The applicability of 10 ml cryotubes for sperm cryopreservation in a Hungarian carp landrace (Cyprinus carpio carpio morpha accuminatus)

In our study, the comparison of 5 ml straw and 10 ml cryotube during sperm cryopreservation in a Hungarian carp landrace (Cyprinus carpio carpio morpha accuminatus) was carried out. Three different dilution ratios (1:1, 1:4 and 1:9) were also tested using the cryotube. A significantly higher pMOT was recorded using the cryotube in comparison with the straw. VCL and STR were similar in both groups. Cryopreservation had a negative effect on pMOT and VCl using the cryotube and also the straw where, STR was not reduced significantly. An increasing tendency was observed using higher dilution of sperm during cryopreservation; however, significant difference was not recorded between the three groups. VCL and STR were similar in all groups. Cryotube was applicable for the sperm cryopreservation of the Hungarian carp landrace. However, the standardization for the freezing method specified for this volume is recommended. The different dilution ratios needed be tested also during fertilization

Development of artificial spawning nests for pikeperch (Sander lucioperca L.) in a highly modified shallow lake (Lake Balaton, Hungary)

The recent fish populations of Lake Balaton considered to be not-self-sustaining, although only recreational angling is allowed in the lake. Stocks of the most important angling fishes (such as common carp, pikeperch), are maintained by artificially hatched and reared specimens by Balaton Fisheries Nonprofit Ltd. The main reason of the decreased reproductive success of native fish species is the lack of natural spawning grounds and substrates. Water regulation works conducted till the middle of the 20th century caused the loss of these important habitats. During these works the water level decreased and most of the nursery areas have been detached from the original lake. The aim of our project is to develop and establish artificial spawning substrates for pikeperch. Previous studies reported, that the success of artificial nests depends mostly on their architectural complexity, and the material has only a secondary role. Tests were conducted for eight types (altogether 72 nests in three sites) of artificial nests over two spawning seasons. More than 70% of the deployed nests were used by pikeperch for spawning. No significant differences were found between the eight trial nest types regarding their occupation. This result confirmed the very low availability of natural spawning substrates and supports that fish may use artificial substrates as spawning grounds. This project was supported by the “GINOP 2.3.2 -15-2016-00004: Establishing the sustainable angling-aimed management of Lake Balaton.”; and the “EFOP-3.6.3-VEKOP-16-2017-00008” projects. Árpád Ferincz and Ádám Staszny was supported by the Bolyai János Postdoctoral Fellowship of the Hungarian Academy of Sciences. Main references: Specziár, A., Turcsányi, B. (2014): Effect of stocking strategy on distribution and recapture rate of common carp Cyprinus carpio L., in a large and shallow temperate lake: implications for recreational put-and-take fisheries management, Journal of Applied Ichtiology 30: 887-894. Gillet, C., Dubois, J. P. (1995): A survey of the spawning of perch (Perca fluviatilis ), pike (Esox lucius), and roach (Rutilus rutilus), using artificial spawning substrates in lakes, Hydrobiologia 300-301: 409-415. Lehtonen, H., Lappalainen, J., Kervinen, J., Fontell, E. (2006): Spatial distribution of spawning sites of pikeperch [Sander lucioperca (L.)] in a highly eutrophic clay-turbid lake – implications for management, Journal of Applied Ichtiology 22: 542-544.peerReviewe