Behavioral changes observed in Black Sea anchovy and its possible causes

The Black Sea anchovy (Engraulis encrasicolus ponticus) is a migratory species spawning and overwintering at two opposite ends of the Black Sea. It has been reported that the species may display significant alteration in their migration routes and in their spawning grounds. That, in turn, affects the stock and the fishery on this species noticeably. This study focuses on these alterations by comparing the age, length and egg-size distributions of the anchovies sampled within the Turkish Exclusive Economic Zone (EEZ). The results showed that all the variables examined decreases along the longitudinal axis extending from the overwintering areas towards the spawning grounds. This indicated that the youngest anchovies, which are smaller than the old ones and lay smaller eggs, spawns in the areas near to the overwintering ground, and that the part of the population returning to the main spawning grounds (continental shelf of the northwestern Black Sea) were composed of older fish. These results may also indicate that the high fishing pressure on this species could possibly increase the proportion of small size fish in the stock by removing the large individuals and lessening the size of the population returning to the main spawning grounds. And this situation is a very important factor that needs to be considered in fisheries assessment in the Black Sea.
Forum on Fisheries Science in the Mediterranean and Black Sea, (10 - 14 Aralık 2018)


Spatial distribution of the Black Sea copepod, Calanus euxinus, estimated using multi-frequency acoustic backscatter
Sakinan, Serdar; Gücü, Ali Cemal (2017-03-01)
The copepod Calanus euxinus is a key prey species for fish in the Black Sea. To estimate the distribution and biomass of the late developmental stages of this species in July 2013, we analysed multi-frequency (38, 120, and 200 kHz) echo-sounder data from a fisheries survey of the Black Sea. The dependence of acoustic backscatter on frequency, i.e. the frequency response, was estimated for daytime scattering layers, which were confirmed by net catches to be dense, post-copepodite-stage (C4) aggregations of C...
Spatial variation of larval ascaridoid nematode (Nematoda: Chromadorea: Ascaridoidea) infections in the Black Sea anchovy (Engraulis encrasicolus)
Akkuş, Gizem; Gücü, Ali Cemal (2021-01-01)
This study evaluates the Black Sea anchovy population infected by parasitic Ascaridoid Nematode larva in the Southern Black Sea. It assesses the larva's effect on fish body condition, energy stored in the body, and anchovy growth. For this, anchovies sampled on July 10-31, 2018, from 30 different stations were examined, and 11.8% of the 825 anchovies were found infected. The observed infection rate was higher on the western side of the study area, suggesting that this rate may be used as a biomarker for the...
Vertical distribution of marine cyanobacteria Synechococcus spp. in the Black, Marmara, Aegean, and eastern Mediterranean seas
Uysal, Zahit (2006-01-01)
The vertical distributions of the unicellular cyanobacteria Synechococcus were studied in several highly contrasting seas: the Black Sea, Sea of Marmara, Aegean Sea, and Mediterranean Sea. Cell abundances varied significantly on both vertical and horizontal scales in all physically and spatially discrete water masses. Epifluorescence microscope cell counts from all seas clearly showed that majority of the population remains suspended in the surface-mixed layer and decreases gradually towards the base of the...
Molecular evolution and phylogeography of the eastern mediterranean water frog (pelophylax) complex
Akın Pekşen, Çiğdem; Bilgin, Cemal Can; Plötner, Jörg; Department of Biology (2015)
Water frogs (genus Pelophylax) in the eastern Mediterranean region represent a genetically and phylogenetically diverse group. Their dependence on freshwater habitats makes them highly sensitive to geological and climatic changes. Thus they are an ideal group to study the effect of past geological processes on molecular evolution of protein-coding and non-coding genes on the genome and on patterns of phylogeography in the eastern Mediterranean region. In the first study, the complete sequence of water frog ...
Adaptive traits of Turkish honeybee subspecies in response to climate A survey and a test of niche overlap
Kükrer, Mert; Bilgin, Cemal Can (null; 2016-09-01)
Citation Formats
G. Akkuş and A. C. Gücü, “Behavioral changes observed in Black Sea anchovy and its possible causes,” presented at the Forum on Fisheries Science in the Mediterranean and Black Sea, (10 - 14 Aralık 2018), Italy, Rome, 2018, Accessed: 00, 2021. [Online]. Available: