Contents lists available at ScienceDirect Aquaculture journal homepage: www.elsevier.com/locate/aquaculture Novel method for induced propagation of fish: Sperm injection in oviducts and ovary/ovarian lavage with sperm T. Müller a,⁎ , L. Horváth a , T. Szabó a , I. Ittzés a , A. Bognár b , P. Faidt b , Á. Ittzés a , B. Urbányi a , B. Kucska c a Department of Aquaculture, Faculty of Agricultural and Environmental Sciences, Szent István University, 2100 Gödöllő, Hungary b BO-FA Fish Farm, 7252 Attala, Hungary c Department of Aquaculture, Faculty of Agricultural and Environmental Sciences, Kaposvár University, 7400 Kaposvár, Hungary ARTICLE INFO Keywords: Artificial reproduction In vitro fertilisation Induced spawning Common carp ABSTRACT Motility of spermatozoa in most freshwater teleost species is suppressed by the osmolality of the seminal plasma in the testes, sperm ducts and initiated by a decrease of osmolality upon spawning in fresh water. We hy- pothesized that, similarly to internally fertilising fish species, spermatozoa of freshly stripped sperm, when injected directly into the ovary through the oviduct, will remain inactivated and maintain its fertilisation ca- pacity for extended periods. Fertilisation is expected to occur after ovulated oocytes with spermatozoa on their surfaces are released into the water. To test this hypothesis, experiments were carried out on carp (Cyprinus carpio) as a model fish. Stripped and pooled sperm samples were injected by catheter into the ovarian cavity through the oviduct 2 h and 12 h before expected spawning. To prevent any loss of gametes the genital area of treated females were stitched by a standard protocol used in large-scale hatchery systems. At ovulation, eggs were stripped and fertilised with salt-carbamide solution. All sperm-injected females produced some fertilised eggs that developed normally while fertilisation rates varied considerably (24.2–81.2%). This proof of principle experiment demonstrates the potential for routine use as alternative to in vitro fertilisation for the propagation of fish species. 1. Introduction One of the prerequisites for the domestication and establishment of sustainable aquaculture is the capacity to control reproductive pro- cesses of fish in captivity, and to acquire high quality gametes (i.e. eggs and sperm) for generation of the marketable product. In most cultured fish species, hormonal manipulations may be used as management tools to enhance the efficiency of egg production, increase spermiation and facilitate hatchery operations. In addition, hormonal therapies may be employed to induce gamete maturation and enable artificial collection in order to implement inter-specific hybridization, chromosome set manipulation or artificial fertilisation for genetic selection programmes (Mylonas et al., 2010). In vitro fertilisation by induced breeding through hormone treat- ment followed by artificial fertilisation and incubation of fertilised eggs has several advantages (Woynárovich and Horváth, 1980) including better rates of fertilisation and hatching, protection against enemies and unfavourable environmental conditions, and better conditions for growth and survival. However, not all fish species ovulate in a predictable fashion. Several fish species including; striped bass Morone saxatilis (Kerby, 1986), white sturgeon Acipenser transmontanus (Conte et al., 1988), channel catfish Ictalurus punctatus (Phelps et al., 2007), pikeperch Sander lucioperca (Zarski et al., 2011), european eel Anguilla anguilla (Mordenti et al., 2014) respond best to final hormonal ad- ministration with high individual fluctuations due to different latency times of ovulation. Therefore, it is preferable to use induced spawning/ captive spawning/natural-like method for such species. Egg fertilisation and hatching performance also exhibited better results than artificial insemination in Japanese and European eel (Tanaka, 2015; Di Biase et al., 2015) probably because the timing of spawning and fertilisation is optimized by the parent eels themselves (Okamura et al., 2013). The problem is that using induced spawning (for instance pikeperch) can reduce the diversity across the genome during long term culture as some parents contribute disproportionately to the next generation. This reduction of variation in the gene pool of stocks can in the culturing of the major Chinese carps; grass carp (Ctenopharyngodon idella), big head carp (Hypophthalmichthys nobilis), common carp (Cyprinus carpio), and silver carp (Hypophthalmichthys molitrix) in Asia. In these cases, http://dx.doi.org/10.1016/j.aquaculture.2017.09.025 Received 19 June 2017; Received in revised form 12 September 2017; Accepted 15 September 2017 ⁎ Corresponding author. E-mail address: Muller.Tamas@mkk.szie.hu (T. Müller). Aquaculture 482 (2018) 124–129 Available online 18 September 2017 0044-8486/ © 2017 Elsevier B.V. All rights reserved. MARK