Daniel Danilewicz

Respiration is a key physiological process in cetaceans, closely linked to energy expenditure, behavior, and physiological state. Using drone‐based surveys, we quantified respiration patterns of southern right whale ( Eubalaena australis ) mother–calf pairs in southern Brazil across two reproductive seasons (2020–2021). Based on over 100 h of observation from 43 identified pairs, we found marked differences between classes: respiration rates were 2.6‐fold higher in calves than their mothers, with median respiration rates of 1.8 and 0.7 breaths per minute, respectively. Respiration rates were significantly influenced by behavioral state, surface duration, and individual identity, decreasing during resting behavior and longer surface intervals. No statistically significant seasonal variation in respiration rates was detected. Comparative analyses revealed that lactating females in Brazil and Argentina exhibited similarly elevated respiration rates, both exceeding those reported for Australian females, suggest population‐level differences that are not solely explained by local environmental conditions. In contrast, calf respiration rates were highest in Argentina, potentially reflecting the combined effects of kelp gull harassment and colder water temperatures. Our findings demonstrate the sensitivity of respiration to behavioral, physiological, and environmental drivers and highlight the value of drone‐based observations for advancing physiological and conservation monitoring of baleen whales.

Gillnet bycatch is the primary global threat to marine mammals. In this study, the effectiveness of upcycled plastic bottles used as acoustic reflectors to reduce dolphin bycatch and their effect on target catch was evaluated. Observed trials with (treatment) and without (control) bottles in bottom‐set trammel nets and bottom‐set gillnets were conducted between November/2020 and April/2025. Across 318 sets (170 control; 148 treatment), bycatch per unit effort (BPUE; based on net length × soak time) was 7.14 × 10 ⁻⁷ in control sets and 0.86 × 10 ⁻⁷ in treatment sets, representing an 88% reduction in BPUE when acoustic reflectors were used. Mean catch of target species did not differ significantly between control (=107 ± 92 kg) and treatment (=118 ± 141 kg) sets. Acoustic monitoring showed that average franciscana dolphin ( Pontoporia blainvillei ) click detections, measured as detection positive minutes (DPM), did not differ significantly between control (DPM = 0.0125) and treatment (DPM = 0.0128) sets. These results demonstrate that plastic bottles used as acoustic reflectors in bottom‐set trammel nets and gillnets reduced the bycatch of dolphins and had no effect on the catch of target species. Given its low cost and lack of impact on target‐species catch, this method can be readily tested in other regions and, if effective, widely adopted to improve the conservation of coastal dolphin species.

Understanding animals' movements is essential to assess habitat use, life‐history strategies, and population dynamics. Here, we investigate the movement and behavior patterns of 153 humpback whales in the Southwest Atlantic Ocean (SWA) using data obtained by satellite telemetry between 2003 and 2019 during the species' breeding season (August–December) off the Brazilian coast. Switching state space models were applied to estimate behavior states (bmode) classified as Area Restricted Search (ARS), Transiting (TRANS), or uncertain. Whales were distributed from 4°S to 24°S, and five clusters of ARS behavior were identified along the Brazilian coast. Generalized linear mixed modeling revealed three main results: (1) a transition towards more sinuous behavioral states with increasing latitude; (2) more sinuous movement behavior around new moons; (3) movement behavior was temporally dynamic throughout the breeding season over the years, particularly in 2019. The results then revealed important regions where humpback whales cluster to engage in mating and nursing behaviors, highlighting the influence of spatial location and environmental cycles on their behavior. Estimated movement behavior presented here improves the knowledge about the habitat use and movement patterns of SWA humpback whales in their breeding ground and can be used to mitigate potential human‐related impacts.

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Age is one of the most important life history parameters required to understand the dynamics of mammalian populations. Growth Layers Groups (GLGs) are incremental units of calcified tissue in the teeth (dentine and cementum), which represent a pattern of cyclical deposition that can be counted. However, the estimation of absolute age in GLGs demands a skull with teeth, the permission to destroy part of a tooth, equipment to cut the teeth, and experienced GLGs readers. In 1954 Sivertsen proposed an alternative method using cranial suture age (CSA) to establish age categories. However, there are no studies validating the CSA in relation to GLGs. Thus, this study examined whether there is a correlation between age categories proposed by the CSA and chronological age in years from GLGs of South American fur seals (Arctocephalus australis) (N = 52) and of South American sea lions (Otaria flavescens) (N = 37). 93% of the skulls ofA. australisand 83.8% ofO. flavescenscorresponded accurately to the age in years estimated by each cranial suture age range. These results indicated the existence of high correspondence between the CSA and the GLGs age (r: 0.491 forA. australisandr: 0.675 forO. flavescens). However, an adaptation to Sivertsen's method is recommended: using only eight sutures (excluding the premaxillary-maxillary suture for CSA analysis, due to its late fusion), and updating the intervals for cranial sutures, that correspond to 16–32 = adults, 11–15 = young and 8–10 = pups.

The southern right whale (SRW), Eubalaena australis, was heavily depleted by the whaling in the Southern Hemisphere. In the southwestern Atlantic, studies on SRWs have been concentrated in two main breeding grounds: Península Valdés, Argentina (~42°′S) and Santa Catarina (SC) State, Brazil (~28°′S). To better understand the ecology of SRWs in the region located between these breeding grounds, shore-based surveys were carried out off Torres (29°19′S, 49°43′W), Rio Grande do Sul (RS). Whales were observed in the area between July and October with peaks in August and September. Group sizes were relatively small (x̅=1.6; range=1–3). Distribution in relation to distance from the coast varied from 0.5 to 8.9 km (median=1.9 km). Unlike in other areas, mother-calf pairs were not observed to occur in shallower waters more often than unaccompanied whales. Mother-calf pairs presented northbound movements to SC more frequently than unaccompanied whales. A comparison of the present data with those from Uruguay and SC revealed that SRWs of different gender/reproductive status may use distinctively the eastern coast of South America. Within these regions, the proportion of mother-calf pairs increases progressively as latitude decreases (from 8% in Uruguay to 58.5% in SC), while the proportion of unaccompanied SRWs presents an opposite trend. This study indicates that RS is an important area for reproduction of SRWs because the three phases (birth, nursing, and mating) proposed for a breeding ground occur there.