Modelling the presence of anchovy Engraulis encrasicolus in the Aegean Sea during early summer, based on satellite environmental data

Abstract

Acoustic and satellite environmental data as well as bathymetry data were used to model the presence of anchovy, Engraulis encrasicolus during early summer in the northern Aegean Sea (Eastern Mediterranean). Generalized Additive Models (GAMs) were used for modelling and subsequently applied in a predictive mode to identify those areas in the Greek Seas and the entire Mediterranean basin that could support species' presence. Model results were evaluated with the estimation of Receiver Operating Characteristic (ROC)-plots as well as qualitatively, based on (a) acoustic data from concurrent studies in certain areas of the northern Aegean Sea that were not included in the estimation of the GAM model and (b) historical acoustic data from the central Aegean and Ionian Seas. Mapping the estimated environmental conditions in the Mediterranean basin indicated areas that generally agree with the known distribution grounds of anchovy, such as the straits of Sicily and coastal waters of Tunisia, areas in the Tyrrhenian Sea, the Adriatic Sea, the Gulf of Lions and the Catalan Sea.

Prediction of marine species distribution from presence–absence acoustic data: comparing the fitting efficiency and the predictive capacity of conventional and novel distribution models

“…These areas are characterized as nutrient-rich resulting in aggregations of small pelagic species. The areas identified are in agreement with other studies on small pelagic species (Somarakis et al, 2002;Giannoulaki et al, 2008;Tsagarakis et al, 2008). Correlations among grids are generally in agreement to correlations among predictions of SDMs on the validation dataset.…”

“…Approaches based on SDMs have only relatively recently been applied to marine species and several novel modelling methods have been proposed (Leathwick et al, , 2006aPhillips et al, 2006;Palialexis et al, this issue). SDMs have been also used to study relationships between environmental variables and species presence (Amara et al, 2004;Giannoulaki et al, 2008;Lefkaditou et al, 2008;Martin et al, 2008), identifying species essential habitats (Planque et al, 2007) and forecasting how species distribution may be affected by climate changes (Siapatis et al, 2008). Easy access to satellite data which cover extended geographical areas is one reason for the increasingly wide use of SDMs.…”

Temporal habitat suitability modeling of Caspian shad (Alosa spp.) in the southern Caspian Sea

“…Caspian shad prefer wintering in deeper waters in the southern Caspian Sea (Coad, 1995;Coad, 1997;Afraei Bandpei et al, 2006), where temperature at deep water was at least two degree more than other season in the southern of Caspian Sea at winter time . The role of SLA has been demonstrated in fish habitat modeling as describes ocean processes (Larnicol et al, 2002;Pujol and Larnicol, 2005), being useful in measuring productivity, and often influencing the distribution of species throughout their life stages (Giannoulaki et al, 2008). Furthermore, SLA was found to be a predictor in fish habitat studies in the southern Caspian Sea (Haghi Vayghan et al, 2013) and Mediterranean Sea (Crechriou et al, 2008;Tserpes et al, 2008).…”

Applying a two-stage Bayesian dynamic model to a short lived species, the anchovy in the Aegean Sea (Eastern Mediterranean). Comparison with an Integrated Catch at Age stock assessment model.

“…Fishery independent information regarding the state of the anchovy stock was obtained from acoustic surveys (Giannoulaki et al, 2008) and the Daily Egg Production Method (DEPM; Somarakis et al, 2012) that were concurrently implemented during June 2003June -2006June and 2008 in the N. Aegean Sea. A pelagic trawl was used to qualify the acoustic targets and to obtain biological samples.…”

“…It belongs to the eastern Mediterranean anchovy stock that presents reduced gene exchange with the respective stocks of the NW Mediterranean and the Adriatic Sea (Magoulas et al, 1996), presenting also differences in terms of population characteristics . The main anchovy distribution grounds in the Aegean Sea (Figure 1) are located within the continental shelf of the North Aegean Sea and the semi-closed areas along the western coast (see more details in Giannoulaki et al, 2004Giannoulaki et al, , 2008Somarakis et al, 2007). Anchovy spawning in the North Aegean Sea occurs from May till September with a peak during June -July.…”