Untitled - CNR

Marine research at CNRvice (TED). TED is a sort of grid, whichdiverts large objects or animals like turtlestowards a special exit positioned beforethe codend. TEDs have demonstratedto be very effective mainly in prawn trawlfisheries; for this reason several countriesadopted TEDs as mandatory managementmeasure.Some authors believed that TEDs availableat present are probably not a realistic solutionfor Mediterranean mixed bottom trawlfisheries. Conversely in two recent experiments,carried out in the Mediterraneantrawl fisheries by [44] and [45], the authorsfound that TEDs can be properly proposedas management tool for the conservationof marine turtle population in the MediterraneanSea, at least in certain periods andareas. They obtained very good results becausesea turtles were excluded by the SupershooterTED, and unwanted incidentalcatches were also excluded. The SupershooterTED also reduced the debris andimproved fish quality in the catch. Thismight imply a reduction of additional sortingoperations on board, increasing timeand costs. Authors, in agreement with thedoubts expressed by [23], stressed the factthat additional tests should be conducted inorder to evaluate the loss of large fish.5 DiscussionThe review allows to conclude that surfacelonglines, bottom trawls and illegaldriftnets are the major threats to the survivalof this species, even if the impactof fixed nets (gillnets and trammel nets),due to their high direct mortality, shouldbe carefully considered. Nevertheless, turtlebycatch assessment reported in severalpapers seem to be unreal. This is mainlydue to the methods applied for the datastandardization. Authors often assumedthat CPUE was homogeneous by area, seasonand boat, which is not exactly so. Webelieve it is incorrect to extrapolate to allboats and all year the results of a fractionof one season and fleet. Thus, a method forhomogenising the data collection throughthe calibration of the procedures for thebycatch estimation would be very useful inthe Mediterranean Sea, in order to providefishing managers with reliable data.Bottom trawls mainly impact turtle populationduring winter time while longlinesand fixed nets have their main influencefrom spring to autumn with most capturesoccurring in the summer. Finally the assessmentof turtle bycatch in some non-EUcountries, mainly in those countries wherenesting beaches are observed, would be essentialfor the conservation of the sea turtlepopulation.The following recommendations and remarkscan be summarized for the Mediterranean.Regarding the longline, the efficacy of circlehooks in reducing the turtle bycatchis widely investigated but contrasting resultshave been obtained. Further investigationof post-hooking mortality in loggerheadsea turtles would be very usefulto determine the real effects of J and circlehooks. Fishermen stated that it is moredifficult to release turtles from circle hooksthan J hooks, which could also affect turtlesurvival and requires further investigation.Thus, it is possible to conclude that circlehooks have the potential to reduce the turtlemortality only in certain fisheries andareas, but rigorous field tests should beconducted before requiring circle hooks asa mandatory measure.In combination with hooks the branchlinesappear to be the major source of sea turtlemortality. A relatively short piece ofbranchline left in the mouth of a releasedturtle can easily cause death if ingestedand further research on branchline characteristics(material, length, thickness etc.)1847