A comparison of variability and bias when ageing Northeastern Atlantic minke whales (Balaenoptera acutorostrata) by counting growth layer groups in the mandible and bulla tympanica

The age of 43 minke whales (Balaenoptera acutorostrata) was estimated by counting growth layer groups (GLGs) GLGs in 500um thick haemotoxylin stained transverse sections of left and right mandible. The same whales were also aged by counting GLGs in 150um unstained sections of left and right bulla tympanica. The staining and preparation methods were also used to prepare and stain mandible sections of a sperm whale and the GLG count of this was the same as the GLG count of a longitudinal section of a tooth from the same animal. Minke whale mandible age estimates had higher CV (63% on average) than the bulla age estimates (36% on average). Comparing the age estimates with the number of ovulations revealed that both methods underestimated the true age of the whales

Seal investigations in the North Atlantic in 1974

Accounts are given of weather and ice conditions, the distribution of seals and of sampling of harp and hooded seals at Newfoundland-Labrador, in the West Ice (at Jan Mayen), in the East Ice (in the Eastern Barents Sea) and in the Denmark trait. A few provisional results of age analysis are given. Some observations from the coast of Norway suggest increasing numbers of local common and grey seals

Seal investigations in the North Atlantic in 1974

Accounts are given of weather and ice conditions, the distribution of seals and of sampling of harp and hooded seals at Newfoundland-Labrador, in the West Ice (at Jan Mayen), in the East Ice (in the Eastern Barents Sea) and in the Denmark Strait. A few provisional results of age analysis are given. Some observations from the coast of Norway suggest increasing numbers of local common and grey seals

Seal investigations in the North Atlantic in 1972

Accounts are given of field work at Newfoundland—Labrador, in the Jan Mayen area of the Greenland Sea (West Ice), in the southeastern Barents Sea (East Ice) and in the Denmark Strait to collect material and data for studies of harp and hooded seals. The distributions of seals and ice are shown on maps

Investigations of common seals (Phoca vitulina) and grey seals (Halichoerus grypus) in Rogaland and Finnmark counties Norway, in 1981

The outer coastline from Bømlafjorden to Jæren and Lysefjorden in Rogaland were surveyed 29 May-5 June. Another survey was carried out on the coast of Finnmark from Varangerfjorden to Sørøya 26 June-7 July 1981. In Rogaland a total of 75 common seals was recorded. The seals were most abundant in the Kvitsøy-Håsteinen area (38 seals) and in Lysefjorden (27 seals). In Kongsfjorden, Finnmark, 23 pups were observed (corresponding to a total stock in excess of 100 seals). Another colony of common seals was found at Sørøya (20 seals), and common seals were also seen in Varangerfjorden, Tanafjorden and Kobbfjorden. Concentrations of grey seals were found in the Espevær-Utsira area (36 seals) and at Kjør (60 seals) in Rogaland, and in Syltefjorden (40 seals) and at Sørøya (70 seals) in Finnmark. Scattered seals or small groups were also seen outside these areas. Due to adverse weather conditions very few common seals were observed during the surveys, and the numbers recorded probably are significantly lower than actual stocks. So far, the available data are insufficient to assess the stocks of common seals in Rogaland and Finnmark. However, the observations of grey seals indicate an increase from assessed stocks in the early 1960-ies. Stomachs from a total of ten common seals and nine grey seals were examined during the surveys. Haddock, sand eels and flatfishes were identified in the common seals, while the grey seal stomachs contained catfish, saithe, haddock, herring, lumpsucker, sand eels and flatfishes. The maximum volume of stomach contents found in a common sea1 was 4 1, and volumes up to 6 l were recorded in grey seals. The average infestation of parasitic nematodes in the stomachs of examined common seals was 64 worms, while the average infestation in the grey seals was 492 worms. An aerial survey to count whitecoated grey seal pups was carried out 7 November in Rogaland. No pup or concentration of grey seals was observed, and if grey seals do produce pups in Rogaland, pupping probably occurs in early Octoher. Aerial surveys were also carried out along the coast of Finnmark 28 and 29 October. No grey seal pup was found, and the surveys were repeated 17-20 November. At that time concentrations of grey seals were ohserved on shore at the presumed breeding localities. It therefore seems likely that pupping in Finnmark occurs later than 20 November

Selundersøkelser i det nordlige Atlanterhav i 1974

Accounts are given of weather and ice conditions, the distribution of seals and of sampling of harp and hooded seals at Newfoundland-Labrador, in the West Ice (at Jan Mayen), in the East Ice (in the Eastern Barents Sea) and in the Denmark trait. A few provisional results of age analysis are given. Some observations from the coast of Norway suggest increasing numbers of local common and grey seals

Seal investigations in the North Atlantic in 1973

Accounts are given of weather and ice conditions, the distribution of seals and sampling of harp and hooded seals at New foundland-Labrador and in the Jan Mayen area of the Greenland Sea through the sealing season in March—April. Information on harp seals and sealing in the southeastern Barents Sea has been compiled from journals kept by four sealing vessels, Bearded seals were studied in the waters of Svalbard in July— August. On this expedition some 350 walruses were recorded and a local population of common seals was sampled for identification

Selundersøkelser i det nordlige Atlanterhav i 1973

Accounts are given of weather and ice conditions, the distribution of seals and sampling of harp and hooded seals at New foundland-Labrador and in the Jan Mayen area of the Greenland Sea through the sealing season in March—April. Information on harp seals and sealing in the southeastern Barents Sea has been compiled from journals kept by four sealing vessels, Bearded seals were studied in the waters of Svalbard in July— August. On this expedition some 350 walruses were recorded and a local population of common seals was sampled for identification