Local knowledge surveys with small‐scale fishers indicate challenges to sawfish conservation in southern Papua New Guinea

Abstract

Sawfish (Pristidae) are considered to be among the most threatened families of elasmobranch (sharks and rays). There is a need to gather information on the status of poorly known sawfish populations to assist in global recovery initiatives. This study used interviews with local fishers to investigate the presence of sawfish in southern Papua New Guinea (PNG) and their interactions with and uses and values for small‐scale fishers. A range of sawfish size classes are still encountered throughout southern PNG, while juvenile largetooth sawfish Pristis pristis were additionally reported in the freshwater reaches of all rivers surveyed. Reports of large size classes in estuarine and marine environments provide an optimistic outlook that sawfish populations persist throughout southern PNG. Most fishers that catch sawfish retain them for various uses including consumption and for the sale of meat, fins and occasionally rostra. Negative population trends including decreases in catch frequency and/or size classes were reported by 66% of interviewees, with the largest declines being reported in the Kikori River. The increasing technical capacity of small‐scale fishers, their preference for gillnetting and the emerging market for teleost swim bladder (a high‐value fishery product) present a major ongoing threat to sawfish in southern PNG. Furthermore, the tendency of fishers to kill or remove rostra from entangled sawfish results in high fishing mortality regardless of any use by the fisher. This study indicates that considerable community engagement will be necessary to manifest any legislative actions or increased enforcement on international trade regulations for sawfish in PNG. This is due to traditional land and waterway ownership values throughout PNG and the local perception of sawfish as a traditional food resource rather than an animal of intrinsic biodiversity value as perceived by global conservationists. Future research should consider exploring culturally appropriate conservation initiatives that are likely to achieve engagement and participation from local fishers.

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

“…Historically, sawfishes have been observed widely throughout PNG (White et al, 2017a) and these recent observations indicate the contemporary presence of all species. Surveys conducted on local knowledge of sawfishes in PNG's north (Leeney et al, 2018) and south (Grant et al, 2021) coasts further substantiate their contemporary presence in small-scale fisheries, although both studies reported declining catch frequency by local fishers. This indicates that conservation initiatives may be required in PNG to prevent similar trends of regional extinction as seen in other Indo-Pacific nations (Dulvy et al, 2016).…”

“…Surveys coincided with the onset of the dry season when most fishing activity occurs (∼September to March), due to safer fishing conditions afforded by calmer whether. Fishers in regions surveyed primarily use gillnets of varied mesh sizes to target croakers (Sciaenidae), barramundi (Lates calcarifer), and elasmobranchs (see Leeney et al, 2018;Grant et al, 2021). With consent from village leaders, local fishermen were invited to present any elasmobranch catch, sawfish rostra, or shark fin.…”

“…Declines in sawfish catch have recently been reported in the northern (Leeney et al, 2018) and southern (Grant et al, 2021) regions surveyed. Present enumerator data suggest a small number of interactions with A. cuspidata (excluding northern PNG), P. clavata, and P. pristis, and rostra from recently caught animals (e.g., <1 month) were not commonly encountered in surveys.…”

“…Collectively, river sharks and sawfishes accounted for over half of observations (50.2%) in the southern region. However, it should be noted that sawfish rostra were more likely to be observed as they have a bias for being kept longer than shark fin or meat, as they are mostly used for decoration rather than sale when retained (Grant et al, 2021). Likewise, shark fin is sold in batches, and species that are finned were more likely to be observed than those retained only for meat (e.g., small sharks and rays that are quickly consumed or sold whole).…”

“…There are presently no protection measures in place for river shark or sawfish species in PNG. This raises concern as small-scale fisheries are prominent throughout PNG's coastal and riverine environments (Leeney et al, 2018;Grant et al, 2021), and the level of threat they pose is presently not well understood for most regions where river sharks and sawfishes likely occur (White et al, 2015(White et al, , 2017a.…”