J Appl Ichthyol. 2017;1–3. wileyonlinelibrary.com/journal/jai | 1 © 2017 Blackwell Verlag GmbH Received: 18 April 2017 | Accepted: 9 May 2017 DOI: 10.1111/jai.13422 TECHNICAL CONTRIBUTION Length–weight relationships of five fish species from Carangidae family in waters of the northern Persian Gulf, Iran M. Parsa | B. Rahnama | M. Mahmoudi Khoshdarehgi Young Researchers and Elite Club, Bandar Abbas Branch, Islamic Azad University, Bandar Abbas, Iran Correspondence Mehran Parsa, Young Researchers and Elite Club, Bandar Abbas Branch, Islamic Azad University, Bandar Abbas, Iran. Email: mehranparsa85@yahoo.com Summary This research describes and presents some biological aspects of five fish species from carangidae family including: Alepes djedaba, Ulua mentalis, Alectis indica, Carangoides coeruleopinnatus, and Carangoides bajad in the Iranian waters of the northern Persian Gulf (Hormozgan Province, Iran). Samples were collected from April to September 2016. The fishing gears were gill nets (80, 100, 120 and 145 mm stretched mesh size), bottom and midwater trawls (30, 40 and 75 mm stretched mesh size in cod-end) of local and commercial fishery. The b values of length–weight relationships ranged from 2.512 (95% CL = 0.054) for U. mentalis to 2.953 (95% CL = 0.155) for C. coeruleopin- natus and the correlation coefficient values (r 2 ) were high for all species. 1 | INTRODUCTION The family Carangidae includes a diverse group of fishes known vari- ously by such common names as jacks, trevallies (crevalles), amberjacks, moonfishes, pompanos, scads, kingfish, pilotfish, rainbow runners and among others (Honebrink, 2000). There are now considered to be about 32 genera and 140 species worldwide (Nelson, 2006; Smith- Vaniz, 2003). 45 species from 21 genera occur in Iranian waters of the Persian Gulf and Oman Sea (Sattari, Shahsavani, & Shafiei, 2004). Length–weight relationship estimates are very helpful in fish- ery management and stock assessment models (Barría, Navarro, Coll, Fernandez-Arcaya, & Sáez-Liante, 2014), and has been widely used in the environmental monitoring programs such as calculation of fish weight at a certain length, conversion of an equation of growth in weight (Oliveira, Loverde-Oliveira, Mateus, & Teixeira-de Mello, 2014; Yoon et al., 2013). Length–weight relationships can also be used to compare life history and morphological aspects of fish populations in- habiting different regions (Stergiou & Moutopoulos, 2001). In this study, length–weight relationships of five species of Carangidae family were estimated in the northern Persian Gulf (Hormozgan Province, Iran). 2 | MATERIALS AND METHODS This research was conducted in the fishing grounds of the northern Persian Gulf (Hormozgan Province) in an area extending from Qheshm island (26° 41′ N, 55° 41′ E) to Kish island (26° 28′ N, 53° 59′ E) from April to September 2016. Fork length (FL) and total weight (TW) of five species of Carangidae family including Alepes djedaba (Forsskål, 1775), Ulua mentalis (Cuvier, 1833), Alectis indica (Rüppell, 1830), Carangoides coeruleopinnatus (Rüppell, 1830) and Carangoides bajad (Forsskål, 1775) were measured to the nearest 1 cm and 1 g, respectively. The fishing methods and sampling gears were monofilament and multifilament gill nets (80, 100, 120 and 145 mm stretched mesh size), bottom and midwater trawls (30, 40 and 75 mm stretched mesh size in cod-end) of local and commercial fishery. The relationship between length and weight was estimated using the following equation: (Jones, 2002) where a is a coefficient related to body form, and b is an exponent isometric growth when equal to 3. The parameters a and b were esti- mated by linear regression on the transformed equation: (Koutrakis & Tsikliras, 2003) The best regression parameters (a and b) were obtained by minimiz- ing the residuals errors by the least square residuals method (Haddon, 2011). 3 | RESULTS Fork length, total weight and length–weight relationship data of all species are summarized in Table 1. The fork length and total weight TW = a × FL b Log W = log a + b log L