Fishers' knowledge as an information source to investigate bycatch of marine mammals in the South China Sea

Abstract

Bycatch mortality is a significant driver of marine mammal population declines. However, there is little information available on patterns or magnitude of bycatch mortality in many heavily fished Asian marine systems such as the South China Sea (SCS). To address this limited knowledge base, we conducted interviews with fishers to gather local ecological knowledge on marine mammal bycatch around Hainan Island, China. Gillnets were the primary fishing gear used in local fisheries, and were also responsible for the majority of reported marine mammal bycatch events in recent decades. Bycatch events were reported from all seasons but were most frequent in spring (38.4%), which might relate to seasonal variation in fishing activities. The spatial pattern of relative bycatch densities for Indo-Pacific humpback dolphins, Indo-Pacific finless porpoises and unidentified small dolphins varied around Hainan and neighbouring waters. A substantial proportion of informants (36.1 and 9.2% respectively) reported that they have eaten or sold marine mammal meat, demonstrating the continued existence of cultural practices of consuming marine mammals on Hainan. Responses of fishers to bycatch events were dependent both on their existing attitudes and perceptions towards marine mammals and on other sociocultural factors. Almost half of informants agreed that marine mammal populations in the SCS have decreased. Declines were thought by informants to have been caused by overfishing, water pollution and vessel collisions, with bycatch responsible for further declines in dolphins.

Fishers' experiences and perceptions of marine mammals in the South China Sea: Insights for improving community‐based conservation

“…This is the first study to examine patterns and determinants of local fishers’ experiences and perceptions of marine mammals in the SCS, a globally important region for marine mammal diversity and conservation. The intensive marine fisheries in the SCS support a large number of professional fishers who engage primarily in coastal or artisanal fishery activities (Liu et al, ), and the great majority of whom (92.7%) have seen or encountered marine mammals during their fishing career (Figure a). This study reveals that a substantial proportion of respondents from fishing communities around Hainan reported negative interactions with marine mammals, such as bycatch, and eating and selling meat (Figures a, b and b–d), and the respondents’ perceptions of marine mammals were also fairly negative (Figure e, f).…”

“…Only one member of each fishing family/boat was interviewed to ensure data independence. Further details of survey methods are given in Liu et al (). The research was approved by the Institute of Deep‐Sea Science and Engineering, Chinese Academy of Sciences.…”

“…If they matched these selection criteria, they were then asked a standard series of 42 questions (both multiple choice and open ended) on: (i) socio‐economic and livelihood characteristics; (ii) fishery interactions with marine mammals; (iii) local fishery characteristics; and (iv) experiences and perceptions of marine mammals (for details, see Appendix S1). They were also shown photographs of 36 marine mammal species (35 cetacean species and dugong Dugong dugon ; Jefferson et al, ; Wang, ) that are known to occur in the SCS to confirm species identification (for details, see Table S1 and Liu et al, ). Basic socio‐economic and non‐sensitive questions were asked first to build rapport and increase the likelihood of honest answers.…”

“…Official data show that there are 340 fishing communities situated along the coast of Hainan, with 155 228 registered marine fishers and 1.28 million tons of marine fishing harvest reported in 2017 (China Fishery Statistics Yearbook, ). Local fishers generally made a professional living by harvesting aquatic resources in marine environments that are also used by marine mammals (Liu, Lin, Turvey, & Li, ); however, so far there has been minimal research conducted into interactions between marine fisheries and marine mammals in the SCS. Furthermore, little is known regarding the attitudes and awareness of local communities about marine mammal conservation in this region.…”

Determining spatial use of the world's second largest humpback dolphin population: Implications for place‐based conservation and management

“…This near-shore preference makes them vulnerable to a variety of anthropogenic threats along the coast, including habitat loss/degradation, fisheries by-catch, vessel-collisions/injuries, chemical, and underwater noise pollution (e.g. Karczmarski et al, 2016;Li et al, 2015;Li, Liu, Dong, Dong, & Wang, 2018;Liu, Lin, Turvey, & Li, 2017;Wang, Wu, Zhu, & Huang, 2017). Establishing MPAs (nature reserves or marine parks) could be an effective conservation measure to protect humpback dolphins (Chen et al, 2009;Jefferson & Smith, 2016).…”