In press. Reducing green sea turtle bycatch in small-scale fisheries using illuminated gillnets: the cost of saving a sea turtle. Marine Ecology Progress Series.

A B S T R A C TSmall-scale fisheries can greatly impact threatened marine fauna. Peru's small-scale elasmobranch gillnet fishery captures thousands of sharks and rays each year, and incidentally captures sea turtles, marine mammals and seabirds. We assessed the ability of a dedicated fisheries remote electronic monitoring (REM) camera to identify and quantify captures in this fishery by comparing its performance to on-board observer reports. Cameras were installed across five boats with a total of 228 fishing sets monitored. Of these, 169 sets also had on-board fisheries observers present. The cameras were shown to be an effective tool for identifying catch, with > 90% detection rates for 9 of 12 species of elasmobranchs caught. Detection rates of incidental catch were more variable (sea turtle = 50%; cetacean = 80%; pinniped = 100%). The ability to quantify target catch from camera imagery degraded for fish quantities exceeding 15 individuals. Cameras were more effective at quantifying rays than sharks for small catch quantities (x ≤ 15 fish), whereas size affected camera performance for large catches (x > 15 fish). Our study showed REM to be effective in detecting and quantifying elasmobranch target catch and pinniped bycatch in Peru's small-scale fishery, but not, without modification, in detecting and quantifying sea turtle and cetacean bycatch. We showed REM can provide a time-and cost-effective method to monitor target catch in small-scale fisheries and can be used to overcome some deficiencies in observer reports. With modifications to the camera specifications, we expect performance to improve for all target catch and bycatch species.

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 technology's relatively low cost, the global ubiquity of net fisheries and the current paucity of bycatch mitigation solutions.

ABSTRACT. Diet and food preferences of the green turtle Chelonia mydas were analyzed based on digestive tract contents of dead specimens caught incidentally by an artisanal gillnet fishery in Sechura Bay, northern Peru. We examined 27 digestive tracts and identified 35 prey items. The sampled turtles were all juveniles (CCL = 53.7 ± 1.2 cm, range 40.5-67.0 cm). The prey items were grouped into six categories: algae, cnidarians, mollusks, arthropods, chordates and garbage/anthropogenic debris. The items with the highest Frequency of Occurrence values (% FO) were: Caulerpa filiformis (77.8%), Loligo gahi (eggs) (51.9%) and Rhodymenia corallina (44.4%). By weight (% W), the most important items, were L. gahi (eggs) (33.3%), Stomolophus sp. (7.3%) and Aphos porosus (6.5%). According to the Preponderance Index (%IP), the preponderant item was L. gahi (eggs) with 6.1% and 61.2% during winter-spring and summer-autumn, respectively. According to the Resultant Weight index (Rw) of wet items, the most important items were: C. filiformis (13.1%), L. gahi (eggs) (10.5%), R. corallina (7.4%), plastic (7.5%), Gigartina chamissoi (5.1%). Garbage/anthropogenic debris was common in the digestive tracts analyzed. Plastic items had a frequency of occurrence of 44.4%. A greater diversity of food items was observed during summer and autumn. This study shows that juvenile C. mydas forage on a variety of resources. We recommend that conservation plans, land use planning and future management plans in the Sechura Bay include green turtles as a sentinel species for monitoring biodiversity of marine resources and the degree of pollution in the Bay.

www.nature.com/scientificreports enhanced, coordinated conservation efforts required to avoid extinction of critically endangered Eastern Pacific leatherback turtles the Laúd opo network † Failure to improve the conservation status of endangered species is often related to inadequate allocation of conservation resources to highest priority issues. Eastern Pacific (EP) leatherbacks are perhaps the most endangered sea turtle population in the world, and continue on a path to regional extinction. To provide coherent, regional conservation targets, we developed a population viability analysis and examined hypothetical scenarios describing effects of conservation activities that either reduced mortality or increased production of hatchlings (or both). Under status quo conditions, EP leatherbacks will be extirpated in <60 yr. To ensure a positive, long-term population trajectory, conservation efforts must increase adult survivorship (i.e., reduce adult mortality) by ≥20%, largely through reduction of fisheries bycatch mortality. Positive trajectories can be accelerated by increased production of hatchlings through enhanced nest protection and treatment. We estimate that these efforts must save approximately 200-260 adult and subadult leatherbacks and produce approximately 7,000-8,000 more hatchlings annually. Critically, reductions in late-stage mortality must begin within 5 years and reach 20% overall within the next 10-15 years to ensure population stabilization and eventual increase. These outcomes require expanded, sustained, coordinated, high-priority efforts among several entities working at multiple scales. Fortunately, such efforts are underway.Species declines driven by human causes have been well-documented across taxonomic groups in recent decades 1 . In some cases, persistent, effective conservation efforts -often coupled with enforced legal protections -have stabilized and even begun to recover populations 2 . Among long-lived marine species such as marine mammals, turtles, birds, and elasmobranchs, there is wide variation in long-term population trends and whether conservation efforts have successfully achieved recovery goals 3-5 . For populations to recover, threats must be reduced to levels that first stabilize, then increase population abundance; however, failure to recover depleted populations often is related to insufficient (i.e., too little for too short a time period) or inefficient allocation of limited resources to conservation actions of highest potential benefit to the target population 6 .Marine turtles exemplify these issues, given their global distributions and varied conservation status among regional population segments (i.e., regional management units, RMUs; Ref. 7 ). Many RMUs within and among the seven extant marine turtle species are depleted relative to historical abundance because of human-caused mortality, namely direct harvest of turtles and their eggs and incidental capture in fisheries 8 . However, some marine turtle populations are showing signs of recovery following conservati...