1. We summarize fin whale Balaenoptera physalus catch statistics, sighting data, mark recoveries and acoustics data. The annual cycle of most populations of fin whales had been thought to entail regular migrations between high-latitude summer feeding grounds and lower-latitude winter grounds. Here we present evidence of more complex and varied movement patterns. 2. During summer, fin whales range from the Chukchi Sea south to 35°N on the Sanriku coast of Honshu, to the Subarctic Boundary (ca. 42°N) in the western and central Pacific, and to 32°N off the coast of California. Catches show concentrations in seven areas which we refer to as 'grounds', representing productive feeding areas.3. During winter months, whales have been documented over a wide area from 60°N south to 23°N. Coastal whalers took them regularly in all winter months around Korea and Japan and they have been seen regularly in winter off southern California and northern Baja California. There are also numerous fin whale sightings and acoustic detections north of 40°N during winter months. Calves are born during the winter, but there is little evidence for distinct calving areas. 4. Whales implanted with Discovery-type marks were killed in whaling operations, and location data from 198 marked whales demonstrate local site fidelity, consistent movements within and between the main summer grounds and long migrations from low-latitude winter grounds to high-latitude summer grounds. 5. The distributional data agree with immunogenetic and marking findings which suggest that the migratory population segregates into at least two demes with separate winter mating grounds: a western ground off the coast of Asia and an eastern one off the American coast. Members of the two demes probably mingle in the Bering Sea/Aleutian Islands area. 6. Prior research had suggested that there were at least two non-migratory stocks of fin whale: one in the East China Sea and another in the Gulf of California. There is equivocal evidence for the existence of additional non-migratory groups in the Sanriku-Hokkaido area off Japan and possibly the northern Sea of Japan, but this is based on small sample sizes.

Resumen. Cuantificar la heterogeneidad genética poblacional dentro de agregaciones no reproductivas puede brindar información sobre patrones de fidelidad a los sitios, conectividad migratoria y flujo génico entre áreas reproductivas y no reproductivas. Sin embargo, antes de poder evaluar con precisión la fidelidad al sitio y la conectividad migratoria es necesario caracterizar los mecanismos que contribuyen a la heterogeneidad, como la migración y la dispersión. Estudiamos grupos no reproductivos de Mergus merganser que se encontraban mudando en la isla Kodiak, Alaska, desde 2005 a 2007, usando datos de anillado para evaluar las tasas de recaptura, ADN mitocondrial (mt) para determinar el área natal y genotipos de microsatélites nucleares para evaluar la dispersión. Utilizando información de base de haplotipos de ADNmt de haplogrupos de ADNmt diferenciados a lo largo de América del Norte, pudimos asignar a los individuos a regiones natales y documentar la heterogeneidad genética poblacional dentro y entre grupos de muda. Los datos de recuperación de anillos y de ADN sugieren que tanto la migración desde las áreas natales como la dispersión entre ellas contribuyen a la conformación de grupos entremezclados de machos que mudan en la isla Kodiak. La falta de diferenciación en el ADN nuclear (de herencia biparental) de M. merganser observada a lo largo de América del Norte, implica que la dispersión puede confundir las evaluaciones genéticas de conectividad migratoria y la asignación de individuos no reproductivos a áreas reproductivas. Por lo tanto, antes de que se puedan hacer evaluaciones precisas de conectividad migratoria, se necesitan datos múltiples e independientes para explicar estos comportamientos. MEChANISMSOf POPULATION hETEROgENEITy AMONg MOLTINg COMMON MERgANSERS ON KODIAK ISLAND, ALASKA: IMPLICATIONS fOR gENETIC ASSESSMENTS Of MIgRATORy CONNECTIVITy Mecanismos de heterogeneidad Poblacional entre Individuos de Mergus merganser que Mudan en la Isla Kodiak, Alaska: Implicancias para las Evaluaciones genéticas de la Conectividad MigratoriaAbstract. Quantifying population genetic heterogeneity within nonbreeding aggregations can inform our understanding of patterns of site fidelity, migratory connectivity, and gene flow between breeding and nonbreeding areas. however, characterizing mechanisms that contribute to heterogeneity, such as migration and dispersal, is required before site fidelity and migratory connectivity can be assessed accurately. We studied nonbreeding groups of Common Mergansers (Mergus merganser) molting on Kodiak Island, Alaska, from 2005 to 2007, using banding data to assess rates of recapture, mitochondrial (mt) DNA to determine natal area, and nuclear microsatellite genotypes to assess dispersal. Using baseline information from differentiated mtDNA haplogroups across North America, we were able to assign individuals to natal regions and document population genetic heterogeneity within and among molting groups. Band-recovery and DNA data suggest that both migration from and dispersal a...

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ABSTR^CT.--Concerns about Harlequin Duck (Histrionicus histrionicus) population recovery following the Exxon Valdez oil spill led biologists to ask whether birds located in different molting and wintering areas belong to genetically distinct and, thus, demographically independent populations. Owing to the lack of direct observations of movements among marine areas, three classes of genetic markers that differed in mode of inheritance were used to evaluate the degree of genetic differentiation among wintering areas within Prince William Sound (PWS) and the Alaska Peninsula and Kodiak Archipelago (APKA). We could not reject the null hypothesis that the wintering aggregations within each region are composed of a single genetically panmictic population. Differences in genotype frequencies among wintering locations within PWS and APKA were low and nonsignificant for all three classes of markers. Furthermore, we saw no evidence for deviations in Hardy-Weinberg equilibrium or gametic disequilibrium between loci within a winter collection site as would be expected if these locales were composed of individuals from reproductively isolated (and genetically distinct) breeding locales. Finally, no evidence for significant structuring was noted between PWS and APKA. Lack of spatial genetic structuring could be due to the cumulative effects of low levels of gene flow over long time periods, low levels of gene flow by immature birds moving between marine habitats, or to episodic dispersal caused by habitat alteration (e.g. volcanic eruptions). Harlequin Ducks are likely to recolonize or enhance populations in areas recovering from environmental damage via emigration of birds from non-affected areas.Demographic studies suggest, however, that levels of movements are low, and that population recovery by emigration is a long-term process.