Estimation of fishing effort in the Southern Hemisphere. New Zealand Aquatic Environment and Biodiversity Report No. 213
Seabird bycatch in commercial fisheries has become a major issue that has prompted considerable worldwide research and mitigation effort. New Zealand has played a leading role in such work, largely because a high proportion of the world's seabird species breed here. Several recent New Zealand studies have assessed the risk of commercial fisheries operating within the New Zealand Exclusive Economic Zone (EEZ) to seabirds that breed in the New Zealand region. This study underpins an expanded risk assessment of the impact of fisheries on seabirds throughout the Southern Hemisphere (SH). The objective was to estimate the total high seas effort expended in the SH by the main fishing methods likely to impact seabirds (surface longline SLL, bottom longline BLL, and trawl TWL). These estimates will be used in a subsequent quantitative risk assessment of SH seabirds.
Fishing effort data were sourced from five tuna Regional Fisheries Management Organisations (RFMOs) and five non-tuna RFMOs having at least partial jurisdiction over SH waters. Although the RFMO areas of responsibility cover most of the SH high seas waters, significant gaps occur in the southwestern Atlantic Ocean and the northern Indian Ocean west of Indonesia. Total SLL effort increased steadily to 1100 million hooks in 2003, and then fluctuated between 780 and 1133 million hooks per year. BLL effort has been relatively constant at an average of 63 million hooks per year since 2005. Trawl effort increased to a peak of over 17 000 tows in 2010, followed by a drop to an average of 13 000 tows since then.