View Full Version : Tuna – importance of ‘tuna longlining’

15-06-2003, 12:51 PM
Tuna has been hailed as the number one marine resource in Papua New Guinea which is doing exceptionally well in terms of financial and export gains. In the last seven years, there was an increase which has led a profitable path for the fishing industry in the country.

There is an abundance of supplies of the target species of tuna in PNG waters and the whole of Pacific Ocean.

PNG National Fisheries Authority (PNGNFA) effectively supports the efficient practice of tuna fishing in the Pacific waters by introducing new sustainable fishing methods. One such method is termed as the ‘tuna longlining’.

What is tuna longlining? This is a pelagic longlining that uses bait hooks hanging from a long drifting mainline to attract and catch fish. This line is usually 10 – 18 kilometer in length with 300 to 300 branchlines, each with a single hook. Longlines with baited hooks and floats are usually laid out (set) and pulled back (hauled) once within a 24-hour period.

The shape of longline, the number of hooks, the distance between floats, and the bait used will vary depending on the target species and the skipper’s judgments.

A shallow (35-110 m) set targeting swordfish will have fewer branchlines (4-6) between floats. A deep (300 - 400 m) set targeting big eye tuna uses more branchlines (15 – 30) between floats which results in deeper sag of the mainline.

Deep sets are also achieved by using a line setter or shooter (machine to shoot the mainline at a faster speed than the boat us traveling). Fishing depth strongly determines the species caught. Bait, time of setting and other factors will also affect the catch.

Yellow Finned Tuna :

15-06-2003, 12:54 PM
Of course this is only one common method but different methods target different fish species – called the target catch – although non-target species are often caught at the same time.

What do you expect when this happens? This is the message for everyone who is involved or interested in tuna:

Initially when someone involves in tuna longlining what usually happens is that there is untargeted catch, and this is where ‘bycatch’ method comes in.

This means the non-targeted species are either:

Bycatch or unwanted catch (discards) that is returned to the sea because it has little or no commercial value ( this includes protected species); or
Byproduct, which like target species, has a value and is kept and landed. In many countries it is an important part of the overall catch.

Why should fisherman care?

15-06-2003, 12:56 PM
First of all, the western and central Pacific Ocean (WCPO) supports the largest and healthiest tuna stocks in the world. Pacific islanders can increase their participation in tuna fisheries by using sustainable and responsible pelagic longline fishing practices.

Secondly, fisherman and nations have an international and moral obligation to look after the resources they harvest including all by product and bycatch. It is especially important to minimize the incidental catch and/or death of protected species such as turtles.

Thirdly higher catch rates of target species and reduced bycatch and bait loss can be achieved by altering fishing practices such as changing fishing depth of setting gear at night. It is in the interest of fishermen to avoid bycatch, so there are more hooks available for target species.

Bycatch should be seriously addressed before restrictions and possible closures are imposed on fisheries.

Finally, self regulation and the cooperative development of solutions by governments, researchers and fisherman is a better approach to solving the bycatch issue than the drastic measures that may be taken.

15-06-2003, 12:59 PM
What can fisherman do?

Follow the advice in this brochure and seek other ways to minimize the incidental catch of unwanted bycatch species.

Cooperate and work with scientists, governments and non-governmental agencies to develop practical methods for reducing bycatch, while supporting viable fisheries.
Keep good data in logbooks on all fishing activities, including the recording of byproduct and bycatch taken, or interactions with protected species.
Keep good data in logbooks on all fishing activities, including the recording of byproduct and bycatch taken, or interactions with protected species.
If a sea turtle is caught, follow the handling techniques to maximize its chances of survival
Cooperate with observer programs of the observer on board your vessel, as they are there to record catch data, including number of target, byproduct, bycatch and protected species for scientific analysis.

Tuna longlines do not touch the seabed and so do no damage to habitat. Longlines are more selective than trawls or gill nets and can target specific species with minimal bycatch.

Beautiful meal of Tuna enjoyed by me the editor last year at the Holiday Inn in Port Moresby.....beautiful !

15-06-2003, 01:00 PM
Pacific island nations have substantially increased their involvement in tuna fishing over the last 10 years, while foreign longline vessel numbers have fallen.

Domestic pelagic long time vessel numbers and local processing facilities provide local employment and a better economic return to island economies.

For some islands, tuna represents the only significant option for island economic growth and food security.

Most island nations have not become involved in other large-scale tuna fishing activities, such as purse seining, because the costs involved are high and the risks are great.

Island nations are working further to develop and expand their pelagic longlining activities in a sustainable manner, as stewards of the resources.


Tuna Cannery :