Killer whale (Orcinus orca) encounters from commercial pelagic trawlers as well as other types of vessels have been documented in several regions of the northeast Atlantic; however, very little published information is available regarding such encounters in mackerel (Scomber scombrus) and herring (Clupea harengus) fisheries, in the waters between northern Scotland and Norway. Mackerel and herring are the two main fish species targeted by the Scottish pelagic fleet, primarily during October to March and June to September, respectively. Encounters with killer whales were recorded during January and February 2006 by observers on a pelagic trawler fishing for mackerel in this area. These recent data, along with historical records collected since 2000, demonstrate the existence of frequent encounters between commercial pelagic trawlers and killer whales. We describe the foraging behaviour displayed by the whales during fishing operations. Killer whales approached the vessels during retrieval of the net, and remained there until this was completed. They were sometimes sighted during steaming and towing, although there was no observed contact with the boat or net at these times. There is no evidence that the presence of killer whales reduced the amount of fish caught by the trawlers or that killer whales ever become entangled in the nets. We suggest that, during the mackerel fishing season, the whales may obtain a significant proportion of their daily energy requirements from this source. Les observations d'orques (Orcinus orca), à partir des chalutiers pélagiques ou d'autres types de bateaux, sont relevées dans plusieurs régions de l'Atlantique Nord-Est ; cependant, très peu d'informations sont disponibles, en ce qui concerne ces observations dans les pêches de maquereaux (Scomber scombrus) et de harengs (Clupea harengus) dans les eaux entre le nord-est de l'Ecosse et la Norvège. Maquereau et hareng sont deux principales espèces recherchées par la flotte pélagique écossaise, d'octobre à mars, et de juin à septembre, respectivement. Les observations d'orques ont été enregistrées durant janvier et février 2006 par des observateurs embarqués à bord de chalutiers pélagiques pêchant le maquereau dans ce secteur. Ces données récentes, avec celles récoltées depuis 2000, démontrent l'existence de fréquentes rencontres entre chalutiers et orques. Nous décrivons le comportement « fourrageant » de ces orques, manifesté lors des opérations de pêche. Les orques approchent les bateaux durant les opérations de tri du chalut, et restent là jusqu'à la fin. Ils sont vus aussi lors du relevé du chalut bien qu'aucun contact avec le bateau ou le filet n'ait été observé alors. Il n'y a pas de certitude que la présence des orques réduise la quantité de poissons capturés par les chalutiers ou même que les orques s'empêtrent dans les filets. Nous pensons que durant la saison de pêche au maquereau, les orques tirent de cette source, une part significative de leurs besoins énergétiques journaliers.

This study deals with important methodology issues that affect age estimates of eastern Atlantic bluefin tuna Thunnus thynnus using dorsal fin spines. Nearly 3800 spine sections were used from fish caught in the north‐east Atlantic Ocean and western Mediterranean Sea over a 21 year period. Edge type and marginal increment analyses indicated a yearly periodicity of annulus formation with the translucent bands (50% of occurrence) appearing from October to May. Nucleus vascularization seriously affected specimens older than 6 years, with the disappearance of 40–50% of the presumed annuli by that age. An alternate sectioning location was a clear improvement and this finding is an important contribution to the methodology of using this structure for ageing the full‐length range of eastern T. thynnus. Finally, there were no significant differences between the coefficients of von Bertalanffy growth model estimated from mean length at age data (L_∞ = 327·4; k = 0·097; t₀ = −0·838) and those estimated from the growth curves accepted for the eastern and western T. thynnus management units.