According to previous information, May and June is the most dangerous time of the year for seabird bycatch in the Western Mediterranean and observer effort has been intensified. The bycatch of the 3 Cory’s shearwaters (Calonectris diomedea) has occurred during three monitored fishing operations. Cory’s shearwater was the main species attending at demersal long-liners during the line setting and hauling.
Cory’s shearwater Calonectris diomedea accidentaly captured on a demersal long-liner. Photo: Albert Cama
The analyses of the corpses indicated that some dead birds could be active breeders, showing breeding patch. The internal analysis of one bird indicated that it was an adult female.
See breeding patch on a Cory’s shearwater Calonectris diomedea Photo: Albert Cama
In addition to the data collected by SEO/BirdLife observers, fishermen reported the bycatch of other seabirds during the last weeks, including another Cory’s shearwater, 2 Atlantic gannets (Morus bassanus) and up to 40 unidentified shearwaters, including a massive event of 20-30 birds. We should mention that the skipper aborted the line setting due to the big amount of seabirds attacking to bait. Two Mediterranean European shags (Phalacrocorax aristotelis desmarestii) were accidentaly captured on cuttlefish pots. Additionally, 2 Cory’s shearwaters, 2 Yelkouan shearwaters (Puffinus yelkouan) and 5 Balearic shearwaters (Puffinus mauretanicus) were found death in one beach in Tarragona, they did not showed the presence of hooks, but some injuries near the mouth, indicating Long-line bycatch.
We wish to thank the collaboration of fishermen by allowing observers on board and reporting data.
Cory’s shearwater Calonectris diomedea eating discarded fish. This has been the most abbundant species attending demersal long-liners. Photo: Albert Cama
De acuerdo con los datos previos, Mayo y Junio es el período más peligroso en cuanto a captura accidental en el Mediterráneo Occidental y se ha intensificado el trabajo de los observadores a bordo de palangreros. Se han capturado 3 pardelas cenicientas (Calonectris diomedea) durante tres operaciones objeto del seguimiento. La pardela cenicienta ha sido la especie más abundante en los palangreros de fondo, tanto durante el calado como la recogida del arte.
Pardela cenicienta Calonectris diomedea capturada accidentalmente en un palangrero demersal
El análisis de los cadáveres indica que algunas aves se podrían encontrar en reproducción activa, mostrando placa incubatriz. El análisis interno de un ave indicó que se trataba de una hembra adulta sexualmente.
Véase la placa incubatriz en una pardela cenicienta Calonectris diomedea
Además de la información recopilado por los observadores de SEO/BirdLife, algunos pescadores han reportado la captura accidental de más aves durante las últimas semanas: una pardela cenicienta más, 2 alcatraces atlánticos (Morus bassanus) y hasta 40 pardelas sin identificar, incluyendo una captura masiva de 20-30 aves. Cabe destacar que el pescador abortó la operación al observar el ataque masivo de las aves a los cebos. Dos cormoranes moñudos (Phalacrocorax aristotelis desmarestii) fueron capturados accidentalmente en nasas para sepia. 2 pardelas cenicientas, 2 pardelas mediterráneas (Puffinus yelkouan) y 5 pardelas baleares (Puffinus mauretanicus) fueron encontradas muertas en una playa de Tarragona, aunque no mostraban anzuelos, sí mostraban heridas alrededor de la boca, lo que podría indicar que fueron capturadas accidentalmente por palangres.
Queremos agradecer una vez más la implicación de los pescadores en el asunto, tanto permitiendo la presencia de observadores a bordo como facilitando información adicional.
Pardela cenicienta Calonectris diomedea comiendo un pez descartado. Ésta ha sido la especie más abundante durante las operaciones de los palangreros demersales
El equipo español se concentra su trabajo en los puertos catalanes, donde se dan diferentes tipos de pesca de palangre. Aunque nosotros nos centraremos en los palangres demersales, existen otros tipos de palangre como el pelágico o el artesanal. De hecho en los puertos desde los que estamos saliendo -Llançà, Roses y Vilanova i la Geltrú- hay embarcaciones que trabajan estos tres tipos de palangre. En esta entrada en el blog vamos a señalar brevemente las diferencias entre estos artes tan relacionados.
