Jorge Gibbons

Abundance estimation of Commersons dolphin in the eastern area of the Strait of Magallan-Chile

Se presentan los resultados de un muestreo de transectos lineales de abundancia de tunina overa Cephalorhynchus commersonii (Lacepede 1804) en el sector oriental del Estrecho de Magallanes realizados durante el otono de 1996. El area se sobrevolo en helicoptero a 100 m de altitud y 129 km h -1 a lo largo de 818,6 km, observandose un total de 98 animales en 58 avistamientos, con un tamano grupal promedio de 1,7 (SD = 0,13). La densidad fue de 0,34 ind km -2 (CV = 0,27) y el tamano poblacional de 1206 (95% c.i. 711 - 2049 individuos). Se observo que la tunina overa presenta mayor preferencia por las angosturas que por las aguas abiertas del area de estudio

Migratory round-trip of individually identified humpback whales at the Strait of Magellan: clues on transit times and phylopatry to destinations

La ballena jorobada migra estacionalmente entre latitudes altas donde se alimenta en verano y latitudes bajas donde cria y se aparea en invierno. En el Pacifico sureste, la especie se reproduce en Colombia y Ecuador y se alimenta principalmente al oeste de la peninsula Antartica, y en el estrecho de Magallanes (EM) recientemente descrito como nueva area de alimentacion. Al comparar las fotografias de las colas de 62 ballenas individualizadas en el EM durante el verano austral entre 1999 y 2005 con 1.042 individuos de Colombia, se encontro a seis individuos comunes, lo que representa un indice de Intercambio migratorio de 0,093. Se registraron ocho migraciones para cuatro de estas ballenas entre el EM y Colombia en el ciclo migratorio de anos consecutivos. La distancia minima recorrida en una sola direccion vario entre 6.650 y 7.000 km. La duracion de los dos viajes mas rapidos registrados entre estos dos destinos fue de 88 y 99 dias, con una velocidad promedio de migracion de 76 y 67 km dia-1 respectivamente. Cinco de las seis ballenas comunes entre las areas fueron machos. Entre las seis ballenas se encontraron tres haplotipos de ADN mitocondrial todos descritos previamente en ballenas jorobadas de Colombia: tres ballenas con el haplotipo EM-1, dos con el EM-2 y uno con el EM-3. Los seis individuos se avistaron reiteradamente en el EM (hasta 39 dias en una estacion en un caso), con una permanencia promedio de 72 ± 40 dias (n = 20) por ano y un rango entre 3 y 125 dias. En promedio, estas seis ballenas se vieron durante el 71 ± 18 % de las siete temporadas muestreadas en el EM y tres se registraron seis de lo siete anos estudiados, por 4-6 anos consecutivos. Esta es la primera evidencia directa para incluir las ballenas jorobadas que se alimentan en el estrecho de Magallanes como parte de la poblacion del Pacifico sureste que se reproduce en aguas colombianas.

DIVERSIDAD Y DISTRIBUCIÓN ESTIVAL DE CETÁCEOS EN AGUAS INTERIORES DEL NORTE DE AISÉN, CHILE

Galletti, B., C. Carlson, E. Cabrera & R.L. Brownell Jr. 2006. Blue, sei and humpback whale sightings during 2006 field season in northwestern Isla de Chiloe, Chile. Paper SC/58/SH17 presented to the International Whaling Commission Scientific Committee, St. Kitts and Nevis, May 2006 (unpublished). 6pp.

DISTRIBUCIÓN DE LA BALLENA FRANCA EUBALAENA AUSTRALIS (DESMOULINS, 1822) DEL ATLÁNTICO SUROCCIDENTAL CERCA DEL ESTRECHO DE MAGALLANES

formerly occurred in very large numbers in the Southern Hemisphere, particularly in coastal waters of the southern part of Australia, New Zealand, American and African continents, as well as in most of the islands between 30°S and 60°S (Townsend 1935, Matthews 1938, Dakin 1963). It has been estimated that by the beginning of its exploitation (late XVIII century), there were between 60,000 and 160,000 individuals. However, severe depletion of this species by commercial whaling may have reached as low as 200-300 individuals by 1920 (Anonymous 2001, Jackson et al. 2007).Off both Pacific and Atlantic coast of South America southern right whales were caught extensi-vely (Townsend 1935). Historical whaling accounts from Chile referred to a well known catching ground called the “Coast of Chile Ground”. This stock of whales seems have been distributed between 30°S and 50°S (Townsend 1935). Based on the logbooks of Yankee and French whalers, and on Chilean whaling catch data it has been estimated that around 9,000 individuals were hunted there between 1785 and 1976 (Aguayo-Lobo et al. submitted

HÁBITAT REPRODUCTIVO Y ESTIMACIÓN DEL TAMAÑO POBLACIONAL DEL PINGÜINO DE MAGALLANES (SPHENISCUS MAGELLANICUS) EN ISLA RUPERT, PARQUE MARINO FRANCISCO COLOANE, ESTRECHO DE MAGALLANES

Tellez. L. Estimacion de la abundancia, exito reproductivo y calendarizacion del ciclo reproductivo en areas con y sin visitantes en la colonia de Spheniscus magellanicus del seno Otway, Provincia de Magallanes. Chile (2005). Tesis de Tecnico Agropecuario no publicada. Universidad de Magallanes 87 pp.Recibido: Mar., 16, 2009 Aceptado: Jun., 30, 2009

Home sweet home: social dynamics and genetic variation of a long-term resident bottlenose dolphin population off the Chilean coast

Coastal resident and pelagic nonresident bottlenose dolphins, Tursiops truncatus , have been described in north-central Chile. Using long-term residence data (over 13 years of photo-identification) and genetic mtDNA information, we analysed the social dynamics through time and the genetic variation of this long-term resident population, and evaluated its sociogenetic interaction with nonresidents. Pelagic nonresident dolphins exhibited a higher level of genetic diversity than coastal residents and a significant difference in genetic structure was detected between them. Based on the difference in haplotype numbers and frequencies between resident and nonresident populations and between resident males and females, we propose a population dynamic model in which the resident population is composed of (1) resident females (founder lineages) and some of their female descendants that were born in and remained in the group, without effective female immigration from the nonresident population, (2) resident male descendants of the founder lineage that were born in and remained in the group and (3) resident males that were incorporated from the pelagic groups. Male-biased migration from nonresident pelagic groups into the resident population likely contributes to genetic variation and therefore may help limit inbreeding in the resident population. Finally, we propose that the peripatric model of population differentiation, where resident groups are sporadically connected to the pelagic population, may explain the origin of this unique resident population of bottlenose dolphins along the Chilean coast.