Fate of three Australian teleosts after ingesting conventional and modified stainless- and carbon-steel hooks

In response to concerns over the fate of three Australian teleosts (mulloway, 'Argyrosomus japonicus', yellowfin bream, 'Acanthopagrus australis', and snapper, 'Pagrus auratus') released with ingested recreational hooks, experiments were carried out to determine whether ejection could be promoted via different wire materials and/or their modification. Between 108 and 114 fish of each species were angled and allowed to ingest conventional or modified (with notches to reduce wire diameter by ∼20%) J-hooks (~250 mm²) made from three materials (stainless steel and nickel-plated and red-lacquer carbon steel), before being released into tanks and monitored with control fish for up to 61 d. Total mortalities were 35, 24, and 25% for mulloway (over 61 d), yellowfin bream (over 35 d), and snapper (over 41 d), respectively. Of the survivors, 30, 61, and 77%, respectively, ejected their hooks (and only one hook-ejected fish died). For yellowfin bream, hook ejection (and hence survival) was positively correlated with total length, and hook oxidation was the key predictor of ejection from mulloway and snapper, which could be promoted by selecting carbon-steel designs with narrow wire diameters and minimal protective coating. The choice of coating might also be important, with relatively greater mortality among mulloway and yellowfin bream that ingested nickel-plated hooks.