The longline vessel 'Portugal II' sailed from the port of Coquimbo (30°S) on the 19th July, with a course set for Robinson Crusoe Island (33°40'S, 78°50'W) on the Juan Fernandez Archipelago.
After three days steaming in rough weather and winds up to 30 knots, we anchored in Cumberland Bay to await improved sea conditions. During the following 10 days we carried out oceanography and fishing surveys around the two sea-mounts west of the island.
On 31 July, we headed for fishing grounds in the north-west. The first set, using a surface longline, gave encouraging results for the crew, who hadn't been able to fish for several days. Over 1,000 kg of swordfish was brought aboard, plus other species of lesser commercial interest such as sharks and tuna.
The weather started to improve, as did the crews' morale. At these latitudes, the seabirds were not particularly abundant, principally small petrels like the Cape petrel plus some black-browed albatrosses, white-chinned petrels and a few wandering albatrosses.
As hauling began, some birds remained close to the vessel, allowing me to gain a count of numbers and observe how the fishing gear behaves in the water and how the birds interact with it. The birds showed interest in spite of low light levels during hauling, and even at night. The next few lines followed suit, although a couple of giant petrels visited to feed on the fishing discards with the black-browed albatrosses.
On 9 August during the eighth haul, the vessel regime changed to set earlier, at around 6 pm. Due to increased light levels at this time, we started using the tori-lines that we had prepared in port before sailing. The lines were set from a specially made metal support bar welded to the aft of the vessel, giving a good 4 m height above sea level.
The first observations of the set were not good as part of the line did not extend far enough behind the vessel, also the seabirds in this area (mainly black-browed albatross and white-chinned petrels) insisted on diving on the bait as we set.
Due to the low catches in the area the captain then decided to fish a day further south, where the birds were much more abundant, especially during the daylight hours when they aggregated to feed on discards. There were many juvenile black-broweds and high numbers of Cape petrels. During the coming sets, we modified the tori line to improve its design as it had become entangled on one set and broke the metal support bar.
On top of this, the same set revealed the first albatross mortality; a black-browed albatross had been caught on one of the hooks. The entanglement of the tori line and broken bar caused a drop in the captain's confidence. However, the crew worked to create a design that the captain was happy with and that would hopefully not interfere with the fishing procedures.
The deck bosun worked with us to produce the new line using light-weight materials found on the ship, including plastic tubing, monofilament line and florescent 'bait' materials normally used for attracting target species during fishing. Finally, whilst testing the new tori line, we found it worked well and fortunately didn't interfere with the fishing gear.
The general abundance of seabirds increased, concentrating in numbers during the day while the crew processed the fish. Therefore, although night-setting returned as routine, we maintained the use of the tori-line. The ease of use with the line plus the good catches in this zone kept crew spirits high and motivation to prevent seabird by-catch was good. Swordfish catches were over 1,200 kg per day and weather stayed fine allowing good observation and photography of such majestic seabirds as the wandering and royal albatrosses.
This good atmosphere crashed with the appearance again of a black-browed albatross on a hook. The hook was baited with squid, which apparently are more buoyant than mackerel-baited hooks and the lighter colour of the squid was easily detected by the seabirds.
Setting continued at night, with torilines in use to avoid further bird mortality. In the subsequent hauls, only a few minor mishaps occurred, such as the arrival of a white-bellied storm petrel, which apparently rested overnight on deck. Other mishaps, such as cut lines, allowed the crew to catch a quick well-earned rest between hauls.
With 17 hauls completed and over 18 tonnes of fish on board, we headed back toward Robinson Crusoe Island to complete the surveys for a couple of days. We then spent a few hours on the island before turning the ship toward the home port of Coquimbo. We arrived on 24 August after 37 days at sea.
Conclusions that were possible from this trip were that in spite of night-setting and tori line use, it was still difficult to completely avoid albatross by-catch. For this reason, it is important to keep improving the mitigation measures and trying new combinations for better results.
Additionally, we found this type of fishing gear too buoyant, staying at the sea surface for over 100 m whilst setting. The 16 m-26 m vessels typical of this fishery do not have 'caladoras', mechanical setting devices which maintain a steady rate of line deployment during the set. This often caused line tension, reducing the sink rate of the fishing gear. This is a key point for avoiding seabird by-catch as the faster the line sinks, the fewer chances the birds have of diving on the bait.
With respect to the participation of the crew, there was absolute collaboration in our attempts to mitigate seabird mortality and constant support in the rigging of the tori line and its installation. However, it's important to mention that this was in some way affected by damaged swordfish which suffered at the sharp beaks of the seabirds whilst close to the surface. This has provided a new challenge for our team, to create a strategy to tackle this problem and keep the goodwill of the fishers.