Age and growth of anglerfish (Lophius piscatorius) in Faroese waters

Abstract

To investigate the reliability of age–length growth estimates of anglerfish Lophius piscatorius in Faroese waters, results from illicia age determination, length frequency and mark-recapture analyses were compared. Features of the illicium, such as the time of deposition and sizes of the benthic and first annual zones, width and the marginal increment progression of the edge were studied in detail. Results showed that the average horizontal diameters of the benthic and first annual zones were 0.18mm (age 0) and 0.32mm (age 1), respectively, and these zones could be identified in anglerfish of any length. There was a strong positive correlation between illicium width and fish length. In transmitted light the edge was usually dark in the winter and light in the summer, and the transition between them took place in May/June. Results from illicia age-readings and length-frequency analysis show that anglerfish in these waters have a very high growth rate during their first years of life (age 0–1, 18.5cmyear−1), after which smaller individuals grow faster than larger fish. Growth rates of fish larger than 35cm in length are comparable to the fastest growth rates in other areas of the North Atlantic. Since the illicia age determinations resulted in growth rates that were consistent with length frequency and mark-recapture analyses, we believe that illicia derived age length keys could be used in age-based assessment of anglerfish in Faroese waters.