Evaluating the influence of environmental variables on the length-weight relationship and prediction modelling in flathead grey mullet, Mugil cephalus Linnaeus, 1758

Abstract

Fish stocks that are grown under diverse environmental conditions have different biometric relationships and growth patterns. The biometric length-weight relationship (LWR) is an essential fishery assessment tool, as fish growth is continuous and depends on genetic and environmental factors. The present study attempts to understand the LWR of the flathead grey mullet, Mugil cephalus Linnaeus, 1758, from different locations. The study area encompassed its distribution in the wild across freshwater location (one), coastal habitats (eight locations), and estuaries (six locations) in India to determine the relationship between various environmental parameters. Specimens (n = 476) of M. cephalus were collected from commercial catches and the length and weight of individual specimens were recorded. Monthly data from the study locations were extracted for nine environmental variables from the datasets downloaded from the Physical Oceanography Distributed Active Archive Center (PO.DAAC) and the Copernicus Marine Environment Monitoring Service (CMEMS) over 16 years (2002 to 2017) on the Geographical Information System platform. The parameters of the LWR, intercept ‘a’ and slope or regression coefficient ‘b’, varied from 0.005321 to 0.22182 and 2.235 to 3.173, respectively. The condition factor ranged from 0.92 to 1.41. The partial least squares (PLS) score scatter plot matrix indicated differences in the environmental variables between the locations. PLS analysis of the regression coefficient and environment parameters revealed that certain environment variables viz., sea surface temperature, salinity, dissolved oxygen, nitrate, and phosphate, played a positive role. However, chlorophyll, pH, silicate, and iron played a negative role in influencing weight growth across various locations. The results revealed that the M. cephalus specimens from three locations, Mandapam, Karwar, and Ratnagiri, possessed significantly higher fitness to their environment than those from the other six locations. The PLS model can be used to predict weight growth under the various environmental conditions of different ecosystems. The three identified locations are useful sites for the mariculture of this species considering their growth performance, the environmental variables, and their interactions. The results of this study will improve the management and conservation of exploited stocks in regions affected by climate change. Our results will also aid in making environment clearance decisions for coastal development projects and will improve the efficiency of mariculture systems.

Length-Weight Relationships of Twenty-Nine Native Fish Species from Hongshui River, Southern China

“…For the twenty-nine native fsh species, all the P values were extremely signifcant (P < 0.001) and the b values were within the expected range between 2.5 and 3.5 [6], which are in accordance with the previous estimates [1]. Although the LWRs presented in this study are frst estimates for most species, some of them must be taken as tentative because of the limited sample size (N < 30) and limited size range covered.…”

“…Te length-weight relationships (LWRs) of fsh are of great signifcance for studying the life history, growth, and reproduction of fsh populations [1]. Although these relationships are widely used in the study of fsh populations, the data on the length-weight relationships for many freshwater fshes are still not available [2].…”

Genetic characterization of minor carp (Labeo gonius) from Indian rivers revealed through mitochondrial ATPase 6/8 and D-loop region analysis: implications for conservation and management

“…fimbriatus (Swain et al, 2014), L. calbasu (Singh et al, 2016), L. rohita (Luhariya et al, 2012), and Chitala chitala (Mandal et al, 2012). The low percentage of GC content and the least representation of nucleotide G (12.50%) were reported in other fish species as well (Swain et al, 2014;Sahoo et al, 2019), and these might be due to anti-G bias, which is characteristic for the mitochondrial genome (Kathirvelpandian et al, 2014;Balasubramaniam et al, 2022).…”

“…Among these markers, the D-loop is a non-coding region and exhibits generally higher genetic variations relative to coding regions. The D-loop control region is the marker of choice and has important value for investigating intraspecific genetic differentiation (Mandal et al, 2012;Sahoo et al, 2020;Zhang et al, 2020), and it has been the most widely used mtDNA marker in many phylogenetic genetic studies in fish (Xie et al, 2006;Paixão et al, 2018;Jiang et al, 2019;Gao et al, 2020;Sahoo et al, 2020). In addition, another important mitochondrial region ATPase 6/8 also mutates at a faster rate compared with the nuclear genes and is a potential marker analyzed for both phylogeny and phylogeography; hence, it is very useful in genetic diversity, population genetics, and evolution studies (Divya et al, 2015;Singh et al, 2016;Balasubramaniam et al, 2022).…”

“…In addition, another important mitochondrial region ATPase 6/8 also mutates at a faster rate compared with the nuclear genes and is a potential marker analyzed for both phylogeny and phylogeography; hence, it is very useful in genetic diversity, population genetics, and evolution studies (Divya et al, 2015;Singh et al, 2016;Balasubramaniam et al, 2022). The ATPase 6/8 gene has been used successfully in many fish species (Behera et al, 2015(Behera et al, , 2018a(Behera et al, , 2018bMandal et al, 2012;Paixão et al, 2018).…”