AQUATIC PLANT MANAGEMENT IN RELATION TO IRISH RECREATIONAL FISHERIES DEVELOPMENT

Aquatic plant control programs are often conducted in isolation rather than as part of an integrated habitat management strategy. The impact that this policy has on recreational fisheries in Irish canals is described. The study examined the ecological impact of aquatic weed control procedures employed in the canals and determined fish-holding capacity in relation to a range of aquatic plant species. Fish standing crop estimates were conducted using electrical fishing apparatus in canal habitats which had been subjected to different forms and intensities of weed control. Approximately 200 km of canal was surveyed during the investigation. Canals with weed cover values between 20 and 70% generally exhibited fish biomass levels which were between two and four times, respectively, greater than those recorded from densely (>70% cover) or sparsely (<20%) vegetated areas. Submerged plants with broad or complex leaf arrangements or mixed species assemblages had a greater fish harboring capacity than had submerged, strap-leaved or floating-leaved forms. The implications of these findings for aquatic plant management in canal fisheries are discussed.