Feasibility of Tagging Walleye Pollock Captured with Hook and Line Using External Tags

• Published in: Marine and coastal fisheries 2016-01, Vol.8 (1), p.374-381
• Main Authors: Rutecki, Thomas L, Ianelli, J. N
• Format: Article
• Language: English
• Subjects: Abrasion; Feasibility studies; Fins; Fish; Fisheries; Fishing; Freshwater fishes; Gadus chalcogrammus; Handling; Marine fishes; Mortality; Mortality factors; Parameter estimation; Procedures; Research ships; Skin; Survival; Tags; Tanks; Wounds
• ISSN: 1942-5120; 1942-5120
• DOI: 10.1080/19425120.2016.1167794

We evaluated methods of minimizing mechanical injury to Walleye Pollock Gadus chalcogrammus when tagging them with external identification tags. Walleye Pollock (20–62 cm FL) were captured with hook and line near Auke Bay, Southeast Alaska, and were tagged with either T-bar anchor tags or lock-on tags, which were anticipated to be used for tagging studies in the Gulf of Alaska and Bering Sea. The tested handling procedures included transferring the tagged fish between live tanks either by using a dip net (dipnetted group) or with wet, bare hands (non-dipnetted group). Sixty percent of the dipnetted fish (63 of 105) died, whereas 12% of the non-dipnetted fish (17 of 138) died. Overall, 50% of the deaths occurred within 7 d after capture, and 89% of the deaths occurred within 10 d after capture. Of the dipnetted fish that died, 68% (n = 43) died from dermal infection due to scale loss, whereas 30% of the non-dipnetted fish mortalities were from dermal infection. Additionally, injuries that were recorded as potential mortality factors included fin loss, torn jaws, internal dysfunction, and unknown. All of the fish that received lock-on tags and 93% of the fish that were anchor-tagged developed an infection at the point of tag insertion. Tag retention rates were 99.5% for lock-on tags and 93.7% for anchor tags, and tag type did not affect survival. Use of hook-and-line capture is an effective method for reducing mechanical injury and mortality in Walleye Pollock. Recommended procedures for capturing and tagging Walleye Pollock include the use of hook and line and the use of wet, bare hands (or a similar low-abrasion approach) when handling the fish.