Elasmobranch bycatch in the demersal prawn trawl fishery in the Gulf of Papua, Papua New Guinea

White, William T.; Baje, Leontine; Simpfendorfer, Colin A.; Appleyard, Sharon A.; Chin, Andrew; Sabub, B.; Rochel, Elisabeth; Naylor, Gavin J. P.

doi:10.1038/s41598-019-45715-w

Cited by 22 publications

(22 citation statements)

References 30 publications

(30 reference statements)

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“…The population is low, approximately 107,000, and relies on subsistence utilization of a range of mangrove resources: mangrove wood for poles for house construction, fuel and tools; edible mangrove fruits and palm hearts; medicinal uses and dyes (Liebezeit and Rau, 2006); thatching and basket weaving using Nypa fruticans fronds. Offshore there is one of the most commercially important fisheries in Papua New Guinea -the demersal prawn trawl fishery that gains an income of (US$3M per year through a local fishing fleet) (Kompas and Kuk, 2008;White et al, 2019).…”

Section: Coastal Wetlands Of Oceaniamentioning

confidence: 99%

Anthropogenic, Direct Pressures on Coastal Wetlands

et al. 2020

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Coastal wetlands, such as saltmarshes and mangroves that fringe transitional waters, deliver important ecosystem services that support human development. Coastal wetlands are complex social-ecological systems that occur at all latitudes, from polar regions to the tropics. This overview covers wetlands in five continents. The wetlands are of varying size, catchment size, human population and stages of economic development. Economic sectors and activities in and around the coastal wetlands and their catchments exert multiple, direct pressures. These pressures affect the state of the wetland environment, ecology and valuable ecosystem services. All the coastal wetlands were found to be affected in some ways, irrespective of the conservation status. The main economic sectors were agriculture, animal rearing including aquaculture, fisheries, tourism, urbanization, shipping, industrial development and mining. Specific human activities include land reclamation, damming, draining and water extraction, construction of ponds for aquaculture and salt extraction, construction of ports and marinas, dredging, discharge of effluents from urban and industrial areas and logging, in the case of mangroves, subsistence hunting and oil and gas extraction. The main pressures were loss of wetland habitat, changes in connectivity affecting hydrology and sedimentology, as well as contamination and pollution. These pressures lead to changes in environmental state, such as erosion, subsidence and hypoxia that threaten the sustainability of the wetlands. There are also changes in the state of the ecology, such as loss of saltmarsh plants and seagrasses, and mangrove trees, in tropical wetlands. Changes in the structure and function of the wetland ecosystems affect ecosystem

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Section: Coastal Wetlands Of Oceaniamentioning

confidence: 99%

Anthropogenic, Direct Pressures on Coastal Wetlands

et al. 2020

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“…Thirty-eight elasmobranch species (22 sharks, 16 rays) were observed in PNG's small-scale fisheries. This represents 29.2% of known PNG elasmobranch diversity (130 species; White et al, 2017b) which is a similar level to the commercial Gulf of Papua prawn trawl (31% of elasmobranch diversity; White et al, 2019) and higher than the former shark long-line fishery (13.8% of elasmobranch diversity; White et al, 2020). The highest species diversity was observed in PNG's southwest (South Fly Coast and Mia Kussa River), encompassing 81.6% of species observed in this study.…”

Section: Species Diversitymentioning

confidence: 82%

“…A brief survey in PNG's Western Province during 2014 resulted in the scientific rediscovery of both G. garricki and G. glyphis outside of Australia (White et al, 2015). All four Indo-Pacific sawfish species were also observed in this survey (White et al, 2017a), while A. cuspidata and P. pristis were also later observed in the Gulf of Papua Prawn Trawl Fishery (White et al, 2019). Historically, sawfishes have been observed widely throughout PNG (White et al, 2017a) and these recent observations indicate the contemporary presence of all species.…”

Section: Introductionmentioning

confidence: 84%

Papua New Guinea: A Potential Refuge for Threatened Indo–Pacific River Sharks and Sawfishes

Grant

White

Amepou³

et al. 2021

Front. Conserv. Sci.

