Fishing methods using in IFCO`s Fleet

Purse seines;

General description:

A purse seine is made of a long wall of netting framed with float-line and headline (usually, of equal or longer length than the former) and having purse rings hanging from the lower edge of the gear, through which runs a purse line made from steel wire or rope which allow the pursing of the net. For most of the situation, it is the most efficient gear for catching large and small pelagic species that is shoaling.

The next drawing is showing the general technical plan of purse seines net:

The fishing vessels; “ AZADEGAN 1 & 2 & 3 “ in IFCO`s fleet are using such gear for catching Tuna. The handling equipments they used on board for such gear are including, the purse seine winch, a purse line reel, a power block. The basic equipment include, in general: a hydraulic power block, a powerful purse seine winch, a number of small winches, an auxiliary boat " skiff" and sometimes, an helicopter.

Fishing Operations: Searching for fish aggregation, then checking (when possible) the fish species and evaluating school sizes and its catch ability, prior to surrounding it are the major part of a purse seine operation. The purse seine is set around a detected school of fish. After that, the net is closed underneath the school by hauling the purse line running through the rings (pursing). Hydro acoustic instruments, like sonar are important tools to locate fish aggregations. Also common is the use of "natural" signs of fish aggregations (often observed with binoculars) to start with the fishing operation, like concentration of sea birds, ruffling of the water surface and presence of groups of dolphins. Artificial " Fish Aggregating Devices" (Fad’s) and light attractions are used in some fisheries to concentrate the fish.
 

Trawling;

The fishing vessels “ FERDOWS 2 & 3 “ (Stern Trawler Type vessel) are using this kind of fishing method. They are using 3 kinds of trawl gears named Mid-Water Trawl & Bottom Trawl & Bottom otter Trawl (For Shrimp Fishing).

General description:

A Mid-water trawl consists of a cone shaped body, normally made of four panels, ending in a codend with lateral wings extending forward from the opening. It is usually much larger than a bottom trawl and designed and rigged to fish in Mid-water, including in the surface water. The front parts are sometimes made with very large meshes or ropes, which herd the targeted fish inwards so that they can be overtaken by smaller meshes in the aft trawl sections. The horizontal opening is maintained either by otter boards or by towing the net by two boats (pair trawling). Floats on the headline and weights on the ground-line often maintain the vertical opening. Modern large Mid-water trawls, however, are rigged in such a way that floats are not required, relying on downward forces from weights to keep the vertical opening during fishing.

A bottom trawl is constructed like a cone-shaped net that is towed (by one or two boats) on the bottom. It consists of a body ending in a codend, which retains the catch. Normally the net has two lateral wings extending forward from the opening. The mouth of the trawl is framed by headline and ground-rope. It is designed and rigged to catch species living on or near the bottom. 

Specific Equipment: Sonar is useful tool to detect fish concentration ahead the trawler and the trawl path and trawl depth can be adjusted accordingly. The fishing depth and the trawl are usually controlled by means of a net sounder (netsonde) or depth recorder.

In Bottom Trawl, The Ground-rope equipped with rubber discs, bobbins, spacers etc. protect the trawl from damage. On very rough bottom special rock hopper gears are used. Beam trawls are designed and equipped in a different way.

Specific Handling Equipment: Trawl winches installed on deck control the trawling wires and store them when not in use. Gilson winches and lifting tackle are provided to assist with handling gear at the vessel. Net drums are common tools to handle Mid-water trawls onboard vessels.

Fishing Operations: Mid-water trawls are rigged to fish in Mid-water, from the surface to great depth depending on the position of the fish. One or two boats may tow it. In other hand, Bottom trawls are designed and rigged to have bottom contact during fishing. They are towed across the bottom at speeds ranging from 1 to 7 knots (0.5-3,5 m/s), frequently between 3 and 5 knots. Duration of a tow mainly depends on the expected density of fish (whether fish is aggregated or not) the shape of the bottom and the slope in the fishing area, from a few (10-15 minutes) up to 10-12 hours, commonly 3-5 hours.

Note: The fishing Vessels “ SIRAF” is actually “ Stern Trawler” type vessel but due to Iranian Fisheries Organization Policy has no permission for fishing (As large trawlers can’t get the license).

Handling and processing of catch

A) On board of “FERDOWS” class Trawlers

Once the fish are on board (after hauling the Trawl net and discharged from codend), they must be handled quickly and carefully. Exposure to sun and wind on deck should be avoided, otherwise spoilage will be increased and chilling made more difficult. An awning should be rigged over the deck in warm weather.

The catch on main deck is transferred to processing deck through RSW tank.

The catch is first sorted or culled; other un-commercial fish, damaged or deformed fish and rubbish are removed by hand or by sieve. The specified catch is then washed thoroughly in fresh water to remove any remaining mud or sand, and to reduce bacterial contamination. After grading the fish is placed to box or basket and are then ready for further processing, usually freezing.

FREEZING ON BOARD

After all above procedures, catch is ready for freezing by cold air in Tunnel freezing or/and plate freezing in very low temperature (-30 ~ -40º C) during 3~4 hours. After packing, the frozen fish are ready to transferred to cold store (cargo) of vessel and keeping there till discharging at port.

B) On board of “AZADEGAN” class Purse Seiners

 After catching the Tuna school by purse seine nets and completed the fishing operations; the Tuna without sorting transfers to brine tanks by conveyer. The temperature of sea water inside the brines is about -24º C and Tuna start to freezing while floating in brine up to -18º C in Back bon.

As the Tuna catch by purse seining for can propose, it keeps in brine till discharging at port and delivery to can factory by freezing containers (on truck).

The main species of Tuna in Iranian fishing ground (Oman Sea) are as following;

C) Shrimp handling and processing on board of “FERDOWS” class Trawlers

At shrimp fishing season, the “ FERDOWS “ class vessels be ready for catching shrimp by Bottom otter Trawling.

The handling of caught shrimp is similar with handling of other fish (sorting, washing, grading & freezing and packing) but if the quantity of catch was the huge, may keep it in RSW tanks and added some chemical material (Meta Be sulfide) to brine.

There are also the special instructions according to buyer orders or market requirements such as Head-On/Headless/PUD/PTO. The weight of shrimp pack should be in 1/2/6 Kg per box and the weight of each master cartoon is 12Kg.

The grading of shrimp is base on the Numbers of it in pound or Kilogram according to following categories:

7/10, 10/20,20/30,30/40,40/60,60/80,80/100,100/120 and 61/70, 71/90,91/100,100up (In pound) and For Headless: 11/15,16/20,21/25,26/30,31/35,36/40,41/50,51/60.