Zoological Studies

Vol. 61, 2022

(update: 2022.9.12)

Reproduction of the Blue Jack Mackerel, Trachurus picturatus, in Western Portugal: Microscopic Gonad Analysis Reveals Indeterminate Fecundity and Skipped Spawning Patterns

Ana Neves1,2,*, Vera Sequeira1,2, Ana Rita Vieira1,2 Elisabete Silva1, Frederica Silva1,3, Ana Marta Duarte4, Susana Mendes3, Rui Ganhão3, Carlos Assis1,2, Rui Rebelo1,5, Maria Filomena Magalhães1,5, Maria Manuel Gil3, and Leonel Serrano Gordo1,2

1Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal. *Correspondence: E-mail: amneves@gmail.com (Neves).
E-mail: vlsequeira@fc.ul.pt (Sequeira); arivieira@fc.ul.pt (Vieira); eli_magalhaes_silva@hotmail.com (E. Silva); frederica.g.silva@ipleiria.pt (F. Silva); caassis@fc.ul.pt (Assis); rmrebelo@fc.ul.pt (Rebelo); lsgordo@fc.ul.pt (Gordo); mfmagalhaes@fc.ul.pt (Magalhães)
2MARE – Marine and Environmental Sciences Centre, Campo Grande, 1749-016 Lisboa, Portugal
3MARE—Marine and Environmental Sciences Centre, ESTM, Polytechnic of Leiria, Cetemares, 2520-620 Peniche, Portugal. E-mail: susana.mendes@ipleiria.pt (Mendes); rganhao@ipleiria.pt (Ganhão); maria.m.gil@ipleiria.pt (Gil)
4MARE—Marine and Environmental Sciences Centre, Polytechnic of Leiria, Cetemares, 2520-620 Peniche, Portugal. E-mail: ana.c.duarte@ipleiria.pt (Duarte)
5CE3C – Centre for Ecology, Evolution and Environmental Changes, Campo Grande, 1749-016 Lisboa, Portugal

Received 4 June 2021 / Accepted 18 May 2022
Communicated by Benny K.K. Chan

Blue jack mackerel, Trachurus picturatus, is the fifth most landed fish species in mainland Portugal, but information on its reproductive biology is scarce. From September 2018 to August 2019, 626 specimens were collected from commercial vessels to clarify the reproductive strategy of the T. picturatus population off the west coast of Portugal. The proportion and length range of males and females were similar. Only three of the specimens collected were categorized as immature, indicating that the fish caught in the fishery are primarily mature. The spawning season lasted from late January until the end of March, with gonadosomatic indices being similar for males and females. Fecundity was indeterminate, and estimated batch fecundity ranged between 6,798 (at 25.4 cm TL) and 302,358 oocytes (at 33.8 cm TL). The low number of females showing direct evidence of imminent or recent spawning suggests a low number of spawning events. In addition, 12.7% of females were considered non-reproductive due to ovary abnormalities including parasitic infection by Kudoa species, atretic structures and skipped spawning
events. This study highlights the importance of accounting for skipped spawning events and ovary abnormalities in the management of species fisheries.

Key words: Carangidae, Low-valued fish, Skipped spawning, Fecundity. Portugal.

Citation: Neves A, Sequeira V, Vieira AR, Silva E, Silva F, Duarte AM, Mendes S, Ganhão R, Assis C, Rebelo R, Magalhães MF, Gil MM, Gordo LS. 2022. Reproduction of the blue jack mackerel, Trachurus picturatus, in western Portugal: microscopic gonad analysis reveals indeterminate fecundity and skipped spawning patterns. Zool Stud 61:41. doi:10.6620/ZS.2022.61-41.