Biological Characteristic of Mediterranean Horse Mackerel (Trachurus Mediterraneus, Steindachner, 1868) from the Montenegrin Shelf (Southern Adriatic)

 

Ana Pešić1, Aleksandar Joksimović1, Mirko Đurović1, Milica Mandić1, Olivera Marković1 and Zdravko Ikica1

 

 

 

1 University of Montenegro, Institute of Marine Biology, Dobrota bb, 85330 Kotor, Montenegro; e-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 

 

Abstract

The paper presents results of studies of biology and fisheries of Mediterranean horse mackerel (Trachurus mediterraneus, Steindachner, 1868) which was done within the frame of FAO AdriaMed Pilot study during the September 2007 – September 2008 and September 2009 – September 2010 period. The Project encompassed monthly research of several target species in Montenegrin fisheries during one year in the three most important fisheries ports in Montenegro (Bar, Budva and Herceg Novi). The total length of T. mediterraneus ranged from 8.9 to 31.3 cm. Length frequency distribution, length-weight relationship, sex ratio and GSI were analyzed.

Keywords: Trachurus mediterraneus, length-weight relationship, sex ratio, GSI, Southern Adriatic

 

 

Introduction


The FAO AdriaMed Pilot study on the biological and economic data collection and monitoring system in Montenegro was planned and carried out with the general aim of establishing a national monitoring system which would include all aspects related to fishing activities: social, biological and economic. To this purpose, a monitoring system for the identification of the main fishing activities, in terms of number of vessels and vessel characteristics, as well as the estimation of catch and effort characteristics of the main fishing segment operating in Montenegro was established, with the support of the FAO AdriaMed project. During the monitoring activities samples of the most important (for quantity landed and economic values) fisheries target species were collected for the investigation of their main biological characteristics in the Montenegrin waters and of their occurrence in the catch.

The horse mackerel (Trachurus mediterraneus, Steindachner, 1868) is distributed in the Mediterranean, Azov Sea and Black Sea (Stoyanov et al., 1963). Investigations regarding various biological aspects of T. mediterraneus have been carried out in Romania (Pora, 1979), Egypt (El-Gharabawy and Abdel-Aziz, 1988), Tunisia (Ben Salem and Ktari, 1981; Ben Salem and Ktari, 1992), Turkey (Demir, 1961), Bulgaria (Yankova and Raykov, 2006; Yankova et al., 2009; Yankova et al., 2010) and Italy (Arneri and Tangerini, 1983; Arneri, 1984; Viette et al, 1997). Since no work has been carried out on T. mediterraneus of the southern Adriatic, some general data regarding the biology of this species in the Montenegrin waters are presented here.

 

 

Materials and methods

For the purposes of the study, the fishing activities of the three main fishing ports were monitored on a monthly basis from September 2007 – September 2008 and September 2009 – September 2010.

The sampling took place in three fishing ports (landing sites) along the Montenegrin coast (according to the classification of the General Fisheries Commission for the Mediterranean Geographical Sub-Area 18 – Southern Adriatic Sea – GFCM, 2009): Herceg Novi, Budva and Bar (Fig. 1), and two minor landing sites, Kotor and Tivat.

To collect information on catch and effort, three stratification levels were considered: port (Herceg Novi, Budva, Bar); fleet segmentation (fishing gear) and number of vessels per fleet segment (total number). Catch and effort data on all active fleet segments in the sampling ports was gathered by interviewing the fishermen at the end of the fishing trip.

The biological samples of the main target species were taken in order to examine their biological characteristics. Total of 730 species of T. mediterraneus were collected on a monthly basis during the period from September 2007 – September 2008 and September 2009 – September 2010. Samples were collected according to the sampling scheme that takes into account both the total official landing statistics provided and the main requirements of regional bodies in terms of fisheries monitoring.

Samples were taken from trawlers and from small-scale fishery vessels (gillnetter, beach seiners, long-liners), the amount of total catch was recorded (total weight for each species in the catch) and a sample of the catch was obtained from the fishermen.

The following data was recorded for each species: Total length (TL) for fish (0.1 cm); Total body weight (TW), (0.01 g); Sex; Sexual maturity was determined according to the four-stage maturity scales proposed by MEDITS; Gonad weight.

The data allowed for estimation of size range and length frequency distribution, the sex-ratio as proportion of males over the combined number of males and females, and the length-weight relationship parameters using a power function. The length–weight relationship was determined according to the logarithmic form of the original exponential equation: log W = log a + b log LT, where a is the proportionality constant, b the allometry coefficient, W is fish weight in grams, and LT is total length in centimetres. The gonadosomatic index (GSI) was determined on the basis of their body mass and their ovary mass by applying the formula: GSI = 100 X G / W, in which G is gonad weight and W is body weight.

 

Fig01

Figure 1: The coastline of Montenegro and the three fishing ports: Herceg Novi, Budva and Bar