Ertuğ Düzgüneş

Deposition of egg capsule and larval development of Rapana venosa (Gastropoda: Muricidae) from the south-eastern Black Sea

Egg capsules and intracapsular embryos of Rapana venosa were studied to determine the reproductive pattern of this invader species in the south-eastern Black Sea. Egg deposition of R. venosa in the laboratory at 25°C was described. Egg laying began in mid-June, reached a peak in July and ended in late August in 1996. The total number of the egg capsules per whelk ranged between 197 and 999 (mean 575 ±41). The mean length of the egg capsules was 13.26 mm. Each capsule contained between 124 and 1090 embryos with a mean of 555 ±10. Mean larval production per rapa whelk was about 392,931 ±42,731. The mean size of eggs produced was 213.8 μm. Five different stages of intracapsular development were observed. Embryos developed without nurse eggs. Veliger larvae completed their intracapsular development and hatched in 22 days at 25°C.

Age, growth and meat yield of the European anchovy (Engraulis encrasicolus, L.1758) in the Black Sea

Abstract This communication gives new information on the population structure and meat yield of anchovy in the Black Sea off the Turkey coast.

Effect of Ballast Water on Marine Ecosystem

The coasts of the world are interconnected by extensive use of shipping routes. Ballast water is carried in ships to provide stability and trim. Discharge of ballast water may impact on the marine environment in various ways, and it is the major vector for the transfer of nonindigenous aquatic species from one region to another. These organisms often include non-native, alien, nuisance, exotic, and invasive species which can cause extensive ecological and economic damage to marine ecosystems. Introduction of invasive species is one of the major factors adversely affecting biological diversity, and they threaten many native species in the host environment till the extinction. To prevent and minimize the risk of introduction of invasive species, ballast water treatment technologies and legislations were developed by the International Maritime Organization (IMO).

Fisheries Management in the Black Sea—Pros and Cons

In Black Sea the term ”management” usually is interpreted as series of regulatory measures introduction in the fishery practice with no doubt, positive influence on the general condition of marine living resources. On the other hand, similar restrictions could not lead conceptually to the “management policy” if they are not systematized with clearly formulated aims and prerogatives. In the presence of introduced “closed area”, ”closed season”, ”minimum mesh size” and other regulations, altogether all of these measures could not serve as restrictions over the yield capacity, i.e. could not influence the fishing effort. The main priority in such a conception is a precautionary approach and responsible fishery practice in force. It could “work” properly with quota principle implementation, together with more effective system control. It is hard for the any single country to follow these regulations and it is harder for all Black Sea countries to do so, because they are exploiting resources from shared fish stocks. In order to have an effective management on these stocks, joint stock assessments are needed. On this basis, the allocation of the catches for the separate Black Sea country could be established. Unfortunately, due to the different reasons, for the time being this is impossible. Hence, it could be assumed that management of the marine living resources shall be fulfilled in its incomplete form, under the national jurisdiction prescript, as they are.

A General Review of Institutional Factors and Marketing Channels in the Fisheries of Turkey

The harvesting, processing and marketing sectors of the Turkish groundfishery are described, as are legal and organizational structures of the fishery. Following a discussion of government economic aid to the industry, the paper concludes with comments which focus on the difficulties faced by the Turkish fishery.