Network analysis of acoustic tracking data reveals the structure and stability of fish aggregations in the ocean

Aggregations in the distribution of individuals are an almost universal phenomenon in living organisms. Groups of animals that display collective coordinated movement without forming stable social bonds such as fish schools are a special type of aggregation. In tropical tuna fisheries, aggregating behaviour is directly exploited through the use of artificial fish aggregating devices (FADs). Hence, understanding the dynamics of schooling behaviour and the potential impacts of FADs upon it may have ramifications for tuna management. As a novel way of quantifying spatiotemporal co-occurrences of animals, we applied network statistics to acoustic tracking data to identify the co-occurrences of individual yellowfin tuna, Thunnus albacares, in an array of FADs and determine the frequency and temporal dynamics of these co-occurrences. We observed large interannual variation in movement rates of tuna between FADs, and corresponding interannual variability in the mean number of spatiotemporal associates for each individual as well as the temporal stability of associations. When movement rates were high, associations within FAD aggregations decayed to randomness three times faster than when movement rates were lower. This raises the possibility that if FADs are sufficiently close for fish to perform frequent between- FAD movements, school mixing may be increased and cohesion reduced.

[1]  R. Hilborn.  Modeling the Stability of Fish Schools: Exchange of Individual Fish between Schools of Skipjack Tuna (Katsuwonus pelamis) , 1991 .

[2]  T. Pitcher,et al.  When fish shoals meet: outcomes for evolution and fisheries , 2003 .

[3]  J. Godin,et al.  The social organization of free‐ranging fish shoals , 2000 .

[4]  A. Ward,et al.  Social aggregation in the pelagic zone with special reference to fish and invertebrates. , 2011, Advances in marine biology.

[5]  Richard James,et al.  Network structure and parasite transmission in a group living lizard, the gidgee skink, Egernia stokesii , 2009, Behavioral Ecology and Sociobiology.

[6]  Truman P. Young,et al.  Measuring association between individuals or groups in behavioural studies , 1992, Animal Behaviour.

[7]  Stephanie G Schuttler,et al.  Movement Patterns and Spatial Relationships Among African Forest Elephants , 2012 .

[8]  Hal Whitehead,et al.  Investigating structure and temporal scale in social organizations using identified individuals , 1995 .

[9]  Gary D. Schnell,et al.  Statistical comparison of proximity matrices: applications in animal behaviour , 1985, Animal Behaviour.

[10]  Hal Whitehead,et al.  Analyzing Animal Societies: Quantitative Methods for Vertebrate Social Analysis , 2008 .

[11]  A. Klimley,et al.  School fidelity and homing synchronicity of yellowfin tuna, Thunnus albacares , 1999 .

[12]  David Itano,et al.  Behavior of yellowfin (Thunnus albacares) and bigeye (T. obesus) tuna in a network of fish aggregating devices (FADs) , 2007 .

[13]  F. Pelletier,et al.  Keep in touch: Does spatial overlap correlate with contact rate frequency?† , 2012 .

[14]  Leo Polansky,et al.  A framework for understanding the architecture of collective movements using pairwise analyses of animal movement data , 2011, Journal of The Royal Society Interface.

[15]  Barbara A. Block,et al.  Movements, behavior, and habitat utilization of yellowfin tuna (Thunnus albacares) in the northeastern Pacific Ocean, ascertained through archival tag data , 2007 .

[16]  D. Parkinson,et al.  Bayesian Methods in Cosmology: Model selection and multi-model inference , 2009 .

[17]  Steven J. Schwager,et al.  A comparison of association indices , 1987, Animal Behaviour.

[18]  R. R. Krausz.  Living in Groups , 2013 .

[19]  P. Cayre.  Behaviour of yellowfin tuna (Thunnus albacares) and skipjack tuna (Katsuwonus pelarnis) around fish aggregating devices (FADs) in the Comoros Islands as determined by ultrasonic tagging , 1991 .

[20]  R. W. Baird,et al.  Social organization of mammal-eating killer whales : group stability and dispersal patterns , 2000 .

[21]  Hal Whitehead,et al.  SOCPROG programs: analysing animal social structures , 2009, Behavioral Ecology and Sociobiology.

[22]  R. Brill.  Handling and manipulating tunas in captivity: a physiologist's perspective , 2003 .

[23]  Steven C. Minta,et al.  Tests of Spatial and Temporal Interaction Among Animals. , 1992, Ecological applications : a publication of the Ecological Society of America.

[24]  G. Helfman.  School fidelity in fishes: The yellow perch pattern , 1984, Animal Behaviour.

[25]  Leo Polansky,et al.  From moonlight to movement and synchronized randomness: Fourier and wavelet analyses of animal location time series data. , 2010, Ecology.

[26]  Carl G. Meyer,et al.  Inter-animal telemetry: results from first deployment of acoustic 'business card' tags , 2009 .

[27]  J. Fewell.  Social Insect Networks , 2003, Science.

[28]  Kim N. Holland,et al.  A rapid ontogenetic shift in the diet of juvenile yellowfin tuna from Hawaii , 2006 .

