Artisanal shark fishing in Milne Bay Province, Papua New Guinea: biomass estimation from genetically identified shark and ray fins

Abstract

Our study is the first detailed examination of species composition using DNA COI barcoding of elasmobranchs from an artisanal fishery of Papua New Guinea. The study is the first in the region to provide biomass estimates based on species confirmation following examination of dried fins. Over 20 species of elasmobranchs were identified from 623 fins from the artisanal fishery in Milne Bay Province of PNG, with Carcharhinus amblyrhynchos and Carcharhinus melanopterus the most abundant species in the catches. Of concern, 21% of fins examined were from IUCN listed threatened species (Vulnerable or Endangered) with 8% of fins from the Endangered scalloped hammerhead (Sphyrna lewini). Following species identifications and use of species-specific length and weight extrapolations, we estimated over 9 t of elasmobranchs contributed to the fin batch. Importantly, the vast majority of the elasmobranchs in this batch were from immature animals. Genetic identification has an important role to play in the ongoing sustainable management of elasmobranchs in artisanal fisheries in PNG and more widely. However in the absence of ongoing genetic testing, recording the species (if known) at the time of catch is more achievable and would provide more robust data for fisheries managers in PNG over the longer term.

Development of a DNA mini-barcoding protocol targeting COI for the identification of elasmobranch species in shark cartilage pills

“…Hellberg, et al, 2019;Ward, Holmes, White, & Last, 2008). While the full-length DNA barcode can effectively differentiate many of these species (e.g., see Appleyard et al 2018;Wong et al 2009), the shorter amplicon generated with mini-barcoding showed reduced differentiation capability when relying on a distance-based approach. In some of these cases, the use of character-based identification keys developed in previous studies (Fields, et al, 2015;Velez-Zuazo, et al, 2015;Wong, et al, 2009) enabled differentiation (Table 4).…”

“…DNA-based techniques, such as DNA barcoding and species-specific polymerase chain reaction (PCR), are commonly used to identify elasmobranch species when morphological indicators are lacking (Appleyard, White, Vieira, & Sabub, 2018;Dudgeon, et al, 2012;Hanner, Naaum, & Shivji, 2016;Rodrigues-Filho, Pinhal, Sondre, & Vallinoto, 2012). While species-specific PCR is preferable for targeted approaches, DNA barcoding is more appropriate for applications involving a wide range of species, such as shark cartilage supplements.…”

Using fisher‐contributed secondary fins to fill critical shark‐fisheries data gaps

“…However, as in Belize, it is common for these fisheries to be highly skewed to a small number of Volume 35, No. 3, 2021 common species (e.g., Appleyard et al 2018), which in some cases could facilitate visual identification of most of the anal fins. The DNA testing could then be reserved for rarer types and ambiguities among common species.…”

Can multi‐species shark longline fisheries be managed sustainably using size limits? Theoretically, yes. Realistically, no

“…Fishing practices may also need to be adapted as in the PNG longline fishery sharks are often electrocuted prior to landing to protect crew (Kumoru, 2003). Overlap with other fisheries must also be considered, as, using the PNG fishery as a further example, some of these species are also caught in trawl, gill net, purse seine and artisanal fisheries (Appleyard, White, Vieira, & Sabub, 2018; Nicol et al., 2009; Teh et al., 2014). The practices or selectivities of these other fisheries could undermine the harvest strategies outlined here.…”