that area today and it is unknown whether or not the population is declining. Data, conservation measures and awareness are lacking. These porpoises are cryptic making surveying a challenge. It is also difficult to estimate bycatch because the sale of porpoise meat is no longer available at markets. Commerson’s dolphins The expanding trawl fisheries devastated the Commerson's dolphin (Cephalorhynchus commersonii) populations in Patagonia. Trawl fisheries greatly expanded for twenty years until they crashed in 1997. Pelagic squid fisheries took over which use pelagic trawls that are harmful to dusky, short-beaked common dolphins, and Commerson’s dolphins. There are approximately 21,000 Commerson’s dolphins remaining today. Two stocks have been identified in the population but genetic information and bycatch levels are unknown. With anchovy fisheries expanding, it is imperative to assess the Commerson’s dolphin population before these fisheries grow. The seasonal operation of in-shore gillnet fisheries are known to involve bycatch of cetaceans. Presently, there are no known estimates of gillnet bycatch. The bycatch problem in Argentina is political in nature. Improvements in fishing technology, awareness, and a large scale survey of Commerson’s dolphin populations and the impact of bycatch is essential. La Plata dolphins The La Plata or Franciscana dolphin (Pontoporia blainvillei) is the most threatened small cetacean in the southwest Atlantic Ocean due to bycatch. They are only found in the coastal waters of Argentina, Brazil, and Uruguay. This species has been divided into four ranges (FMU’s: Franciscana Management Units) for management and conservation purposes. These populations are genetically different. Mortality rates are 1.6% for FMU 4 and 3.3% for FMU 3 but it is unknown whether these estimates are accurate. Aerial surveys have proven inconclusive so far as to the population numbers of franciscanas. To rectify this situation, more surveys are needed as well as political commitment, awareness campaigns and bycatch mitigation techniques. Harbour porpoises There is substantial incidental catches in fishing operations. Often, the harbour porpoise (Phocoena phocoena) is killed by incidental by-catch (10, 11, 12). Gillnets pose a serious threat to the harbour porpoise as they are extremely susceptible to entanglement. A study by Caswell et al. in the western North Atlantic combined the mean annual rate of increase of the harbour porpoise with the uncertainty of incidental mortality and population size. It was found that the incidental mortality exceeds critical values and therefore by-catch is a significant threat to the harbour porpoise. Harbour porpoises become entangled in