Length‐weight and length‐length relationships of the genus Alosa (Clupeoidei: Clupeiformes: Clupeidae) along the southern Caspian Sea coast

Length–weight (LWR) and length–length (LLR) relationships were estimated for four shad species of the genus Alosa, reported from along the southern Caspian Sea coast, north of Iran in a study from March 2014. Two of these species are endemic to the Caspian Sea. The length–weight parameter b for these species ranged from 2.99 to 3.24, with regression coefficients (r²) ranging from 0.91 to 0.99. All LLRs were highly significant (r² > 0.96).     

Feeding habits of the Pacific bearded brotula Brotula clarkae Hubbs, 1944 (Ophidiidae) along the Pacific coast of Costa Rica,Central America

The present study analyzed the diet composition, ontogenetic shifts and dietary overlap of Brotula clarkae in relation to stage of maturity and sex. Samples were collected from the trawling fishery along the Pacific coast of Costa Rica (2011–2012) at depths ranging from 41.4 to 168.3 m; however, over 80% of the sampled fish were obtained at depths between 50 and 75 m. Size ranged from 14.4 to 98.4 cm total length. Of the 323 analyzed stomachs, 44.3% were from males, 86% were from immature individuals, and 49.8% had at least one prey item. According to the prey‐specific index of relative importance (P_SIRI), decapod shrimps were the most important prey (57.6% P_SIRIi) followed by teleosts (28.2% P_SIRIi), stomatopods (10.8% P_SIRIi), and crabs (3.3% P_SIRIi). Male and female B. clarkae exhibited a high dietary overlap (C_H = 0.94). Immature B. clarkae consumed primarily shrimps and crabs (71.5% of stomachs from immature specimens contained shrimps, which accounted for over 66.0% P_SIRIi); mature individuals consumed a large proportion of teleosts and stomatopods, which together contributed to over 91.0% P_SIRIi. Both immature and mature B. clarkae overlapped spatially with the commercial trawling fishery grounds along the Pacific coast of Costa Rica. However, juveniles feed predominantly on shrimps, suggesting that immature B. clarkae may be subjected to high fishing pressure as by‐catch, making them particularly vulnerable to overexploitation.     

Measuring fish length and assessing behaviour in a high‐biodiversity reach of the Upper Yangtze River using an acoustic camera and echo sounder

In the past decade improved acoustic hard‐ and software have enabled estimations of abundance and distribution patterns of aquatic organism, including non‐intrusive monitoring of fish migrations and behaviour. In this study, a high frequency acoustic camera (DIDSON‐LR, 1.2 MHz, 0.7 MHz) and a portable split‐beam scientific echo sounder (Simrad EY60, 200 kHz) collected acoustic data on 192 and 157 individuals within 24 hr (19–20 April 2011) in the Mituo reach of the Yangtze River, China. Mean fish length estimated from the acoustic camera data was 18.7 ± 5.6 cm, with an average swimming speed of 0.19 ± 0.13 m s^?1. The mean fish target strength (TS) produced by the echo sounder was ?43.8 ± 4.4 dB, which corresponded to 5.7–119.9 cm fish length when converted by three different TS‐length equations. Average swimming speed was 0.11 ± 0.06 m s^?1 from the echo sounder. Compared with the actual fish catch by the three layers of drift gill net in the survey area, the target length indicated by DIDSON was more accurate than the EY60 results, which were highly affected by the choice of TS length equations. It was determined that the two devices used synchronously could estimate fish length effectively to investigate their behaviour and distribution.     

Length–weight and length–length relationships of 139 Indo‐Pacific fish species (Teleostei) from the Davao Gulf,Philippines

Length–weight relationships (LWRs) of 139 coral reef and pelagic fish species (representing 34 fish families) were calculated based on 3806 individuals measured at local fish markets near the Davao Gulf in the southern Philippines during weekly visits between March 2009 and July 2011, as well as in June 2012. Fishes were caught with a variety of fishing methods, corroborated by abrasions and injuries. Forty‐seven of 139 LWRs were firstly reported and new to science. The mean slope b of the LWRs was 3.035, indicating that the majority of studied species followed isometric growth. Standard length – total length relationships were calculated for all measured fish species. Additionally, standard length – fork length relationships are presented for 108 species. Moreover, fifteen new records of maximum fish length and weight are reported.     

Length–weight and length–length relationships of seven fish species from the Ili River and tributaries,northwest China

Length–weight and length–length relationships were estimated for seven fish species belonging to four families from the Ili River and its tributaries, northwest China. From April to October 2013 and May to October 2014, specimens were collected monthly for a total of 783 specimens. This study presents the first references on LWRs for Diptychus maculates, Gymnodiptychu dybowskii, Perca schrenkii, Silurus meridionalis and Schizothorax pseudoaksaiensis pseudoaksaiensis, and LLRs for G. dybowskii, P. schrenkii, S. meridionalis, S. pseudoaksaiensis pseudoaksaiensis, Triplophysa strauchii and Triplophysa stoliczkai.     

Length–weight relationships for 36 deep‐sea fish in the Colombian Caribbean Sea

Length–weight relationships (LWR) for 36 deep‐sea fish species belonging to 22 families are provided. Samples were collected during 2009 by trawling with the sampling design stratified by depths ranging from 200 to 550 m in the Colombian Caribbean Sea. To the best knowledge of the authors, this study represents the first study on length–weight relationships for 17 species worldwide, as well as 13 new maximum lengths.     

Length–weight relationships of freshwater fishes of the Alto Madre de Dios River (Manu Biosphere Reserve,Peru)

The present work provides the estimates of morphometric relationships for 22 native freshwater fish species (11 Characidae, five Loricariidae, two Heptapteridae, one Astroblepidae, one Crenuchidae, one Curimatidae and one Erythrinidae) collected in the Alto Madre de Dios River (Cuzco and Madre de Dios, Peru) in June 2012 using a mobile backpack electrofishing unit. These are the first length–weight relationships reported for 24 species, mostly endemic to the Amazonian basin. Knowledge regarding these biometric relationships can be relevant in the management and conservation of the local fishes and fisheries.