Effects of habitat modifications on the movement behavior of animals: the case study of Fish Aggregating Devices (FADs) and tropical tunas

Movement Ecology

Kim Holland¹  David Itano²  Shiham Adam³  Manuela Capello⁴  Laurent Dagorn⁴  Riyaz Jauharee⁴  Géraldine Pérez⁴  Fabien Forget⁴  Sunil P. Beeharry⁵  John D. Filmalter⁶  Jean-Louis Deneubourg⁷ 

[1] Hawai’i Institute of Marine Biology at University of Hawai’i, Kane’ohe, Hawai’i, USA;Institute for Marine and Atmospheric Reserch at University of Hawaiʻi, Mānoa, Hawai’i, USA;International Pole and Line Foundation, 1 London Street, RG1 4QW, Reading, UK;MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Sète, France;Ministry of Ocean Economy, Marine Resources, Fisheries and Shipping, Port Louis, Mauritius;South African Institute for Aquatic Biodiversity, Grahamstown, South Africa;Unit of Social Ecology, Université Libre de Bruxelles (ULB), Bruxelles, Belgium;

关键词: Acoustic tagging;    Associative behavior;    Density of floating objects;    Movement behavior;    Tropical tuna;   

DOI  :  10.1186/s40462-020-00230-w

来源: Springer

【 摘 要 】

BackgroundAggregation sites represent important sources of environmental heterogeneity and can modify the movement behavior of animals. When these sites are artificially established through anthropogenic actions, the consequent alterations to animal movements may impact their ecology with potential implications for their fitness. Floating objects represent important sources of habitat heterogeneity for tropical tunas, beneath which these species naturally aggregate in large numbers. Man-made floating objects, called Fish Aggregating Devices (FAD), are used by fishers on a massive scale to facilitate fishing operations. In addition to the direct impacts that fishing with FADs has on tuna populations, assessing the effects of increasing the numbers of FADs on the ecology of tuna is key for generating sound management and conservation measures.MethodsThis study investigates the effects of increasing numbers of FADs (aggregation sites) on the movements of tunas, through the comparison of electronic tagging data recorded from 146 individuals tunas (yellowfin tuna, Thunnus albacares, and skipjack tuna, Katsuwonus pelamis) tagged in three instrumented anchored FAD arrays (Mauritius, Oahu-Hawaii and Maldives), that differed according to their distances among neighboring FADs. The effect of increasing inter-FAD distances is studied considering a set of indices (residence times at FADs and absence (travel) times between two visits at FADs) and their trends.ResultsWhen inter-FAD distances decrease, tuna visit more FADs (higher connectivity between FADs), spend less time travelling between FADs and more time associated with them. The trends observed for the absence (travel) times appear to be compatible with a random-search component in the movement behaviour of tunas. Conversely, FAD residence times showed opposite trends, which could be a result of social behavior and/or prey availability.ConclusionOur results provide the first evidence of changes in tuna associative behavior for increasing FAD densities. More generally, they highlight the need for comparing animal movements in heterogeneous habitats in order to improve understanding of the impacts of anthropogenic habitat modifications on the ecology of wild animals.

【 授权许可】

CC BY