Altering gillnet soak duration and timing minimizes bycatch and maintains target catch

Area of Science:

• Marine Biology
• Fisheries Science
• Conservation Biology

Background:

• Seabirds face significant threats from global fishing practices, with incidental catch (bycatch) being a primary concern.
• Vulnerable seabird foraging strategies, such as surface feeding and diving, increase their susceptibility to bycatch.
• Current bycatch mitigation methods, like gear modifications, show varied effectiveness and can negatively impact target catch.

Purpose of the Study:

• To experimentally evaluate the effectiveness of modified soak timing and duration for shallow-set gillnets in mitigating seabird bycatch.
• To assess the impact of different gillnet deployment strategies on target catch (Atlantic herring) and incidental bycatch.
• To inform conservation strategies for seabirds by identifying optimal fishing practices.

Main Methods:

• Conducted field experiments in Newfoundland and Labrador, Canada, targeting the Atlantic herring bait fishery.
• Compared catch and bycatch rates between control (approx. 24-hour soak) and short (approx. 12-hour soak) gillnet sets.
• Analyzed soak durations set overnight versus during daylight hours, alongside seabird activity monitoring.

Main Results:

• No significant difference in Atlantic herring catch between control and short overnight sets.
• Short daytime sets resulted in a substantial reduction in target herring catch.
• Nearly all bycatch, including all instances of seabird bycatch, occurred in the control (24-hour) sets.
• Seabirds were observed associating with fishing vessels throughout the day.

Conclusions:

• Shallow-set gillnets soaked overnight and hauled early morning minimize seabird bycatch risk.
• Catching herring in gillnets primarily occurs at night, outside of most coastal seabirds' foraging periods.
• Implementing short overnight soak times is a viable strategy to reduce seabird bycatch in this fishery.