-The Antillean manatee (Trichechus manatus manatus) is considered to be one of the most endangered aquatic mammals in Brazil. From 1981 through 2002 an extensive research was performed to collect information about stranding of manatees on the northeast coast of Brazil. Data were separated in two distinct periods (1981-1990 and 1991-2002) and analyzed according to specific categories: stranded dead (captured by nets, captured by harpoons and undefined cause) and stranded alive (dead in captivity and captive population). There were 74 events of stranding manatees in the period surveyed. Thirty-one events of dead manatees and 43 events of specimens that survived until December 2002 were recorded. In the last years of the study there were more strandings of alive animals than dead. The main reason for the strandings of manatee calves in northeastern Brazil is the separation from their mothers. The largest numbers of stranded manatees occurred in Ceará and Rio Grande do Norte states.Resumo -O peixe-boi marinho (Trichechus manatus manatus) é considerado um dos mamíferos aquáticos mais ameaçados do Brasil. Entre 1981 e 2002 foi realizado um extenso levantamento de informações sobre os encalhes de peixes-boi marinho na costa nordeste do Brasil. Os dados foram dispostos em dois períodos distintos (1981-1990 e 1991-2002)

Data on Sotalia guianensis Van Bénéden, 1864 occurrence on the beaches of Pernambuco (Northeastern Brazil) is restricted to information on stranding and on printed material from local newspapers; actual observations of such animals have not been published. This study intends to determine the use of habitat, behavioral activities and assess the relationships between environmental factors and the recorded behavior. Observations were conducted on open sea coastal areas, on the beaches of Olinda and Piedade, as well as in sheltered areas, in the ports of Recife and Suape. Monitoring was carried out every month in each area, during two consecutive days, from September 2004 to August 2005. Results corroborate that this species prefers to occupy more protected environments, the port of Recife being the main concentration area for such species. Piedade is just an exploratory area, possibly due to shark occurrence. Olinda is only occasionally used. Concentration areas seem to be used for feeding, and incidence of caudal exhibition suggests that most of the estuarine dolphin prey items are demersal. Environmental conditions (seasonality, tide and time) did not show to be significant when related to the estuarine dolphin behavior.

. Based on these equations, length at birth for the Amazonian manatee is estimated at 133.2 cm (average = 113.0 cm; SD = 34.4 cm) for males, and 131.0 cm (average = 124.7 cm; SD = 22.0 cm) for females. Among the males, the annual growth rate was 0.09 cm (95% CI: ± 0.002), with a maximum length of 299.4 cm (95% CI: ± 2.039), while females presented a growth rate of 0.24 cm per year (95% CI: ± 0.004), reaching up to 256.1 cm (95% CI: ± 0.4832) of total length. Even though von Bertalanffy's equation is not commonly used for sirenians, and considering that when previously applied it did not obtain satisfactory results, in this study it proved adequate for the establishment of the growth curve for free-ranging Amazonian manatees. Resumo: O objetivo deste trabalho foi descrever curvas de crescimento para peixes-boi-da-Amazônia de vida livre no Brasil. Foram utilizados dados etários e biométricos de 60 peixes-boi-da-Amazônia, 33 machos e 27 fêmeas, capturados entre 1993 e 2006 por pessoas ribeirinhas do médio Solimões e do Rio Pirativa, na região Amazônica, oriundos do Instituto de Desenvolvimento Sustentável Mamirauá e do Centro Nacional de Conservação e Manejo de Mamíferos Aquáticos/ICMBio. O modelo matemático não-linear utilizado para análise desses dados foi a equação derivada de von Bertalanffy, sendo calculadas duas equações de crescimento, uma para os machos L(t) macho = 299,4 [1-e -0,0897507(t+6,55696) ], e outra para as fêmeas L(t) fêmea = 256,1 [1-e -0,23731(t+ 3,01921) ]. Com o desenvolvimento dessas equações, o comprimento do peixe-boi-da-Amazônia ao nascer foi de 133,2 cm (média = 113,0 cm; SD = 34,4 cm) quando macho, e 131,0 cm (média = 124,7 cm; SD = 22,0 cm) quando fêmeas. Nos machos a taxa de crescimento anual obtida foi de 0,09 cm (IC 95%: ± 0,002), atingindo uma envergadura máxima de 299,4 cm (IC 95%: ± 2,039), enquanto as fêmeas apresentaram uma taxa de crescimento de 0,24 cm ao ano (IC 95%: ± 0,004), podendo alcançar até 256,1 cm (IC 95%: ± 0,4832) de envergadura. Apesar da equação de von Bertalanffy não ser comumente utilizada para sirênios, e quando aplicada anteriormente não ter obtido resultados satisfatórios, neste estudo apresentou-se adequada para a elaboração da curva de crescimento para peixe-boi-da-Amazônia de vida livre. Palavras-chave: peixe-boi-da Amazônia, estimativa de idade, von Bertalanffy, sirênios.

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