Guy Harvey

Supplemental Feeding for Ecotourism Reverses Diel Activity and Alters Movement Patterns and Spatial Distribution of the Southern Stingray, Dasyatis americana

Southern stingrays, Dasyatis americana, have been provided supplemental food in ecotourism operations at Stingray City Sandbar (SCS), Grand Cayman since 1986, with this site becoming one of the world’s most famous and heavily visited marine wildlife interaction venues. Given expansion of marine wildlife interactive tourism worldwide, there are questions about the effects of such activities on the focal species and their ecosystems. We used a combination of acoustic telemetry and tag-recapture efforts to test the hypothesis that human-sourced supplemental feeding has altered stingray activity patterns and habitat use at SCS relative to wild animals at control sites. Secondarily, we also qualitatively estimated the population size of stingrays supporting this major ecotourism venue. Tag-recapture data indicated that a population of at least 164 stingrays, over 80% female, utilized the small area at SCS for prolonged periods of time. Examination of comparative movements of mature female stingrays at SCS and control sites revealed strong differences between the two groups: The fed animals demonstrated a notable inversion of diel activity, being constantly active during the day with little movement at night compared to the nocturnally active wild stingrays; The fed stingrays utilized significantly (p<0.05) smaller 24 hour activity spaces compared to wild conspecifics, staying in close proximity to the ecotourism site; Fed stingrays showed a high degree of overlap in their core activity spaces compared to wild stingrays which were largely solitary in the spaces utilized (72% vs. 3% overlap respectively). Supplemental feeding has strikingly altered movement behavior and spatial distribution of the stingrays, and generated an atypically high density of animals at SCS which could have downstream fitness costs for individuals and potentially broader ecosystem effects. These findings should help environmental managers plan mitigating measures for existing operations, and develop precautionary policies regarding proposed feeding sites.

Repeated, long-distance migrations by a philopatric predator targeting highly contrasting ecosystems

Long-distance movements of animals are an important driver of population spatial dynamics and determine the extent of overlap with area-focused human activities, such as fishing. Despite global concerns of declining shark populations, a major limitation in assessments of population trends or spatial management options is the lack of information on their long-term migratory behaviour. For a large marine predator, the tiger shark Galeocerdo cuvier, we show from individuals satellite-tracked for multiple years (up to 1101 days) that adult males undertake annually repeated, round-trip migrations of over 7,500 km in the northwest Atlantic. Notably, these migrations occurred between the highly disparate ecosystems of Caribbean coral reef regions in winter and high latitude oceanic areas in summer, with strong, repeated philopatry to specific overwintering insular habitat. Partial migration also occurred, with smaller, immature individuals displaying reduced migration propensity. Foraging may be a putative motivation for these oceanic migrations, with summer behaviour showing higher path tortuosity at the oceanic range extremes. The predictable migratory patterns and use of highly divergent ecosystems shown by male tiger sharks appear broadly similar to migrations seen in birds, reptiles and mammals, and highlight opportunities for dynamic spatial management and conservation measures of highly mobile sharks.

Satellite Telemetry Reveals Higher Fishing Mortality Rates Than Previously Estimated, Suggesting Overfishing of an Apex Marine Predator

Overfishing is a primary cause of population declines for many shark species of conservation concern. However, means of obtaining information on fishery interactions and mortality, necessary for the development of successful conservation strategies, are often fisheries-dependent and of questionable quality for many species of commercially exploited pelagic sharks. We used satellite telemetry as a fisheries-independent tool to document fisheries interactions, and quantify fishing mortality of the highly migratory shortfin mako shark (Isurus oxyrinchus) in the western North Atlantic Ocean. Forty satellite-tagged shortfin mako sharks tracked over 3 years entered the Exclusive Economic Zones of 19 countries and were harvested in fisheries of five countries, with 30% of tagged sharks harvested. Our tagging-derived estimates of instantaneous fishing mortality rates (F = 0.19–0.56) were 10-fold higher than previous estimates from fisheries-dependent data (approx. 0.015–0.024), suggesting data used in stock assessments may considerably underestimate fishing mortality. Additionally, our estimates of F were greater than those associated with maximum sustainable yield, suggesting a state of overfishing. This information has direct application to evaluations of stock status and for effective management of populations, and thus satellite tagging studies have potential to provide more accurate estimates of fishing mortality and survival than traditional fisheries-dependent methodology.

Ontogenetic Partial Migration Is Associated with Environmental Drivers and Influences Fisheries Interactions in a Marine Predator

James S. E. Lea*, Bradley M. Wetherbee, Lara L. Sousa, Choy Aming, Neil Burnie, Nicolas E. Humphries, Nuno Queiroz, Guy M. Harvey, David W. Sims, and Mahmood S. Shivji* The Guy Harvey Research Institute, Nova Southeastern University Oceanographic Centre, 8000 North Ocean Drive, Dania Beach, FL 33004, USA The Laboratory, Marine Biological Association of the United Kingdom, Citadel Hill, Plymouth PL1 2PB, UK Marine Research Facility, PO Box 10646, Jeddah 21443, Saudi Arabia School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth, Devon, PL4 8AA, UK Department of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA Centro de Investigaç~ao em Biodiversidade e Recursos Genéticos, CIBIO – Universidade do Porto, Campus Agrário de Vair~ao, Rua Padre Armando Quintas, Vair~ao 4485-668, Portugal Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK Bermuda Shark Project, Bermuda Aquarium, Museum and Zoo, 40 North Shore Road, Bermuda Centre for Biological Sciences, Building 85, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK *Corresponding authors: tel: þ18 005 416 682; fax: þ1 954-262-4098; e-mail: james@eatonlea.co.uk and mahmood@nova.edu These authors contributed equally to this work.

Horizontal and Vertical Movements of White Marlin, Kajikia albida, Tagged Off the Yucatan Peninsula

Original Article Horizontal and vertical movements of white marlin, Kajikia albida, tagged off the Yucatán Peninsula J. J. Vaudo*, M. E. Byrne, B. M. Wetherbee, G. M. Harvey, A. Mendillo Jr , and M. S. Shivji The Guy Harvey Research Institute, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL 33004, USA Department of Biological Sciences, University of Rhode Island, 120 Flagg Road, Kingston, RI 02881, USA Keen M International, Av Rueda Medina 318, Centro Supmza. 001, Isla Mujeres, Quintana Roo 77400, Mexico *Corresponding author: tel: þ1 (954) 262 3677; fax: þ1 (954) 262 4098; e-mail: jvaudo@nova.edu Current address: School of Natural Resources, University of Missouri, Columbia, MO, USA.