Efficiency Comparison between Conventional and Vented Trap in Ghost Fishing Experiment, Si Racha Bay, Gulf of Thailand

raps are an effective and economically important multi-species fishing gear used widely for harvesting crustaceans and finfish around the world. The collapsible trap targeting blue swimming crab (Portunus pelagicus) has recently becomes a major type of fishing gear and operated over year in the Gulf of Thailand. Small scale fishers operate their traps inshore with the numbers of 200-300 traps/boat while commercial scale fishers operate further (offshore) with the numbers of 2,000-5,000 traps onboard. Both fishing types have possibilities become lost or derelict as a result of several processes. Lost traps are widely thought to result in mortality because of “ghost fishing” a term used to describe the process by which derelict fishing gear continues to trap organisms and induce mortality in an uncontrolled manner (Matsuoka et al. 2005). The phenomenon of ghost fishing is a concern to fisheries managers and the fishing community interested in long term sustainability of the trap fishery. The ghost fishing effects on the blue swimming crab and other animals from the trap fishing in Thailand have been very poor evaluated and reported. Accordingly, the objectives of this study were to examine the ghost fishing characteristics of the conventional trap used by small scale fishers compared to the vented trap. Specifically, the rates of entrance and mortality of the target species and the by–catch species were assessed and compared between both trap types

Catch Analysis of Squid Trap Fishing in Coastal Area of Rayong Province, Thailand

Bigfin reef squid (Sepioteuthis lessoniana Lesson, 1830) is one of the important economic squid in Indo-Pacific waters including in the Gulf of Thailand and Andaman Sea. The catch in the Gulf of Thailand was 4,728 tons (fisheries statistics of Thailand, 2013). The squid is also important commercial resource for small-scale fisheries and the major fishing gear that fishers use to catch this species is squid trap, with the annual production was 1,665 tons (fisheries statistics of Thailand, 2013). It has high value for domestic markets in Thailand. In Rayong province, Eastern Gulf of Thailand, Bigfin reef squid production is higher than other provinces indicates that the squid trap fishery is important to the livelihood and economic of small-scale fishers. The squid trap is a traditional type of fishing gear widely used in Thai waters. It was modified from fish trap that represent one of the most effective fishing gear type. This trap has a high selectivity in order to catch squids for targeting Bigfin reef squid (Chotiyapuita and Yamrungreung, 1998).The catch compositions of squid trap composed Bigfin reef squid 86% (Udom and Nunthapon, 2012). This trap is usually deployed in the day time with the fishing ground of 3-40 m depth. It is set floating individually with the float line (Fig. 3). The operation methods, first place the squid eggs and white plastic bags in the trap after that shooting the trap, followed with the sinker and flag pole for marking position. After 1-2 days fishers approach to the fishing ground and trap positions, the fisher hauling up the rope line by winch. The traps are retrieved by moved up to sea surface onboard and scoop the catch out through the entrance and keep squids in the box, then fisher change the new squid eggs and continue deploy the traps in the same position for next shooting. The squids from the trap are very fresh and still alive. Squid trap fishery has a potential to make a significant seafood in Rayong province, but there are very few study reports and lack of data and information about this gear. The objectives of this study the catch of squid trap, catch species, catch compositions, relation between squid and fishing ground. Catch analysis of Rayong squid trap will be useful for fisheries data base and underwater observations to understand the capture process and the trap efficiency in the future

Study on Bycatch and Discards of Bottom Crab Gillnet Targeting Blue Swimming Crab (Portunus pelagicus) in Rayong Province, Thailand

