Age, growth and mortality of the Brazilian sharpnose shark, Rhizoprionodon lalandii, from south-central coast of São Paulo state: contributions to conservation and fishery management

• Grant number: 12/00713-4
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: May 01, 2012
• End date: April 30, 2014
• Field of knowledge: Biological Sciences - Zoology
• Principal Investigator: Otto Bismarck Fazzano Gadig
• Grantee: Fabio dos Santos Motta
• Host Institution: Universidade Estadual Paulista (UNESP). Campus Experimental do Litoral Paulista. São Vicente , SP, Brazil

Abstract

The Brazilian sharpnose shark, Rhizoprionodon lalandii, is a small coastal species (maximum length 80 cm) widely distributed in the Western Atlantic from Panama to Uruguay. In Brazilian waters it is an important resource in artisanal fisheries, especially in the southeast areas, representing 60% of the total shark landings. Nevertheless, little information is available on its basic biology. Moreover, its population dynamic remains a critical knowledge gap for management and conservation measures. The project intend to study the age, growth and mortality rates of the R. lalandii based on specimens caught by artisanal fisheries from south-central coast of São Paulo (Pescadores Beach, Itanhaém City, 24o 11' S; 46o 48' W). The fishing fleet comprised 12 small motorized boats (4 - 10 m long), using monofilament gill nets with 1500 m length and stretched mesh sizes of 7, 12 and 14 cm on average. The nets are set within an area of 2 - 12 nautical miles from the shore, in waters between 5 and 30 m deep. The age will be determined through readings of rings in vertebrae for both sexes. Two different approaches will be used to determine the growth parameters, the direct method (using the vertebral structure) and the indirect method (using the length frequency analysis). Different methodologies will be used to calculate mortality rates. Age, growth and mortality are key parameters in understanding the dynamics population of sharks. Without knowledge of how fast individuals are removed from a population it is impossible to model the population dynamics or estimate sustainable rates of exploitation or other useful management parameters. On these bases, the present project will be produce relevant data for management and conservation of Brazilian sharpnose shark.

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

CALTABELLOTTA, FABIO P.; SIDERS, ZACHARY A.; MURIE, DEBRA J.; MOTTA, FABIO S.; CAILLIET, GREGOR M.; GADIG, OTTO B. F.. Age and growth of three endemic threatened guitarfishes Pseudobatos horkelii, P. percellens and Zapteryx brevirostris in the western South Atlantic Ocean. Journal of Fish Biology, v. 95, n. 5, p. 1236-1248, NOV 2019. (10/02397-7, 12/00713-4)

CORSSO, JESSICA T.; GADIG, OTTO B. F.; CALTABELLOTTA, FABIO P.; BARRETO, RODRIGO; MOTTA, FABIO S.. Age and growth of two sharpnose shark species (Rhizoprionodon lalandii and R. porosus) in subtropical waters of the south-western Atlantic. MARINE AND FRESHWATER RESEARCH, v. 72, n. 3, p. 398-410, 2021. (10/02397-7, 12/00713-4)