Oceanological and Hydrobiological Studies International Journal of Oceanography and Hydrobiology Volume 49, No. 4, December 2020 ISSN 1730-413X pages (383-390) eISSN 1897-3191 Growth parameters of invasive gibel carp Carassius gibelio (Bloch, 1782) in Lake Marmara (Turkey) by Abstract The objective of this study was to determine growth Ali Ilhan, Hasan M. Sarı, Irmak Kurtul* parameters, such as age–length and length–weight relationships, as well as condition factors and sex ratio, of the Carassius gibelio (Bloch, 1782) population in Lake Marmara (western region of Turkey), which is one of the most important fishing areas. Fish were caught on a monthly basis by gillnets and trammel nets (mesh size 10–50 mm) between March 2012 and February 2013. A total of 1058 specimens (809 females and 249 males) were examined. The female– DOI: 10.1515/ohs-2020-0033 male ratio was 1:0.31. The maximum age was determined as Category: Original research paper VI and V for females and males, respectively. The total length of females and males ranged from 10.0 to 27.5 cm and from Received: February 20, 2020 10.2 to 24.0 cm, respectively. Their weight varied from 17.1 Accepted: May 18, 2020 to 378.4 g and from 17.7 to 244.9 g, respectively. Length– weight relationship parameters were a = 0.014 and b = 3.040 for females and a = 0.015 and b = 3.039 for males. Von Bertalanffy growth parameters of the C. gibelio population Ege University, Faculty of Fisheries, Marine −1 were as follows: L∞ = 35.86 cm, k = 0.189 year , t0 = −1.238 and Inland Waters Sciences and Technology years. Minimum and maximum condition factors were 1.56 Department, 35100 Izmir, for females in October and 1.82 in May and 1.67 for males in Turkey September and 1.94 in January. Key words: Carassius gibelio, invasive species, length–weight relationship, Fulton’s condition factor * Corresponding author: [email protected] online at www.oandhs.ug.edu.pl ©Faculty of Oceanography and Geography, University of Gdańsk, Poland. All rights reserved. 384 Oceanological and Hydrobiological Studies, VOL. 49, NO. 4 | DECEMBER 2020 Ali Ilhan, Hasan M. Sarı, Irmak Kurtul Introduction Balık et al. (İlhan et al. 2005). At present, C. gibelio can be observed in almost all Turkish freshwater bodies With its original geomorphological features and (Ekmekçi et al. 2013). three (Caucasus, Irano-Anatolian and Mediterranean) Known globally as a highly invasive species, of the 34 hot spots on Earth, Turkey is considered C. gibelio is one of the most precarious species for a unique country on the international scene native fish communities (Crivelli 1995), which can pose (Şekercioğlu et al. 2011). In addition, this geographical considerable threat to natural fish faunas and related area provides a natural passage for species to spread ecosystems. When introduced into a new region, its (Özuluğ et al. 2013), with very rich freshwater fauna predation characteristics and impact on other species in terms of diversity and endemism. There are 368 with which it shares the same habitat are likely to fish species in freshwaters of the country, 153 (41.8%) turn C. gibelio into the most dominant fish in a given of which are known as endemic (Çiçek et al. 2015). A ecosystem (Paulovits et al. 1998). It is believed that total of 25 invasive and potentially invasive freshwater C. gibelio is responsible for the disappearance of many species have been reported there, including C. gibelio native populations in Europe (Lusk et al. 2010), which (Innal & Erk’akan 2006). may have had a negative impact on the quality of Lake Marmara is one of the very important natural ecosystems. lakes in Turkey with fishing activities and richness The main reason for such an increase in the of endemic species. A total of 20 fish species occur spread of the carp is that it has been introduced into in Lake Marmara (İlhan & Sarı 2013), most of which water resources for various purposes. It is difficult to are cyprinid species; five of them are known as distinguish fingerlings of the species from those of endemic species in Turkish freshwaters (İzmir minnow others, because they are so similar to each other that Ladigesocypris mermere, Marmara goby Knipowitchia they can easily be confused with C. carpio (Aydın et mermere, Bergama barb Capoeta bergamae, İzmir al. 2011; İlhan et al. 2005). They generally reproduce nase Chondrostoma holmwoodi, Küçük Menderes bisexually, but also occasionally through gynogenesis spined loach Cobitis fahirae). Some translocated (Vetemaa et al. 2005), and C. gibelio could hybridize species (sand smelt Atherina boyeri, common carp with other Cyprinidae members, such as C. carpio, Cyprinus carpio and pikeperch Sander lucioperca) C. auratus, C. carassius (Belgium Forum on Invasive and some exotic species (gibel carp Carassius gibelio, Species 2011). Due to its gynogenetic breeding topmouth gudgeon Pseudorasbora parva and eastern characteristics and hybridity with other cyprinids, the mosquitofish Gambusia