Stock Discrimination in the Horse Mackerel Trachurus trachurus (Teleostei: Carangidae) off the Moroccan Atlantic Coastal Waters using a Morphometric-Meristic Analysis

• Hayat El Mghazli ^[1] ; Mohammed Znari ^[1] ; Abdelaziz Mounir ^[1]
  1. [1] Cadi Ayyad University

     Cadi Ayyad University

     Marrakech-Medina, Marruecos

     
• Localización: Thalassas: An international journal of marine sciences, ISSN 0212-5919, Vol. 38, Nº. 1, 2022, págs. 171-181
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • The Atlantic horse mackerel Trachurus trachurus, the family Carangidae, is a small pelagic with high commercial importance.

    This species is classifed as globally vulnerable (IUCN) due to fshing pressure and low recruitment. It has drastically declined during the last three decades. In contrast, to the well-studied Euro-Mediterranean stocks, the putative Moroccan-Saharan stock has been poorly investigated. A frst step is to discriminate potential subunits within this large stock for a better assessment management and practice. We examined variation in morphometric and meristic characters in this species from three fshing areas (from the North to the south: Larache, Saf and Dakhla) of the Moroccan Atlantic coastal waters. We used a linear morphometric approach based on body weight, 14 body dimensions and 5 meristic characters in 147 fsh specimens.

    We compared fsh from the three areas using a multivariate analysis including discriminant function analysis (DFA) and principal component analysis (PCA). Based on morphometric data, we distinguished three subunits: a frst subgroup of Larache in the north, probably a self-recruiting population or a locally adapted morphotype, and a second and third units in the mid and southern Moroccan Atlantic coasts, respectively of Saf and Dakhla fshing areas. On the other hand, the result of DFA for meristic characters confrmed the diferentiated southern subgroup of Dakhla, but two overlapped subunits including Saf and Larache areas. Examination of the contribution of each morphometric variable to canonical functions indicated that diferences among samples seemed to be associated with morphological changes in the lateral line. Further investigations using other methods such as genetics, otoliths, and parasites are needed to confrm the identifed stock units.

    Our fndings on such a threatened small pelagic species would be useful for the stock management in the Moroccan Atlantic coastal waters. They also have ecological and evolutionary implications related to local adaptations in fsh populations that are under intense fshing pressure