Como sabemos, los palangres se componen por una línea madre, de la que cuelgan diversos anzuelos, pero esta estructura general se puede configurar de una multitud de forma que se pueden agrupar en 3 grandes categorías:
–Palangre pelágico o de superficie: El arte se mantiene cerca de la superficie mediante el uso de flotadores. En la costa catalana, tiene como objetivo principal grandes depredadores pelágicos como peces espada o atunes. Se calan unos pocos miles de anzuelos de gran tamaño separados por una distancia que puede sobrepasar los 30 m. En este proyecto no trabajaremos con este tipo de arte, ya que el Instituto Español de Oceanografía tiene en marcha un proyecto a largo plazo de observadores.
Palangrero pelágico en el puerto de Torredembarra. Foto: Matxalen Pauly
Esquema de la disposición de un palangre pelágico. Fuente: Bycatch mitigation factsheet 8. BirdLife
–Palangre demersal o de fondo: Con el objetivo de pe pescar especies de fondo, como la merluza o espáridos de fondo, el arte se hunde mediante pesos que se combinan con flotadores para situar el arte en el lugar preciso para cada especie objetivo. Utilizan un número similar de anzuelos más pequeños, que se separan sólo unos pocos metros.
Palangre demersal en aguas de la Catalunya central
Cajón con los anzuelos del palangre, algunos ya cebados. Foto: Pau Calero
–Palangre artesanal o palangrillo: La principal característica de este arte es su pequeña escala. Puede ser similar al palangre de fondo, pero se calan unos pocos cientos de anzuelos siempre cerca de la costa en aguas menos profundas.
The Spanish team is focused in the Catalan harbours, where different kinds of long-liners operate. The main target of this project is the demersal long-liner fleet, but other boats using artisanal or pelagic long-lines also operate in the area. In fact, in the harbours where we have started our work -Llançà, Roses and Vilanova i la Geltrú- we can find boats using the different long-line types. In this blog post, we will quickly point out the differences between these similar fishing gears.As we know, long-lines are composed by a main line with several hooks attacked to it, but this general configuration can be set in a plethora of different variations which can be grouped in 3 main classes:
– Pelagic long-lines: This fishing gear requires floats to keep the gear close to the sea surface. In the Catalan coast, the fishermen generally target large pelagic predators like swordfish or tunas. They set a few thousand large hooks separated by a distance that can exceed 30 m. In this project we do not pay attention to this fishing method, since the Spanish Oceanographic Institute has an on-going long-term project with on-board observers on these fishing boats.
Example of pelagic longline configuration. Bycatch mitigation factsheet 8. BirdLife
Pelagic longliner at Torredembarra harbour. Photo: Matxalen Pauly
– Demersal long-lines: Targeting bottom species, like hake or breams, the fishing gear is sunk by the use of weights, which are combined with floats to keep the gear on the right placement for the target species. They set a similar amount of smaller hooks, which are spaced very few meters.
Longline box with the hooks, some with the bait. Photo: Pau Calero
Demersal long-liner off central Catalonia
–Artisanal long-lines: The main characteristic of this fishing gear is its small scale. This fishing gear can be very similar to demersal long-liners, but they use a few hundreds of hooks which are set in relatively shallow waters close to the coast line.
After some weeks of continuous northern winds, the 2nd and 3rd of March the first STF surveys on-board of demersal long-liners in Spain were conducted. One observer of SEO/BirdLife shipped on a demersal long-liner based in Llançà, one of northernmost Catalan harbours next to the Spanish-French border. The main target of the fishing boat was the Blackspot seabream Pagellus bogaraveo. These first surveys were worth improving the methodology, getting familiar with it and collecting the first data. We characterised the fishing gear configuration and effort and observed no seabird bycatch. We also enjoyed of a very tasty on-board meal, which was worth recovering strength and knowing the fishermen from a personal point of view.
Black legged kitty-wake Rissa tridactyla following the vessel during the operations
Only very few Yellow-legged gulls Larus michahellis, Mediterranen gulls L. melanocephalus and Kittywakes Rissa tridactyla followed the vessel during the operations. Seabirds ate discarded baits and one kittiwake stole one bait when setting but was not hooked. The shearwaters (only Mediterranean, Puffinus yelkouan) were very scarce during the operations, and most individuals were observed in coastal waters when returning to port.
