I recently returned from a routine Albatross Task Force at-sea trip onboard a conventional wet fish trawl vessel in Argentina (fish are stored on ice, but not frozen like on the larger freezer vessels). The trip lasted a total of 16 days and fishing was concentrated around 300 km east of the Valdéz Peninsula, where I carried out various different initiatives in relation to seabird conservation and fisheries.
Specifically, I was studying the impacts between seabirds and trawl warp cables, counting the number of times seabirds collide with or are struck by the cables that tow the fishing nets during the trawl. I was also monitoring the birds that become entangled with the fishing nets when they are brought to the surface, or when the gear is deployed again for the next haul.
This fleet sets and hauls the nets over the starboard side of the vessel, quite different from other fleets which haul via an aft ramp. The side hauling operation makes this fishery similar to purse-seine fisheries in some respect as the net remains floating at the surface of the water while the catch is unloaded from the cod end (see image below).
The most vulnerable birds in this operation are the diving petrels and shearwaters, the White-chinned petrel (Procellaria aequinoctialis), Great shearwater (Puffinus gravis) and Sooty shearwater (Puffinus griseus) all become entangled in the mesh of the trawl nets.
During this trip only a single White-chinned petrel was caught, but the crew told of multiple entanglements during certain times of the year. The presence of the ATF in this fleet will be fundamental to help understand and mitigate this interaction.
During all operations we conduct seabird counts to determine the abundance and diversity of seabirds that accompany the vessels in each fleet. What caught my attention this trip was the relatively low abundance of seabirds – typically we see over 2,000 birds per operation but this trip I only counted an average of 500 birds. This is due to the time of year and the characteristics of the fleet. However there were large numbers of marine mammals in the area including Peales’ dolphin (Lagenorhynchus australis), Dusky dolphin (Lagenorhynchus obscurus) and the enormous Southern Right whale (Eubalaena australis).
Skuas and Jaegers (Catharacta antárctica, Stercorarius pomarinus and S. longicaudus) were also present but the most important sighting was that of several Shy albatross (Thalassarche cauta) which are tricky to separate at-sea from White-capped albatross (Thalassarche steadi) - can you tell which of the two species is in the photo below?.
Many of these species are on the Red List of endangered species (IUCN 2011) and so their presence around, and interaction with fishing vessels is of great importance. It was the first time that the ATF in Argentina had recorded these species foraging within the ‘danger zone’ (the area directly between the trawl warp cables) and this time I am pleased to say there was no impact between the birds and the fishing gear.