| Summary: | Cetaceans inhabit marine coastal ecosystems where numerous human activities take place. Most the them as marine traffic, whale-watching tourism and/or pollution may put at risk the welfare and survival of cetacean species. In countries of the Southeastern Pacific as Chile and Peru, there is a lack of information regarding how human activities may disturb cetacean species behavior or conservation status. It is neccessary to know which activities affect negatively or positively their behavior or welfare in order to establish management strategies and guarantee their conservation. In this thesis I analized the impacts and benefits ofwhale-watching tourism has on the behavior of humpback whales (Megaptera novaeangliae) behavior in Peru, the marine traffic and collision risk with humpback whales and fin whales (Balaenoptera physalus) in Mejillones Bay (Chile) and the role of traze elements and persistent organic pollutants in the mass stranding of long-finned pilot whales (Globicephala melas) in southern Chile. In this sense two main methodologies were performed, (i) land-based surveys with the use of a total station to track behavioral variables such as breathing frequency, swimming speed, navigation path, diving times, surface time and distribution of whales. On the other hand, navigation speed, number and distribution of boats were registered; (ii) at the laboratory, population genetic analysis of mtDNA Control Region gene and 12 loci microsatellites were performed to stablish kinship in a mass stranding of pilot whales. Traze elements (Hg, Se, Cd, As), persistent organic pollutants (PCBs, DDTs, HCH and HCB) concentrations and stable isotopes analysis (δ15N y δ13C) were also performed to stablish pollutants levels in different age classes and trophic levels. Both methodologies were accompained by different statistical analysis such as null-hipothesis test and Bayesian inference, as well as the use of Geographic Information Systems software (ArcGIS) to create risk maps. Results of whale-watching study in Peru showed that the presence of whale-watching boats alter the behavior of humpback whale groups with and without calves. Groups with calf avoid boats by increasing their diving times, changes of navigation path and decreasing their breathing frequency. Groups without calf increase their swimming speed, surface time and breathing frequency during whale-watching boat encounters. On the other hand, the results of questionnaire surveys performed to whale-watchers tourists showed that if the activity is carried out with environmental education on board, it improves the tourist knowledge regarding whales and their ecology and promotes conservation awareness among tourists. These results highlight the needed to regulate under national legislation whale-watching tourism in Peru. Results regarding marine traffic and collision risk with whales in Mejillones Bay showed that the distribution area of fin whales and humpback whales concur with the high intensity marine traffic path of large cargo vessels. In addition, navigation path of artisanal and industrial fishing boats also concurs with the distribution of small cetaceans species such as long-beaked common dolphin (Delphinus capensis), Dusky dolphin (Lagenorhynchus obscurus), bottlenose dolphin (Tursiops truncatus), Risso’s dolphin (Grampus griseus) and Burmeister’s porpoise (Phoconea spinipinnis) in the bay. Moreover, navigation speed of large cargo vessels is higher that the maximum speed allowed for vessels into the bay (10 knots). These facts put at risk the survival of whales that visit Mejillones Bay for feeding. This thesis proposes regulations of marine traffic in Mejillones Bay through Marine Spatial Planning and the creation of a chanel for the entrance and exit of large cargo vessels in the nautical chart of the bay. The restuls obtained in the study of pollutants on mass stranding of pilot whales in Southern Chile showed that the concentrations of trace elements and persistent organic pollutants were lower for chilean pilot whales than Australian or New Zealand pilot whales. However, the results showed the biomagnification of PCBs, DDTs and Cd with the age of pilot whales in the mass stranding. The study of stable isotopes showed that adults had a more generalist diet that juveniles, being their carbon source different. Kinship analysis showed a strong social structure among individuals, belonging all individuals to the same population and the existence of 4 maternal lineages. Genetic and pollutant analysis showed the existence of at least three genetic groups in the mass strading. This study remarks the persistence of pollutants in pristine marine ecosystems of Southern Chile and its biomagnification through trophic levels as well as the needed to generate collaborative studies of ecotoxicology and molecular ecology to understand causes driving mass mortalities in cetacean species.
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