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A alimentação de otárias-do-cabo (Arctocephalus pusillus pusillus (Schreber, 1776) num parque zoológico: aspectos energéticos, digestão e variações comportamentais
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Abstract(s)
Numa boa prática de manutenção de mamíferos marinhos em condições artificiais é importante acompanhar cuidadosamente a alimentação e os seus efeitos na evolução do peso dos animais, em articulação com outras variáveis ambientais.
Este trabalho consiste num estudo de alimentação com dez leões marinhos da espécie Arctocephalus pusillus pusillus (5 machos adultos, 2 fêmeas adultas e 3 machos juvenis) no parque oceanográfico Zoomarine (Albufeira, Portugal).
Os objectivos foram a determinação dos valores calóricos das espécies de produtos da pesca usadas na alimentação destes animais e os seus efeitos na evolução do peso corporal em função da idade, peso e história comportamental.
O estudo estendeu-se ao longo de quatro anos e tendo sido dividido em três fases. Na primeira, foi quantificado o valor calórico do alimento efectivamente tomado por cada indivíduo. Na segunda fase não houve controlo calórico, tendo apenas sido registado a quantidade total em quilos de alimento. Na terceira e última fases, fez-se um planeamento da alimentação dos animais baseado em valores calóricos. Além da alimentação tomada por cada sujeito foram registados diariamente as temperaturas do ar e da água e eventos comportamentais relevantes (tais como incidentes de agressão). Foram igualmente testados alguns métodos de medição dos tempos de passagem dos diferentes tipos de alimento no tubo digestivo de três machos adultos com a utilização de esferas radiopacas para visualização radiográfica.
Em termos gerais, verificou-se que as espécies Scombrus japonicus, Trachurus trachurus e Sprattus sprattus apresentaram valores calóricos mais elevados, embora muito variáveis, enquanto as espécies Loligo vulgaris e Trisopterus minutus mostraram valores mais baixos mas mais estáveis. As espécies de maior valor calórico mostraram tempo de passagem mais elevado pelo tubo digestivo, com o máximo de 33 horas para a espécie Sprattus sprattus.
As temperaturas da água e do ar mostraram uma relação previsível com as oscilações no peso dos animais, que mostraram uma relação inversa com às oscilações anuais da temperatura.
O presente trabalho contribuiu para um melhor conhecimento do valor do conteúdo calórico dos diferentes produtos da pesca fornecidos aos leões-marinhos, conhecimento esse hoje utilizado pelo parque na planificação da alimentação dos seus mamíferos marinhos em geral. Fica igualmente demonstrada a relevância da planificação alimentar de acordo com os valores calóricos no que concerne aos cuidados e bem-estar dos animais exibidos.
In a good practical maintenance of marine mammals in artificial conditions it is important to carefully control the feeding of the animals and its effects on the evolution of their weight, combined to other environmental variables. This research consists on the feeding study of ten fur seals (five adult males; two adult females and three juvenile males) of the species Arctocephalus pusillus pusillus at the oceanographic park Zoomarine (Albufeira - Portugal). The goals were to measure the values in calories of each fish species used for the feeding of those animals and their effects on body weight and behavior, in relation to their ages, weights and historical behavior. The study lasted four years and was divided in three periods. During the first period the caloric values of the food, effectively ingested by each animal were measured after the ingestion. During the second period there was no control of caloric values, only the total amount in kilogram of food intake has been registered. During the third and last period, the food intake of the animals was established based on a pre-determined caloric value. Besides the food taken by each animal, the air and water temperatures and relevant animal’s behaviors (such as aggressive incidents) were registered daily. A few measure methods - of the period of time each type of food had taken to go along the digestive tube - were also tested in three adult males. This has been done by using radioactive spheres for radiographic visualization. In general the species Scombrus japonicus, Trachurus trachurus and Sprattus sprattus presented higher caloric values even if very variable, while the species Loligo vulgaris and Trisopterus minutus showed lower and more stable values. The species of higher caloric values had the longest time of digestion with a maximum of thirty-three hours for the specie Sprattus sprattus. Water and air temperatures seemed to have an effect on the animal’s weight variation, which showed an inverse relation to the annual temperature varieties. However this variation could also be related to their own species seasonal physiological adaptation. This study allowed a better understanding of the importance of the different caloric values in the various species given to the fur seals. This knowledge is applied today at the park on food planning for its marine mammals in general. It has also shown the relevance of food planning according to the caloric values in relation with the husbandry and well-being of the exhibited animals.
In a good practical maintenance of marine mammals in artificial conditions it is important to carefully control the feeding of the animals and its effects on the evolution of their weight, combined to other environmental variables. This research consists on the feeding study of ten fur seals (five adult males; two adult females and three juvenile males) of the species Arctocephalus pusillus pusillus at the oceanographic park Zoomarine (Albufeira - Portugal). The goals were to measure the values in calories of each fish species used for the feeding of those animals and their effects on body weight and behavior, in relation to their ages, weights and historical behavior. The study lasted four years and was divided in three periods. During the first period the caloric values of the food, effectively ingested by each animal were measured after the ingestion. During the second period there was no control of caloric values, only the total amount in kilogram of food intake has been registered. During the third and last period, the food intake of the animals was established based on a pre-determined caloric value. Besides the food taken by each animal, the air and water temperatures and relevant animal’s behaviors (such as aggressive incidents) were registered daily. A few measure methods - of the period of time each type of food had taken to go along the digestive tube - were also tested in three adult males. This has been done by using radioactive spheres for radiographic visualization. In general the species Scombrus japonicus, Trachurus trachurus and Sprattus sprattus presented higher caloric values even if very variable, while the species Loligo vulgaris and Trisopterus minutus showed lower and more stable values. The species of higher caloric values had the longest time of digestion with a maximum of thirty-three hours for the specie Sprattus sprattus. Water and air temperatures seemed to have an effect on the animal’s weight variation, which showed an inverse relation to the annual temperature varieties. However this variation could also be related to their own species seasonal physiological adaptation. This study allowed a better understanding of the importance of the different caloric values in the various species given to the fur seals. This knowledge is applied today at the park on food planning for its marine mammals in general. It has also shown the relevance of food planning according to the caloric values in relation with the husbandry and well-being of the exhibited animals.
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Keywords
Mamíferos Hábitats artificiais Alimentação Leões marinhos Parque zoológico Otária-do-cabo