[29]  I. Ohta,et al.  Periodic behavior and residence time of yellowfin and bigeye tuna associated with fish aggregating devices around Okinawa Islands, as identified with automated listening stations , 2005 .

[30]  Daniel W. Fuller,et al.  Movements, behavior, and habitat selection of bigeye tuna (Thunnus obesus) in the eastern equatorial Pacific, ascertained through archival tags , 2002 .

[31]  K. Holland,et al.  HORIZONTAL AND VERTICAL MOVEMENTS OF YELLOWFIN AND BIGEYE TUNA ASSOCIATED WITH FISH AGGREGATING DEVICES , 1990 .

[32]  L. Edelstein-Keshet,et al.  Complexity, pattern, and evolutionary trade-offs in animal aggregation. , 1999, Science.

[33]  Daniel W. Franks,et al.  The impact of social networks on animal collective motion , 2011, Animal Behaviour.

[34]  Steven V. Viscido,et al.  Self-Organized Fish Schools: An Examination of Emergent Properties , 2002, The Biological Bulletin.

[35]  J. Krause,et al.  Potential banana skins in animal social network analysis , 2009, Behavioral Ecology and Sociobiology.

[36]  David R. Anderson,et al.  Model selection and multimodel inference : a practical information-theoretic approach , 2003 .

[37]  A. Desurmont,et al.  The use of anchored FADs in the area served by the Secretariat of the Pacific community (SPC): Regional synthesis , 2000 .

[38]  Patrick J Butler,et al.  Biotelemetry: a mechanistic approach to ecology. , 2004, Trends in ecology & evolution.

[39]  Christopher G. Lowe,et al.  Movement Patterns, Habitat Utilization, Home Range Size and Site Fidelity of Whitesaddle Goatfish, Parupeneus Porphyreus, In a Marine Reserve , 2000, Environmental Biology of Fishes.

[40]  Daniel W. Fuller,et al.  Behavior of bigeye (Thunnus obesus) and skipjack (Katsuwonus pelamis) tunas within aggregations associated with floating objects in the equatorial eastern Pacific , 2005 .

[41]  K. Holland,et al.  Movement and vulnerability of bigeye (Thunnus obesus) and yellowfin tuna (Thunnus albacares) in relation to FADs and natural aggregation points , 2000 .

[42]  Simon Benhamou,et al.  FAD: Fish Aggregating Device or Fish Attracting Device? A new analysis of yellowfin tuna movements around floating objects , 2004, Animal Behaviour.

[43]  M. Kelly,et al.  Ocelot home range, overlap and density: comparing radio telemetry with camera trapping , 2008 .

[44]  Edward J. Brooks,et al.  Developing a deeper understanding of animal movements and spatial dynamics through novel application of network analyses , 2012 .

[45]  P. Marler,et al.  Species-universal microstructure in the learned song of the swamp sparrow (Melospiza georgiana) , 1984, Animal Behaviour.

[46]  Jean-Louis Deneubourg,et al.  Size-dependent behavior of tuna in an array of fish aggregating devices (FADs) , 2012 .

[47]  E. Cillaurren.  Daily fluctuations in the presence of Thunnus albacares and Katsuwonus pelamis around fish aggregating devices anchored in Vanuatu, Oceania , 1995 .

[48]  C. Nielsen,et al.  Effects of Joint Space Use and Group Membership on Contact Rates Among White-Tailed Deer , 2007 .

[49]  D. Krakauer,et al.  Policing stabilizes construction of social niches in primates , 2006, Nature.

[50]  J. Godin,et al.  Association patterns and shoal fidelity in the three–spined stickleback , 2002, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[51]  Jens Krause,et al.  Novel Acoustic Technology for Studying Free-Ranging Shark Social Behaviour by Recording Individuals' Interactions , 2010, PloS one.

[52]  Monika Böhm,et al.  Contact Networks in a Wildlife-Livestock Host Community: Identifying High-Risk Individuals in the Transmission of Bovine TB among Badgers and Cattle , 2009, PloS one.

[53]  Irene Giardina,et al.  Collective behavior in animal groups: Theoretical models and empirical studies , 2008, HFSP journal.

[54]  F. Marsac,et al.  Telemetry applied to behaviour analysis of yellowfin tuna (Thunnus albacares, Bonnaterre, 1788) movements in a network of fish aggregating devices , 1998, Hydrobiologia.

[55]  J. Castro,et al.  A general theory on fish aggregation to floating objects: An alternative to the meeting point hypothesis , 2002, Reviews in Fish Biology and Fisheries.

[56]  Pierre Fréon,et al.  Tropical tuna associated with floating objects: a simulation study of the meeting point hypothesis , 1999 .

[57]  Pierre Fréon,et al.  Review of fish associative behaviour: Toward a generalisation of the meeting point hypothesis , 2000, Reviews in Fish Biology and Fisheries.

[58]  L. Dagorn,et al.  First field-based experiment supporting the meeting point hypothesis for schooling in pelagic fish , 2009, Animal Behaviour.

[59]  L. Dagorn,et al.  Using local ecological knowledge (LEK) to provide insight on the tuna purse seine fleets of the Indian Ocean useful for management , 2007 .