This technique has also not too long ago come below focus inthe research for approaches to provide fisheries-unbiased abundance indicators for tuna stockassessment . In this context, an once-a-year aerial study program was initiated in 2000 tomonitor juvenile ABFT abundance in the GoL in the Northwestern Mediterranean Sea1333377-65-3 .This area represents an important nursery ground for ABFT. It is characterized by a big continentalshelf, several canyons, massive runoff from the Rhone river, and substantial frontal and eddyactivity. It is situated to the west of the Pelagos Sanctuary, a Marine Safeguarded Area that includes breeding and feeding habitats of several endangered cetacean species, of whichstriped dolphins and fin whales are the most considerable . In fact, each species are frequentlyobserved in the course of tuna aerial surveys. Even so, tiny is known of their abundance inthe GoL and similarly, of the co-occurrence of ABFT with other marine predators, i.e. cetaceans.ABFT apparently affiliate considerably less usually with dolphins than yellowfin tuna, althoughmature ABFT occasionally take part in blended-species feeding aggregations around the Azores. By contrast, some reports point out the use of cetacean sightings by purse seine fishermento find ABFT in the Mediterranean Sea . Furthermore, dolphins have occasionallybeen documented as bycatch in the ABFT purse seine fishery in the Mediterranean, even though atvery low numbers .In this research, we investigate patterns of spatial co-event and density of these 3 speciesin the GoL, based on aerial survey knowledge, and examine them in terms of identified species feedingpreferences and environmental attributes in the survey spot. Aerial surveys targeting ABFT ended up carried out in the GoL from August to Oct between2000 and 2003 and from 2009 till present . During this season juvenile ABFT are particularlyabundant in this region . Apart from ABFT, a range of cetacean species, notably fin whales and striped dolphins, and less regularly pilot whales , Rissossdolphins , limited-beaked frequent dolphins and bottlenose dolphins, ended up sighted for the duration of the aerial surveys. Striped dolphins and the morphologicallyvery comparable quick-beaked frequent dolphins could not constantly be distinguished,but as the latter has apparently practically vanished from the Northwestern Mediterranean Sea,we suppose that these kinds of sightings exclusively symbolize striped dolphins . A standardsurvey consisted of ten study transects, positioned randomly in North-South path more than thestudy region, covering mainly the shelf break of the Gulf of Lions, which corresponds to thehistorical fishing ground for juvenile ABFT in this region. To obtain statistical validity,approximately 4 replicate aerial surveys had been performed throughout every study year. Startingpoints and time breaks amongst replicates have been selected primarily based on weatherconditions. A total randomization of beginning factors, examined in 2000, proved not to be feasiblesince the temperature conditions, in specific the wind strength, ended up usually very differentbetween the western and jap component of the survey region .Flights were conductedNH125 close to noon to steer clear of sunlight glare and only beneath ideal weather circumstances. Surveys ended up executed with a Cessna C337 Push Pull from 2000 to 2011, although a Cessna 208 ISR has been utilised because 2012.
