Abstract:Significance
Global vessel traffic is increasing alongside world economic growth. The potential for rising lethal ship strikes on endangered species of marine megafauna, such as the plankton-feeding whale shark, remains poorly understood since areas of highest overlap are seldom determined across an entire species range. Here we show how satellite tracking whale sharks and large vessel movements globally provides a means to localize high-overlap areas and to determine how collision risk changes in ti… Show more
“…Different species of marine megafauna were not evenly protected by marine parks, with whale sharks found more frequently within moderate exposure areas in marine parks. This occurrence of whale sharks in areas with high shipping densities was also observed in Womersley et al (2022), and could be due to a lack of avoidance mechanisms of these sharks, as in some whales (McKenna et al 2015), although avoidance behaviours have been observed in odontocetes (Martin et al 2022). Although being strongly dependent on vessel design, reduced shipping speeds have been successful at lowering The movement patterns of marine giants suggest that they are exposed to shipping at over a third of the locations where tags recorded positions.…”
Context. Shipping impacts are a major environmental concern that can affect the behaviour and health of marine mammals and fishes. The potential impacts of shipping within marine parks is rarely considered during the planning process. Aims. We assessed the areal disturbance footprint of shipping around Australia, its overlap with marine parks, and known locations of megafauna, so as to identify areas of concern that warrant further investigation. Methods. Automatic Identification System (AIS) shipping data from 2018 to 2021 were interpreted through a kerneldensity distribution and compared with satellite data from ~200 individuals of megafauna amalgamated from 2003 to 2018, and the locations of marine parks. Key results. Over 18% of marine parks had shipping exposure in excess of 365 vessels per year. Around all of Australia, 39% of satellite-tag reports from whale shark and 36.7% of pygmy blue and humpback whale satellite-tag reports were in moderate shipping-exposure areas (>90 ships per year). Shipping exposure significantly increased from 2018 despite the pandemic, including within marine parks. Conclusions. These results highlight the wide-scale footprint of commercial shipping on marine ecosystems that may be increasing in intensity over time. Implications. Consideration should be made for assessing and potentially limiting shipping impacts along migration routes and within marine parks.
“…Different species of marine megafauna were not evenly protected by marine parks, with whale sharks found more frequently within moderate exposure areas in marine parks. This occurrence of whale sharks in areas with high shipping densities was also observed in Womersley et al (2022), and could be due to a lack of avoidance mechanisms of these sharks, as in some whales (McKenna et al 2015), although avoidance behaviours have been observed in odontocetes (Martin et al 2022). Although being strongly dependent on vessel design, reduced shipping speeds have been successful at lowering The movement patterns of marine giants suggest that they are exposed to shipping at over a third of the locations where tags recorded positions.…”
Context. Shipping impacts are a major environmental concern that can affect the behaviour and health of marine mammals and fishes. The potential impacts of shipping within marine parks is rarely considered during the planning process. Aims. We assessed the areal disturbance footprint of shipping around Australia, its overlap with marine parks, and known locations of megafauna, so as to identify areas of concern that warrant further investigation. Methods. Automatic Identification System (AIS) shipping data from 2018 to 2021 were interpreted through a kerneldensity distribution and compared with satellite data from ~200 individuals of megafauna amalgamated from 2003 to 2018, and the locations of marine parks. Key results. Over 18% of marine parks had shipping exposure in excess of 365 vessels per year. Around all of Australia, 39% of satellite-tag reports from whale shark and 36.7% of pygmy blue and humpback whale satellite-tag reports were in moderate shipping-exposure areas (>90 ships per year). Shipping exposure significantly increased from 2018 despite the pandemic, including within marine parks. Conclusions. These results highlight the wide-scale footprint of commercial shipping on marine ecosystems that may be increasing in intensity over time. Implications. Consideration should be made for assessing and potentially limiting shipping impacts along migration routes and within marine parks.
“…A single population is easier to conserve, but the international movements exhibited by some individuals in this study mean that cooperation between Red Sea countries may be necessary for protection to be effective (Gajdzik et al, 2021). Additionally, recent evidence suggests that cargo ship strikes could be an under‐reported and significant contributor to whale shark mortality (Womersley et al, 2022). A high degree of surface occupation (Andrzejaczek et al, 2021) and the frequent movements of oceanic manta rays across one of the busiest shipping lanes in the world may also make this species vulnerable to similar threats (Braun, 2013).…”
1. Despite the large size and economic value of the species, populations of oceanic manta ray (Mobula birostris) are often poorly studied and almost completely undescribed in the Red Sea. Here, photo-identification (photo-ID) was used to provide the first description of M. birostris movement patterns and population demographics for the northern Red Sea. 2. Images collated from social media, researchers, and photo-ID databases from 2004 to 2021 identified 267 individual M. birostris from 395 sightings in Egypt, Israel, Jordan, Saudi Arabia, and Sudan. Sexual parity was observed in the population with 134 females, 111 males, and 22 individuals of undetermined sex. Nearly half of the individuals in this study were first identified through social media searches, highlighting the value of the sightings data collected by the public. 3. The regular presence of juveniles in Sharm el-Sheikh, Egypt, indicates that this area is a potential nursery, which is the second identified for this species globally and the first in the Indo-Pacific. Encounter data from this study recorded the first known movements of juvenile M. birostris and demonstrate that they can travel long distances of at least 525 km. 4. Within the recorded population, 24.7% (n = 67) of individuals were resighted, including 21 oceanic manta rays that were encountered in more than one location. These records reveal long-distance migrations of up to 700 km and confirm the international connectivity of M. birostris in the Red Sea. The lagged identification rate data are best fitted with an open-population model, implying that the northern Red Sea is represented by one well-mixed population. 5. The baseline data presented here should encourage the expansion of directed research and citizen science initiatives for M. birostris. Increased knowledge of movement patterns and site use will be crucial to successfully protecting this
“…Higher speed swimming (derived by using trigonometry on body pitch and vertical velocity) was also highlighted on occasion in individual whale sharks by short-term substantial PPA min values both for descents (e.g., Figure 5 B) and ascents although the reasons for them doing this are unclear. We speculate that the animals were either reacting to vessels or other perceived threats and inspection of where these events occurred may prove useful for conservation reasons ( Womersley et al., 2022 ). Figure 4 PPA min at different depths A dive by a whale shark between periods swimming at the surface, showing depth (blue line) and vertical velocity (yellow line) and the proxy for power above the minimum (PPA min ) (black line).…”
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
