Ecological risk assessment of elasmobranchs caught in the Gulf of Papua prawn fishery

Abstract

1. One-third of all elasmobranch species currently known to occur in Papua New Guinea are taken as bycatch in the Gulf of Papua trawl fishery. An ecological risk assessment was conducted on the 16 species of sharks and 23 species of rays caught by the fishery.2. Eight species were classified to be at low risk, 28 species were at medium risk while three species -Rhynchobatus palpebratus (eyebrow wedgefish), Carcharhinus coatesi (Australian blackspot shark) and Maculabatis astra (blackspotted whipray), all endemic to New Guinea and northern Australiafaced the highest level of risk from the fishery at current fishing levels.3. There is potential for more vessels to enter the fishery in future, which is likely to elevate the risk for a greater proportion of elasmobranch species.Ongoing monitoring of bycatch levels, supported by biological and ecological studies on frequently caught species, is required to assess and manage risk in the future.4. The development and use of trawl excluder devices or bycatch reduction devices in this fishery have the potential to reduce bycatch levels and reduce risk levels.

Dietary overlap of carcharhinid sharks in the Gulf of Papua

“…Defining the ecological niche of a species is a multivariate exercise requiring empirical evidence from multiple sources (Munroe et al 2014), therefore, future research should complement dietary information with fishery independent surveys, tag-recapture and acoustic tracking to investigate the ecology of species across time and space (Wiley and Simpfendorfer 2007;Donaldson et al 2014) if possible. The Gulf of Papua is a hot spot for species diversity (Pernetta and Hill 1981) including a large proportion of elasmobranchs that are encountered in the GoPPF, some of which are endemic (White et al 2017;Baje et al 2021). Ecological data and information from this region are therefore important to support ecosystem approaches to fisheries management and conservation of vulnerable species.…”

Reimagining conservation practice: Indigenous self-determination and collaboration in Papua New Guinea

“…Large indicator species such as sharks and rays and large fish such as groupers are at particular risk as fishermen preferentially select larger fishes (Drew et al, 2015). Larger-scale fisheries to the south of Papua New Guinea also threaten sharks and rays as bycatch of non-specific prawn fishing gear (Baje et al, 2021). Furthermore, studies show that changes in terrestrial habitats have serious impacts on the health of marine habitats (Huber, 1994).…”

Estimating intrinsic susceptibility to extinction when little ecological information is available: The case of Neotropical freshwater stingrays (Chondrichthyes: Potamotrygoninae)

“…Most standard ERA methods applied to chondrichthyans are designed to assess the effect of fisheries (Gallagher et al, 2012; but see Chin et al, 2010; Walker et al, 2021). The most common form of ERA applied to chondrichthyans is a semiquantitative assessment called Productivity‐Susceptibility Analysis (PSA) (e.g., Baje et al, 2021; Lin et al, 2020; Micheli et al, 2014). Such PSAs rely on many life history traits, such as age at maturity, fecundity, and reproductive cycle, as well as on measurements of exposure to fisheries, to produce a ranking of species according to their risk of being affected by such fisheries (Dulvy et al, 2004; Gallagher et al, 2012).…”