Illegal recreational fishing causes a decline in a fishery targeted species (Snapper: Chrysophrys auratus) within a remote no-take marine protected area

RESEARCH ARTICLE Illegal recreational fishing causes a decline in a fishery targeted species (Snapper: Chrysophrys auratus) within a remote no-take marine protected area David Harasti ID*, Tom R. Davis, Alan Jordan, Luke Erskine, Natalie Moltschaniwskyj Port Stephens Fisheries Institute, NSW Department of Primary Industries, Nelson Bay, NSW, Australia * a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Harasti D, Davis TR, Jordan A, Erskine L, Moltschaniwskyj N (2019) Illegal recreational fishing causes a decline in a fishery targeted species (Snapper: Chrysophrys auratus) within a remote no-take marine protected area. PLoS ONE 14(1): e0209926. https://doi.org/10.1371/journal. pone.0209926 Editor: Craig A. Radford, University of Auckland, NEW ZEALAND Received: September 3, 2018 Accepted: December 13, 2018 Published: January 8, 2019 Copyright: © 2019 Harasti et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract One role of Marine Protected Areas is to protect biodiversity; however, illegal fishing activity can reduce the effectiveness of protection. Quantifying illegal fishing effort within no-take MPAs is difficult and the impacts of illegal fishing on biodiversity are poorly understood. To provide an assessment of illegal fishing activity, a surveillance camera was deployed at the Seal Rocks no-take area within the Port Stephens-Great Lakes Marine Park from April 2017-March 2018. To assess impacts of illegal fishing activity in the no-take area, Baited Remote Underwater Video Systems (BRUVs) were used to quantify abundance and size of snapper Chrysophrys auratus from 2011–2017. BRUVs were also deployed at two nearby fished locations and two other no-take areas to allow comparison. Over 12 months of camera surveillance, a total of 108 recreational vessels were observed illegally fishing within the no-take area (avg 9.0 ± 0.9 per month). The greatest number of vessels detected in a single month was 14 and the longest a vessel was observed fishing was ~ 6 hours. From 2011– 2017, the abundance of C. auratus within the Seal Rocks no-take area significantly declined by 55%, whilst the abundance within the other fished areas and no-take areas did not significantly decline over the same period. Lengths of C. auratus in the Seal Rocks no-take area were significantly smaller in 2017 compared to 2013 which was driven by a decline in the number of legal sized fish over 30 cm. Based on mean number of illegal fishers per vessel recorded in the no-take area, and an allowable bag limit of 10 C. auratus per person, it is possible that more than 2,000 C. auratus are removed annually from this no-take area. There is a strong likelihood that illegal recreational fishing is causing a reduction on a fishery targeted species within a no-take MPA and measures need to be implemented to reduce the ongoing illegal fishing pressure. Data Availability Statement: All BRUVs data is available within the online Global Archive database (http://globalarchive.org/) under ’Port StephensGreat Lakes Marine Park’. Funding: The author(s) received no specific funding for this work. Introduction Competing interests: The authors have declared that no competing interests exist. Marine Protected Areas (MPAs) provide conservation benefits to many of the species and habitats within their boundaries [1, 2]. However, not all MPAs meet their conservation objectives PLOS ONE | https://doi.org/10.1371/journal.pone.0209926 January 8, 2019 1 / 20 Illegal recreational fishing causes a decline in a fishery targeted species in a MPA [3] as the response of species to protection within MPAs is influenced by a range of factors, including age and size of the MPA [4, 5], degree of isolation [6], extent and types of habitats [7, 8], and enforcement of regulations about activities that are illegal within the boundaries [9, 10]. No-take areas are of particular significance in MPAs as they generally provide the highest level of protection due to the removal of fishing pressure, and are often identified as providing valuable reference areas to evaluate changes in biodiversity when harvest is removed [11]. However, their value is affected by adherence of the rules by fishers and by formal enforcement of regulations. Unfortunately, voluntary adherence to the rules by fishers of MPA rules combined with minimal formal enforcement often results in illegal activities, such as fishing, contributing to reduced effectiveness in meeting their conservation objectives [12]. Fishing within no-take areas is a problem world-wide, with numerous studies demonstrating various levels of illegal fishing often occurs within these areas [13, 14]. Declines in species abundance, particularly that of target species, and diversity occurs in no-take areas with declines attributed to illegal fishing activities [12, 15]. The direct impacts of illegal fishing on fishery species in no-take areas are seldom quantifiable, however, poaching was shown to cause a decrease in species such as abalone [16], limpets [15], and target fish species [13, 17], although the magnitude of change is strongly influenced by the life history characteristics of the exploited species [18]. MPAs that are considered to have good enforcement are known to have a greater positive influence on target fish abundance, particularly within no-take areas compared to fished areas [19], whilst areas with weak enforcement are less likely to achieve their conservation objectives [6,9]. While many factors that contribute to the success of an MPA have been well documented [10, 20]; very little effort has been directed to quantifying the potential impacts of levels of illegal fishing within MPAs, which can both reduce the effectiveness of an MPA in achieving the key objectives of conservation [21], and use as scientific reference sites. Non-compliant fishing activity in no-take areas is generally difficult to assess and quantify as vessels generally actively try to avoid detection. Assessment methods for quantifying illegal fishing include aerial surveys [17, 22], estimates of discarded fishing gear [23, 24], and fisher interviews [25, 26]. More recently, with advancements in camera technology, remotely deployed cameras are being used to quantify fishing activity around features such as artificial reefs [27, 28], and to assess illegal fishing activity and effort [29–31]. The aim of this study was to evaluate whether illegal fishing activity within a no-take area can significantly reduce the relative abundance and size of pink snapper (Chrysophrys auratus), the most important recreational fishery targeted species in the Port Stephens-Great Lakes Marine Park (PSGLMP); a large multi-use marine park in temperate waters on the east coast of Australia. Chrysophrys auratu (...truncated)