| Coastal fishing is an important component of China's capture fisheries.At the end of 2018,China had about 154,400 domestic marine fishing vessels,which contributed two-thirds of China's fishing output,but it produced non-negligible abandoned,lost or otherwise discarded fishing gear(ALDFG).The problems of the ALDFGs have attracted increasing attention from many countries and international organizations around the world.ALDFG is the main cause of ghost fishing,which not only impacts fishery resources and other marine animals(such as seabirds,turtles,whales and seals),but also reduces fishery economic benefits.In addition,floating ALDFG can hinder navigation and can lead to conflicts with other fishing gears in operation,resulting in the loss of additional gear.The introduction of synthetic fibers in fisheries is an important technological advance,but its persistence use in the marine environment and its plastic component have become the main source of marine pollutionAs China pays more and more attention to the protection of marine environment,national researchers have conducted in-depth research on marine garbage and debris in China,but there is no ALDFG related research.Taking into account the fact that foreign research on ALDFG has gradually formed a system,this study refers to the ALDFG survey and research methods commonly used abroad in recent years,and designs the content and forms of the questionnaire surveys adapted to China.Through a questionnaire survey,we investigated the loss of coastal fishing gear from the main fishing operation methods in waters near ChinaBased on the actual survey data,we used ArcMap 10.3 mapping software to analyze and display areas with high loss rate of fishing gear in waters near China,and used generalized addictive model(GAM)to analyze the main causes of the loss of fishing gear in waters near China.GAM is applied to analyze the factors affecting the loss rate of trawl and gillnet in waters near China.The main findings are as follows(1)In China,trawlers and gillnetters have a relatively high net loss rates,and trap fishing vessels have a relatively low net loss rate.Bohai Sea,Yellow Sea,East China Sea and South China Sea,all are high net loss fishing areas,and the high net loss fishing zones are mainly distributed close to the mainland or islands and reefs.There are conflict fishing areas in Bohai Sea,Yellow Sea,East China Sea and South China Sea.In addition to the fishing areas where two types of fishing gears conflict,there are also three types of fishing gears in which fishing gears conflict.The sea areas with high loss rate of fishing gear are mainly distributed in the Yellow Sea and the East China Sea at 30°-32 ° N,123 ° 30'-124 0 E;30°-33 0 N,123°-123 0 30'E;31°-32 0 N,124°-124 °30'E;31 0 30'-32°N,122 ° 30'-123 ° E and 32°-32 0 30'N,122°-122 ° 30'E The high loss rates areas of trawls are mainly distributed in the areas of 21°-21°30'N,111°30'-123°E(Net loss rate between 100 and 150 g/kg)and 20°30'-22°N,110°-114°E(Net loss rate more than 200 g/kg).The area with high net loss rate of gillnetters are mainly distributed in the areas of 26°30'-31°N,121°-124°30'E(Net loss rate between 50 and 100 g/kg)and 9°30'-10°30'N,114°-115°30'E(Net loss rate more than 200 g/kg).The area with high net loss rate of stow netter are mainly distributed in the areas of 31°-32°30'N,122°-122°30'E;31°-32°30'N,124°-124°30'E and 31°-32°N,125°-125°30'E(Net loss rate between 15 and 20 g/kg)and 33°-33°30'N,121°30'-122°30'E and 33°30'-34°N,121°30'-122°30'E(Net loss rate more than 20 g/kg)(2)There are many factors that affect the loss of gear net of fishing vessels for trawlers,gillnetters,stow netters,trappers and purse seiners.Among them,the main factors that affect the net loss of trawlers are as follows:submarine obstacles(58.44%)and operational conflicts(19.48%),etc.The main causes that affect the net loss of gillnetters are as follows:submarine obstacles(31.78%),fishing conflict(29.91%),taking the catch from the net panel(14.02%)and improper operation(13.08%),etc.The main causes that affect the net loss of trappers are as follows:the passing of cargo ship(25%),submarine torrent(20.83%),turbulence(20.83%),fishing conflicts(16.67%)and submarine obstacles(12.50%),etc(3)The factors(explanation deviation)that effect on the netting loss rate(RT)of trawlers in waters near China are mainly:fishing depth(58.3%),average days per voyage(11.4%),single trawl net panel weight(10.5%),vessel length(7.2%),annual fishing gear purchased weight(7.1%),tonnage(2.5%),and number of crew(1.6%)(4)The factors(explanation deviation)that effect on the netting affecting the net loss rate(Rg)of gillnetters in waters near China are mainly:average days per voyage(86.8%),annual fishing days(4.2%),average carrying net panel weight per voyage(2.8%),fishing depth(2.4%),tonnage(0.9%)and annual fishing gear purchased number(0.1%)In order to reduce the loss rate of marine fishing gears in waters near China,the recommendations are as follows(1)Further refine and improve China's relevant laws and regulations and abandoned fishing gear recycling facilities in the port,macro controlling the number and density of fishing vessels in fishing areas;carry out pilot projects for removing marine debris and abandoned fishing gear at sea;establish and improve marine fishing gear reporting system,and strengthen multilateral cooperation with neighboring countries to remove abandoned fishing gears in co-managed waters,etc;strengthen the propagation and education of fishermen,as well as increase fishermen's awareness on environmental protection(2)Real-time update of the position of submarine obstacles on electronic charts,hire fishing vessels to periodically remove submarine obstacles during the summer fishing moratorium;encourage fishermen to bring ALDFG found at sea back to the port for treatment,and grant certain subsidies(3)Using the degradable materials to make gillnet netting and using the AIS position indicator to mark the position of passive fishing gears such as gillnets,and carry out relevant research to determine the optimal water depth,soak time and length of gillnet. |
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