Crab gillnet targeting blue swimming crab (Portunus pelagicus) is a small scale traditional fishing gear that operates on seabed which the most widely used in Rayong province, Thailand. The net made from nylon monofilament (PA, mesh size 100 mm, 12 meshes depth, 450 meshes in horizontal/net). They are operated about 3-5 sets/day/fisher. The head rope made from polyethylene (PE) z twisted (dia. 3 mm, 2 ropes, length 450 m/set). The float is plastic (38×10 mm). The sinker rope is from polyethylene z twisted (dia. 4 mm, 1 rope, length 450 m/set). The sinker is lead (weight 10 g/lead). Hanging ratio of the net about 50% . The stone weights at the both side ends are about 5-8 kg. Generally the crab gillnet fishing operates in early morning in the fishing ground of 5-25 m depth with the socking time of 3-5 days. It operates at sea bottom, target species is blue swimming crab. According to fisheries statistics of Thailand (Department of fisheries, 2012) reported that in year 2010 Thailand caught the blue swimming crab 22,800 tons in total, with the value of 2,520.7 million baht. The crab is very important economic for fishers. They have high price, about 100-300 baht/kg, depends on the crab size and season. However the crab gillnet can catch not only blue swimming crab but also other marine species which many of them become discards species. Puntip et al. (2013) surveyed the diversity of crabs from bottom gillnet, Rayong province, The species of crabs collected from bottom gill net at Banpae, Suanson and Makampom Bay in Rayong province were totally 83 species. The species richness in each station, Banpae, Makampom Bay and Suanson were 65, 52 and 48 species, respectively. The species of crabs as trash fish (discarded) was quite high comprising 81.93 % of total numbers of caught species. The fishers actually do not want to catch non- marketable value or undersize species. In order to reduce the bycatch and discards and protect the marine species, besides to find the possibility methods to reduce the discards species, this study was done to understand the catch species, catch compositions, bycatch and discards from this fishery

Underwater Observations inside the Fish trap in Rayong Province, Thailand

Fish trap fishery is one of the most important small-scale fisheries in Thailand. Fish trap used all over the world. Fish trap is a type of passive fishing gear that allow fish to enter and then make it hard for them to escape. The main target species are fish. Rayong province is one that the fish trap widely used for small fishery. It is used throughout the coastal areas to catch a variety of coral reef fish. But there were very few of fish behavior underwater observations to understand the capture process of fish trap research in Thailand, Attempts to modify Fish trap or improve fishing efficiency in the fisheries future may prove more easy if understanding of fish behavior in Fish trap (Bardach and Magnuson, 1980) The study of fish behavior in Rayong fish trap have not been investigated by using underwater camera system. In situ Underwater camera observations have even been to use for fish behavior research work all over the world, Cole et al (2004) used video camera recordings of entries and exits from blue cod pots for improve the fishing efficiency, Renchen et al. (2014) studied on the fish behavior responses to fish trap by using underwater video camera. such underwater camera observations have not been conducted for Rayong Fish trap fisheries in Thailand. This study focused on the investigating fish shows behavior inside fish trap by using two underwater cameras surveillance in Rayong coastal area

Use of escape vents to improve size and species selectivity of collapsible pot for blue swimming crab Portunus pelagicus in Thailand

Abstract Laboratory experiments were firstly conducted to determine the possibility of modification of the collapsible pot for blue swimming crab Portunus pelagicus by designing appropriate escape vents in terms of shape, position, and size to improve size selectivity by reducing the catch of immature crabs. In laboratory observations, nearly square-shaped vents of 35 mm height and 45 mm length, located at the lower part of the side panel, showed the best performance to allow the escape of immature-size crabs by side-crawling escape behavior through the vents, with L 50% selection carapace length (CL) of 39.1, 44.4, and 48.7 mm CL for 40, 45, and 50 mm vent length, respectively. Comparative fishing trials between conventional and vented pots with vents of 35 9 45 mm size were conducted to examine the crab size and species selectivity. Use of the vented pots was found to reduce the number of immature crabs in the catch from 70.5% to 11.0% on average, while not affecting the catch efficiency of maturesize crabs. The vented pots also had a selective effect for reducing the catch of bycatch species in comparative fishing trials