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Several seabird bycatch mitigation techniques were tested aboard distant water tuna fisheries in the South African EEZ.  Two types of bird scaring designs, light lines with short streams vs. hybrid lines with a mix of streamer lengths were compared with unweighted branch lines. In addition, unweighted to weighted branch lines were tested and night vs. day setting with a combination of bird scaring lines were tested for their effects on seabird avoidance and targeted fish catch rates.  A total of twenty seven seabird species were observed, but white-chinned petrels were the most common seabird observed and had the highest seabird mortality rate in the study. Albatross (black-browed, yellow-nosed and shy-type) also suffered high mortality rates while stealing bait from the petrels.  Other common surface foraging species included cape petrels. Hybrid lines did appear to reduce sea bird attacks for both species, but the results are not conclusive because the birds could still attack the line at points not protected by the bird scaring lines.  Sets made at night caught far fewer seabirds (0.439 birds/1000 hooks vs. 2 birds/1000 hooks) and catch rates were 18 times higher on the unweighted compared to weighted branch lines (1.07 birds/1000 hooks and 0.06 birds/1000 hooks respectively). The weighted and unweighted branch lines did not affect targeted fish catch rates.

Tests with lanthanide metals were conducted to determine their potential application as a shark repellent in longline fisheries.  Six lanthanide metals were tested (cerium (Ce), neodymium (Nd), praseodymium (Pr), cerium-lanthanum mischmetal (CeLa), praseodymium neodymium metal alloy (PrNdA) and praseodymium neodymium mischmetal (PrNdM)) to quantify their voltage and compare dissolution rates in seawater. A behavioral study was used to determine their efficacy in deterring bonnethead and lemon sharks.  There were no differences in the voltages produced by the metals and their voltages decreased with distance from the samples.  Freshwater produced the greatest voltages, which decreased logarithmically as salinity increased to 10 ppt.  The metals had significantly different dissolution rates, except Nd and Pr.  The time to dissolution ranged from 15.6 hrs for PrDnA to 107.6 for CeLa (lot 2). Behavioral tests were only conducted with Nd, which was not effective in repelling either shark species.

Two experiments were conducted to determine if 1) UV illumination reduced green sea turtle capture rates in large mesh gilllnets and 2) what was the impact of UV illumination on target catch rates in bottom-set gillnets.  Paired tests were conducted using a control net and an experimental net with UV LEDs placed every 5 m on the floatlines for the sea turtle experiment.  In the target catch experiment, inactive LEDs were also placed on the control net at 5 m spacing's.  Sea turtle catch rates were significantly higher in the control nets and there was a 39.7% reduction in mean catch rates with the experimental net.  There was no significant difference in catch rates of target species between the control and experimental nets.

This paper presents a review of studies on gear technologies used to improve species and size selection in Nephrops trawl fisheries in the North Sea, Irish Sea, Kattegat and Skaggerak.  The following categories of gear modifications were analyzed: separator grids, separator/guiding panels, square-mesh panels, capture avoidance designs, and codend modifications.  The best gear design depends on the management objectives of the fishery.  Square mesh panels, combined with guiding panels, proved most beneficial in retaining marketable bycatch, while reducing discards and maintaining target catch levels. Grid systems should be used if managers want to reduce all bycatch and have a single species fishery.

This paper presents a review of studies on gear technologies used to improve species and size selection in Nephrops trawl fisheries in the North Sea, Irish Sea, Kattegat and Skaggerak.  The following categories of gear modifications were analyzed: separator grids, separator/guiding panels, square-mesh panels, capture avoidance designs, and codend modifications.  The best gear design depends on the management objectives of the fishery.  Square mesh panels, combined with guiding panels, proved most beneficial in retaining marketable bycatch, while reducing discards and maintaining target catch levels. Grid systems should be used if managers want to reduce all bycatch and have a single species fishery.

At sea trials were conducted comparing the catch composition and weight of standard Nephrops scraper trawls and a new trawl termed the Flip Flap netting Grid trawl (FFG).  The FFG includes a 160 mm mesh size netting in the top wing and top sheet netting panels, flip-flap netting grid, and fish outlet hole and 200 mm square mesh panel fitter in front of the fish outlet hole. The FFG trawl resulted in a ~30% reduction (number) of small cod around 32 cm in length but not in fish smaller than this.  A 33% reduction was seen for cod sized 35 cm and a 76% reduction for cod 87 cm in size.  In addition, there was a 73% reduction in cod by weight.  For haddock, there was a 51% reduction of haddock around 21 cm, 67% for fish 30 cm in size (MLS) (and weight), and a 73% reduction for fish 44 cm in size.  For the smallest whiting (26 cm) there was a 62% reduction, at the MLS (27 cm) there was a 64% reduction and for 48 cm fish an 84% reduction. By weight, there was an 82% reduction.  Catches of Nephrops were similar for the two gear types.  

