Rebuttal to published article “A review of ghost gear entanglement amongst marine mammals, reptiles and elasmobranchs” by M. Stelfox, J. Hudgins, and M. Sweet

Asmutis-Silvia, Regina; Barco, Susan G.; Cole, Timothy V. N.; Henry, Allison; Johnson, A.R.; Knowlton, Amy R.; Landry, Scott; Mattila, David K.; Moore, Michael J.; Robbins, Jooke; Hoop, Julie van der

doi:10.1016/j.marpolbul.2016.11.052

Cited by 16 publications

(6 citation statements)

References 11 publications

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“…Poorly managed tourism development could also be impacting these species, especially at ecologically important aggregation sites (Rohner et al 2013;Venables et al 2016;Stevens and Froman 2018), although the impact tourism is having on these species behaviours and population dynamics is still unknown. Entanglement and boat strikes have also been identified as important sources of mortality to many threatened marine species (Mazzuca et al 1998;Adimey et al 2014;Asmutis-Silvia et al 2017) and are being increasingly reported on mobulids Stewart et al 2018;Stevens and Froman 2018). Both manta ray species are listed as 'Vulnerable' on the IUCN Red List of threatened species (Marshall et al 2011a(Marshall et al , 2011b, on Appendix II of the Convention on International Trade in Endangered Species (www.cites.org), and on Appendices I and II of the Convention on Migratory Species of Wild Animals (www.cms.int).…”

Section: Introductionmentioning

confidence: 99%

Preliminary insights into the population characteristics and distribution of reef (Mobula alfredi) and oceanic (M. birostris) manta rays in French Polynesia

et al. 2019

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In French Polynesia, both currently recognized manta ray species, Mobula alfredi and M. birostris, are observed. Despite being an important cultural asset and generating significant economic benefits through manta ray watching tourism, published data on the ecology and threats to these species in the region are scarce. Based on an 18-year dataset of sighting records collected by citizen scientists and during two scientific expeditions, this study provides the first insights into the population characteristics and regional distribution of the two manta ray species in French Polynesia. A total of 1347 manta ray photographs (1337 for M. alfredi and 10 for M. birostris) were examined for the period January 2001-December 2017, with photo-identification techniques leading to the successful identification of 317 individual M. alfredi and 10 individual M. birostris throughout the Society, Tuamotu and Marquesas Islands. We provide the first confirmation of sympatric distribution of both species in the Society Islands. Our results highlight strong and long-term site fidelity of M. alfredi individuals to certain aggregation sites (> 9 years for 16 individuals) and reveal some degree of connectivity between populations, with 10 individuals recorded moving between islands located up to 50 km apart. Analysis of photographs of individuals bearing sub-lethal injuries (n = 68) suggests that M. alfredi are more likely to be injured at inhabited islands (Maupiti or Bora Bora; 75% of all injured individuals) than at uninhabited islands, with 75% of injuries related to boat propeller strikes and fishing gear entanglements. Our findings emphasize the need for further research to allow for a comprehensive evaluation of population structure, size and threats to manta rays in this region.

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Section: Introductionmentioning

confidence: 99%

Preliminary insights into the population characteristics and distribution of reef (Mobula alfredi) and oceanic (M. birostris) manta rays in French Polynesia

et al. 2019

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“…For cases where gear could be identified to target species, most leatherback turtles were entangled in actively fished (as opposed to lost or abandoned traps), commercial lobster gear, specifically the buoy lines of single traps, with a negligible number of cases associated with purported marine debris. Almost half of the 'debris' cases had current-year trap tags, highlighting the difficulty of distinguishing active fixed-gear fisheries from marine debris (Asmutis-Silvia et al 2017). A wide variety of buoy and line styles/colors were observed, and although we do not know the proportion of styles/colors available, the diversity in our data suggests that these characteristics had no obvious effect on the risk of entanglement.…”

Section: Discussionmentioning

confidence: 67%

Disentanglement network data to characterize leatherback sea turtle Dermochelys coriacea bycatch in fixed-gear fisheries

Dodge¹,

Landry²,

Lynch³

et al. 2022

Endang. Species. Res.

