Cachalotera

Cachalotera

In southern Chile, as in many South American countries, artisanal shing is very common. The main target species are Austral hake (Merluccius australis), ling (Genypterus blacodes) and Patagonian toothfish (Dissostichus eleginoides) which is exported as 'Chilean Sea Bass'.

Vessels in the Chilean artisanal toothfish fishery are limited to a maximum size of 18 metres. Fishermen in this fleet consider sperm whales (cachalote in Spanish) a problem in their fishery.

To address the issue of sperm whales stealing their fish, the artisanal fleet uses a local adaptation of the Spanish longline system. This 'Chilean longline' system was developed in the mid-1990s and uses short main lines (2000 metres), with multiple 9-metre droplines off the main line. Each dropline has a number of hooks.

This Chilean system allows these small vessels to set short lines that can be hauled quickly (reducing the impact of sperm whales on their catch), while still letting them put a lot of hooks in the water.

Professor Carlos Moreno, Instituto de Ecología y Evolución, Universidad Austral de Chile, noticed that fishermen using this method caught virtually no seabirds, despite the fact they were fishing in waters frequented by many albatrosses and petrels. He reports that scientific observers on 6 artisanal vessels reported only 4 white-chinned petrels caught for 27 million hooks set (despite the fact these vessels used no seabird mitigation device at all).

The reason for the near-zero bycatch is that each dropline ends with a stone weight (around 300-500 grams) and this weight quickly drags the baited hooks out of reach of birds as soon as the line is cast in the water.

Meanwhile, Chile's industrial toothfish fleet operated larger vessels using the traditional Spanish longline system. This fleet found it was losing 3% or more of its catch to orca and sperm whales. Given the value of toothfish, this fish-loss to whales was identified as a significant issue by the Chilean government's Fishery Research Fund.

Carlos got grants from the Fishery Research Fund to solve the birds and whale/toothfish issue, and worked with Pesca Suribérica skippers on this. Carlos proposed using mesh nets on the droplines, instead of pots, and the 'cachalotera' was born. With government funding they continued to develop this into a workable system.

Shortly afterwards, all 10 vessels in Chile's industrial toothfish fleet were using the 'cachalotera' in conjunction with the Chilean longline system. They reported CPUEs similar to the Spanish longline system they had been using, but lost only 0.3% of their catch to whales instead of 3% or more.

The conversion from Spanish to Chilean longline methods in this fleet has reduced seabird bycatch from 1542 birds (2002 season observer data) to 0 birds (2006 season observer data).

References

C.A. Moreno et al. Significant conservation benefits obtained from the use of a new fishing gear in the Chilean Patagonian toothfish fishery CCAMLR Science, Vol. 15 (2008): 79-91

C.A. Moreno, J.A. Arataa,*, P. Rubilarb, R. Hucke-Gaetea, G. Robertson Artisanal longline ?sheries in Southern Chile: Lessons to be learned to avoid incidental seabird mortality

G. Robertson; et al. CCAMLR Science, Vol. 15 (2008): 93-106 Line weights of constant mass (and sink rates) for Spanish-system Patagonian toothfish longline vessels

Brothers, N.; Cooper, J.; Løkkeborg, S. 1999 The incidental catch of seabirds by longline fisheries: worldwide review and technical guidelines for mitigation Food and Agriculture Organization of the United Nations Fisheries Circular No.937 (http://www.fao.org/docrep/005/W9817E/W9817E00.HTM)

Eric Gilman References on Seabird Bycatch in Longline Fisheries Blue Ocean Institute Western Pacific Regional Fishery Management Council, September 2004

http://www.wpcouncil.org/protected/Documents/Reference%20List%20Seabird%20bycatch%20Longline%20Fisheries.pdf

Seabird Bycatch Mitigation: Minimum Standards for Pelagic Longline Fishing and Priorities for Further Research Prepared by the Agreement on the Conservation of Albatrosses and Petrels (ACAP) 2007