An observer program assessed the impact of the Costa Rican longline fishery on bycatch species from 1999 to 2010. Observers recorded species, sex, reproductive state, and dimensions of all animals captured. They also recorded information about individual longlines, including location, set and haul back times, hook type, hook number, bait used, target species, and total number of hooks. The longline fishery caught a large number of silky sharks (Carcharhinus falciformis), olive ridley turtles (Lepidochelys olivacea), and pelagic stingrays (Pteroplatytrygon violacea). The authors estimate that 699,600 olive ridleys were caught between 1999 and 2010, including 92,300 adult females. The captures correspond with a decline in nesting populations nearby and statistically significant size decreases in mature turtles. They also observed a decline in the average size of silky sharks. Geospatial analysis of the data indicated that there were temporal shifts in mahi-mahi abundance, but fishing efforts did not shift with abundance. The authors suggest marine protected areas and/or time area closure to reduce the bycatch of sea turtles and sharks.  

Acoustic pingers (Dukane Netmark 1000; frequency of 10-12 kHz and emit 300 ms tone every 4 sec with a source level range of 120-146 dB) were assessed to determine the effectiveness for reducing bycatch of dolphins and porpoises (common dolphins, dusky dolphins, bottlenose dolphins, Burmeister's porpoise, and pilot whales) by Peruvian small-scale driftnet fleets. Pingers were tested between April 2009 and August 2011. Twenty-two percent of the control nets captured small cetaceans and 16% of experimental nets captured small cetaceans. This was a 37% reduction in bycatch rates, suggesting that pingers may be effective in reducing bycatch of small cetaceans in this fishery. Catch rates of the fishery's target shark and ray species was not changed. 

Shrimp is one of the most valuable fishery resources of Venezuela, with landings about 12 400 t (2007) and worth more than US $35 million. Fishing is carried out along the coast; the industrial trawl fleet used to operate at depths between 10 and 120 m, while fishing with artisanal gears is done close to shore, in coastal lagoons, gulfs and in Lake Maracaibo at depths from 1 to 40 m. The latter represent 84% of landings, mainly from Lake Maracaibo. While only the shrimp is sold by the artisanal fleet, the industrial fleet also sells some fish species, crabs and mollusks. It is been estimated that discards can reach 100 thousand t per year. Due to differences in the spatial distribution of the shrimp and the bycatch, as well as the behavior of the shrimp, more selective fishing systems towards the shrimp were designed, or technological changes in nets were used to restrict the capture of bycatch or facilitate its release after entering the net. In this paper, discards were characterized and various technological changes were tested in nets of common use in shrimp fisheries of Venezuela. The tested systems were: the double lower rope in the industrial trawl; the "fish eye" in the artisanal trawl and the Suripera net. Discards in the industrial fleet were reduced very significantly with the double lower rope, between 26 and 32%, while the commercial catch was maintained or increased. In the artisanal fleet, fish eye allowed reductions of discards between 38 and 54%, without significantly affecting shrimp capture. The Suripera net is very selective, capturing 98% of shrimp, compared to the traditional seine which has 28% efficiency. The possibility of reducing discards is high in industrial or artisanal shrimp fleets operating with trawls, but the seine used by the artisanal fleet operating in Lake Maracaibo may have to be replaced with another more selective gear towards shrimp, like the bottom tangling net. These are examples of how to implement Article 8 of the FAO Code of Conduct for Responsible Fishing (selectivity of the arts in fishing operations) in fisheries of high environmental impact.

The white shrimp, Litopenaeus schmitti, is one of the fishery resources of greater monetary value in Venezuela. This species represents about 90% of the catch of penaeid shrimp of Lake Maracaibo, where one of the largest populations of the species is found within the area of distribution of the species. The remaining catches are made up of three species of the genus Farfantepenaeus (F. subtilis, F. notialis and F. brasiliensis). The mesh opening of beach seine (BS) or Mandinga used to catch shrimp in Lake Maracaibo and Bay El Tablazo is not regulated and varies between 1 ", ¾" and ½ ". On the other hand, since 2005 the bottom tangling net (BTN) with mesh opening of 2" started being used for shrimp capture of shrimp in the Bay of the Tablazo. In 2006 the Suripera net (SN) was introduced on an experimental basis in this area with 1" mesh opening. The objective of the present study was to evaluate the composition by length and weight of shrimp caught with these gears. From February to April 2007 the average size of shrimp obtained with the three gears in the Bay of El Tablazo were compared with ANOVA, and selectivity curve for each gear was obtained according to Sparre and Venema (1995). It was concluded that there were significant differences between the average sizes of shrimp for each gear. The BTN allowed the capture of individuals of greater length and weight, with average size and weight of 14.25 cm and 18,04 g, respectively; followed by the SN with 12,86 cm and 12,80 g and finally the BS with 10,72 cm and 5.72 g. Many of the individuals caught in the BTN and the SN had already reached sexual maturity, and both nets had a low bycatch capture rate (0.26 kg of fish was captured for each kilogram of shrimp). The shrimp caught by these two gear types were mostly adults, which represents higher economic benefits for fishers since larger shrimp have a higher price in the national and international markets. A more sustainable use of resources in Lake Maracaibo would be obtained if the use of the BTN or the SN were implemented in the shrimp fisheries of the region.