New evidences about small delphinids stranding in the west Algerian coast

Abstract

The Cetaceans are marine mammals that often get stranded along the Algeri-an coast, due to several factors (parasitism, marine pollution, injuries, acci-dental fishing, etc.). In view of the growing interest in the knowledge of ma-rine mammals stranding, an effort to collect this information in the west Al-gerian coast has been carried out by the Environmental Monitoring Network Laboratory since 80s. The aim of this study is to describe and provide new evidences about the stranding of the small delphinids in the Algerian west-ern coast. The study was conducted on 35 individuals of small delphinids reported stranded and dead on-shore from three districts (Mostaganem, Oran and AinTemouchent). Five different specieshave been identified, in-cluding three frequent common species (D. delphis, S. coeruleoalba, T.truncatus) along with two relatively less frequent species (G. melas, G.griseus). Life history information was gathered in terms of morphometrics and sex. The stranded individuals were small to medium-sized cetaceans, ranging from about 0.6 meter to almost 5 meter in length, with an average languor of 2.25 ±1.01 meter. Aside from undetermined individuals due to advanced decomposition of the carcass, the sex ratio of male vis a vis of fe-male was of 0.78 clearly indicating a female predominance. An assessment of causes of mortality was conducted using different observing indexes. It turns out that the most likely cause of the mortality is attributed to inci-dental human actions by entanglement in fishing gear and ships collisions with small delphinids are a conservation problem of growing concern world-wide. This study improves knowledge on small delphinids stranding through the west Algerian coast and has broad implications in establishing a conser-vation management program.