Summary
Length‐weight relationships (LWRs) were estimated for five needlefish species such as Ablennes hians (Valenciennes, 1846), Tylosurus crocodilus (Péron & Lesueur, 1821), Tylosurus acus melanotus (Bleeker, 1850), Strongylura leiura (Bleeker, 1850), and Strongylura strongylura (van Hasselt, 1823). Specimens were collected on weekly basis from Cochin Fisheries Harbour (Lat. 09056′327″N, Long. 76015′764″E), Munambam Fisheries Harbour (Lat. 10010′965″N, Long. 76010′258″E), Kalamukku (Lat. 09059′924″N, Long. 76014′564″E) and Chellanam (Lat. 09047′950″N, Long. 76016′551″E), between October 2015 to August 2017. Fish were captured by traditional long liner (hook no. IX‐XIV) and ring seiner (mesh size 8–24 mm). The estimated allometric co‐efficient b values ranged from 3.063 (Tylosurus acus melanotus) to 3.962 (Strongylura leiura) and r2 values ranged from 0.850 (Tylosurus acus melanotus) to 0.992 (Tylosurus crocodilus). All the LWRs were highly significant, with p < .001. In addition, the study provides the first estimate of LWR for Tylosurus acus melanotus and new estimate for other four species of needlefish.
Summary
The present study reports the length‐weight relationships (LWRs) of two clupeoid fish species, Thryssa malabarica (Bloch, 1795) and Thryssa dayi Wongratana, 1983 from Kerala waters, southwest coast of India during the period October 2015 to September 2016. Altogether 88 specimens of T. malabarica and 97 T. dayi were collected on weekly basis from gill nets (mesh size, 2.6–5.0 cm) and ring seines (mesh size, 0.8–2.6 cm) during the period. The value of parameter b in the equation of LWRs was estimated as 3.237 and 3.248 for T. malabarica and T. dayi respectively.
Landings of the white sardine Escualosa thoracata (Valenciennes, 1847) indicated a shift in their abundance from northeast to south-west coast of India and a sharp decline in the resource landings during the last decade along the entire range of its distribution. High local demand coupled with competitive price for the species might have led to overexploitation of this otherwise seasonal resources along the major areas of its abundance along the Indian coast. Detailed study on the systematics, fishery and biology of the species landed along Kerala coast was undertaken during 2015 and 2016. Stock assessment studies indicated near optimum fishing pressure on the resource along the Kerala coast.
Aim: The study was carried out to ascertain whether morphotype of Scomberoides commersonnianus (Talang queenfish) existing along the Indian coast is a new species or not. Methodology: Talang queenfish and the morphotype were tested for their uniqueness using systematic and molecular tools. The morphometric and meristic details including otolith morphometry were analysed and compared for taxonomic divergence and Cytochrome Oxidase I and Cytochrome b gene sequences for quantifying genetic divergences. Results: The systematic analysis indicated significant morphometric differences between both. The otolith morphometry and phylogeny also confirmed the divergence between them, and qualified the morphotype as an independent species status and named Scomberoides pelagicus sp. nov. Interpretation: The new species is distinct by deep ovate body, concave dorsal head profile, anal fin origin anterior to second dorsal fin and pelvic to pectoral fin, helical arrangement of body scale and stout and less numerous gill rakers on the first gill arch. The phylogeny as on Cytochrome b and Cytochrome Oxidase 1 sequences are very distinct, with 11.2% and 2.0% divergence respectively. Their known distributional range are peninsular region of Indian coast, Malaysian region of the South China Sea and Manila Bay, Philippines.
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