Preliminary Report of a Biometric Analysis of Greater Pipefish Syngnathus Acus Linnaeus, 1758 for the Western Black Sea
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Turkish Journal of Zoology Turk J Zool (2015) 39: 917-924 http://journals.tubitak.gov.tr/zoology/ © TÜBİTAK Research Article doi:10.3906/zoo-1408-57 Preliminary report of a biometric analysis of greater pipefish Syngnathus acus Linnaeus, 1758 for the western Black Sea Taner YILDIZ*, Uğur UZER, Firdes Saadet KARAKULAK Department of Fisheries Technology, Faculty of Fisheries, İstanbul University, Laleli, İstanbul, Turkey Received: 22.08.2014 Accepted/Published Online: 27.02.2015 Printed: 30.09.2015 Abstract: The main objective of this study was to analyze the differences and similarities in morphometric characteristics among specimens of greater pipefishSyngnathus acus Linnaeus, 1758 that were collected and described based on data from bottom-trawl surveys and commercial trawl fisheries in the western Black Sea between September 2010 and October 2011. A total of 280 specimens were analyzed, of which 191 were female and 89 were male. Female individuals ranged from 15.6 to 33.8 cm in total length, whereas male individuals ranged from 16.6 to 39.2 cm. For the biometric analysis, 14 morphometric characteristics were analyzed. The females and males were found to differ in maximum body height, maximum body width, and head length (P < 0.05). The length–length equations for overall converted body lengths of fish were linear. The morphometric characteristics were strongly positively correlated except for head length / total length and snout width / head length (P < 0.05). The length–weight relationship of this species was described by the following equation: TW (g) = 0.0001 × TL3.415 (cm). Relationships between the characteristics were defined separately for both sexes. Key words: Biometry, length–length, greater pipefish, Syngnathus acus, western Black Sea 1. Introduction and are a common bycatch. This species is not of concern Morphometric and meristic features are used primarily on the IUCN Red List presently, but it is likely to become to study relationships among stocks, such as stock endangered in the future. membership, the spatial distribution of stocks, and the Although a few ichthyological studies have focused phylogeny of stocks (Coyle, 1997; Turan, 2004). According on pipefish morphometrics (Cakić et al., 2002; Mwale, to Begg et al. (1999), phenotypic markers may be more 2005; Gürkan, 2008; Gürkan and Taşkavak, 2012), there applicable for studying short-term, environmentally is currently no information on the greater pipefish’s (S. induced variation, which is perhaps more applicable for acus) morphological structure in the Turkish waters of fisheries management. Ibanez-Aguirre et al. (2006) also the Black Sea. The purpose of this study was to analyze noted that it is of vital importance to identify the study morphological variation of S. acus among different population to understand its dynamics. locations along the western Black Sea coasts of Turkey. There are 300 species of pipefishes in 35 genera, and their taxonomy is in urgent need of revision (www. 2. Materials and methods zoonetics.com). The Mediterranean basin has 9 species A total of 280 individuals of S. acus were collected from that belong to the genus Syngnathus (Dawson, 1986); 6 bottom-trawl surveys and commercial bottom-trawl species are distributed in the Black Sea (Bilecenoğlu et catches in the western Black Sea. Surveys were carried al., 2002; Gürkan and Çulha, 2008). Syngnathus acus can out in 2 different seasons (spring and autumn) and at 3 be found in coastal and estuarine waters to depths of 90 locations. In total, 39 stations were sampled between m or more on sandy, muddy, and rough bottoms; it is September 2010 and October 2011. Specimens were relatively common among algal and eelgrass habitats captured using a 20-mm stretch cod-end mesh size, at (Dawson, 1986). Pipefishes, like most other syngnathids, a depth of 10–100 m. The study area was divided into 3 are characterized by restricted distributions, low mobility, sublocations considering local differences (Figure 1). small home ranges, and low fecundity (Vincent, 1996). The body parts were measured following standard Although they have no commercial importance in fisheries, anatomical landmarks (Cakić et al., 2002; Gürkan, they are threatened by incidental capture in fishing gears 2008). The landmarks include the following: total length * Correspondence: [email protected] 917 YILDIZ et al. / Turk J Zool Figure 1. Sampling stations. (TL), total weight (TW), maximum