Unfortunately seabirds caught as byctach in pelagic longline fisheries are generally only brought onboard once they are already dead (they are hooked and drown during the set when lines sink into the water). In Uruguay birds killed at sea are returned to the laboratory for analysis. By doing so we can recover valuable information that helps us identify the problem and ultimately work to improve their conservation.
During the last three weeks I received carcasses from four fishing boats that anchored in the port of Montevideo after fishing trips of about two months each. Fortunately, very few birds were captured, mainly White-chinned petrels and shearwaters. An important observation to note is the very low proportion of albatross.
Prior to these vessels leaving port, I provided them with and configured their tori lines (see image below). This work was done in cooperation with the National Observer Programme, which places an observer on board each vessel. The tori line, created by the ATF team in Uruguay (Projecto Albatros y Petreles – Uruguay), was used by ships throughout the duration of the fishing trip. In conjunction with strict night setting, this measure is producing results that benefit seabirds.
Some fisheries in the Southern Hemisphere dedicated to fishing for Patagonian toothfish have significantly decreased the mortality of sea birds, using tori lines and night setting. One of the main results of the use of this combination of measures is the reduction of albatross bycatch. The remaining bycatch is mainly White-chinned petrels and shearwaters.
It is more complicated to prevent White-chinned petrel bycatch because of their deep diving capabilities and their nocturnal habits, which makes them particularly susceptible during the full moon when ambient lighting is sufficient for them to spot and dive down for baited hooks. This is a point where we need to complete more work to decrease the minimum catch of all species of seabirds.
Along with Martin process all birds that are brought to the laboratory. This process takes several days. However, it is extremely worthwhile as we learn a lot about these species. We record sex, morphometric measurements, analyse the moult stage, take genetic samples and collect stomach contents.
All this information provides us with information about the origin of the birds (which archipelago they come from), what kind of birds are captured (age and sex) in the region which gives us an idea of the impact of our local fishery. It is also important to understand what areas these birds are travelling to and what they are feeding on.
All this can be supplemented with information obtained at sea or in the breeding colonies, all critical information if we are to conserve these species.