Porovnání účinnosti dvou typů plůdkové zátahové sítě
| Title in English | Efficiencies of two types of seine net for 0+ fish sampling |
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| Authors | |
| Year of publication | 2006 |
| Type | Article in Proceedings |
| Conference | 9. Česká ichtyologická konference |
| MU Faculty or unit | |
| Citation | |
| Field | Fishing |
| Keywords | seine net; 0+ fish sampling |
| Description | Young of the year (YOY) fish assemblages are used as indicators of a river ecological state. Though, some aspects of YOY fish sampling methodics are still not definitely solved. Present study compared YOY sampling efficiency of 5 m beach seine net and 10 m beach seine net. Study took place in a regulated upstream weir stretch of Morava River near the Lanžhot town (83. r. km) in September 2002. Shore line consisted of submerged bank vegetation, maximum shore depth was 80 cm and maximum current velocity 0.1 m/s. Ten localities were sampled by both types of net. Simultaneously, comparative electrofishing survey was conducted in the same river stretch. Both types of net caught the same species, but relative proportion of species differed significantly. Bleak (Alburnus alburnus) dominated in assemblage obtained by 10 m net (80%). In assemblage obtained by 5 m net, roach (Rutilus rutilus), bitterling (Rhodeus sericeus) and stone moroko (Pseudorasbora parva) co-dominated along with bleak. Therefore assemblage obtained by 5 m net was more similar to the assemblage obtained by electrofishing than to one obtained by 10 m net. Difference was caused by difficult hauling of the 10 m net lead line through submerged vegetation, missing this way YOY fish sheltering in vegetation (e.g. roach, bitterling, stone moroko). No significant difference was found in size structure of species obtained by seine nets. Ten meter net appeared as a selective gear, having underestimated density (inds/m) of species sheltering in submerged vegetation. Therefore 5 m seine net seems to be more appropriate gear for sampling YOY fish assemblages in slow flowing rivers with submerged vegetation. |
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