Jeffrey C. Mangel

Interactions Between Leatherback Turtles and Peruvian Artisanal Fisheries

ABSTRACT From 1985 to 1999, data were gathered opportunistically on the bycatch of 33 leatherback turtles in coastal Peru, and from 2000 to 2003, a dockside observer program provided data on an additional 133 leatherbacks caught in the coastal gillnet and longline fisheries targeting mahi mahi, sharks, and rays. These data stress the need for programs to monitor bycatch in artisanal fisheries, enforce regulations prohibiting sea turtle capture, and increase the environmental awareness of fishermen.

Phylogeography of the copper shark (Carcharhinus brachyurus) in the southern hemisphere: implications for the conservation of a coastal apex predator

The copper or bronze whaler shark (Carcharhinus brachyurus) is a large, coastal top predator that is vulnerable to overexploitation. We test the null hypothesis that copper sharks are panmictic throughout the southern hemisphere. We analysed part of the mitochondrial control region (mtCR) in 120 individuals from eight sampling areas, defining 20 mtCR haplotypes (h = 0.76 ± 0.06, π = 0.016 ± 0.0007). Significant genetic structure was detected among the following three major coastal regions separated by oceanic habitat: Australia–New Zealand, South Africa–Namibia and Peru (AMOVA ΦST = 0.95, P < 0.000001). A major phylogeographic discontinuity exists across the Indian Ocean, indicating an absence of at least female-mediated gene flow for ~3 million years. We propose that this species originated in the Atlantic, experienced vicariant isolation of Pacific and Atlantic lineages by the rise of the Isthmus of Panama and, subsequently, dispersed across the Pacific to colonise Australasia. Oceanic expanses appear to be traversed over evolutionary but not ecological timescales, which means that regional copper-shark populations should be assessed and managed independently.

Fisheries Bycatch of Marine Turtles: Lessons Learned from Decades of Research and Conservation

Sea turtles spend the majority of their lives in coastal or pelagic waters, making in-water sources of mortality critical to population viability. Sea turtles have been negatively impacted by a number of human-mediated factors including oil spills (Antonio et al., 2011), contaminants (van de Merwe et al., 2010; Swarthout et al., 2010; Komoroske et al., 2011; Stewart et al., 2011), and other types of marine pollution, namely debris ingestion and entanglement (Lazar and Gracan, 2011; do Sul et al., 2011). Coastal and in-water shoreline development also have been shown to degrade ocean habitat, which can negatively affect resident turtles (Harewood and Horrocks, 2008; Pike, 2008). While all of these factors likely have some negative effect on sea turtle populations, the human activity that has the largest impact on sea turtles is fisheries bycatch (Lewison et al., 2004a; Wallace et al., 2011). Although directed take of turtles is one form of fisheries impact, and in some regions opportunistic take of captured turtles is still prevalent (Alfaro-Shigueto et al., 2011), turtles are generally an CONTENTS

Trading information for conservation: a novel use of radio broadcasting to reduce sea turtle bycatch

Bycatch of non-target animals in small-scale fisheries poses a major threat to seabirds and marine mammals and turtles. This is also a problem for small-scale fisheries in Peru because of the magnitude of these fisheries and the important marine biodiversity in Peruvian waters. Here we describe how we implemented a novel approach to mitigate bycatch impacts on marine turtles in Peru. We used high-frequency (HF) two-way radio communication to exchange information with fishers. We sought data that would afford insights into fishing patterns and levels of turtle bycatch so that we could identify areas of high-density bycatch in real time and warn other fishers. In return we provided oceanographic and atmospheric information useful for the fishers. Radio communication also served as a platform to promote the use of safe handling and release techniques for incidentally caught animals. During the 24 months of the programme we communicated with over 200 vessels and with 200–1,400 fishers, who used primarily longlines, gillnets, jiggers, purse seiners and trawlers. Our findings suggest that HF radio communication is a useful tool (low cost and widely used by fishers, with extensive spatial coverage), helps build links with fishers that potentially reduces fishery impacts on marine turtles, and can also provide information on poorly documented fisheries and the relevant bycatch data associated with small-scale fishing practices.

Big catch, little sharks: Insight into Peruvian small-scale longline fisheries

Shark take, driven by vast demand for meat and fins, is increasing. We set out to gain insights into the impact of small-scale longline fisheries in Peru. Onboard observers were used to document catch from 145 longline fishing trips (1668 fishing days) originating from Ilo, southern Peru. Fishing effort is divided into two seasons: targeting dolphinfish (Coryphaena hippurus; December to February) and sharks (March to November). A total of 16,610 sharks were observed caught, with 11,166 identified to species level. Of these, 70.6% were blue sharks (Prionace glauca), 28.4% short-fin mako sharks (Isurus oxyrinchus), and 1% were other species (including thresher (Alopias vulpinus), hammerhead (Sphyrna zygaena), porbeagle (Lamnus nasus), and other Carcharhinidae species (Carcharhinus brachyurus, Carcharhinus falciformis, Galeorhinus galeus). Mean ± SD catch per unit effort of 33.6 ± 10.9 sharks per 1000 hooks was calculated for the shark season and 1.9 ± 3.1 sharks per 1000 hooks were caught in the dolphinfish season. An average of 83.7% of sharks caught (74.7% blue sharks; 93.3% mako sharks) were deemed sexually immature and under the legal minimum landing size, which for species exhibiting k-selected life history traits can result in susceptibility to over exploitation. As these growing fisheries operate along the entire Peruvian coast and may catch millions of sharks per annum, we conclude that their continued expansion, along with ineffective legislative approaches resulting in removal of immature individuals, has the potential to threaten the sustainability of the fishery, its target species, and ecosystem. There is a need for additional monitoring and research to inform novel management strategies for sharks while maintaining fisher livelihoods.

