New Evaluation of Postovulatory Follicle Degeneration at High-Temperature Regimes Refines Criteria for the Identification of Spawning Cohorts in the European Anchovy (Engraulis encrasicolus)

• Published in: Animals (Basel) Vol. 11; no. 2; p. 529
• Main Authors: Ferreri, Rosalia, Barra, Marco, Gargano, Antonella, Aronica, Salvatore, Bonanno, Angelo, Genovese, Simona, Rumolo, Paola, Basilone, Gualtiero
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 18.02.2021; MDPI
• Subjects: anchovies; Animal reproduction; Biomass; case studies; Commercial fishing; daily spawning cohort; Digital cameras; egg production; Eggs; Engraulis encrasicolus; European anchovy; Fish; Fisheries; fisheries management; Fishing; histology; marine fish; Mediterranean Sea; Ovaries; Ovulation; postovulatory follicle size; reproductive success; resorption rate; summer; water temperature; Mediterranean Sea; European anchovy; histology; daily spawning cohort; postovulatory follicle size; resorption rate
• ISSN: 2076-2615; 2076-2615
• DOI: 10.3390/ani11020529

Accurate stock assessment estimates of fish resources are essential in fishery management. Wide fluctuations in abundance arising from variations in reproductive success are characteristic of many marine fish populations, including multiple spawner species. The proportion of females spawning per day is crucial in the application of egg production methods for spawning biomass evaluation and, usually, is assessed by postovulatory follicle (POF) method. Describing each degeneration stage of POF based upon its histological features allows for obtaining an aging key for postovulatory follicles. The commercially valuable European anchovy (Engraulis encrasicolus) was selected as a case study, which breeds during the summer in temperate waters (24 °C–25 °C). A collection of ovary slides, sampled in the central Mediterranean Sea during the spawning peak, provided a 24 h cycle coverage. These observations allowed us to evaluate the duration of each POF stage at water temperature experienced by anchovy in the study area. Present results demonstrated the POF degeneration progress at a faster rate than reported by previous investigations, carried out in cooler oceanic waters. Furthermore, the present study displayed the presence of two anchovy spawning cohorts sampled along a 24-h cycle. Therefore, this study not only provides useful insight for more accurate POF degeneration evaluation in temperate waters, but also suggests that current estimates should be complemented with validation studies according to different temperature regimes.