Hooking pattern, and short term survival in genetically improved farmed tilapia (GIFT) caught by different hook types

Abstract

Fishes are physically damaged by hooking or handling. Handling time and physical injury or stress influence survival of hooked fish in recreational fishing. ‘J’ hooks are reported to show deep hooking whereas circle hooks show lip or jaw hooking. In the present communication, we tried to study hooking pattern, extent of bleeding and survival of Genetically Improved Farmed Tilapia (GIFT) caught by J hooks and circle hooks. Experiments were conducted at two aqua tourism sites in Narakal, Kerala with J hook and circle hook using shrimp as bait. Hooking location and presence and extent of bleeding were recorded soon after hooking and immediately the fishes were tagged and released to floating cages of 1x0.6x0.6 m. Incidence of mortality was observed for 72 h. In the case of circle hook, maximum fishes were hooked at upper lip (56.25 per cent), followed by buccal cavity (31.25 per cent) and lower lip (12.5 per cent). In J hook, incidence of buccal cavity hooking (56.25 per cent) was predominant followed by upper lip (43.75 per cent) and lower lip hooking (6.25 per cent). Contrary to most reports, no deep hooking was observed in either J or circle hooks and consequently, the extent of bleeding at the hooking point was also very minimal. In fishes caught by J hook, 57.14 per cent did not have bleeding while 17.85 per cent had slight bleeding, moderate bleeding in 14.28 per cent and severe bleeding in 10.71 per cent . In fishes caught by the circle hook, values were 54.54, 36.36 and 9.09 per cent respectively for no bleeding, slight bleeding, and moderate bleeding. In circle hook, no severe bleeding was recorded in any of the fishes caught. No fish mortality was recorded within 72 h of post-release. Low physical injury coupled with less handling time and sturdy nature of fish could be the reasons for no mortality and the very small mouth opening of tilapia would have prevented deep hooking. This study is preliminary and more studies using different types of fishes needs to be undertaken for substantiating the results.