Seasonal growth and reproduction biology of the Baltic prawn, Palaemon adspersus (Decapoda: Palaemonidae), in the southern Black Sea sabri bilgin 1 , osman samsun 2 and ozcan ozen 1 1 Canakkale Onsekiz Mart University, Faculty of Fisheries, Canakkale - 17100, Turkey, 2 Sinop University, Faculty of Fisheries, Sinop - 57000, Turkey Seasonal growth pattern and reproductive biology of the Baltic prawn, Palaemon adspersus, were studied in the southern Black Sea between February 2002 and January 2004. The seasonal von Bertalanffy growth parameters, computed from monthly length – frequency distributions, were estimated as L 1 ¼ 62.99 mm TL, K ¼ 1.190 year 21 ,C ¼ 0.815, and WP ¼ 0.847 for females and as L 1 ¼ 49.63 mm TL, K ¼ 1.085 year 21 ,C ¼ 0.011, and WP ¼ 0.407 for males. Growth performance index of females (F 0 ¼ 3.67) was greater than it was for males (F 0 ¼ 3.43). Based on latitudinal gradients, water temperature negatively affected F 0 of P. adspersus. Sexual dimorphism in size was evident, females being larger than males. This typically shallow water species was observed in water depths as deep as 30 m. Compared to shallower water depths, larger individuals were observed in deeper water depths. The size at sexual maturity for females (TL 50 ) was estimated as 53.60 mm TL. Ovigerous females were recorded from March to August and juveniles appeared in the benthic population in August. Ovary development was related to photoperiod and occurrence of ovigerous females was linked to increased water temperature. Keywords: Baltic prawn, Palaemon adspersus, seasonal growth, reproduction, maturity, Black Sea, ELEFAN Submitted 8 April 2008; accepted 16 September 2008; first published online 17 November 2008 INTRODUCTION The Baltic prawn, Palaemon adspersus Rathke, 1837, occurs along the coasts of the North Sea, Baltic Sea, Mediterranean Sea and the Black Sea (d’Udekem d’Acoz, 1999). The shrimp is especially associated with Cymodocea nodosa, Zostera marina, and Zostera noltii beds as well as rockpools (Berglund, 1980, 1982; Guerao & Ribera, 1995; Manent & Abella-Gutie ´rrez, 2006; Schaffmeister et al., 2006; Bilgin et al., 2008). It has a wide tolerance range for temperature and salinity and is commonly distributed in shallow waters, often in estuarine conditions (Berglund, 1980, 1982, 1985; Berglund & Bengtsson, 1981). Palaemon adspersus are omni- vorous, and feed on small crustaceans such as ostracods, cope- pods and nauplii as well as polychaetes, algae and detritus (Berglund, 1980). Palaemon species play an essential role in the food chain of the aquatic ecosystem and are reported in diets of many fish and cephalopods. Palaemon spp. have been recorded in the diet of young sea bass, Dicentrarchus labrax (Linnaeus, 1758), in the Tagus estuary (Cabral & Costa, 2001) and in Scorpaena species in seagrass beds near Marseilles (Harmelin-Vivien et al., 1989). Cephalopods such as Sepia officinalis (Linnaeus, 1758), were found to feed on P. adspersus in Morbihan Bay (Blanc & Daguzan, 2000). Baltic prawn is commercially captured in small-scale fishery in many areas (Holthuis, 1980; Guerao et al., 1994; Manent & Abella-Gutie ´rrez, 2006) and is also known to be commercially cultivated in some regions. According to the statistics of the FAO, the aquaculture production of P. adsper- sus was about 3.5 tons in the Ukraine between 2001 and 2003 (FAO, 2007). The growth and reproduction biology of P. adspersus was investigated in the shallow waters of the North Sea (Berglund, 1984; Berglund & Rosenqvist, 1986), in the Mediterranean (Conides et al., 1992a, b; Guerao et al., 1992; Guerao & Ribera, 1995; Manent & Abella-Gutie ´rrez, 2006), and Atlantic Ocean (Figueras, 1986). Three species of the genus Palaemon exist in the Black Sea: P. elegans Rathke, 1837, P. serratus Pennant, 1777, and P. adspersus (Bilgin & Go ¨nlu ¨gu ¨r Demirci, 2005). In addition, a new distribution record of a single specimen of P. longirostris H. Milne-Edwards, 1837 was recently reported for the Black Sea (Sezgin et al., 2007). However, no population dynamics information exists for these unexploited Palaemon species inhabiting the Black Sea. The aim of this study was to investi- gate growth and reproduction biology of P. adspersus in the southern Black Sea. In addition, seasonal growth pattern, very common in many other decapod crustaceans, was inves- tigated in detail for the Baltic prawn. Corresponding author: O. Ozen Email: oozen@comu.edu.tr 509 Journal of the Marine Biological Association of the United Kingdom, 2009, 89(3), 509–519. #2008 Marine Biological Association of the United Kingdom doi:10.1017/S0025315408003056 Printed in the United Kingdom