holbrooki) occur there species can grow very rapidly and put pressure on (C. carpio indeed belongs to the native fauna of Lake other species of an ecosystem. Marmara, which is continuously stocked to increase Several aspects of the species C. gibelio were inventory). studied during various research projects in Turkey. Lake Marmara is a habitat for approximately 144 For instance, its growth was determined by Emiroğlu different bird species (Gül 2008), which makes it a (2008), the ecological impact was established by matchless wetland. The lake has been hypertrophied as Gaygusuz et al. (2007), the feeding regime was a result of eutrophication caused by the accumulation investigated by Yılmaz et al. (2007), fecundity of agricultural fertilizers and pesticides (Gülersoy 2013). characteristics were researched by Tarkan et al. (2007), Gibel carp C. gibelio as a member of the length–weight relationships and reproduction were Cyprinidae family, feeds on zooplankton, zoobenthos, determined by Şaşı (2008) and distribution by Yerli et macrophytes and detritus in particular (Specziar et al. (2014). al. 1997). Males can grow to a maximum length of Length–weight relationships are crucial for a wide 35 cm and live about 10 years (Kottelat & Freyhof range of studies, such as presenting growth rates 2007). Carassius gibelio has a strong ability to adapt and establishing the age structure and many other to environmental changes. It inhabits all categories population parameters. Moreover, length–weight of water bodies, such as lakes, ponds, lagoons and relationships help compare populations of the same swamps, which are its main habitats (Solarz 2005). The species living in different habitats (Sangun et al. species is native to Asia, was introduced to Europe 2007). The results of applying Fulton’s condition factor in the 17th century and was first recorded in North for species would enable the standard of research America in 2000 (Froese & Pauly 2010; Docherty et al. to be established and would also contribute to the 2017). management of invasive fish stocks. Populations of The species was first recorded in the Thrace invasive species inhabiting important fishing areas region of Turkey in 1988 (Baran & Ongan 1988) and should be regularly monitored based on the above in Anatolian freshwaters (Lake Marmara) in 1991 by mentioned studies. www.oandhs.ug.edu.pl Faculty of Oceanography and Geography, University of Gdańsk, Poland Oceanological and Hydrobiological Studies, VOL. 49, NO. 4 | DECEMBER 2020 385 Growth parameters of invasive gibel carp Carassius gibelio (Bloch, 1782) in Lake Marmara (Turkey) Materials and methods composition, age–length relationships, length– weight relationships (LWR), von Bertalanffy growth Study Area parameters and Fulton’s condition factor. LWR was determined using the formula W = aLb, Lake Marmara, 12 km long and 6 km wide, is where W = weight, L = length, a = intercept and located 75 m above sea level. The area of the lake is b = regression coefficient (Ricker 1975). The correlation 4500 ha and the average depth is approximately 5 m coefficient significance test was used (Sümbüloğlu & (Ustaoğlu 1993). This alluvial lake is an extension of the Sümbüloğlu 2005). Gediz River between the towns of Gölmarmara and The von Bertalanffy growth model (Sparre et al. Salihli in the Manisa province in West Anatolia (Fig. 1). 1989) was calculated using the following formulas: −k(t−t0) −k(t−t0) b According to the Köppen–Geiger climate classification Lt = L∞ [1 − e ] and Wt = W∞ [1 − e ] , where system, continental climate prevails in the lake area Lt = length (cm) at age t, L∞ = asymptotic length, and the area is rarely affected by the Mediterranean k = Brody growth coefficient, t = age (years), t0 = age climate (Kottek et al. 2006). As mentioned above, the at zero length, e is the base of natural logarithm, Wt is lake plays an important role in fisheries and irrigation weight (g) at age t, W∞ is asymptotic weight. of the region and Turkey as a whole. The age was estimated for each sample from fish scales. Scales for the analysis were removed from Field study and analysis the lateral side, above the lateral line, near the dorsal fin of each specimen (Baglinière & Le Louarn 1987). All samples were collected monthly between Scales were preserved in 3% sodium hydroxide (Agger March 2012 and February 2013 using 10–50 mm mesh et al. 1974; Bagenal 1978) and alcohol (70–90%) to trammel nets, gillnets and seines. A total of 1058 clean them before the reading process. Scales were specimens (809 females and 249 males) of C. gibelio examined under a binocular microscope for age were examined during the study. determination using a 10× stereomicroscope. Age Fish specimens were preserved in 4% readings were performed according to Chugunova formaldehyde solution and transported to the (1959) and Lagler (1966). Scale readings were taken Limnology Laboratory, Faculty of Fisheries, Ege twice by two independent readers (Avşar 2005).