Study

Hooking locations in sea turtles incidentally captured by artisanal longline fisheries in the eastern Pacific Ocean

  • Published source details Parga M.L., Pons M., Andraka S., Rendón L., Mituhasi T., Hall M., Pacheco L., Segura A., Osmond M. & Vogel N. (2015) Hooking locations in sea turtles incidentally captured by artisanal longline fisheries in the eastern Pacific Ocean. Fisheries Research, 164, 231-237.

Actions

This study is summarised as evidence for the following.

Action Category

Use larger hooks

Action Link
Reptile Conservation

Use a different bait type: Sea turtles

Action Link
Reptile Conservation

Use circle hooks instead of J-hooks

Action Link
Reptile Conservation
  1. Use larger hooks

    A replicated study in 2004–2011 in pelagic waters in the Eastern Pacific Ocean (Parga et al. 2015) found that using larger hooks reduced the likelihood of olive ridley turtles Lepidochelys olivacea swallowing hooks in an artisanal surface longline fishery. All results were reported as odds ratios, see original paper for details. Overall, larger hook sizes were less likely to be swallowed than smaller hook sizes. Using fish bait in combination with larger circle hooks lead to the largest proportion of external hookings (which are preferable to internal hookings). In 2004–2011 incidental sea turtle catch rates of circle hooks (sizes 12/0–18/0), tuna hooks and traditional J-hooks (see original paper for hook specifications) were compared by placing hooks in alternative sequence along longlines (3.5 million total hooks used in 8,996 line deployments). Bait used was classed as squid (Dosidicus gigas, Illex sp. and Loligo sp.) or fish (Opisthonema spp., Scomber japonicus, Auxis spp. and Sardinops sagax) and only deployments using one type of bait were included in analysis (4,838 of 8,996 line deployments). Information on hooking location and entanglement of sea turtles was recorded (1,823 total olive ridley turtles).

    (Summarised by: Katie Sainsbury)

  2. Use a different bait type: Sea turtles

    A replicated study in 2004–2011 in pelagic waters in the Eastern Pacific Ocean (Parga et al. 2015) found that using fish instead of squid bait reduced the likelihood of olive ridley turtles Lepidochelys olivacea swallowing hooks in an artisanal surface longline fishery. When fish bait was used, hooks were less likely to be swallowed by olive ridley turtles than when squid bait was used (results reported as odds ratios, see original paper for details). Using fish bait in combination with larger circle hooks lead to the largest proportion of external hookings. In 2004–2011, incidental catch rates of sea turtles on circle hooks (sizes 12/0–18/0), tuna hooks and traditional J-hooks (see original paper for hook details) were compared by placing hooks in alternative sequence along longlines (3.5 million total hooks used in 8,996 line deployments) in an artisanal longline fishery. Bait used was classed as squid (Dosidicus gigas, Illex sp. and Loligo sp.) or fish (Opisthonema spp., Scomber japonicus, Auxis spp. and Sardinops sagax) and only deployments using one type of bait were included in the analysis (4,838 of 8,996 line deployments). Information on hooking location and entanglement of sea turtles was recorded (1,823 total olive ridley turtles).

    (Summarised by: Katie Sainsbury)

  3. Use circle hooks instead of J-hooks

    A replicated study in 2004–2011 in pelagic waters in the Eastern Pacific Ocean (Parga et al. 2015) found that using circle hooks or tuna hooks instead of traditional J-hooks reduced the likelihood of olive ridley turtles Lepidochelys olivacea swallowing hooks in an artisanal surface longline fishery. All results were reported as odds ratios, see original paper for details. Both circle and tuna hooks were less likely, and circle hooks least likely to be swallowed overall, by olive ridley turtles compared to J-hooks. In 2004–2011 incidental sea turtle catch rates of circle hooks (sizes 12/0–18/0), tuna hooks and traditional J-hooks (see original paper for hook specifications) were compared by placing hooks in alternative sequence along longlines (3.5 million total hooks used in 8,996 line deployments). Bait used was classed as squid (Dosidicus gigas, Illex sp. and Loligo sp.) or fish (Opisthonema spp., Scomber japonicus, Auxis spp. and Sardinops sagax) and only deployments using one type of bait were included in analysis (4,838 of 8,996 line deployments). Information on hooking location and entanglement of sea turtles was recorded (1,823 total olive ridley turtles).

    (Summarised by: Katie Sainsbury)

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