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The conservation of threatened elasmobranchs in tropical regions is challenging due to high local reliance on aquatic and marine resources. Due primarily to fishing pressure, river sharks (Glyphis) and sawfishes (Pristidae) have experienced large population declines in the Indo-Pacific. Papua New Guinea (PNG) may offer a refuge for these species, as human population density is low, and river shark and sawfish populations are thought to persist. However, few data are available on these species in PNG, and risk posed by small-scale fishers is poorly understood. This study observed elasmobranch catches in small-scale fisheries in riverine and coastal environments in the East Sepik (northern region), Gulf, and Western Provinces (southern region) of PNG. Surveys were conducted over a period of weeks to months in each region, during the dry season across seven field trips from 2017 to 2020. We observed a total of 783 elasmobranchs encompassing 38 species from 10 families. River sharks made up 29.4% of observations in the southern region, while sawfishes made up 14.8 and 20.3% in the northern and southern regions, respectively. River sharks were commonly caught by small-scale fishers in lower riverine environments in southern PNG, while sawfishes were generally less common and mainly observed through dried rostra. The primary threat to river shark and sawfish populations is their capture by small-scale fishers targeting teleosts for swim bladder. Persisting populations of river sharks and sawfishes indicate that PNG is the second known nation with viable populations of multiple species in the Indo-Pacific. However, populations are declining or at high risk of decline, and fisheries management and conservation are required to realize the potential of PNG as a long-term refuge.

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“…Susceptibility studies on the various shark and ray species in Papua New Guinea deemed P . jenkinsii at the highest risk in trawl fisheries [ 73 ]. This was one of the most dominant species landed in the Andaman and Nicobar Islands.…”

Section: Discussionmentioning

confidence: 99%

Catch composition and life history characteristics of sharks and rays (Elasmobranchii) landed in the Andaman and Nicobar Islands, India

et al. 2020

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Detailed information on shark and ray fisheries in the Andaman and Nicobar Islands, India are limited, including information on the diversity and biological characteristics of these species. We carried out fish landing surveys in South Andamans from January 2017 to May 2018, a comprehensive and cost-effective way to fill this data gap. We sampled 5,742 individuals representing 57 shark and ray species landed from six types of fishing gears. Of the 36 species of sharks and 21 species of rays landed, six species of sharks ( Loxodon macrorhinus , Carcharhinus amblyrhynchos , Sphyrna lewini , C . albimarginatus , C . brevipinna , and Paragaleus randalli) comprised 83.35% of shark landings, while three species of rays ( Pateobatis jenkinsii , Himantura leoparda and H . tutul ) comprised 48.82% of ray landings, suggesting a species dominance in the catch or fishing region. We provide insights into the biology of species with extensions in maximum size for seven shark species. Additionally, we document an increase in the known ray diversity for the islands and for India with three previously unreported ray species. We found that amongst sharks, mature individuals of small-bodied species (63.48% males of total landings of species less than 1.5 m total length when mature) and immature individuals of larger species (84.79% males of total landings of species larger than 1.5 m total length when mature) were mostly landed; whereas for rays, mature individuals were predominantly landed (80.71% males of total landings) likely reflecting differences in habitat preferences along life-history stages across species and fishing gear. The largest size range in sharks was recorded in landings from pelagic longlines and gillnets. Further, the study emphasizes the overlap between critical habitats and fishing grounds, where immature sharks and gravid females were landed in large quantities which might be unsustainable in the long-term. Landings were female-biased in C . amblyrhynchos , S . lewini and P . jenkinsii , and male-biased in L . macrorhinus and H . leoparda , indicating either spatio-temporal or gear-specific sexual segregation in these species. Understanding seasonal and biological variability in the shark and ray landings over a longer study period across different fisheries will inform future conservation and fishery management measures for these species in the Andaman and Nicobar Islands.

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Elasmobranch bycatch in the demersal prawn trawl fishery in the Gulf of Papua, Papua New Guinea

Cited by 22 publications

References 30 publications

Anthropogenic, Direct Pressures on Coastal Wetlands

Anthropogenic, Direct Pressures on Coastal Wetlands

Papua New Guinea: A Potential Refuge for Threatened Indo–Pacific River Sharks and Sawfishes

Catch composition and life history characteristics of sharks and rays (Elasmobranchii) landed in the Andaman and Nicobar Islands, India

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