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

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.

Natural mortality of Trachurus novaezelandiae and its size selection by purse seines off south‐eastern Australia

“…Natural mortality was estimated to fall within a range of values (0.17–0.26/year) encompassing those provided by Horn () for conspecifics and the congeneric T. declivis (0.17–0.20/year) off New Zealand, but substantially less than estimates for many Trachurus in other studies including T. trachurus ( M = 0.46/year, Šantić et al., ); T. declivis (M = 0.63–0.70/year; Stevens & Hausfeld, ) and T. mediterraneus ( M = 0.86 and 1.08/year Yankova & Raykov, ; Yankova, ). Some of these differences might be partially attributed to divergent modelling approaches, although Horn's () similar intraspecific estimate was derived from catch curves (on an unexploited stock).…”

“…This study provides the first estimates of M, catchability and fishery selectivity for T. novaezelandiae off south-eastern Australia, contributing towards the limited relevant published work among both regional (Stewart & Ferrell, 2001) and New Zealand (Horn, 1993) conspecifics, and for the genera more broadly (e.g., Stevens & Hausfeld, 1982;Šantić, Jardas & Pallaoro, 2003;Yankova & Raykov, 2012;Yankova, 2013). The parameters derived here represent an important first step for estimating exploitation and harvestable yields;…”

“…Natural mortality was estimated to fall within a range of values T. mediterraneus (M = 0.86 and 1.08/year Yankova & Raykov, 2012;Yankova, 2013). Some of these differences might be partially attributed to divergent modelling approaches, although Horn's (1993)…”

Age structure and growth of the rough scad, Trachurus lathami (Teleostei: Carangidae), in the Southeastern Brazilian Bight

“…This value seldom has a biological meaning, since it would represent the zero length age whenever the growth continues following the same pattern described by the equation (Pauly 1984), which is not true. Several authors (Abaunza et al 2003, Yankova et al 2010, Yoda et al 2014, working on Trachurus, also found inconsistent t 0 values due to the lack of small fish in their samples. In the present study, the t 0 value led to overestimated ages, and it should not be used.…”

Seasonal distribution of Trachurus mediterraneus (Steindachner, 1868) in the Golden Horn Estuary, İstanbul

“…Stability of low GSI values during the whole year including the spawning period also supported our observations. Previous studies indicated that T. mediterraneus spawns from May to September both in the Sea of Marmara (Demirel and Yüksek, 2013b) and in the Black Sea (Genç et al, 1998, Yankova, 2011. Furthermore, it has been reported that this species preferred not to spawn in the estuary and relocated to other regions in the Sea of Marmara (Demirel and Dalkara-Murat, 2012) as well as in the Black Sea through the İstanbul Strait (Yankova, 2013).…”