Dear Editor, I wish to respond to recent letters by Messrs Reuben Tylor and Josh Mitchell.

Like Josh and I suspect many of your readers, I am at a loss to understand the value of Reuben’s latest opinion piece – it would appear he is becoming a “keyboard warrior”.

Without doubt, diminishing fish stocks due to overfishing is a worldwide reality with some species already extinct and others including yellowfin under serious threat. Like humans, fish need to feed in order to survive. And like humans, the tuna and other “pelagic” fish food source flourish under defined climatic conditions related to sea surface temperature and currents. Closer to land, manmade factors like overfishing, pollution, diverting or drying up rivers reduces baitfish that attracts and retains tuna and other pelagic fish close to the reef. 

During El Nino weather pattern, the warm water that attracts yellowfin shifts to the eastern Pacific, (to the west coast of America), favouring the American tuna fishermen at the expense of the Western Pacific tuna fleet. The opposite occurs during La Nina. The Cook Islands is between the two areas but limited local data would suggest tuna catches at least here in Rarotonga are better during El Nino years while wahoo and other cooler water pelagic fish are more plentiful during la Nina, depending of course on the sea surface temperature and currents at the time.

For most of its life, tuna and other pelagic fish live deep (around the thermocline) where most of its food sources are and only come up to the surface at brief intervals and again, related to the presence of baitfish. Only a small percentage of the tuna is up at the surface at any one time – this partly explains the discrepancy between MMR (Ministry of Marine Resources) claiming there are “plenty of fish out there” and the diminished catch rates by the local artisanal fishermen.

The Cook Islands, especially Rarotonga, do not have significant numbers of seamounts and shallow underwater reefs that attract and sustain significant populations of baitfish. Due to avoidable manmade factors, the large numbers of baitfish schools (ika tauira) we used to see in our lagoons are now very much a rarity. I believe, this a significant reason why catching tuna or wahoo closer to the coast is becoming increasing difficult. There is recent evidence from tagging that some pelagic fish including tuna and striped marlin are territorial – they “hang around” or stay for up to long periods of time provided of course they have enough baitfish to keep them in the area.

Some of us still find fishing according to the Arapo as practiced and handed down the generations by our tupunas a useful guide to improving the fishing effort. There is a wealth of modern information/data available to MMR and not being shared with the local fishermen.

In spite of the doom and gloom, much can be done at little cost to improve and sustain the artisanal fishery here in the Cook Islands. Addressing the partially controlled overfishing by foreign commercial fleet is work in progress. The 50-mile limit for commercial fishing is commendable and any attempt to reduce the limit is to be resisted. The economic benefit of improving and sustaining the baitfish food chain by an adequately funded and resourced FAD programme is relatively low cost.   

Under the current leadership, there have been progress but it is still a long way from best practice. Ideally, Rarotonga need at least six deep water and a similar number of shallow water FADs permanently installed and serviced, to hold sufficient numbers of tuna and other pelagic fish to satisfy the needs of the artisanal and charter fishery. It is my understanding the MMR Act, requires MMR to ensure a sustainable artisanal fishery. 

Yours sincerely,

George Ngaei

Invercargill

New Zealand