Latin American Journal of Aquatic Mammals (LAJAM)
Not a member yet
358 research outputs found
Sort by
Diet of the manatees (Trichechus manatus manatus) in Chetumal Bay, Mexico
No full textManatees, as well as other sirenians, are aquatic, opportunistic herbivores. Knowledge of their diet is important to determine habitat requirements. This is the first study of manatee diet in México. Our main objective was to identify the plant species eaten by manatees in Chetumal Bay, and to establish if diet composition varied by climatic season, sex or age class. We compared plant epidermal fragments found in feces with histological descriptions and permanent collections of suspected plants and algae. Thirty-six fecal samples and nine tract digestive content samples (mouth, stomach, and cecum) were examined. We found eight distinct plant items, including seagrasses, freshwater grasses, algae and vascular plants. Halodule wrightii and Thalassia testudinum were found in 41 samples (92%), and Ruppia sp. was present in 57.8%. Another common item was red mangrove (Rhizophora mangle), found in 66.7% of samples. Additionally, we report Chara sp. and Najas sp. as part of the West Indian manatee's diet outside of Florida. A multivariate analysis based on a presence/absence triangular matrix and a similarity analysis were used to test differences among samples. Season, sex or age class did not influence diet composition. All species identified are present in Chetumal Bay, suggesting that manatees do not move long distances at sea in search of food. We postulate that consumption of red mangrove by Chetumal Bay manatees may occur as compensation for the scarcity of submersed aquatic plants, which has not been reported for other habitats for this species
By-catch of franciscana Pontoporia blainvillei in Uruguayan artisanal gillnet fisheries: an evaluation after a twelve-year gap in data collection
No full textThe franciscana dolphin (Pontoporia blainvillei) is the most threatened small cetacean in the southwestern Atlantic Ocean. Its incidental capture in the Uruguayan fisheries of the Atlantic oceanic coast (AOC) has been recorded since 1940 and was systematically studied from 1974 to 1994, providing the most recent by-catch per unit of effort estimate (BPUE) for the AOC region (0.0064 franciscanas per 1000m net per fishing set). The lack of new by-catch data during the past 12 years has led to a data gap in by-catch estimates for the species in Uruguay. The current study was developed in two separate stages, a first stage (July 2004 - December 2005) designed to identify fisheries that interact with franciscana, and a second stage (2006), designed to determine new BPUE and franciscana mortality estimates for the selected fisheries. During the first stage, 13 artisanal fisheries of the Uruguayan coast were visited monthly, while in the second stage five fisheries (including the Rio de la Plata estuary and the AOC) were selected for monitoring. During 2006, 26 fishermen recorded all the information related to each fishing event, allowing the estimation of fishing effort calculated in linear units multiplied by hour (FEL). We also estimated a fishing set (FES) based by-catch rate which allowed the comparison with previously reported results. For 2006, the BPUEL (based on FEL) was estimated at 0.0020 franciscanas per 1000m net per hour and the BPUES at 0.0286 franciscanas per 1000m net per fishing set. The BPUEL was extrapolated to the surveyed fishing fleets during 2006, resulting in a mortality estimate of 289 (95% CI: 266-350) franciscanas. Based on the fishing dynamics reported herein, we consider the BPUEL the most accurate estimate of by-catch for the Uruguayan coast. This research updates the values of BPUE in the AOC after a 12-year information gap and includes the first by-catch evaluation in the Uruguayan estuarine coast. We highly recommend an abundance estimation of the species to complement the information reported herein in order to know the current status of franciscana dolphin population in Uruguay
Photo-identification of the vaquita (Phocoena sinus): the world's most endangered cetacean
No full textThe false killer whale (Pseudorca crassidens) in the southwestern Caribbean: first stranding record in Colombian waters
No full text
Incidental capture of a spinner dolphin, Stenella longirostris (Gray, 1828), in a shark gillnet off southeastern Brazil
No full text
The odontocete community and its environment in the southwestern Gulf of California
No full textCommunity structure is a function of the number of species, their relative abundance and the characteristics of the dominant, common and rare species that are part of it. It also can be described by changes in its physical and biological environment. The aim of the present work is to describe the odontocete community, its temporal changes and the relationship with environmental variability and food availability in the southwestern Gulf of California (GC). Information was obtained from 21 sampling trips from September 2003 to March 2006 between La Paz Bay and Loreto, with a sampling effort of 8769.1km. We recorded the presence, location and other biological parameters of odontocete sightings. Data on environmental variability was obtained from satellite images of sea surface temperature and chlorophyll concentration, and food availability from published reports. A total of 30201 odontocete cetaceans were recorded from 353 sightings, belonging to 10 different species. We observed a temporal lag between the peaks in productivity and an increased presence of odontocete species. The community structure showed a seasonal change in the abundance of the dominant (Tursiops truncatus and Delphinus sp.) and common species (Globicephala macrorhynchus and Kogia sp.), as well as by the absence or presence of scarce (Physeter macrocephalus and Orcinus orca) and rare species (Pseudorca crassidens and Lagenorhynchus obliquidens). This seasonal community change is in agreement with the known seasonal movements of its main prey inside the GC, which, in turn, is related to seasonal environmental variation. We observed that the community structure was dominated by fish-eating species during the temperate season and responded to the increased presence and aggregation of sardines (Sardinops sagax caerulea) in the southern GC, whereas the warm season was dominated by squid-eating species and related to the increased presence and aggregation of the jumbo squid (Dosidicus gigas) in the GC's west coast