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title: "Investigating a weighty problem:  sink rates, seabird bycatch and reduction in marketable catch"
---

# Investigating a weighty problem:  sink rates, seabird bycatch and reduction in marketable catch

*![Weighty Hooks](https://acap.aq/images/stories/acap/Mitigation/Weighty_Hooks.jpg)  
Control and experimental hooks, the weighted hook is on the left; *from the publication.**

 Eric Gilman ([The Safina Center](https://www.safinacenter.org/), Honolulu, Hawaii, USA) and colleagues have published open access in the journal *[Scientific Reports](https://www.nature.com/srep/)* on researching weighting longliner hooks tor reduce seabird bycatch.

 The paper’s abstract follows:

 “Fisheries bycatch threatens the viability of some seabird populations and reduces fishing efficiency. Albatross bycatch in a US North Pacific tuna longline fishery has increased over the past decade and now exceeds 1000 annual captures. Seabirds interacting with this fishery reach hooks at depths up to 1 m. A branchline weight’s mass and distance from the hook affect seabird catch rates. We conducted experimental fishing to compare the commercial viability of a weighted hook relative to conventional gear with weights attached 0.75 m from the hook. We used a Bayesian random effects meta-analytic regression modelling approach to estimate pooled expected species-specific log relative risk of capture on conventional versus experimental gear. There was a significant 53% (95% HDI: − 75 to − 25%) decrease in retained species’ catch rates on experimental hooks, indicating an unacceptable economic cost, and no significant effect for discarded species. Using a Bayesian general linear mixed regression modelling approach, experimental hooks sank to 85 cm *ca*. 1.4 times (95% HDI: 1.37–1.48) faster than control hooks. Given their potential to reduce seabird catch rates, eliminate safety risks from bite-offs and facilitate robust compliance monitoring, it is a priority to find a weighted hook design with acceptable catch rates.”

 **Reference:**

 Gilman, E., Musyl, M., Wild, M., Rong, H. & Chaloupka, M. 2022.  Investigating weighted fishing hooks for seabird bycatch mitigation.  [*Scientific Reports*doi.org/10.1038/s41598-022-06875-4](https://www.nature.com/articles/s41598-022-06875-4?fbclid=IwAR3lHDslK_FnX1ObPpSPgxk1cYBkq_omATD45Q08kGLwDZ9nNCXqng1QBlE#citeas).

 *John Cooper, ACAP Information Officer, 27 April 2022*