body height (BH), 0.01 millimeter) on the right side of the pipefish. The maximum body width (BW), length of pectoral fin (PFL), specimens were weighed using a digital balance to the length of dorsal fin base (DFL), height of dorsal fin (HD), nearest 0.01 g. The sex of the specimens could easily be head length (HL), occipital height of head (OHH), mouth determined macroscopically. height (MH), mouth width (MW), eye diameter (ED), A linear regression of various body parts against the snout length (SL), snout depth (SD), and snout width total length and head length was carried out using the (SW). The 14 morphometric characteristics are explained least-squares method. Thorpe (1976) noted that only in Figure 2. To ensure standardization, all measurements morphometric data could be statistically adjusted to were performed by the same person using calipers (nearest permit the comparative analysis of shape independent of Figure 2. Diagram of morphometric measurements of pipefishes. 918 YILDIZ et al. / Turk J Zool size in variations in the size of fish from different locations. BW, PFL, DFL, HD, and HL relative to the TL, and the Thus, to minimize the influence of size differences on OHH, MH, MW, ED, SW, SL, and SD relative to the HL the subsequent results, the original measurements of (Table 1). The coefficients of variation (CVs) indicated the morphometric characteristics were standardized. Six highest variability in the SW / HL ratio (CV = 23.0% for morphometric characteristics were expressed as % TL males, 20.1% for females), whereas the lowest variability and 7 as % HL. This technique is commonly used in was noted in the HL / TL ratio (CV = 7.2% for male, 6.8% ichthyological studies. Morphometric characteristics were for female). Differences between females and males were analyzed by ANOVA followed by Holm–Bonferroni’s post found in the maximum body height, maximum body hoc test (Sokal and Rohlf, 1981) for all possible pairwise width, and head length as a result of Bonferroni’s test (P comparisons from different locations and between sexes. < 0.05). The length–weight relationship was calculated with the The comparisons of the morphometric characteristics equation W = aLb, where W is the weight (g), L is the total of S. acus between different locations are given in Table length (cm), a is the intercept, and b is the slope (Ricker, 2. There were significant differences in 10 morphometric 1975). Lengths and weights were log-transformed, and the characteristics (Holm–Bonferroni’s test). The specimens resulting linear relationship was fitted by the least-squares of location 1 were morphologically different from the regression. To ensure the quality of the linear regression, individuals of location 2 in the BH, BW, PFL, DFL, MH, the coefficient of determination (r2) was used. Data were and SW characters. The specimens of location 1 were analyzed using SPSS 16.0. morphologically different from the individuals of location 3 in the BW, PFL, OHH, SD, SL, and SW characters. The 3. Results specimens of location 2 were morphologically different Of the 280 specimens, 191 were females (68.2%) and from the individuals of location 3 in the HL, OHH, SD, SL, 89 were males (31.8%). The lengths and weights of S. and SW characters. acus ranged from 156 to 392 mm and from 1 to 16.66 The estimated parameters of the length–length g, respectively. The morphology of the sampled fish was relationships as well as the coefficients of correlation (r) described as the relative body proportions of the BH, are presented in Table 3. The morphometric characteristics Table 1. Morphometric characteristics of S. acus caught in the western Black Sea during the period from September 2010 to October 2011. Morphometric Females Males characters Min. Max. Mean ± SD Min. Max. Mean ± SD P TL (mm) 156 338 270.59 ± 29.45 166 392 264.06 ± 29.42 0.055 % TL BH 1.24 4.65 3.37 ± 0.51 1.91 4.44 2.80 ± 0.46 0.000* BW 1.63 3.86 3.01 ± 0.43 1.49 3.76 2.68 ± 0.39 0.000* PFL 0.97 2.53 1.80 ± 0.33 1.01 2.67 1.78 ± 0.30 0.545 DFL 6.48 14.76 10.53 ± 1.12 6.15 12.83 10.50 ± 1.26 0.832 HD 1.19 3.46 2.58 ± 0.43 1.29 3.58 2.63 ± 0.47 0.408 HL 12.87 19.09 15.69 ± 1.07 10.10 18.37 15.06 ± 1.09 0.000* % HL OHH 11.83 30.42 16.52 ± 2.30 12.13 24.32 16.78 ± 2.02 0.412 MH 6.60 14.46 8.98 ± 1.36 5.49 12.58 9.24 ± 1.27 0.099 MW 2.25 5.04 3.43 ± 0.56 1.71 4.99 3.51 ± 0.64 0.296 ED 5.45 16.19 9.25 ± 1.69 6.78 14.06 9.61 ± 1.66 0.095 SW 1.85 5.03 3.23 ± 0.65 1.68 5.48 3.26 ± 0.75 0.129 SL 40.53 73.63 55.99 ± 5.40 43.01 68.24 54.56 ± 5.27 0.193 SD 4.19 11.91 6.55 ± 0.90 4.68 10.97 6.69 ± 0.90 0.238 *Significantly different at P < 0.05.