Baseline, post‐angling and maximum attainable blood lactate concentrations were measured for the fishery species redthroat emperor Lethrinus miniatus to gain insight into the condition of fish released following c . 30 s angling and <45 s air exposure. Mean ± s.d . baseline blood lactate was 1·5 ± 0·6 mmol l −1 , which increased and plateaued around 6 mmol l −1 at 15–30 min post‐angling. These values were significantly lower than those obtained from fish maximally exhausted with a prolonged chase and air exposure protocol following capture (10·9 ± 1·8 mmol l −1 ), suggesting that L. miniatus is not maximally exhausted during standard angling practices.
It is a golden age for animal movement studies and so an opportune time to assess priorities for future work. We assembled 40 experts to identify key questions in this field, focussing on marine megafauna, which include a broad range of birds, mammals, reptiles, and fish. Research on these taxa has both underpinned many of the recent technical developments and led to fundamental discoveries in the field. We show that the questions have broad applicability to other taxa, including terrestrial animals, flying insects, and swimming invertebrates, and, as such, this exercise provides a useful roadmap for targeted deployments and data syntheses that should advance the field of movement ecology.
Tissue responses to the application of Rototags and Jumbo Rototags in the first dorsal fin of Carcharhinus melanopterus, C. obscurus and C. plumbeus were examined. The acute response included tissue tearing and haemorrhage and was present by 5 days post-tagging. The intermediate response had begun by 20 days post-tagging and continued beyond 207 days. This response involved decreased red blood cell activity as the inflammatory response commenced. The chronic response had begun by 301 days and was complete by 553 days with a layer of fibrous connective tissue walling off the tag. External damage to the fin was caused by continued abrasion by the tag. Repair scales were observed at 242 days using scanning electron microscopy and were confirmed histologically in 61- and 553-day samples. Repair scales were not seen in areas of continuous abrasion. No infection was observed in tissues surrounding the wound. Disruption of the fin surface was observed due to abrasion by the tag, but did not appear to cause a severe tissue reaction. The tissue responses observed were consistent with a normal, but relatively slow, healing in the vicinity of the tag wound. Use of Rototags or Jumbo Rototags appears to be an efficient way of marking elasmobranchs with minimal damage to the shark.
Understanding the extent of movements and space use of animals is necessary to identify vital habitats and better conserve and manage vulnerable species. We used acoustic telemetry to examine movement patterns and habitat use of juvenile mangrove whiprays (Himantura granulata) in an intertidal bay at Orpheus Island, Australia. Thirteen juveniles were acoustically monitored between March and December 2012, and in July 2012, four active tracks were completed. The majority of the acoustically monitored rays remained within the intertidal bay for the entire monitoring period. Tidal changes caused rays to move from the inner-bay mangrove (high tide) habitat to coral reef in the outer bay (low tide). Actively tracked rays moved in a directed way during running tides, remaining in shallow water. During periods of high and low tide, when rays refuged in mangrove or reef habitats, movement was limited and sinuosity was high. In mangrove areas, rays were most commonly observed refuging under or close to mangrove roots, and rarely in open sand areas. Refuging behaviour in mangrove and reef habitats suggested that predation risk may be the predominant factor influencing the movement of small rays. The continuous use of intertidal habitats demonstrates their importance to Himantura granulata.
Seventy‐two epaulette sharks, Hemiscyllium ocellatum (Bonnaterre), were infected with the nematode parasite Proleptus australis Bayliss, 1933. The parasite population was overdispersed. Infection intensity ranged from 3 to 1002 worms per fish stomach, and there was a positive correlation between shark length and number of parasites present. The majority of worms were attached to the stomach wall, and scanning electron microscopy and histological examination showed that worms penetrated the stomach lining. Worms were observed within the lamina propria of the stomach and occasionally penetrated the muscularis mucosa. Little to no inflammatory or cellular immune reaction to the presence of the parasites was observed, except in one case where a worm was being degraded by a host tissue response. There was a large amount of connective tissue proliferation as a result of nematode attachment, but no obvious effects on the overall health of the sharks were seen. Three sharks were also found to be infected by the cestode Callitetrarhynchus sp.
An array of acoustic receivers deployed in Cleveland Bay, north Queensland, Australia, passively tracked 20 adult spottail sharks Carcharhinus sorrah over 2 years (2009–2010) to define patterns in movement and habitat use. Individuals were present in the study site for long periods, ranging from 8 to 408 days (mean = 185). Size and location of home ranges did not vary over time. A high level of segregation occurred among C . sorrah , with individuals using different types of habitat and showing strong attachment to specific regions. The depth of habitat individuals used varied between sexes. Males tended to use a narrow range of habitat depths within the study site (2·8–6·0 m), whereas females used shallower habitats (1·4–6·2 m) and displayed a seasonal shift in the depth of habitat used. Mean monthly habitat depth used varied by as much as 2 m for females, with individuals using shallower habitats during the winter months. Long‐term presence and consistent home ranges suggest that Cleveland Bay provides important habitat for C . sorrah . By defining patterns in the use of nearshore habitats for C . sorrah , this study improves the understanding of the movement and habitat use of smaller‐bodied coastal sharks and may help provide guidance for the management of their populations.
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