An index of risk of co-occurrence between marine mammals and watercraft: Example of the Florida manatee

Bauduin, Sarah; Martin, Julien; Edwards, H. G. M.; Giménez, Olivier; Koslovsky, Stacie M.; Fagan, Daniel E.

doi:10.1016/j.biocon.2012.10.031

Cited by 29 publications

(34 citation statements)

References 28 publications

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“…; Vanderlaan & Taggart ; Van Der Hoop, Vanderlaan & Taggart ; Bauduin et al . ). Regulating speed or rerouting vessel traffic can have economic consequences, so it is important to quantify potential effects of watercraft on animal populations.…”

Section: Introductionmentioning

confidence: 97%

A quantitative framework for investigating risk of deadly collisions between marine wildlife and boats

et al. 2015

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Summary1. Speed regulations of watercraft in protected areas are designed to reduce lethal collisions with wildlife but can have economic consequences. We present a quantitative framework for investigating the risk of deadly collisions between boats and wildlife. 2. We apply encounter rate theory to demonstrate how marine mammal-boat encounter rate can be used to predict the expected number of deaths associated with management scenarios. We illustrate our approach with management scenarios for two endangered species: the Florida manatee Trichechus manatus latirostris and the North Atlantic right whale Eubalaena glacialis. We used a Monte Carlo simulation approach to demonstrate the uncertainty that is associated with our estimate of relative mortality. 3. We show that encounter rate increased with vessel speed but that the expected number of encounters varies depending on the boating activities considered. For instance, in a scenario involving manatees and boating activities such as water skiing, the expected number of encounters in a given area (in a fixed time interval) increased with vessel speed. In another scenario in which a vessel made a transit of fixed length, the expected number of encounters decreases slightly with boat speed. In both cases, the expected number of encounters increased with distanced travelled by the boat. For whales, we found a slight reduction (~0Á1%) in the number of encounters under a scenario where speed is unregulated; this reduction, however, is negligible, and overall expected relative mortality was~30% lower under the scenario with speed regulation. The probability of avoidance by the animal or vessel was set to 0 because of lack of data, but we explored the importance of this parameter on the model predictions. In fact, expected relative mortality under speed regulations decreases even further when the probability of avoidance is a decreasing function of vessel speed. 4. By applying encounter rate theory to the case of boat collisions with marine mammals, we gained new insights about encounter processes between wildlife and watercraft. Our work emphasizes the importance of considering uncertainty when estimating wildlife mortality. Finally, our findings are relevant to other systems and ecological processes involving the encounter between moving agents.

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Section: Introductionmentioning

confidence: 97%

A quantitative framework for investigating risk of deadly collisions between marine wildlife and boats

et al. 2015

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“…These 2 mortalities show that watercraft impact can occur even in large areas of water, such as Mobile Bay, with relatively few manatees compared with traditional habitats in Florida. If, as data suggest, more manatees are seasonally occupying areas of increased boating activity in the north-central Gulf of Mexico and elsewhere, then the risk of mortality due to vessel strike will continue to increase (Bauduin et al 2012). Additional understanding of the relationship between manatee occurrence and boating activity, along with other potential anthropogenic stressors, in understudied areas of the species' range will be important to guide future management and recovery efforts for this endangered species.…”

Section: Human Influence On Manatee Sightingsmentioning

confidence: 99%

“…Increased use of manatee-inhabited waters by commercial and recreational boaters also increases the likelihood of watercraft-related manatee mortalities, which have been the leading human-related cause of death for manatees in Florida since the mid1970s (Ackerman et al 1995, Bauduin et al 2012. Manatee carcasses have been reported in Alabama and Mississippi dating back to 1912, but only 2 recent deaths are known to be due to watercraft impact (2013 in Mississippi and 2015 in Alabama while this manuscript was in preparation).…”

Section: Human Influence On Manatee Sightingsmentioning

confidence: 99%

Sighting demographics of the West Indian manatee Trichechus manatus in the north-central Gulf of Mexico supported by citizen-sourced data

Hieb¹,

Carmichael²,

Aven³

et al. 2017

Endang. Species. Res.

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Traditional research methods are often limited in their ability to capture broad spatial and temporal changes in species distribution that affect global patterns of biodiversity. To provide range-wide demographic data needed to quantify and evaluate changes in habitat use and support ongoing recovery efforts for the endangered West Indian manatee Trichechus manatus, we analyzed data from a formal manatee sighting network that uses citizen-sourced data for the understudied north-central Gulf of Mexico region. Although historically considered to be outside manatees' typical US range, more than 1700 opportunistic, publicly reported manatee sightings and 23 mortalities have been documented in Alabama and Mississippi since the early 1900s. Live manatee sightings have occurred primarily during warmer months in rivers and subembayments. Manatee mortalities have significantly increased since the mid-1980s and have most often been attributed to cold stress, with 2 known mortalities due to vessel strikes in recent years. Sightings of individual manatees were most common, but group sizes of up to 17 were reported, typically in late summer. Decadal-scale trends in opportunistic sighting records demonstrate persistent spatial and temporal patterns of manatee occurrence in the north-central Gulf of Mexico and suggest greater use and importance of the region as seasonal manatee habitat than previously documented. If applied appropriately, citizen-sourced data have the potential to enhance targeted research efforts, significantly contribute to ecological datasets for a number of species, and provide a useful tool to enhance conservation and management.

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“…Many managed or protected species that are hard to detect occupy large areas, and the methodology that we present could be adapted for monitoring other systems (e.g., crocodilians in wetland systems, estuarine dolphins, sea turtles). Our study could also be used to improve risk assessment (e.g., to identify areas with the greatest risk of collision between marine mammals and watercraft (Bauduin et al, 2013)) by correcting counts using estimates of detection probability obtained from our study. This is a useful example of the benefits of modeling detection associated with observers and availability separately.…”

Section: Resultsmentioning

confidence: 98%

“…Abundance can be estimated without repeated passes by decomposing detection, which would reduce cost (Bauduin et al, 2013 , though the use of repeated passes could still improve precision (see Mackenzie and Royle (2005) for discussion of optimal trade-off between temporal replicates and the number of sampling units). In other words, the availability estimates from this study could be applied to data from other surveys (e.g., Bauduin et al, 2013) to correct for imperfect availability. This opens an interesting consideration about the opportunity for research teams to coordinate their sampling efforts and share information to increase efficiency of large-scale monitoring.…”

Section: Resultsmentioning

confidence: 99%

Combining information for monitoring at large spatial scales: First statewide abundance estimate of the Florida manatee

Martin

Edwards

Fonnesbeck

et al. 2015

Biological Conservation

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An index of risk of co-occurrence between marine mammals and watercraft: Example of the Florida manatee

Cited by 29 publications

References 28 publications

A quantitative framework for investigating risk of deadly collisions between marine wildlife and boats

A quantitative framework for investigating risk of deadly collisions between marine wildlife and boats

Sighting demographics of the West Indian manatee Trichechus manatus in the north-central Gulf of Mexico supported by citizen-sourced data

Combining information for monitoring at large spatial scales: First statewide abundance estimate of the Florida manatee

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