Shedding light on the deep: The case of the velvet belly lanternshark in the North Aegean Sea
| Autor: | Vasiliki Kousteni |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Male
0106 biological sciences Morphometrics Sex Characteristics 010604 marine biology & hydrobiology Fisheries Zoology Aquatic Science Biology biology.organism_classification 010603 evolutionary biology 01 natural sciences Sexual dimorphism Mediterranean sea Etmopteridae Mediterranean Sea Sharks Etmopterus Animals Sexual maturity Female Sex Ratio Allometry Ecology Evolution Behavior and Systematics Sex ratio |
| Zdroj: | Journal of Fish Biology. 99:101-117 |
| ISSN: | 1095-8649 0022-1112 |
| Popis: | Main biological features were assessed for the first time in the deep-water shark Etmopterus spinax from Hellenic waters by examining 150 individuals caught incidentally in the bottom-trawl commercial fishery off Skyros island. Females outnumbered males and the overall sex ratio was 1.38:1. Females ranged from 122 to 311 mm in total length (LT ) and males from 129 to 270 mm LT , both exhibiting positive allometric growth. Total length-total mass relationships and frequency distributions did not show significant differences between females and males. Sexual dimorphism was not either found by analysing 56 different morphological characteristics. The effect of sex and season was more prominent on the gonadosomatic and hepatosomatic indices compared to the relative condition factor. Most of the individuals were sexually immature, with two specimens classified as mature, one gravid female reaching 311 mm LT with undeveloped gonads and enlarged uteri with embryos, and one male reaching 270 mm LT with enlarged gonads and rigid claspers with hooks. The present study highlights the importance of the sampling location as a breeding and nursery ground for E. spinax in the eastern Mediterranean Sea that should be taken into account for the species' conservation considering its intrinsic characteristics, which make it vulnerable to fishing pressure. |
| Databáze: | OpenAIRE |
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