Monthly monitoring of length-weight relationships of allis shad (Alosa immaculata Bennett, 1835), horse mackerel (Trachurus mediterraneus Steindachner, 1868) and sprat (Sprattus sprattus Linnaeus, 1758) from the Southern Black Sea, Turkey

Length-weight relationships are presented monthly for allis shad (Alosa immaculata), horse mackerel (Trachurus mediterraneus) and sprat (Sprattus sprattus) sampled with a commercial pelagic trawl vessel at depths ranging from 20 to 80 m between October 2008 and May 2009 in Black Sea, Turkey. The mean monthly values of the exponent b of the length-weight relationships ranged from 3.043 to 3.658 for allis shad, from 3.016 to 3.357 for horse mackerel and from 2.813 to 3.253 for sprat. Taking into account monthly confidence intervals, the length-weight relationships generally indicated a positive allometric growth in allis shad but an isometric growth in February, April and May 2009; it indicated a positive allometric growth in horse mackerel except in November and December 2008 (isometric growth), whereas it denoted isometric growth in sprat in October 2008, negative allometric growth from November 2008 to February 2009, isometric growth again in March 2009 and positive allometric growth in April and May 2009. Results showed that b value of allis shad, horse mackerel and sprat varied with season in the Black Sea.