It is in these areas where natural floating objects are less abun

It is in these areas where natural floating objects are less abundant that fishers have subsequently

deployed the greatest number of artificial objects. FADs have a short life time (generally <6 months; [29]) and can sink or be appropriated by other vessels. Thus skippers constantly deploy new FADs or relocate older FADs (e.g. objects that have drifted into areas with poor fishing opportunities) and in doing so have effectively created a perpetual artificial floating object habitat across much of the northwest Indian Ocean. Seliciclib Seasonal patterns of fishing activity by the purse seine fleet follow a roughly cyclical movement around the western Indian Ocean that is largely influenced by the distribution of floating objects and by seasonal changes in fishing opportunities (T. Davies; unpublished data). The main FAD-fishing season extends from August to November and the fleet fishes predominantly in the northwest Indian Ocean to the east of Somalia. Although this northwest selleck chemicals llc region is reasonably small, catches are high and almost exclusively made on floating objects.

The use of FADs in particular has consistently been high in this sector with a northwards extension of the fleet in the Arabian Sea region during the mid-1990s. It is interesting to note that these new northerly fishing grounds were discovered by FADs fitted with satellite buoys drifting into previously unfished (but productive) areas [29]. As primary productivity levels fall from November, catch rate on FADs decreases and the fleet moves into the equatorial

Indian Ocean (southeast Seychelles and Chagos regions) in search of free-swimming schools. At this time schools of yellowfin and bigeye tunas are generally feeding or spawning near the surface and thus 3-oxoacyl-(acyl-carrier-protein) reductase are easier to find and catch [30]. However, the spatial distribution of schools can vary considerably and as a result there is marked variation in the proportion of catches on free schools in the Chagos region during this period; vessels enter the region to search for free schools but will also fish on FADs where available, resulting in a higher proportion of FAD catches when free schools are scarce. From March to July the fleet fishes mainly in the Mozambique Channel and northwest Seychelles region using a mixed strategy of floating objects (both natural and artificial) and free school sets. As there has always been an abundance of natural floating objects in this region [31] the proportion of catch on floating objects has always been reasonably high and the deployment of FADs has been more limited than further north in the Somali region. Although no distinction is made in the data, up until the late 1980s ‘floating objects’ are generally considered to be have been natural flotsam [3].

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