Differential growth of the brown mussel,Perna perna(Linnaeus, 1758), in longline and pole cultures in Dakhla Bay (SWMorocco, Atlantic Ocean)

Abstract

There is a great interest in establishing mussel farming in Dakhla bay. Selection of suitable sites is more meaningful only if a reliable culture method at proposed site is included. We compared two different culture methods, longline and pole, over 1 year (June 2016 to June 2017). Growth indicators for Perna perna (size and weight growth rates, frequency distributions and estimating growth curves) were analysed from seeding to harvest. The results highlighted the influence of culture method on growth rates of mussels (p < 0.05). At harvest, individuals reared on longline presented higher growth rates and consequently reached greater weight and length values than those reared on pole. Mussels reared at the longline grew 73.2 mm and gained 53.5 g W L (live weight) and 3.3 g W t (tissue dry weight) after 12 months of cultivation. However, mussels cultured at the pole gained only 52.3 mm, 26.7 g W L and 1.6 g W t . Aerial exposure of mussels at low tides could explain this reduced performance on pole compared with longline. Size frequency distributions at harvest fitted bimodal distribution in both cultures due to an asymmetric competition among individuals. Effect of density started in both treatments after 7 months of culture when mussels reached 60-70 mm, implying an increment of their food and space requirements. To prevent overcrowding, the initial density should have been reduced through "thinning-out." The longline method exhibited high-performance growth and hence is highly recommended for cultivation of P. perna in Dakhla bay. K E Y W O R D Saerial exposure, crowding conditions, mussel culture, mussel growth, Perna perna, suspended culture, time

Influence of Pediveliger Larvae Stocking Density on Settlement Efficiency and Seed Production in Captivity of Mytilus galloprovincialis in Amsa Bay, Tetouan

“…From an ecological perspective, the suitability of this mussel as a bio-monitor of environmental fluctuations has been shown [20][21][22][23]. Also, investigations of its growth performance in different culture systems suggest that the offshore mussel technology (longline systems) can assure higher yield and is deemed to a convenient solution for seed supply [17,24,25].…”