Age and Growth of Bluemouth Helicolenus dactylopterus (Delaroche, 1809) in the Northern Waters of Tunisia (Central Mediterranean)

Abstract

Data on age and growth of the bluemouth Helicolenus dactylopterus (Delaroche, 1809) from the Southern central Mediterranean Sea are provided in this paper. Ages of bluemouth rockfish (Scorpaenidae) in the northern Tunisian waters were estimated by otolith readings and verified by marginal increment analysis. A total of 513 individuals were measured, weighed and their sex was determined. The fish total length (TL) range between 8 and 30.6 cm, which corresponded to individuals between 0 to 9 years old. The otoliths showed the typical teleost fish pattern with alternated opaque and hyaline rings. Marginal increment analysis of specimens suggested that a single annulus was formed each year. The Von Bertalanffy growth function was selected as the most adequate model to fit this species' growth. Parameters of the growth curve were L∞ =37.17cm, K=0.142year -1 , t0= -1.67years. The weight-length relationship (TW= 2.2092 x10 -5 TL 2.870 ) described a negative allometric growth of the species. The growth parameters obtained from the age-length relationships showed higher differences between sexes.

Population pattern and dynamics of the Bluemouth Helicolenus dactylopterus (Delaroche, 1809) in the eastern Mediterranean Sea

“…In accordance to previous reports (Cartes, Sorbe, & Sarda, ; Massutí et al., ; Mili et al., ; Pirrera et al., ), 80.9% of the total catch (in number) of H. dactylopterus caught 200–499 m, where middle‐sized decapod crustaceans available. It is known that decapod crustaceans were the preferred prey of H. dactylopterus in early stages of their lives (Consoli et al., ; Neves, Sequeira, Paiva, Vieira, & Gordo, ; Nouar & Maurin, ).…”

“…Considering the distribution patterns of H. dactylopterus in the above‐mentioned areas, species showed a clear size‐related depth distribution pattern (“bigger–deeper” phenomenon), which suggests that between distribution of the species between different depths reflects the food availability. The same bathymetrical distribution was verified in the western Mediterranean (Massutí et al., ) and in the central Mediterranean (D'Onghia et al., ; Mili et al., ; Pirrera et al., ; Ribas, Muñoz, Casadevall, & de Sola, ). Our results confirmed that recruit reach the edge of the continental shelf (4–7 cm, 200 m) and move toward bathyal grounds (25–30 cm, 700 m) as they grow (Table ).…”

“…Recruitment period of the species starts with a delay from west to east in the Mediterranean Sea. Population distributed in the Beleric Sea recruits in the spring (Massutí et al., ; Mili et al., ), while recruitment occurs spring to summer in the waters of Tunis and Ionian Sea (D'Onghia et al.,; Mili et al.,) and in autumn in the Antalya Bay (Table ) Present study recorded the young‐of the‐year first time in September (in 2009 and 2010), and the smallest recorded individual was 4.0 cm in TL.…”

“…It is known that males of H. dactylopterus grow larger than females, which is also apparent in the differences in the values of Von Bertalanffy growth parameters (Table ) and the length frequency distribution between sexes (Figure a). This indicate that sexual development and life strategy affect the growth rate of this species (Abecasis et al., ; Massutí,; Massutí et al., ; a; Mili et al., ). Gunderson () was reported that the reproductive effort, considering the bio‐energetic constraints of the energy budget of the organisms, which implies the reduced growth rates of females.…”

“…Regarding the population of the bluemouth located in the Italian waters, otolith and growth (Consoli et al., ) and information on diet (Nouar & Maurin, ) are available. While first maturation size and sex ratio (Massutí et al., ), reproduction and growth (Mili, Ennouri, Amdouni, Chammam, & Missaoui, ; Muñoz et al., ) and spatio‐temporal distribution (Massutí, Moranta, de Sola, Morales‐Nin, & Prats, ) of the species were known for the western Mediterranean Sea populations.…”