Age and growth of the axillary seabream (Pagellus acarne, Sparidae), in the central coast of Algeria, Mediterranean Sea
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1
École Nationale Supérieure des Sciences de la Mer et de l'Aménagement du Littoral, Algeria
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2
L'Ifremer en Manche Mer du Nord, France
Growth estimation is a fundamental information in population dynamics studies of commercial species. Axillary seabream, Pagellus acarne (Risso, 1827), is a bony fish, which has a high economic value in the Algerian fisheries. The aims of the current study were to measure the relationship between otolith morphology and the fish length and to estimate age to evaluate the growth patterns of the species in the Algerian coast.
A total of 322 specimens of P. acarne were sampled from the commercial fisheries of the central part of Algerian coast. The fishes ranged from 6.3 cm to 31.5 cm in total length and weighed between 3.45 g and 391.53 g. Fish age was determined from the whole sagittal otoliths. Identification and measurements of growth structures on otoliths were realized from images analysis using the TNPC software. The frequency of appearance of growth rings on otoliths was validated by the marginal increment analysis.
There was no significant difference between the left and right otoliths for the relationship between otolith and fish lengths (ANCOVA, P > 0.05). Consequently, we selected arbitrary the right otolith for the ageing data and to analyse relationships between otolith shape and fish length. The correlation between each biometric parameter (length and width) of the otolith and fish length (TL) was significant. The maximum value of the marginal distance was estimates at 1.24 mm /year; it occurs in October. Contrariwise, this distance is slowed down from the end of autumn until the beginning of spring. This observation confirmed that hyalines rings are marks of slowdown of growth. The maximum observed size of 31.5 cm (one bisexual individual at 8-year-old) was observed and reported for the first time in Algerian coasts. In the study area, the species lives up to 10 years. At the end of their first years of life (age classes of 0, I and II), fishes reach nearly 50% of their maximum length. Overall, the most represented year classes were I to III (78.26% of the sample). Most male specimens were 1 to 2 years old (65.9%) while majority of females were between 1 and 5 years old. All immature specimens were determined to be either at the age of 0 or 1 years. Growth analysis was estimated by the von Bertalanffy model. The values of growth parameters in females were: TL∞ = 28.5 cm, K = 0.24 yr–1, and t0 = −0.99 yr, while in males TL∞ = 24.09 cm and K = 0.38 yr–1, t0 = −0.52 yr. The asymptotic length was higher in females than in males. The presently reported results serve as baseline data on the south-western Mediterranean Sea and will improve future stock management to get a sustainable fishery. For future biological studies on this species, the application of the relation between fish length and sagittal otolith measures could be used for age estimation.
Keywords:
Pagellus acarne,
age,
otolith,
Growth,
Algerian coast
Conference:
XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019.
Presentation Type:
Poster
Topic:
OTOLITHS AS A TOOL TO STUDY FISH LIFE CYCLES
Citation:
BOUFERSAOUI
S,
KHERBACHE
A,
ELLEBOODE
R and
MAHE
K
(2019). Age and growth of the axillary seabream (Pagellus acarne, Sparidae), in the central coast of Algeria, Mediterranean Sea.
Front. Mar. Sci.
Conference Abstract:
XVI European Congress of Ichthyology.
doi: 10.3389/conf.fmars.2019.07.00089
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Received:
27 May 2019;
Published Online:
14 Aug 2019.
*
Correspondence:
Dr. SAMIRA BOUFERSAOUI, École Nationale Supérieure des Sciences de la Mer et de l'Aménagement du Littoral, Algiers, Algeria, samira.boufersaoui@gmail.com