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Cooler Atlantic Temperatures Cause 70% Tuna Catch Decline St. Helena, August 30, 12

Cooler Atlantic temperatures seen as a contributing factor in this year’s St. Helena tuna fisheries decline
Source: By Trevor Thomas, Chairman of the St Helena Fisheries Association, The Independent
May I share some thoughts on the current situation regarding our local Fishing Industry? Last year the local fishing industry experienced the most productive period for some time, which even resulted in the reintroduction of the dreaded imposition of catch quotas due to lack of storage space at the cold store in Ruperts. This year has been the exact opposite which started with very poor skipjack landings being almost non-existent, then followed by poor tuna landings up until present. From this it can be seen that with fishing you need to strike while the iron is hot, pile it in when you can. Statistically total landings for this year to date may have dropped as low as 70% compared to the last 2 years.

Whats wrong? Please may I venture some of the following thoughts?

We know that it is indeed very cold this year with very bad bouts of bad weather and we also know wind and weather plays a large role in determining ocean currents and water temperatures. Any good fishermen will know that currents and water temperature plays a vital role in the actual game of fishing and can make a difference even to the point of a half a degree either way. We understand that fishing is presently good in Ascension (has been good for a month or more) yet we are experiencing extremely poor fishing in our sector.

For the past year we have been fortunate to receive a weekly water surface temperature chart giving a satellite print out of the water temps in our 200 mile fishing sector. (This was kindly arranged by Mr. Peter Thomson of Argos). For a period we also received print outs of the Ascension fishing sector which clearly showed that the water temps there were always much better suited for feeding tuna shoals.

Currently we are down to 19.5 - 20 degrees compared to our summer months’ recordings of 24 - 25 degrees.

So why was the fish also slow in the summer fishing season if water temp alone plays such an important part in deciding fish catches?

The weather patterns are changing around the world and it seems like St Helena is not in a good spot. I decided to publish the sea temperature map below even if it is difficult to read in black and white print. This is important because it shows that the water temperatures around the Island are less than 20 degrees Celsius at the moment, which is not a good environment for the passing shoals of Tuna travelling between the Gulf of Guinea and the problem with migrating fish like tunas lies in their ability to move vast distances in 24 hours hour in search of food.

Weather conditions, currents are just part of the parcel, but they do play a vital role in determining the connecting pattern of the massive food chain that links us with the tunas migrating route. We know from the Japanese that Ascension lies in a better location and much more nearer the main migrating core route of these ocean feeders. There is always a 90% chance that there will be much greater abundance of tuna in the Ascension rectangle than where we are. Last year conditions for us appeared just right and the fish went mad.

I am sure it also depends on the quantities or sizes of the shoals of migrating tunas that pass through here. It would appear that the main concentration of fish shoals passed much further to the NE this year leaving us with a few promises here and there. But it could still mean a very late season for us with better stocks of tunas arriving later into this calendar year. There have been occasion when the long fin has shown up as late as September with large yellow fin also making an appearance. So we live in hope for now.

As a rule we usually start catching long fin around about August; however there have been no landings to date except for the odd one in late July. Fishermen have been out scouting but see no concentrations of birds or feeding fish. There has however been promising signs of the mackerel fry shoals that is quite abundant in our deeper waters around about now. Normally this causes the long fin tuna to hang around our waters for several days or betters still some weeks feeding on the vast shoals of juvenile fish. Unlike the yellow tuna species, long fin are quite at home in colder water even as low as 16C - 18 C.

So our current spate of cold weather should not really affect these ravenous feeders should they show up. Also at this time we start to observe the soupy water (green water) which we believe may be pumped in from the nutrient rich waters of the cold Bengualla current as it extends it arm out into the Atlantic during our winery months. Mostly this can have an adverse effect on the inshore fish shoals (Yellow fin - Wahoo, etc) with fish extremely reluctant to take baited hooks. Few catches there are is more likely to occur very late into the day or near sunset.

We will see little change in this until about November when our waters start to take on the cobalt blue affect again.

At that time water temperature starts to get warmer and fish like the smaller yellow fin tunas and Wahoo again shows interest in feeding. Also around that time large shoals of flying squid is seen as frenzied shoals of tuna and others fish feed ravenously on them. Then fishermen must work harder to entice fish to take the baited hooks as they seem interested in the shoals of squid.

Current reports from local fishermen are not good and if things do not improve with the showing of the long fin, then we have the bitter effects of the September - October to face (and we all know how bad things get then). With extremely bad weather to boot some fishermen have already through sheer necessity taken up temporary shore based employment. I worry that this could mean losing more fishermen from an industry that is already short-handed.

The price of fuel and other rising costs means local fishermen can no longer spend fruitless days scouting for fish, you very quickly end up with a huge bill around your neck. There are still one or two diehards trying to find fish, but with very little harvest to show for their efforts.
It times like this when you wish you had a proper offshore fishing boat to hunt further out i.e. the seamounts, etc. But that’s fishing for you, when its good, its good, but when its bad…, well work that out for yourself.