Fish studies undertaken by AQUENS on morphometric, meristic character and electrophoretic features of freshwater and estuarine species can establish age, growth, fecundity and population dynamics. Analyses of heavy metals, particularly lead, zinc, copper and cadmium, can be carried out on fish tissues from waters subjected to contamination. Production studies of salmonids in rivers and streams may also be undertaken.
Only nineteen species of freshwater fish occur in Ireland which is low by European standards. The ‘game’ fish, comprising of four species, have been considered to be the most valuable down the years and include Atlantic salmon, sea trout, brown trout and char. A second group, collectively known as the ‘coarse fish’, have become important from a tourist angler viewpoint. Coarse fish include species like rudd, roach, perch, bream, tench, carp and pike. Apart from the pike, a noted solitary predator of other fish, the rest tend to move in shoals, particularly in lakes and canals.
AQUENS has vast experience in all facets of fieldwork connected with these species including gill netting, electrofishing, tagging, restocking and the collection of biological data. Ancilliary work involves removal of scales for aging purposes (and back-calculations), stomach flushing for dietary content and gonad examination to determine sex, maturity stages and condition factor. Appropriate statistical methodology viz., von Bertalanffy growth equations is used to determine recruitment mechanisms, spawning potential, predation and survival. The combinaton of field research and laboratory work enables management strategies to be devised and put in place for a particular lake or river.