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To characterize sea turtle bycatch in fixed-gear fisheries in Massachusetts, USA, we analyzed a 15 yr dataset of entanglement reports and detailed documentation from disentanglement operations. Almost all (272) of the 280 confirmed entanglements involved leatherback turtles Dermochelys coriacea. The majority of turtles were entangled in actively fished (96%), commercial (94%) pot/trap gear with unbroken/untriggered weak links, specifically the buoy lines marking lobster, whelk, and fish traps. Most reports came from recreational boaters (62%) and other sources (26%), rather than commercial fishers (12%). Leatherback entanglements occurred from May to November, with peak reporting in August, and included adult males, adult females, and subadults. All entanglements involved the turtle’s neck and/or front flippers, with varying degrees of visible injuries; 47 entangled leatherbacks were dead in gear, 224 were alive at first sighting, and 1 case was unknown. Post-release monitoring suggested turtles can survive for days to years after disentanglement, but data were limited. While the observed entanglements in our study are low relative to global bycatch, these numbers should be considered a minimum. Our findings are comparable to observed numbers of leatherbacks taken in Canadian fixed-gear fisheries, and represent just one of multiple, cumulative threats in the North Atlantic. Managers should focus on strategies to reduce the co-occurrence of sea turtles and fixed-fishing gear, including reductions in the number of buoy lines allowed (e.g. replace single sets with trawls), seasonal and area closures targeted to reduce sea turtle-gear interaction, and encourage the development of emerging technologies such as ‘ropeless’ fishing.

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“…(2019), but see Asmutis‐Silvia et al . (2017) and Stelfox (2017)). On the west coast of the United States, there are approximately 400,000 Dungeness crab traps fished each year and the annual loss rate is estimated to be up to 10% (Pacific Fishery Management Council, 2013).…”

Section: Discussionmentioning

confidence: 99%

“…While the present analyses were mainly focused on contemporaneous overlap between fishing activity and entanglement sightings, there may also be lagged impacts of fisheries on whales due to derelict gear. Derelict fishing gear poses a chronic threat to marine organisms, including cetaceans, that persists even after active fishing has ceased and may be increasing in magnitude over time (Arthur et al (2014); Stelfox et al (2016); Richardson et al (2019), but see Asmutis-Silvia et al (2017) and Stelfox (2017)). On the west coast of the United States, there are approximately 400,000 Dungeness crab traps fished each year and the annual loss rate is estimated to be up to 10% (Pacific Fishery Management Council, 2013).…”

Section: Discussionmentioning

confidence: 99%

Footprints of fixed‐gear fisheries in relation to rising whale entanglements on the U.S. West Coast

Feist

Samhouri

Forney

et al. 2021

Fisheries Management Eco

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On the U.S. West Coast, reports of whales entangled in fishing gear increased dramatically in 2014. In this study, a time series of fishing activity maps was developed from 2009 to 2016 for the four fixed‐gear fisheries most commonly implicated in entanglements. Maps were generated using vessel monitoring system (VMS) data linked to port‐level landings databases, which were related to entangled whale reports over the same time period and with modelled distributions of humpback whales Megaptera novaeangliae Borowski. Over the full study period, neither marked increases in fishing activity nor changes in fisheries footprints within regions with high whale densities were detected. By contrast, a delayed fishery opening in California due to a harmful algal bloom in spring of 2016 led to ~5–7 times average levels of Dungeness crab Metacarcinus magister (Dana) fishing activity, which was consistent with a high rate of entanglement in that year. These results are consistent with current hypotheses that habitat compression caused by a marine heatwave increased the overlap of whales with fishing activity, despite minimal changes in the fisheries themselves. This study adds to literature on bycatch of protected species in otherwise sustainable fisheries, highlighting the value of using VMS data for reducing human–wildlife conflict in the ocean.

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Rebuttal to published article “A review of ghost gear entanglement amongst marine mammals, reptiles and elasmobranchs” by M. Stelfox, J. Hudgins, and M. Sweet

Cited by 16 publications

References 11 publications

Preliminary insights into the population characteristics and distribution of reef (Mobula alfredi) and oceanic (M. birostris) manta rays in French Polynesia

Preliminary insights into the population characteristics and distribution of reef (Mobula alfredi) and oceanic (M. birostris) manta rays in French Polynesia

Disentanglement network data to characterize leatherback sea turtle Dermochelys coriacea bycatch in fixed-gear fisheries

Footprints of fixed‐gear fisheries in relation to rising whale entanglements on the U.S. West Coast

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