Management of pikeperch stocking in Lake Balaton: effect of season, area, fish size and method of release on the rate and distribution of recaptures

Abstract

-Pikeperch Sander lucioperca is an economically important fish which depleted populations need intensive management and supplemental stocking. We aimed to assess the relative influence of various pikeperch stocking strategies in Lake Balaton, Hungary, and tested 60 stocking set-ups (two seasons  three lake areas  shore vs. offshore release  five size groups) by releasing 3000 tagged yearlings. Anglers reported data of 522 recaptures within four years after stocking. Recapture rate was highest in stocking of the most productive lake area, increased with fish size, was higher in shore than offshore releases, but did not differed between stocking seasons. Fish stocked to oligotrophic areas travelled longer distances and dispersed more than those stocked to the mesotrophic area. Fish size had little effect, whereas season and method of stocking had no effect on dispersal of fish. To conclude, in pikeperch, autumn stocking with large yearlings released directly from the shore is recommended over other set-ups. Stocking quotas may be concentrated in space in low productivity areas, but should be dispersed between multiple sites in food rich areas to attain complete dispersal. This study provides a framework for testing fisheries management alternatives and behaviour of stocked fish in intensively utilized habitats.Keywords: angling / fisheries management / mark and recapture / Sander lucioperca / stocking strategy Résumé -Gestion de l'empoissonnement de sandre dans le lac Balaton: effet de la saison, de la localisation, de la taille du poisson et de la méthode de déversement sur le taux et la distribution des recaptures. Le sandre Sander lucioperca est un poisson économiquement important dont les populations appauvries ont besoin d'une gestion intensive et d'un empoissonnement de soutien. Nous avons cherché à évaluer l'influence relative de diverses stratégies d'empoissonnement de sandre dans le lac Balaton, en Hongrie, et nous avons testé 60 configurations d'ensemencement (deux saisons  trois zones lacustres  zone riveraine  zone de remise à l'eau au large  cinq groupes de taille) en relâchant 3 000 animaux d'un an marqués. Les pêcheurs à la ligne ont apporté des données sur 522 poissons recapturés dans les quatre ans suivant le déversement. Le taux de recapture était le plus élevé dans la zone lacustre la plus productive, il augmentait avec la taille des poissons, était plus élevé sur le rivage que dans les eaux hauturières, mais ne différait pas d'une saison à l'autre. Les poissons déversés dans les zones oligotrophes ont parcouru de plus longues distances et se sont dispersés davantage que ceux déversés dans la zone mésotrophe. La taille du poisson a eu peu d'effet, alors que la saison et la méthode de mise à l'eau n'ont eu aucun effet sur la dispersion du poisson. Pour conclure, pour le sandre, il est recommandé de faire des empoissonnements d'automne avec de grands alevins de l'année relâchés directement du rivage plutôt que d'autres solutions. Les quotas de mise en charge peuvent être concentrés...

Genetic consequences of pond production of a pikeperch (Sander luciopercaL.) stock with natural origin: the effects of changed selection pressure and reduced population size

“…In spite of its higher diversity, the wild population showed the signs of a recent bottleneck event. Specziár & Turcsányi (2017) reported that the pikeperch population of Lake Balaton is characterized by a high rate of harvesting, an early-life dietary bottleneck and a high rate of predation and cannibalism-related juvenile mortality. All of these factors can greatly reduce population size, resulting in changes in the genetic structure.…”

“…The importance of β increases as the proportion of reproductive captive individuals within the stock increases. Specziár & Turcsányi (2017) reported on the annual stocking of 1-1.5 million fingerlings into Lake Balaton. Based on mark-recapture data, they found an average 7.7% survival at the size category <150 g and a rate of 30.1% if fingerling above 300 g weight were stocked.…”

“…Although commercial fishing has been banned there since 2014, the maintenance of the pikeperch population requires regular stocking due to the high rate of angler catches. Until recently, 1-1.5 million of 3-5 cm length fingerling produced in fish ponds were stocked annually in the lake (Specziár & Turcsányi, 2017). These fish ponds represent natural or semi natural conditions, as food availability and predation are the most important differences compared to Lake Balaton (Tölg, 1984).…”

Development of a fish-based index for the assessment of the ecological status of Lake Balaton in the absence of present day reference condition

“…Therefore, we supposed that of the key native pelagic species, the bleak, the common bream and the razor fish are less effected by anthropogenic pressures, and thus, could have a density close to the range of the assumed reference status. On the other hand, population of pikeperch likely is depressed by intensive angling (Specziár and Turcsányi, 2017). On the contrary, as discussed above, both the species richness and the abundance of the phytophilous group could have been much higher in the undisturbed status of Lake Balaton.…”

Variability of pikeperch Sander lucioperca (L. 1758) cohorts in early life history

“…In this study, pikeperch Sander lucioperca (L. 1758) was used as a model species. Sander lucioperca is a commercially valuable and a game fish, native to eastern Europe and western Asia and introduced to other European, Asian and north African countries (Specziár and Turcsányi, 2017;FAO, 2018). In natural water bodies, S. lucioperca is a top-predator and therefore it is used in many biomanipulative projects to reduce zooplanktivorous species and increase water quality (Wysujack et al, 2002;Blabolil et al, 2016).…”