Long-term trends of polychlorinated biphenyls and chlorinated pesticides in franciscana dolphin (Pontoporia blainvillei) from Southern Brazil

Selected POPs were analyzed in blubber samples of Pontoporia blainvillei from Southern Brazil to appraise temporal trend over a 10 year period (1994-2004). Overall, levels of POPs were relatively low, especially when compared to Northern Hemisphere concentrations. Apart from Mirex and PCBs, which showed stable concentrations, DDTs, HCB, CHLs, Dieldrin levels presented a slight decrease over the studied period. In addition, the increase in the PCBs/DDTs ratio supports the idea that inputs of DDTs are decaying faster than PCBs.     

Photogrammetry using in-field calibration: a non-invasive tool for predicting sex and life stages tested on Hector's dolphins in the wild

Accurate data on sex and life stage are essential for building realistic population models, which in turn are essential for sustainable conservation management. This case study develops and validates an improved photogrammetry method that allows for in-field calibration. The method was used to measure Hector's dolphins’ dorsal fins in the wild. Seven independent measurements of one dolphin resulted in a coefficient of variation of 1.39% for fin base length and 2.33% for fin height. Test measurements on shore at different distances and angles resulted in a mean error smaller than 1% up to a distance of 10?m and an angle of 40°. Dorsal fin dimensions from necropsied Hector's dolphins were analysed to evaluate the potential of predicting sex and life stage based on a dorsal fin measured in the wild. Dorsal fin shape was significantly related to sex. However, sex estimations based on this model turned out to be not accurate enough to replace traditional sexing methods for Hector's dolphins. Fin base length was significantly related to life stage for females. Estimations based on this model appear to be accurate.     

Abundance and distribution of avian and marine mammal predators of sardine observed during the 2005 KwaZulu-Natal sardine run survey

Opportunistic observations to determine the relative abundance and distribution of marine mammal and seabird predators of sardine Sardinops sagax were carried out during a dedicated multidisciplinary research survey off the South African east coast in June and July of 2005 that was timed to coincide with the annual sardine run. Associations between different predator species, between predators and clupeoids, and between predators and oceanographic variables, were examined. Species’ distributions were primarily separated by latitude and distance from shore. Bryde's whale Balaenoptera edeni, African penguin Spheniscus demersus, Cape cormorant Phalacrocorax capensis and West Coast round herring Etrumeus whiteheadi were predominantly found in the cool southern part of the survey region. Peak sardine run activity occurred within 4 km of shore at the northward limit of a strip of cool water (<21 °C) stretching along the East Coast. The principal predators associated with this activity were common dolphins Delphinus capensis and Cape gannets Morus capensis, and their nearshore distribution was associated with sardine and East Coast round herring E. teres. Few clupeoids were encountered along the KwaZulu-Natal continental shelf, although patches of high sardine abundance were recorded near the shore immediately south of Durban. It is clear that during the 2005 survey the sardine run terminated in this region, probably as a result of the nearshore intrusion of warm water from the Agulhas Current.