Age, growth and reproduction of European hake (Merluccius merluccius (Linn., 1758)) in the Central Aegean Sea, Turkey

Abstract

Specimens of European hake were collected by a traditional demersal trawl between July 2004 and June 2007 from İzmir Bay, Central Aegean Sea. A total of 2108 individuals were sampled during the study and the female: male sex ratio of the stock was 1:0.89. The length–weight relationship was W = 0.00341L3.24 (R2 = 0.994) for all individuals. A high gonadosomatic index was evident over most of the year but it was minimal from August to October. The estimated age composition was 1–5 years; the length and weight at infinity were calculated as L∞ = 54.53 cm and W∞ = 1455.77 g respectively. In addition, growth coefficient was found to be k = 0.315 y−1 and to = −0.223 y (R2 = 0.99). Total mortality ratio of the stock was calculated as Z = 1.539 y−1, while natural and fishing based mortality ratio were estimated as M = 0.579 y−1 and F = 0.959 y−1 respectively, with the exploitation ratio (E) of the stock estimated to be 0.624.

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“…Although it was determined that a total of 13 species were commercial, only four minimum landing size regulations were found for them (MFALT, 2016). While one regulation conformed to our findings, that for red mullet (Mullus barbatus barbatus), the others did not; these were the regulations for European hake (Merluccius merluccius) (Soykan et al, 2015a) and common pandora (Pagellus erythrinus) (Metin et al, 2011b). For these two species, we recommend a total length of 26 cm and 17 cm respectively as the minimum landing sizes.…”

“…In addition, hermaphroditism is well known in the marine fish, especially in the Sparidae family, and also in the Serranidae family (Mitcheson & Liu, 2008) that together made up nearly half of the species in the present study. It was determined that common pandora (P. erythrinus) (Metin, İlkyaz, Soykan, & Kınacıgil, 2011b), European hake (M. merluccius) (Soykan, İlkyaz, Metin, & Kınacıgil, 2015a) and blotched picarel (S. maena) (Soykan, İlkyaz, Metin, & Kınacıgil, 2010) males reached first maturity at a greater length than females. Therefore, the suggested minimum landing sizes considered which sex had the greater length, because of the need to allow reproductive activity.…”

“…LSE: Arithmetical mean of length and its standard error (TL, cm). (Soykan et al, 2015b), e: Buglossidium luteum (İlkyaz et al, 2010a), f: Cepola macrophthalma, g: Citharus linguatula, h: Deltentosteus quadrimaculatus (Metin et al, 2011a), i: Dentex macrophthalmus (Soykan et al, 2015b), j: Diplodus annularis, k: Diplodus vulgaris (Soykan et al, 2015b), l: Gobius niger, m: Lepidotrigla cavillone (İlkyaz et al, 2010b), n: Merluccius merluccius (Soykan et al, 2015a), o: Mullus barbatus barbatus, p: Pagellus acarne (Soykan et al, 2015b), q: Pagellus erythrinus (Metin et al, 2011b), r: Serranus cabrilla, s: Serranus hepatus (Soykan et al, 2013), t: Spicara maena (Soykan et al, 2010) …”

Age composition, growth, and mortality of European hake Merluccius merluccius (Actinopterygii: Gadiformes: Merlucciidae) from the northern Aegean Sea, Turkey

“…The information on the age, growth, and reproduction of the species has an important role in the management and sustainable exploitation of the stock. Several authors have studied the age estimation and growth parameters of hake , Uçkun et al 2000, Godinho et al 2001, Piñeiro and Saínza 2003, de Pontual et al 2006, Ismen et al 2010, Murua 2010, Belcaid and Ahmed 2011, Gurbet et al 2013, Costa 2013, , Khoufi et al 2014, Philips 2014, Soykan et al 2015. On the other hand, many studies on stock assessment, population dynamics, and spatial distribution of hake have been implemented by Aldebert and Recasens (1996), Orsi-Relini et al (2002), Lleonart and Maynou (2003), Stergiou et al (2003), Abella et al (2005), Gurbet et al (2013), Yalçın and Gurbet (2016).…”

Length–weight relationships of 14 fish species from the Gulf of Antalya (northeastern Mediterranean Sea, Turkey)

“…The functional regression b value represents the body form, and it is directly related to the weight, affected by ecological factors (temperature, food supply, and spawning conditions) and other factors (sex, age, fishing time, area, and fishing vessels) (Ricker, 1973 Karakulak et al, 2006Cengiz, 2013 Serranus hepatus Çakır et al, 2008Merella et al, 1997Keskin and Gaygusuz, 2010Sangun et al, 2007 Citharidae Citharus linguatula Sangun et al, 2007Moutopoulos and Stergiou, 2002Karakulak et al, 2006Çakır et al, 2008Merella et al, 1997 Triglidae Chelidonichthys lastoviza Moutopoulos andStergiou, 2002 Sangun et al, 2007 Mullidae Mullus surmuletus Bök et al, 2011Maci et al, 2009Karakulak et al, 2006Keskin and Gaygusuz, 2010Merella et al, 1997Moutopoulos and Stergiou, 2002 Mullus barbatus barbatus Merella et al, 1997Moutopoulos and Stergiou, 2002Cherif et al, 2007Çakır et al, 2008Karakulak et al, 2006Çakır et al, 2008Cengiz, 2013 Upeneus moluccensis Sangun et al, 2007 Synodontidae Saurida undosquamis Sangun et al, 2007Ceyhan et al, 2009 Centracanthidae Spicara flexuosa Soykan et al, 2010 I: Isometric, A+: positive allometric, A-: negative allometric growth.…”