Tracking the invasion of Hemiramphus far and Saurida undosquamis along the southern Mediterranean coasts: A Local Ecological Knowledge study

Abstract

Local Ecological Knowledge of 92 professional fishers from Tunisia and Libya was used to investigate the occurrence and establishment of the exotic Hemiramphus far and Saurida lessepsianus along the southern Mediterranean coasts. According to fisherman's knowledge, H. far and S. lessepsianus appeared in Libya in 1980 and 1989, respectively. In Tunisia these species were observed later on, in 2004 and 2007. Currently both H. far and S. lessepsianus are well distributed and established, along the entire surveyed area, from Tobruk (eastern Libya) to Tabarka (western Tunisia). A statistical analysis of the qualitative trends in abundance perceived by the respondents shows that both species have significantly increased in abundance in Tunisia. In Libya an increase in the abundance of H. far was also apparent during the first decade of the 21 st century, but the current abundance of S. lessepsianus was found to be stable at the level of occasional captures. Given the lack of regular environmental monitoring programmes in the area, these findings provide information that could not have been obtained otherwise. Besides improving our understanding on the status and chronology of these invasions, this approach highlights the value of fisherman's knowledge to reconstruct ecological processes in the course of rapid historical modifications.

Overview on the distribution of gorgonian species in Tunisian marine coastal waters (central Mediterranean)

“…Nevertheless, when necessary the samples collected by divers and fishermen were identified in the laboratory. The LEK approach was successfully applied to compile information on the distribution and to track temporal changes of the presence and abundance of different marine species (Azzurro et al 2011, Boughedir et al 2015.…”

On the occurrence of the bluefin driftfish Psenes pellucidus Lütken 1880 (Perciformes, Nomeidae) in Tunisian waters (Mediterranean Sea)

“…Furthermore, the observation of juveniles supports the notion that there is a reproductive population in the Mediterranean Sea, being that their arrival from the Atlantic Ocean is less likely because of the long distance (circa 2000 km from Gibraltar). Increasing transnational surveillance (Azzurro et al., ) and new monitoring approaches, such as participatory monitoring (Azzurro et al., ; Ben Souissi et al., ; Boughedir et al., ), are therefore recommended in order to track the occurrence of these newcomers across various Mediterranean countries.…”

Updated checklist of bony fishes along the Libyan coasts (Southern Mediterranean Sea)

“…An expert evaluation of nonindigenous species (NIS) abundances was performed by the authors from data collected by both field surveys and interviews with local fishermen. These interviews were performed by showing pictures of NIS and asking fishermen to express the perceived abundance of species in six ranks of abundance, according to the approach given by Azzurro et al (2011) and Boughedir et al (2015): 0 = absent or not recorded; 1 = single record (caught only once); 2 = rare (caught once a year); 3 = occasional (caught sometimes in the fishing period): 4 = frequent (caught once a month or less in the fishing period); and 5 = common (caught regularly in the fishing period). When doubts arose on the correct identification of the species, the data collected from the interview were discarded.…”