[MARMAM] Habitat characterization of two populations of bottlenose dolphins
Dear All, For those who might be interested, the following paper was recently published: VÁZQUEZ-CASTÁN, L., SERRANO, A., LÓPEZ-ORTEGA, M., GALINDO, J.A., VALDES-ARELLANES, M. NAVAL-ÁVILA, C. 12007. Habitat characterization of two populations of bottlenose dolphins (Tursiops truncatus Montagu 1821) in the Northern coast of the State of Veracruz, Mexico. UDO Agrícola. 7(1): 285-292. ABSTRACT Marine mammals require special habitat characteristics for their reproduction, breeding and feeding. There are no studies regarding marine mammal habitat characterization in the northern coast of the state of Veracruz, Mexico. The goal of this study was to characterize the habitat of two populations of bottlenose dolphins (Tursiops truncatus, Montagu 1821) along the northern coast of Veracruz, Mexico. The study area was divided into two zones: Tamiahua, and Tuxpan; 22 boat-based surveys were carried out during 18 months, and dolphins where sighted in 16 of these surveys. The environmental variables measured included: depth, bottom type, sea surface temperature, salinity, pH, sea conditions, conductivity, salinity and total dissolved solids. Also, we estimated chlorophyll concentration (mg/m3) using images obtained by the SeaWifs satellite. The main factors that characterized bottlenose dolphins habitat for these 16 sightings were: bottom type, water depth, sea conditions and chlorophyll concentration. In all the areas dolphins preferred the sandy bottom over other bottom types. Mean bottom depth for sightings were observed was 25,9 m (s.d. ±18,33) in Tamiahua, and 28,9 m (s.d. ±26,50) in Tuxpan. Mean chlorophyll concentration for dolphin sighting locations were 663,6 mg/m3 (s.d. ±871,08) in Tamiahua, and 1.579,63 mg/m3 (s.d. ±1525,68) in Tuxpan. This study shows that there are differences in habitat characteristics among the two bottlenose dolphins populations studied. Key words: Habitat characterization, population, bottlenose dolphins, bathymetry, physical-chemical parameters. __ Dr. Arturo Serrano Laboratorio de Mamíferos Marinos Universidad Veracruzana km 7.5 Carretera Tuxpan-Tampico C.P. 92850 Tuxpan, Veracruz MEXICO Cel.: (783) 112 0346 ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] new paper on manatee status in Mexico
Dear colleagues, A new paper was recently published in the Latin American Journal of Aquatic Mammals: SERRANO, A., GARCÍA-JIMÉNEZ, A. AND GONZÁLEZ-GÁNDARA. 2007. HAS THE MANATEE (TRICHECHUS MANATUS) DISAPPEARED FROM THE NORTHERN COAST OF THE STATE OF VERACRUZ, MEXICO? LAJAM 6(1): 109-112. ABSTRACT: Knowledge about the distribution and abundance of the manatee (Trichechus manatus) along the coast of the Mexican state of Veracruz is scarce. Since few studies have been undertaken in this area, boat-based surveys and interviews with local fishermen were carried out to determine if there are remaining herds of manatees in the vicinity of the coastal towns of Tamiahua, Tuxpan, Tecolutla, and Casitas-Nautla. All of the fishermen interviewed noted that they used to see large herds of manatees in the area. Seventy-four percent (371 fishermen) of the survey respondents had not seen a manatee over the last 10 years, and 26% (131 fishermen) responded that the last time they saw large or small groups of manatees was in 1986 and 1995, respectively. However, since 1996, none of the fishermen had observed any manatees in the area. Similarly, no manatees were observed during the boat-based surveys (effort of approximately 1200km). It is almost certain that anthropogenic influences have altered manatee habitat significantly and thus affected the numbers of animals using the area. Also, fishermen speculated that natural phenomena such as cyclones, flooding, and storms caused manatees to move away from the area. More surveys along the coast of Veracruz are needed to determine if manatees still occur in this Mexican state. Also, it is urgent to implement conservation measures in the northern range of the manatee in Mexico to ensure the survival of this species along its original distribution. KEYWORDS: manatee, Trichechus manatus, population status, conservation, Gulf of Mexico Please send PDF requests to: [EMAIL PROTECTED] [EMAIL PROTECTED] __ Dr. Arturo Serrano Laboratorio de Mamíferos Marinos Universidad Veracruzana km 7.5 Carretera Tuxpan-Tampico C.P. 92850 Tuxpan, Veracruz MEXICO Cel.: (783) 112 0346 ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
