WHAT ARE THE CURRENT BOUNDARIES WITHIN THE OCEAN?
The Cook Islands Territorial Seas extend for 12 nautical miles (22.2km) from each island (a nautical mile (nm) is 1.85km and is 15% longer than a normal land mile). Around each of the 15 islands is a marine protected area extending 50 nautical miles from each island and encircling the island. The marine protected areas prohibit large scale commercial fishing and seabed minerals activities.
The Cook Islands Exclusive Economic Zone (EEZ) extends for 200nm (370km) from each island, except where a neighbouring country’s land is within 400nm (740km) of the Cook Islands land area. In this instance the distance between the two land masses is divided in two.
WHAT TYPE OF FISHING BOATS ARE LICENSED TO FISH IN THE COOK ISLANDS EEZ?
There are two types of commercial fishing boats permitted to fish in our waters – longline and purse seine vessels. Longline vessels mainly catch albacore tuna but they also catch some yellowfin and bigeye tuna. Lines with baited hooks are strung at evenly spaced intervals along a central fishing line, which can be up to 100 km in length (FAO, 2003). Tuna longliners generally set between 1500 and 3000 hooks on a daily basis. They can catch about 2,000 kilos of tuna in one day.
Purse seine fishing vessels set a large net around a school of fish. They close the net at the bottom, similar to closing a purse. They catch mostly skipjack tuna because they swim in surface waters. Sometimes purse seiners drop FADs (Fish Aggregation Devices) in the water to attract a school of fish. If they set their net around a FAD, they will also catch other species, including whale sharks, turtles and juvenile yellowfin and bigeye tuna. Purse seine nets can be up to 1.5km long and 150m deep (FAO,2003). Purse seine boats can catch about 20,000 kilos of tuna per day.
Because skipjack tuna populations are healthy and at low risk of being overfished, regulated purse seine fishing, when closely monitored, can sustainably harvest skipjack tuna. However, purse seine fishing on FADs is unsustainable because of the bycatch (juvenile bigeye tuna and other species) that are caught as well.
CAN FISHING AFFECT WHAT TUNA EAT?
A study of the stomach contents of yellowfin tuna showed that they adapt their diet according to what is available in their environment. The main prey is fish, with squid being second most important (Allain,2005). The study found the following animals are part of their diet: crustaceans, flying fish, skipjack tuna, other tuna, deep sea fish (such as lancetfish and barracudina), puffer fish, crab larvae and reef fish (such as triggerfish, surgeonfish and rabbitfish). This shows that the tuna food web may extend across large scales from the coral reef to the surface of the ocean to the deep ocean. Fishing that affects one part of the food web, has the potential to impact on the food supply for tuna.
Allain, V 2005. What do tuna eat? A tuna diet study. SPC Fisheries Newsletter #12, New Caldedonia
FAO, 2003. Managing Fishing Capacity of the World Tuna Fleet