Engraulis anchoita (Clupeiformes: Engraulidae) eggs and larvae in the Southeastern Brazilian Bight: new perspectives from a historical data set (1974 - 2010)

Author(s)

Jana Menegassi Del Favero

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto Oceanográfico (IO/DIDC)
• Defense date: 2016-08-23

Examining board members

Mario Katsuragawa; Steven Xavier Cadrin; June Ferraz Dias; José Henrique Muelbert; Jefferson Taylor Turner

• Advisor: Mario Katsuragawa

Abstract

The main objective of this dissertation was to evaluate long-term fluctuations in the distribution and abundance of Engraulis anchoita eggs and larvae in the Southeastern Brazilian Bight (SBB). Engraulis anchoita is a fish species that is ecologically and economically important. We analyzed samples and abiotic data from eighteen oceanographic cruises conducted during austral late spring and early summer from 1974 to 2010. Two different stocks were detected in the SBB based on egg size, with the predominant stock in the area having smaller eggs than the stock in the region further south. Using indicative kriging, we identified occasional (e.g. Florianópolis - 27°S and off Santos Bay) and avoided (e.g. off São Sebastião Island and off Cananéia-Iguape Coastal System) spawning sites. Through zero-inflated models, spatial factors (different areas and the local depth) were related to the probability of sampling false zeros and temporal and oceanographic conditions (different years and temperature) with egg and larvae abundance. We also described faster and more accurate methodology to identify E. anchoita eggs, and compared the mesh-size efficiency to sample eggs and analyzed how egg size varied seasonally. Our results may support future studies and may assist a future fishery management of E. anchoita, a species not yet exploited in the SBB. (AU)

• FAPESP's process: 11/23332-3 - Inter-decadal fluctuations (1970-2010) in the distribution and abundance of larvae and eggs of Engraulis anchoita (Clupeiformes, Engraulidae) at Brazilian Southeast Continental Shelf
• Grantee: Jana Menegassi Del Favero
• Support Opportunities: Scholarships in Brazil - Doctorate