Population dynamics of an emergent invasive fish, striped piggy, Pomadasys stridens (Actinopterygii, Perciformes, Haemulidae) in the Gulf of İskenderun, north-eastern Mediterranean

Abstract

The striped piggy, Pomadasys stridens (Forsskål, 1775), is a recent invasive fish species in the eastern Mediterranean. Although its population dynamics was investigated in detail in its natural distribution area, the western Indian Ocean, an important data gap still exists in the Mediterranean. This study was carried out to determine the growth, mortality, and the length–weight and length–length relations of invasive striped piggy right after its establishment in the area. Samples were collected seasonally between April 2014 and December 2015 by using bottom trawl from 10 and 20 m depth contours off the north-western coast of the Gulf of Iskenderun. After the length, weight, and sex of fish were recorded, sagittal otoliths were extracted and examined for age determination. Then length–length, length–weight, and length at age relations, growth performance, and mortality rates were calculated for both sexes and pooled data. In the study, a total of 1131 individuals were investigated, the total length of which ranged between 7.3 and 18.9 cm. The mean length was 12.32 ± 0.11 cm. There was no significant difference between the length–weight relation (LWR) parameters of sexes and pooled data. The overall LWR was found to be TW = 0.0113 * TL^3.096 in all specimens. The von Bertalanffy growth parameters were not significantly different between males and females. The model parameters for both sexes were L∞ = 22.01 cm, K = 0.22 years–1, t0 = –1.30 years. The growth performance index (Ø′) was calculated as Ø′ = 2.03. For combined sexes, the total, natural and fishery mortality rates were Z = 1.14 years–1, M = 0.66 years–1, and F = 0.48 years–1, respectively. The exploitation rate of the stock was found to be E = 0.42. The growth performance of the invasive striped piggy population was determined to be similar to the ones reported from the Gulf of Suez where was the closest natural distribution area of the species. Although striped piggy is proper for human consumption and commercially caught in its native range, its fishery has not yet been established in the Eastern Mediterranean and we found that there was insufficient fishery pressure on the invasive population.