Trophic ecology of the smooth hammerhead shark (Sphyrna Zygaena) off the coast of northern Peru

The smooth hammerhead (Sphyrna zygaena) is the third most captured shark species in Peru, a nation with one of the largest shark fisheries in the Pacific Ocean. We sought to better understand the trophic ecology of this shark in northern Peru by analyzing stomach contents. From 2013 through 2015, we collected 485 samples of gut contents from sharks measuring 53-294 cm in total length. Our results show that the smooth hammerhead is a top predator with a diet dominated by jumbo flying squid (Dosidicus gigas) and the Patagonian squid (Doryteuthis (Amerigo) gahi). Smooth hammerheads displayed different diets with different body size, and this finding indicates that sharks change their distribution and habitat during development. This study represents the most comprehensive investigation to date of the trophic ecology of smooth hammerhead in waters off Peru. We propose that these waters represent an important eastern Pacific Ocean feeding ground for smooth hammerhead. Because this species is commercially important and also preys upon other commercial species, these findings could contribute to the design and implementation of plans for ecosystembased fisheries management.

Hematologic, Morphometric, and Biochemical Analytes of Clinically Healthy Green Sea Turtles (Chelonia mydas) in Peru

Abstract Hematologic and biochemistry ranges were established for 31 clinically healthy green sea turtles (Chelonia mydas) incidentally captured in artisanal fisheries in Sechura Bay, Peru. Postcapture stress may have influenced heterophil values and glucose concentration. Sechura Bay provides abundant dietary protein affecting urea and glucose values.

Entanglements of Large Cetaceans in Peru: Few Records but High Risk

Abstract: Entanglements of large cetaceans with fishing gears were only recorded four times in Peru before 1995, despite the intensive use of gill nets and longlines. This work compiles recent events of large cetacean entanglement in Peru, from direct observations, local news, and online graphical evidence. A total of 15 confirmed entanglements was recorded between 1995 and 2012, involving humpback whales, Megaptera novaeangliae (n = 10); sperm whales, Physeter macrocephalus (n = 3); an Antarctic minke whale, Balaenoptera bonaerensis; and an unidentified balaenopterid. Gill nets were involved in 80% of the entanglements, followed by longlines. Prevalence of humpback whale entanglements may be associated with the neritic location of the majority of gill net fishing sets, interfering with the whales migratory routes and reproductive habitat in northern Peru. Intensive use of gill nets and increasing use of longlines in artisanal fisheries represent serious threats to conservation of large cetaceans in Peru and the Southeast Pacific and need to be addressed by national and regional conservation authorities.

Natal foraging philopatry in eastern Pacific hawksbill turtles

The complex processes involved with animal migration have long been a subject of biological interest, and broad-scale movement patterns of many marine turtle populations still remain unresolved. While it is widely accepted that once marine turtles reach sexual maturity they home to natal areas for nesting or reproduction, the role of philopatry to natal areas during other life stages has received less scrutiny, despite widespread evidence across the taxa. Here we report on genetic research that indicates that juvenile hawksbill turtles (Eretmochelys imbricata) in the eastern Pacific Ocean use foraging grounds in the region of their natal beaches, a pattern we term natal foraging philopatry. Our findings confirm that traditional views of natal homing solely for reproduction are incomplete and that many marine turtle species exhibit philopatry to natal areas to forage. Our results have important implications for life-history research and conservation of marine turtles and may extend to other wide-ranging marine vertebrates that demonstrate natal philopatry.

Illuminating gillnets to save seabirds and the potential for multi-taxa bycatch mitigation

Bycatch in net fisheries is recognized as a major source of mortality for many marine species, including seabirds. Few mitigation solutions, however, have been identified. We assessed the effectiveness of illuminating fishing nets with green light emitting diodes (LEDs) to reduce the incidental capture of seabirds. Experiments were conducted in the demersal, set gillnet fishery of Constante, Peru and compared 114 pairs of control and illuminated nets. We observed captures of a total of 45 guanay cormorants (Phalacrocorax bougainvillii), with 39 caught in control nets and six caught in illuminated nets. Seabird bycatch in terms of catch-per-unit-effort was significantly (p < 0.05) higher in control nets than in illuminated nets, representing an 85.1% decline in the cormorant bycatch rate. This study, showing that net illumination reduces seabird bycatch and previous studies showing reductions in sea turtle bycatch without reducing target catch, indicates that net illumination can be an effective multi-taxa bycatch mitigation technique. This finding has broad implications for bycatch mitigation in net fisheries given LED technologys relatively low cost, the global ubiquity of net fisheries and the current paucity of bycatch mitigation solutions.