Using growth rates and otolith shape to identify the population structure of Umbrina canosai (Sciaenidae) from the Southwestern Atlantic

ABSTRACT

Identifying populations and establishing the connectivity between neighbouring stocks are central issues for the assessment and management of coastal marine fish species. In this paper, we analysed the population structure of the demersal sciaenid argentine croaker Umbrina canosai, endemic in the warm, temperate southwestern Atantic between southeastern Brazil (SE) and Argentina, by combining two phenotypic techniques: otolith shape analysis and fish growth rate. Three otolith morphotypes were consistently identified, one in the northern latitudinal range in SE, and two in the southern range of the species from southern Brazil to Argentina. Two stocks with differences in growth rate were identified, one with a significantly smaller asymptotic length in the northern range (L_∞= 340.08; k = 0.267; t₀ = −2.177) and the second in the southern range (L_∞= 425.08; k = 0.236; t₀ = −2.46), where no growth differences were observed between fishes with the two otolith morphotypes. Although genetically U. canosai can be considered to form a single panmictic population, growth and otolith shape indicate that there are two different stocks, one in southeastern Brazil and another in the southern distribution, confirming previous parasitological studies. The difference in otolith morphotypes in the southern range suggests that two subpopulations share the same reproductive grounds, although probably feed in different locations.

KEYWORDS:

• Coastal
• fish
• demersal
• ShapeR
• subpopulations
• stocks

Acknowledgements

We thank Marcio de Araújo Freire and Davi Vasconcellos Machado for their participation in the collection of data. We also thank an anonymous reviewer for his useful recommendations. Francyne Vieira (Rio de Janeiro Fishing Institute Foundation) and Laura Wilwock Miranda (Fisheries Institute of Sao Paulo) provided otoliths from southeastern Brazil.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

E.K. received a scholarship (88882.347007/2019-01) from the Coordination for the Improvement of Higher Education Personnel (CAPES). M.H. is a research fellow (3007994/2020-1) of the Brazilian National Council for Scientific and Technological Development (CNPq). Financial support to D.C. and J.T.T. (PICT 2018 No. 01981) was provided by a grant from the Argentinian Fund for Research and Technology (FOMCyT).