J Appl Ichthyol. 2017;1–3. wileyonlinelibrary.com/journal/jai | 1 © 2017 Blackwell Verlag GmbH Received: 2 April 2017 | Accepted: 18 October 2017 DOI: 10.1111/jai.13545 TECHNICAL CONTRIBUTION Length–weight and Length-length relations of four fish species from the Chilika Lake, East coast of India S. K. Karna | V. R. Suresh | M. Mukherjee | R. K. Manna ICAR- Central Inland Fisheries Research Institute, Barrackpore, Kolkata, India Correspondence Subodha Kumar Karna, ICAR- Central Inland Fisheries Research Institute, Barrackpore, Kolkata, India. Email: subodhaindia@gmail.com Funding information Chilika Development Authority (CDA), Odisha (India) for financial support through the World Bank sponsored project “Post restoration assessment of the ecology and fisheries diversity of Chilika Lake”. Summary This study reports the length–weight relationship (LWR) and length-length relation- ship (LLR) estimated for four fish species inhabiting in Chilika Lake, India. Total 504 specimens were sampled from mono-filament gill nets (mesh size 12 mm, 22–24 mm, 34–38 mm, 42 mm) during January 2015 to December 2015. The estimated b values from LWR ranged between 2.79 (T. biaculeatus) to 3.29 (C. praeustus). In all species, the relationships between length-weight and length-length were highly correlated (p < .05). The study provides first world reports on LWRs and LLRs for all the 4 studied species. 1 | INTRODUCTION Management for fisheries or conservation requires information about body weight for regulation of catch and estimation of biomass (Froese, Thorson, & Reyes, 2014). Similarly, estimation of particularly the standing stock, yield and biomass of a fish population, requires both length and weight data. But in field data collection, it is more convenience to record fish size in length than body weight when data requirement is huge for an individual species. It is very practical to record both length and weight of each specimen from an unsorted catch, is time consuming as well as cost expensive. Therefore, for quick assessment, body weight can be pre- dicted from length with the help of length-weight relationships (LWR) (Froese, 2006). So, LWR database is an important part of fish biology, for any type of fish (commercial, non-commercial, food fish, thrashed fish or prey fish) species is highly essential. Such database can be useful for esti- mation of biomass in any corner of the globe because, every species has a unique shape in general. The value ‘a’ of LWR is a parameter describ- ing body shape and condition, if b ~ 3 (Froese, 2006). The information on length-weight relationship and length-length relationship (LLR) for fish species inhabiting in Chilika is limited. Thus, the goal of this study was to report data of LWR and LLR, for 4 fish species caught from Chilika. 2 | MATERIALS AND METHODS Chilika (19°28′–19°54′N; 85°05′–85°38′E), the largest brack- ish water lake of Asia and a designated Ramsar site of International importance, is situated along the east coast of India. The lake is one of the most diverse aquatic ecosystems of the tropics and a hotspot in bio-diversity. The water spread area of the lake ranges between 906 km 2 (dry season) to 1165 km 2 (monsoon season) with a maximum 6.2 m water depth (Mohanty et al., 2015). The Lake supports liveli- hood and nutritional security to about 0.2 million local fishers living in and around the lake (Mohanty et al., 2015). Samplings in Chilika Lake were conducted from January 2015 to December 2015 and fresh fish specimens were collected randomly from the fishing boats of all cor- ners of the lake with targeting mono-filament gill net fishing of mesh size 12 mm, 22–24 mm, 34–38 mm and 42 mm. As soon as collection, the fishes were transported to research laboratory maintaining cold chain. Species were confirmed following Fischer and Bianchi (1984), Day (1986) and Rao (2009). Total lengths (TL) and standard lengths (SL) were measured to the nearest 0.1 cm using a digital caliper and weights (W) were recorded to the nearest 0.1 g (smaller specimens) and 1.0 g (bigger specimens) using an electronic balance (Model: Precisa XB 320 M). The counts of all the species, length parameters (minimum and maximum) and weight parameters (minimum and maximum) were determined. The parameters of the length-weight relationship W = aL b were calculated by the least squares method through the transformed equation, log W = log a + b * log L where, W is the body weight (g), L is the total length (cm), a is the intercept and b is the slope of the linear regression (Froese, 2006). Prior to linear regression analysis, outliers in the log–log plots were identified and removed from the data (Froese, 2006). The statistical significance,