During the following weeks we will keep contacting long-liner skippers and continue with on-board observations.
BirdLife International is extending its Albatros Task Force, the initiative to reduce seabird bycatch in collaboration with fishermen, to Europe. Here, the so called Seabird Task Force starts at two bycatch hotspots, Lithuania and the Spanish Mediterranean. Reasons to prioritise this latter area deserve some further explanation.
Spain has a wide diversity of seabirds, with over 40 regular species, more than 20 of them breeding, spread across three distinct geographical regions: the Macaronesia, the European Atlantic and the Mediterranean. Of these, the Mediterranean hosts smaller seabird numbers, but a relatively high diversity of species, many of them of conservation concern precisely due to their tiny populations, as well as restricted distribution ranges. Moreover, the Mediterranean region is highly populated and therefore supports high human pressure, which affects seabirds in several ways: coastal development, introduced predators, pollution, fisheries overexploitation, etc. Among these, bycatch appears to be one of the most serious threats for some species.
Of the seabirds of conservation concern, two species deserve particular attention, the Balearic shearwater Puffinus mauretanicus (Critically Endangered) and the Yelkouan shearwater P. yelkouan (Vulnerable). Both are endemic to the Mediterranean, with small global populations and sharp declining trends, that could lead to their extinction in the near future. Although they are affected by introduced predators and other threats in their colonies, the major drivers of their decline seem to occur at sea, and bycatch postulates itself as the most important of them, particularly on longlines.
Balearic shearwater seeking discards behind a fishing vessel
Why these birds are prone to be caught in longlines? Both Balearic and Yelkouan shearwaters are often seen following fishing vessels to capture discards, and can get captured in the longline baited hooks when these are thrown overboard during the setting operations. Demersal longlines are particularly dangerous for them, as they operate over the continental shelf, where both species of shearwaters tend to forage (while pelagic longlines often operate further offshore), and use smaller hooks, as well as more suitable bait (often sardine or similar sized fish, ideal for the shearwaters). Moreover, these seabirds are highly gregarious in their foraging grounds, and can “attack” a longline by the hundreds, with the risk of “massive captures” (several tens or more).
Balearic and yelkouan shearwaters off Roses, Catalonia, NE Spain. The gregarious behaviour of these two species makes them susceptible of “massive” catches, which have been often reported in this area
Information supporting the idea that demersal longline is a major threat for the two small shearwaters endemic to the Mediterranean is still patchy, but increasing. Events of “mass” mortality have been reported by fishermen (up to over 200 small shearwaters in a single line), or deduced from stranded birds on the beach. Questionnaires to fishermen also point in that direction, with a described event of up to 3,900 seabirds reported!!! And observers onboard demersal longlines have reported the regular capture of the shearwaters, though effort is still limited.
The new Seabird Task Force brings the opportunity to reinforce observers’ effort in the Demersal longline fishery operating off Catalonia, NE Spain, one of the main foraging grounds for the Balearic shearwater in winter and spring (pre-breeding and breeding periods), and also the main foraging area for Yelkouan shearwaters in Spain. Other seabirds regularly captured include Scopoli’s shearwater Calonectris diomedea and Audouin’s gull Larus audouinii, both endemic to the Mediterranean. Recent observers’ work has been conducted in the region by a team from the University of Barcelona (and the Spanish Institute of Oceanography in pelagic longlines), plus questionnaires and workshops by SEO/BirdLife, but further effort is necessary to refine the existing information, most important to provide an accurate estimate of bycatch rates, given the high variability observed. During 2015, SEO/BirdLife’s observers will get onboard demersal longliners across the Catalan coast to address these issues. Later, in 2016, mitigation measures will be tested to assess their efficiency at solving the problem. The close collaboration with fishermen will be essential to achieve any success. We’ll keep you posted of future advances with the project.
Main foraging grounds of Balearic (left) and Yelkouan shearwaters (right) off eastern Spain. From blue trough yellow to red, areas low to highly selected. Both species tend to forage in waters over the continental shelf. Sorce: SEO/BirdLife
