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Passive acoustic monitoring (PAM) has become a popular method for studying both marine mammal behavior and distribution, especially among cetaceans. The Antarctic minke whale (Balaenoptera bonaerensis) occurs in the Southern Hemisphere, and our knowledge concerning its vocal behavior is very limited. Along the coast of Uruguay, minke whales constitute one of the species with the most stranding data collected. Until now, sounds of Antarctic minke whales had never been recorded off the Uruguayan coast. Two different bio-duck call types were recorded along the Atlantic Ocean and the Río de la Plata River coasts by employing PAM stations off the coast of Uruguay in five different positions. One call was recorded off the Atlantic coast, and the four other calls were recorded along the Río de la Plata River, including the classic bio-duck call. In addition to the aforementioned bio-duck call, evidence of a novel call, the bio-duck pulse train, was found. This call was produced in an environment very different from the oceanic environment. The bioduck pulse train has never been described in previous works, making the findings of the present work all the more novel. [ABSTRACT FROM AUTHOR]

Paralichthys species have high commercial value and constitute a resource for demersal fisheries in the Southwestern Atlantic Ocean. Although six species have been described based on morphological characters for the Uruguayan and Argentinean waters, only the presence of three species is accepted, being their distribution still uncertain. Genetic tools are useful for species identification as a complement of morphological characters. This paper determines the genetic and morphometric variation between three species of Paralichthys that inhabiting Uruguayan waters. The interorbital width (IN) and the length from the mouth to the dorsal fin base (SD) of P. patagonicus differed significantly from the other two species (P. orbignyanus and P. brasiliensis). From a morphological perspective, individuals identified as P. orbignyanus formed two different groups. Clade Po_A included those belonging to oceanic coastal waters of Uruguay and deeper waters of the Rio de la Plata together with individuals of P. brasiliensis from ItajaÃ-, Santa Catarina (Brazil). Individuals collected in the Rio de la Plata coastal and beach zone formed the clade Po_B group. Genetic analysis confirmed for the first time the presence of P. brasiliensis in Uruguayan and Rio de la Plata shelf waters and extends its known distribution area further south. Discriminant scores for P. orbygnianus separate individuals in two groups corresponding to the presence of two species. Molecular and morphological analysis showed individuals in the clade Po_A includes those collected in Uruguayan waters together with those collected in northern Brazilian waters belonging to the species P. brasiliensis. [ABSTRACT FROM AUTHOR]

Many species of fishes use acoustic signals for a variety of purposes, and sciaenid are well-known producers of sound. The Southern King Weakfish (Macrodon atricuada- Sciaenidae) possesses sexually dimorphic bilateral sonic muscles used for sound production. The bilaterally paired muscles lie on the inner body wall of the male, surrounding the swimbladder. The Southern King Weakfish produces three different sounds: advertisement calls, disturbance calls and dual-knocks, these sounds were recorded from Rio de la Plata estuary, Uruguayan coastal waters and laboratory. The advertisement call, related to courtship, was recorded in the field and from spawning males in the laboratory. Disturbance calls were produced when captive M. atricauda were startled, chased with a net or grabbed by the tail. Disturbance calls consist of a burst of pulses produced at short intervals. In disturbance call interpulse interval increased and dominant frequency decreased linearly (P < 0.05), pulse duration did not change with fish size. M. atricauda start producing disturbance call at 14 cm LT (Total Length), but only individuals over than 25 cm LT were who produced the advertisement call. Dual-knocks, call compose of only two pulses together, was recorder only in captivity. Sounds are a valuable non-invasive tool for fisheries biologists can used to monitor on males in spawning populations. [ABSTRACT FROM AUTHOR]

The article presents a study on difference on the disturbance and advertisement calls between the Northern and Southern hemisphere populations of black drum (pogonius cromis). It states that the sounds produced by fishes from Rio de la Plata estuary, Atlantic Ocean, and Southwest Florida were compared. It says that the disturbance and advertisement calls, its changes with fish size, and sex were quantified. It mentions that both sexes have robust sonic muscles and produce disturbance calls when they are handled. It says that the duration, dominant frequency of pulses, and interpulse interval in males and females are similar and changes developmentally because there is an increase and decrease in the interpulse interval and dominant frequency, respectively depending on the fish size.