The length–weight relations of ten fish species representing eight genera and four families and that formed the backbone of the subsistence fishery in the Lakshadweep islands were estimated. These fishes which included four species of tuna [Katsuwonus pelamis (Linnaeus, 1758); Thunnus albacares (Bonnaterre, 1788); Auxis thazard (Lacepède, 1800); Euthynnus affinis (Cantor, 1849)], three species of needlefishes[Ablennes hians (Valenciennes, 1846); Tylosurus crocodilus (Péron et Leseur, 1821); Tylosurus acus melanotus (Bleeker, 1850)], two species of bait fishes [Spratelloides delicatulus (Bennett, 1832); Spratelloides gracilis (Temminck et Schlegel, 1846)], and one species of halfbeak (Hemiramphus archipelagicus Collette et Parin, 1978) contributed to 96% of the total fish landings. The samples were collected from fish landing centers of ten inhabited islands of Lakshadweep from 2015 to 2017. Katsuwonus pelamis showed isometric growth, S. delicatulus and S. gracilis exhibited positive allometry, while negative allometric growth was seen in other species. The coefficient a of the LWR ranged from 0.001 (A. hians) to 0.035 (T. albacares), while b ranged from 2.7 (T. acus melanotus) to 3.4 (S. delicatulus). The results of the presently reported study provide useful biological information on the stock of ten commercially important pelagic fish species supporting the traditional fisheries in Lakshadweep waters.

The length–weight relations of ten fish species representing eight genera and four families and that formed the backbone of the subsistence fishery in the Lakshadweep islands were estimated. These fishes which included four species of tuna [Katsuwonus pelamis (Linnaeus, 1758); Thunnus albacares (Bonnaterre, 1788); Auxis thazard (Lacepède, 1800); Euthynnus affinis (Cantor, 1849)], three species of needlefishes[Ablennes hians (Valenciennes, 1846); Tylosurus crocodilus (Péron et Leseur, 1821); Tylosurus acus melanotus (Bleeker, 1850)], two species of bait fishes [Spratelloides delicatulus (Bennett, 1832); Spratelloides gracilis (Temminck et Schlegel, 1846)], and one species of halfbeak (Hemiramphus archipelagicus Collette et Parin, 1978) contributed to 96% of the total fish landings. The samples were collected from fish landing centers of ten inhabited islands of Lakshadweep from 2015 to 2017. Katsuwonus pelamis showed isometric growth, S. delicatulus and S. gracilis exhibited positive allometry, while negative allometric growth was seen in other species. The coefficient a of the LWR ranged from 0.001 (A. hians) to 0.035 (T. albacares), while b ranged from 2.7 (T. acus melanotus) to 3.4 (S. delicatulus). The results of the presently reported study provide useful biological information on the stock of ten commercially important pelagic fish species supporting the traditional fisheries in Lakshadweep waters.

Marine fish stocks are depleting at an alarming rate. Skipjack tuna, Katsuwonus pelamis has been exploited in Lakshadweep Island area in the Indian Ocean mainly by pole and line fishery which constituted one-third of its production in the country. Age, growth, demographics and stock assessment of this species were investigated from the Lakshadweep waters. The von Bertalanffy growth factors were estimated as asymptotic length 72.5 cm, growth constant 0.480 and the theoretical age at zero-length as –0.1097. This study showed that skipjack grows from 30 to 68.26 cm from first to sixth year. The natural mortality, fishing mortality and total mortality were 0.82, 1.51 and 2.33 respectively. The exploitation ratio was 0.65, while the exploitation which maximises relative yield per recruit (Emax) was 1.0.  Recruitment pattern showed that young recruits entered the fishing grounds in most months, with peaks during June–July. Length based Virtual Population Analysis indicated that the major loss in its stock up to 22 cm was due to natural causes. At the same time, higher fishing mortality was registered in 40–60 cm length group. The present study provides knowledge on the demographics of K. pelamis, pertinent for formulating an effective fisheries management in the region.