Population Dynamics of Horse Mackerel (Trachurus Mediterraneus Ponticus) in the Bulgarian Black Sea Coast

Maria Yankova

doi:10.1155/2013/127287

Abstract

The horse mackerel Trachurus mediterraneus is a commercially important pelagic fish species in the Black Sea fishery. The present investigation was carried out between May and December 2010 along the Bulgarian coast of the Black Sea. Population parameters of horse mackerel from the trawl and fishing nets catches were estimated from length frequency data, by using ELEFAN-I computer program. The ELEFAN-I analysis gave the following Von Bertalanffy Growth Function (VBGF) parameters: the asymptotic length cm, growth coefficient value was , and the hypothetical age at which length is zero was . Based on these growth parameters, the total mortality coefficient () during the study period was estimated to be 2.99. The estimated value for natural mortality () was 1.08; hence, the fishing mortality coefficient () was 1.91. The estimated value for the exploitation rate () using the length converted catch curve was 0.64. The estimated sizes of T. mediterraneus at 25, 50, and 75 percent probabilities of capture were 16.80 cm, 18.72 cm, and 20.64 cm, respectively.

Highlights

Carangidae in the Black Sea is represented by Trachurus trachurus and Trachurus mediterraneus ponticus
On the basis of investigation carried out by [5, 6] on size composition and tagging experiments of horse mackerel caught off the Bulgarian coast, they concluded that in the Black Sea, two subpopulations occur that belong to the small size-type of Trachurus mediterraneus ponticus, the eastern and western ones, respectively
Examination of age and growth is very important in ichthyologic investigations, because fish growth is one of the four main factors determining stock condition [10]

Summary

Introduction

Carangidae in the Black Sea is represented by Trachurus trachurus and Trachurus mediterraneus ponticus. On the basis of investigation carried out by [5, 6] on size composition and tagging experiments of horse mackerel caught off the Bulgarian coast, they concluded that in the Black Sea, two subpopulations occur that belong to the small size-type of Trachurus mediterraneus ponticus, the eastern and western ones, respectively. According to the same authors, the Black Sea horse mackerel represents a single population, as the environmental conditions are almost one and the same in the whole inhabited area and there exists no positive evidence for the occurrence of two distinct subpopulations differing substantially in their biological parameters. For this reason according to [8] the large size type occurrence can be explained as a result of heterosis effect between the aforementioned subspecies. Population parameters such as asymptotic length L∞ and growth coefficient k, mortality (natural and fishing) rate, and exploitation level E were studied with the major objective of rational management and resource conservation [13, 14]

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