Habitat suitability modelling for sardine Sardina pilchardus in a highly diverse ecosystem: the Mediterranean Sea

Abstract

Integrated information from different parts of the Mediterranean Sea was used to model the spatial and temporal variability of the distribution grounds of the sardine population. Acoustic data from the North Aegean Sea (Eastern Mediterranean), the Adriatic Sea (Central Mediterranean), the Sicily Channel (Central Mediterranean) and Spanish Mediterranean waters (Western Mediterranean) were analysed along with satellite environmental and bathymetric data to model the potential habitat of sardine during summer, autumn and early winter. Generalized additive models were applied in a presence−absence approach. Models were validated in terms of their predictive ability and used to construct maps exhibiting the probability of sardine presence throughout the entire Mediterranean basin as a measure of habitat adequacy for sardine. Bottom depth and sea surface temperature were the environmental variables that explained most of the data variability. Several areas along the Mediterranean coastline were indicated as suitable habitat for sardine in different seasons. An expansion of these areas over the continental shelf, up to 100 m depth, was consistently noticed from summer to winter. This was attributed to the horizontal movements of sardine related to spawning (i.e. winter period) and the peculiarities of the Mediterranean Sea where areas favouring growth, feeding and spawning processes tend to be localised and prevent a long range, offshore migration as opposed to large upwelling ecosystems. Moreover, within the study period, a positive relationship between the extent of sardine preferred habitat and landings was revealed for both summer and winter seasons throughout the entire Mediterranean Sea.

Assessing the Impact of Temperature and Chlorophyll Variations on the Fluctuations of Sardine Abundance in Al-Hoceima (South Alboran Sea)

“…On the Moroccan side, this has led to a gradual warming of the waters over the same period, particularly in the Al-Hoceima region, due to the lack of transfer of cold water from the north to the south by the Gyre [30,31]. The upwelling mechanisms of the Spanish coast and dynamic characteristics of the WAG, associated to changes in hydro-meteorological characteristics as drought and rainfall, seem to have great impact on the environmental conditions such as SST and phytoplankton biomasses in south of Alboran Sea (Figure 11).…”

“…Indeed, the Atlantic jet (AJ) feeds the WAG by means of a meandering structure of ~ 100-150 km of diameter and, occasionally, defines the Eastern Anticyclonic Gyre (EAG) as well ( Figure 1). This dynamic and complex system is regulated by the interaction of local and regional processes [30,32].…”

“…The main goal of these efforts was the understanding of the inter-annual variability of biomass in fish species, related to environmental condition. Many studies were realized on the Northern Alboran Sea [15,[30][31][32][33], but very few of them have been carried out on the southern part. We here recognize and analyze fluctuations of sardine's abundance at one of the most important fishing establish the proportional relationship between CPUE and abundance: CPUE = C t / E t = q N t [2] In practice, q is usually considered as a constant.…”

European anchovy (Engraulis encrasicolus) age structure and growth rate in two contrasted areas of the Mediterranean Sea: the paradox of faster growth in oligotrophic seas

“…Each area has distinct hydrographic conditions, bathymetries, and productivities. Our attention was focused on areas over the continental shelf, i.e., the main habitat and spawning grounds for anchovy (Tugores et al, 2011;Giannoulaki et al, 2013;Basilone et al, 2013).…”

“…Finally, in order to extract the environmental conditions related to the main spawning habitat of anchovy, all satellite datasets were clipped considering the 200 m isobath ( Fig. 1) (Tugores et al, 2011;Giannoulaki et al, 2013;Basilone et al, 2013).…”