ACAP Small Grant 2023-07

Trialling seabird bycatch mitigation measures for Brazilian demersal longline fisheries

Project Leader: Gabriel Canani Sampaio, LAATM-FURG / Projeto Albatroz, Brazil

Co-investigators: Dimas Gianuca, BirdLife International/SAVE Brasil Leandro Bugoni, LAATM-FURG Tatiana Silva Neves, Projeto Albatroz Fernando Niemeyer Fiedler, IFSC-Itajaí Danilo Geraldo Filipkowski, Projeto Albatroz Caio Azevedo Marques, Projeto Albatroz

Amount Awarded: AUD 36,800

The subtropical southwest Atlantic Ocean, including the Brazilian Exclusive Economic Zone, is a known hotspot for albatross and petrel bycatch in pelagic longline fisheries (Bugoni et al. AC14 Inf 01 Agenda Item 15.4 9 2008; Birdlife International, 2019; Jiménez et al., 2020). In contrast, much less is known about seabird bycatch in Brazilian demersal longline fisheries in this region, including small-scale vessels. Few early studies have reported high bycatch rates (Neves & Olmos, 1997; Vooren & Coelho, 2004; Bugoni et al. 2008), however, in the main estimate of global seabird bycatch in longline fisheries, Anderson et al. (2011), neglected bycatch in Brazilian demersal longline, assuming this fishery had collapsed. Nonetheless, this fleet has continuously operated since the 90s, with 129 vessels recorded in the port of Cabo Frio (RJ) alone, between 2003 and 2018 (Pimenta et al. 2020). In addition, a recent assessment confirmed high bycatch rates in Brazilian demersal logline fisheries, suggesting that given the fleet size and effort, possibly thousands of seabirds are killed year-round, and mostly ACAP listed species (Canani et al. 2023).

This fleet preferentially set the longline during daylight, does not use torilines and the line-weighting regimes are inadequate and highly variable among vessels (Canani et al. 2023). Currently, there is no regulations pertaining seabird bycatch reductions in Brazilian demersal longline, nor information on hook sink rates, which is determinant to assess bycatch risk and develop adequate mitigation measures. In addition, the small size of vessels of this fleet, predominantly small-scale, is a challenge for the deployment of torilines with desirable aerial coverage.

Our study aims to evaluate line sink rates of current line weighting regimes commonly used by Brazilian demersal longline vessels, compared with an additional weighting regime aligned with ACAP best practice advice for reducing bycatch in demersal longline fisheries. In addition, to evaluate line tension and aerial coverage of a toriline prototype designed for small vessels, potentially suitable for the Brazilian small-scale demersal longline fleet.

Different toriline configurations will be tested under varying conditions, including vessel speed and wind direction, and configurations of main line and dragging device lengths, attachment pole height. The tests will be conducted aboard the research vessel "Aprendendo com o Mar", from Federal Institute of Santa Catarina (IFSC – Campus Itajaí) to verify the aerial coverage and drag force achieved with the combinations of toriline configurations and conditions. Given the influence of wind direction on aerial coverage, sea state (Beaufort scale) and wind direction relative to the bow and stern will be recorded.

The toriline prototypes, a scaled-down version of the model specified in INI 07/2014 (Brazil 2014), and broadly aligns with the toriline recommendation for demersal longline vessels with less than 24 m length (Melvin et al. 2021);

The sinking rates of four configurations of line weight regimes utilized by Brazilian demersal longline vessels will be compared against a configuration recommended by ACAP, using Time and Depth Recording Devices (TDRs). Sinking rates will be determined under experimental conditions using approximately 8.5 kg granite blocks, already acquired, in two different setting speeds (4 and 6 knots). These experiments will be conducted aboard the research vessel "Aprendendo com o Mar”.

Our research aims to contribute to the development of mitigation measures suitable for small-scale demersal longline vessels operating in southern and southeast Brazil and beyond. The results of the present project will provide valuable information to guide future and expected regulations in Brazil to reduce seabird bycatch in demersal longline fisheries, and to the development of mitigation measures in other fleets with similar characteristics.