, to differentiate population-units in the purse seine fishery off Brazil.
Front. Mar. Sci.
Conference Abstract:
XVI European Congress of Ichthyology.
doi: 10.3389/conf.fmars.2019.07.00094
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Received:
13 Jun 2019;
Published Online:
14 Aug 2019.
*
Correspondence:
Mr. Rafael Schroeder, Centro Interdisciplinar de Investigação Marinha e Ambiental. Terminal de Cruzeiros do Porto de Leixões, Avenida General Norton de Matos S/N, 4550-208, Matosinhos, Portugal, schroederichthys@gmail.com