This approach has also just lately appear underneath target inthe research for methods to give fisheries-unbiased abundance indicators for tuna stockassessment . In this context, an once-a-year aerial survey program was initiated in 2000 tomonitor juvenile ABFT abundance in the GoL in the Northwestern Mediterranean Sea1435488-37-1 .This location signifies an essential nursery floor for ABFT. It is characterized by a huge continentalshelf, several canyons, large runoff from the Rhone river, and higher frontal and eddyactivity. It is situated to the west of the Pelagos Sanctuary, a Maritime Secured Location that consists of breeding and feeding habitats of numerous endangered cetacean species, of whichstriped dolphins and fin whales are the most ample . In reality, the two species are frequentlyobserved in the course of tuna aerial surveys. Nevertheless, little is known of their abundance inthe GoL and similarly, of the co-occurrence of ABFT with other marine predators, i.e. cetaceans.ABFT seemingly affiliate considerably less regularly with dolphins than yellowfin tuna, althoughmature ABFT often take part in mixed-species feeding aggregations around the Azores. By contrast, some reports reveal the use of cetacean sightings by purse seine fishermento identify ABFT in the Mediterranean Sea . In addition, dolphins have occasionallybeen noted as bycatch in the ABFT purse seine fishery in the Mediterranean, although atvery low figures .In this study, we investigate designs of spatial co-incidence and density of these a few speciesin the GoL, based on aerial study info, and evaluate them in conditions of identified species feedingpreferences and environmental characteristics in the study area. Aerial surveys concentrating on ABFT ended up carried out in the GoL from August to October between2000 and 2003 and from 2009 right up until present . During this period juvenile ABFT are particularlyabundant in this region . Aside from ABFT, a variety of cetacean species, notably fin whales and striped dolphins, and significantly less regularly pilot whales , Rissos™sdolphins , brief-beaked frequent dolphins and bottlenose dolphins, were sighted throughout the aerial surveys. Striped dolphins and the morphologicallyvery equivalent brief-beaked frequent dolphins could not always be distinguished,but as the latter has apparently virtually vanished from the Northwestern Mediterranean Sea,we suppose that this kind of sightings solely depict striped dolphins . A standardsurvey consisted of ten study transects, placed randomly in North-South path above thestudy region, masking primarily the shelf break of the Gulf of Lions, which corresponds to thehistorical fishing ground for juvenile ABFT in this location. To achieve statistical validity,approximately 4 replicate aerial surveys had been carried out throughout every single survey year. Startingpoints and time breaks among replicates had been chosen dependent on weatherconditions. A complete randomization of beginning details, examined in 2000, proved not to be feasiblesince the climate situations, in particular the wind strength, have been usually very differentbetween the western and japanese portion of the survey spot .Flights had been executedNH125 about midday to steer clear of solar glare and only below suited weather conditions problems. Surveys ended up executed with a Cessna C337 Push Pull from 2000 to 2011, while a Cessna 208 ISR has been utilized given that 2012.
