Reproduction of the blue jack mackerel, Trachurus picturatus, in western Portugal: microscopic gonad analysis reveals indeterminate fecundity and skipped spawning patterns

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.info:eu-repo/semantics/publishedVersio

Determinate versus indeterminate fecundity in horse mackerel

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Molecular barcoding of NE Atlantic deep-water sharks: species identification and application to fisheries management and conservation

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Life history parameters as basis for the initial recognition of stock management units in horse mackerel (Trachurus trachurus)

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Negative impact on the reproductive potential of blue jack mackerel Trachurus picturatus by Kudoa infection of the ovary

Reproduction of Trachurus picturatus off the western Portuguese coast was studied over 1 yr. During histological analyses, the presence of Kudoa sp. was detected in advanced vitellogenic oocytes. Kudoa infections are known to cause economic loss through the induction of postmortem liquefaction of fish muscles, but ovarian infection as reported in this study will seriously affect the reproductive potential of the species and thus impact fisheries productivity. Only females showed gonad infection which led to total degradation of advanced vitellogenic oocytes. No macroscopic, somatic or condition indices revealed differences between infected and uninfected females, rendering this infection event a concealed suppression of reproduction.info:eu-repo/semantics/publishedVersio

Intercalibration of age reading of depwater black scabbardfish, Aphanopus carbo (Lowe, 1839).

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Growth and reproduction of horse mackerel, Trachurus trachurus (Carangidae)

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Stock identity of horse mackerel (Trachurus trachurus) in the Norheast Atlantic and Mediterranean Sea: Integrating the results from different stock identification approaches

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Considerations on sampling strategies for an holistic approach to stock identification: The example of the HOMSIR project

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