May 8th, 2010 
molitva leyli Tuna purse seine vessels use a variety of auxiliary vessels to enhance fishing and searching operations. Figure 1 shows a highly specialized net skiff from a Japanese group purse seiner, complete with mounted tow line winch, deck mounted pelican hooks to release messenger cables and a full suite of electronics for communication and school assessment. Japanese auxiliary vessels and towboats are often equipped with telesounder units that transmit depth sounder images to the mothership for direct evaluation by the fishing master.
Figure 1. Japanese net skiff and towboat from group seiner
Heavy duty, diesel powered towboats are a standard item on WCPO purse seiners as they are needed to tow large logs out of the net and are used to investigate and mark floating objects. Figure 2 shows a towboat that has been modified to a light boat used to attract fish to anchored or drifting FADs. Such auxiliary craft are equipped with a generator and above and/or underwater lights and are deployed on a FAD the evening before a set is planned to attract baitfish and tuna. This is a common feature of the Philippine purse seine fishery but is practiced by several fleets.
Figure 2. Purse seine light boat for use on FADs.
The following figures show large vessels that assist purse seine operations. Figure 3 is actually a Japanese pole and line boat but has been converted to serve as a refrigerated carrier within a group seine fleet. Carriers can take any form or size, but most are large purpose built vessels that accept and transport the catch of several vessels.
Figure 3. Former Japanese pole and line vessel converted to carry frozen catch for a group seiner.
Figure 4 is of a search vessel that is a key component of a Japanese group seine operation. These vessels are used to expand the range of searching for the group. This particular vessel was also used as a large light boat on floating object sets and was equipped with a telesounder that send readings to the catcher vessel of the group. A saltwater spray system was also installed on the vessel and she was used in attempts to stabilize unassociated tuna schools prior to setting operations (Itano, 1991).
Figure 4. Search boat as part of a Japanese group seine operation.
Figures 5 and 6 are examples of Spanish supply vessels that work in conjunction with one or more single purse seine vessel of the same company. The main activity of these boats is to search for, assess, maintain, retrieve, monitor and deploy drifting FADs for the benefit of their purse seiner(s).
Arrizabalaga et al. (2001) provides detailed information on the activities of anchored and seagoing supply vessels in the Indian Ocean. A similar analysis has been conducted for Spanish purse seiners operating in the Atlantic (Pallares, et al. 2001). In the Indian Ocean, Spanish purse seiners first began utilizing supply vessels in 1999, with five to eight supply vessels in operation between 1999 – 2002 (Molina, et al. 2003).
Figure 5. Purse seine supply vessel and FAD tender.
Seagoing supply vessels appear to engage mostly in searching operations for their own FADs, other vessels FADs and natural objects (Arrizabalaga 2001). Communication between the fishing and supply vessel is constant, with the captain relaying instructions to the supply vessel, who in turn sends email providing all details of FADs visited that day (i.e. location, amount of tuna, species, estimated sizes). When a productive floating object is located, the supply vessel may stand guard over it or use stealth in attempting to disguise its purpose to other purse seiners in the vicinity. On the other hand, the supply vessels monitor closely the activities of other purse seiners in an attempt to locate their more productive FADs. Deploying or “seeding” of drifting FADs is another important activity of supply vessels which provides more time for their purse seiner to engage in searching and actual fishing activities.
Figure 6. Purse seine supply vessel in Victoria, Seychelles.
Anchored supply vessels primarily hold position on productive seamounts and light the area at night to enhance the tuna aggregation effect. These boats are primarily “place holders”, preventing other purse seiners from capitalizing on the tuna aggregations over the shallow area of a seamount. In particular, there are two anchored supply vessels that maintain a near constant presence on the Coco de Mer Seamount north of the Seychelles, Indian Ocean (Figures 7 and 
. These vessels clearly benefit from their anchored supply vessels that act like huge FADs on the seamount summit. The setting operation is made early in the morning with the buoyed mooring line released after the ship is encircled but before pursing is well advanced (Itano, 2002a). The mooring line passes beneath the chainline as the vessel drifts to deeper water where the set is completed and the supply vessel exits the net.
Supply vessel Explorer III anchored on the Coco de Mer Seamount
Figure 7. Supply vessel Explorer III anchored on the Coco de Mer Seamount
Figure 8. Supply vessel Ocean Scout I anchored on the Coco de Mer Seamount for the exclusive benefit of a single purse seine vessel. Note the large array of lights that are illuminated every night to attract bait and tuna.
source; Documentation and classification of fishing gear and technology on board tuna purse seine vessels. David G.Itano
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