Observer programmes to record marine mammal and seabird distribution and interactions with fishing operations in Southwest Atlantic waters

Abstract

Since 1993, fishery observers from the Instituto Español de Oceanografía (lEO) have recorded incidental sightings and by-catches of marine mammals and seabirds from Spanish fishing boats in intemational waters of the southwest Atlantic. The lEO recently implemented an observer pragramme on-board research vessels in the area, recording data on marine mammal and seabird sightings. The objectives of this programme inc1ude (a) determining the distribution of marine marnmals and seabirds, (b) modelling habitat use, and (e) monitoring interactions with fishing operations. Data are collected on species present, numbers, behaviour, enviranmental conditions and interactions with fishing activities. Here we present a summary of results fram the fishery observers and a preliminary report on the results from surveys inc1uding distribution maps. The cetacean species most frequently sighted fram commercial vessels were Peale's dolphin (Lagenorhynchus australis) and hourglass dolphin (Lagenorhynchus cruciger). Other species of cetaceans observed inc1uded common dolphin (Delphinus sp.), pilot whale (Globicephala sp.), sperm whale (Physeter macrocephalus) and southem right whale (Eubalaena australis), minke whale (Balaenoptera acutorostrata), killer whales (Orcinus orca) and southem right whale dolphin (Lissodelphis peronii), . Recent observations fram a longliner inc1ude spenn whales following the boat for several days, suggesting that they were feeding in association with the boat, e.g. on fish hooked on the lines. Pinnipeds were observed frequently in the vicinity of the boats. By-catches of small numbers of marine mammals and seabirds were recorded, inc1uding hourglass dolphin and several pinniped species. During a hydrographic survey in December 2007 and a fishing survey in March-April 2008, the most frequently sighted cetaceans were dusky dolphin (Lagenorhynchus obscurus) and fin whale (Balaenoptera physalus). Other marine mammals recorded inc1ude hourglass dolphin, sperm whale, South American fur seal Arctocephalus australis, pilot whale, minke whale and Peale's dolphin.