Consequences of drift and carcass decomposition for estimating sea turtle mortality hotspots

Santos, Bianca Silva; Kaplan, David M.; Friedrichs, Marjorie A. M.; Barco, Susan G.; Mansfield, Katherine; Manning, James P.

doi:10.1016/j.ecolind.2017.08.064

Cited by 34 publications

(27 citation statements)

References 24 publications

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“…These events, whose causes can be related to biotoxins, bacteria, parasites, human interactions and oceanographic conditions, are also spatially unpredictable phenomena, in which marine mammals strand in a delimited space and during a limited time (Wilkinson 1991). Stranding data can reveal supplementary information on the spatial distribution of fatalities and their post-mortem movements: from the position of the stranding it is possible, in fact, to estimate the original location where the animal died by reconstructing the animal's drift by modelling local sea currents and tides (Peltier et al 2012;Santos et al 2018).…”

Section: Carrion Exchange At the Terrestrial-aquatic Interfacementioning

confidence: 99%

Carrion Availability in Space and Time

Moleón

Selva

Quaggiotto

et al. 2019

Wildlife Research Monographs

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Section: Carrion Exchange At the Terrestrial-aquatic Interfacementioning

confidence: 99%

Carrion Availability in Space and Time

Moleón

Selva

Quaggiotto

et al. 2019

Wildlife Research Monographs

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“…If visible signs of disease are reliable diagnostics, this approach can be employed without knowledge of the disease etiology or the entire life history of the host. Moreover, this approach demonstrates the increasing utility of using coupled hydrodynamic-biogeochemical models (e.g., also see Santos et al, 2018) to produce environmental forcing information for fisheries modeling studies. Data collection for these analyses can be annexed onto studies where mark-recapture techniques are already being employed.…”

Section: Discussionmentioning

confidence: 98%

Dermal mycobacteriosis and warming sea surface temperatures are associated with elevated mortality of striped bass in Chesapeake Bay

Groner

Hoenig

Pradel

et al. 2018

Ecology and Evolution

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Temperature is hypothesized to alter disease dynamics, particularly when species are living at or near their thermal limits. When disease occurs in marine systems, this can go undetected, particularly if the disease is chronic and progresses slowly. As a result, population‐level impacts of diseases can be grossly underestimated. Complex migratory patterns, stochasticity in recruitment, and data and knowledge gaps can hinder collection and analysis of data on marine diseases. New tools enabling quantification of disease impacts in marine environments include coupled biogeochemical hydrodynamic models (to hindcast key environmental data), and multievent, multistate mark–recapture (MMSMR) (to quantify the effects of environmental conditions on disease processes and assess population‐level impacts). We used MMSMR to quantify disease processes and population impacts in an estuarine population of striped bass (Morone saxatilis) in Chesapeake Bay from 2005 to 2013. Our results supported the hypothesis that mycobacteriosis is chronic, progressive, and, frequently, lethal. Yearly disease incidence in fish age three and above was 89%, suggesting that this disease impacts nearly every adult striped bass. Mortality of diseased fish was high, particularly in severe cases, where it approached 80% in typical years. Severely diseased fish also had a 10‐fold higher catchability than healthy fish, which could bias estimates of disease prevalence. For both healthy and diseased fish, mortality increased with the modeled average summer sea surface temperature (SST) at the mouth of the Rappahannock River; in warmer summers (average SST ≥ 29°C), a cohort is predicted to experience >90% mortality in 1 year. Regression of disease signs in mildly and moderately diseased fish was <2%. These results suggest that these fish are living at their maximum thermal tolerance and that this is driving increased disease and mortality. Management of this fishery should account for the effects of temperature and disease on impacted populations.

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“…4) but there is little information on the decay rate of turtles in this region. Research in other areas of the tropics suggest that turtles may decay rapidly in only 5 to 18 d (Santos et al 2018). With a decay rate of 5 d, if we assume that on average nets drift for 1 yr and turtles are evenly distributed across the region where ghost nets drift, then the portion of turtles entangled that could be detected would be 0.0137 yr −1 .…”

Section: Impact On Sea Turtlesmentioning

confidence: 98%

Untangling the origin of ghost gear within the Maldivian archipelago and its impact on olive ridley (Lepidochelys olivacea) populations

Stelfox¹,

Bulling²,

Sweet³

2019

Endang. Species. Res.

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There is little documentation available on the impact of abandoned, lost or discarded fishing nets ('ghost nets') on turtle populations. Here, we utilise data collected over a 5 year period to assess (1) if a particular net type or characteristic was identifiable as entangling more turtles and (2) if particular fishing practices (i.e. types of nets) could be managed to reduce turtle entanglement in the Maldivian archipelago. A total of 131 turtles were entangled in the 752 reported ghost nets, and olive ridley turtles Lepidochelys olivacea appeared to be the most vulnerable (making up 97% of entangled turtles). However, we estimate that the 752 nets in this study, reported over a 51 month period, could have entangled between 3400 and 12 200 turtles across the Indian Ocean prior to being detected in the Maldives. Mesh size, seasonality (i.e. north east monsoon), and the presence of floats were all identified as variables significantly affecting the likelihood of turtle entanglement. The probability of entanglement increased as the mesh size increased but decreased when floats were present. Additionally, turtles were more likely to be entangled during the north east monsoon when currents flow from east to west. Cluster analysis indicated that there were at least 11 broadly assigned net types found floating in the study area, and these were dominated by trawl and gill nets. Our analyses highlight the need for a detailed database of existing gear types coupled with gear marking to improve traceability of ghost nets in the Indian Ocean.

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Consequences of drift and carcass decomposition for estimating sea turtle mortality hotspots

Abstract: Main text word count (from Introduction to end of Discussion): 7832 Figures: 8 Tables: 7 conditions. Knowledge of these parameters will improve our ability to interpret stranding events around the globe.

Cited by 34 publications

References 24 publications

Carrion Availability in Space and Time

Carrion Availability in Space and Time

Dermal mycobacteriosis and warming sea surface temperatures are associated with elevated mortality of striped bass in Chesapeake Bay

Untangling the origin of ghost gear within the Maldivian archipelago and its impact on olive ridley (Lepidochelys olivacea) populations

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