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Simple Summary: Dolphins alter their behavior and movement in response to human coastal activities (e.g., commercial shipping, dredging, ecotourism). The Port of Corpus Christi, Texas, is the largest port in the USA based on total revenue tonnage, yet little research has been conducted on the local bottlenose dolphins since the 1980s, prior to major oil exportation and infrastructure growth. The behavior and movement patterns of dolphins in the presence and absence of vessels were recorded using a shore-based digital theodolite and analyzed using multinomial logistic regression and generalized additive models. Dolphins frequently foraged, traveled, socialized, and milled in the Corpus Christi Ship Channel despite the presence of one or more vessels within 300 m of dolphins during 80% of observations. Dolphin behavior and movement patterns were significantly affected by season, time of day, group composition, and vessel characteristics. Dolphins appear to remain in the active Texas ship channel despite high vessel traffic. The observed dolphin–vessel interactions emphasize the need for long-term monitoring of dolphins near human activities and enforced boating regulations near important marine mammal habitats. Although the Port of Corpus Christi, Texas, has become a top oil exporter, it is unknown if local dolphins are disturbed by high year-round vessel traffic. A shore-based digital theodolite and automatic identification system receiver were used to record data to assess common bottlenose dolphin (Tursiops truncatus) behavioral states and movement patterns in the Corpus Christi Ship Channel (CCSC) in relation to vessel traffic. Multinomial logistic regression and generalized additive models were applied to analyze the data. Vessels were present within 300 m of dolphins during 80% of dolphin observations. Dolphins frequently foraged (40%), traveled (24%), socialized (15%), and milled (14%), but rarely oriented against the current (7%) or rested (1% of observations). Season, time of day, group size, vessel type, vessel size, and number of vessels were significant predictors of dolphin behavioral state. Significant predictors of dolphin movement patterns included season, time of day, group size, calf presence, vessel type, and vessel numbers. The CCSC is an important foraging area for dolphins, yet the high level of industrial activity puts the dolphins at risk of human-related disturbance and injury. There is a crucial need to monitor the impact of increased anthropogenic influences on federally protected dolphins in the active CCSC, with broad application to dolphins in other ports. [ABSTRACT FROM AUTHOR]

The Galveston Ship Channel (GSC) is a narrow, congested waterway that supports large-scale shipping, commercial fishing, dolphin tourism, and recreation. Human activity and common bottlenose dolphins (Tursiops truncatus) converge in the GSC with potentially negative consequences on the dolphins. Elevated land-based tracking and behavioral observation of dolphins and vessels were conducted along the GSC in June-August 2013 using a digital theodolite. Positional information was used to calculate dolphin movement patterns and proximity to vessels. Log-likelihood ratio and Chi-square contingency tests were used to assess behavioral states, and generalized additive models were used to analyze movement patterns (i.e., swimming speed, reorientation rate, and linearity) relative to endogenous and exogenous factors and vessel presence. Dolphins regularly use the GSC to forage (57% of observed behavioral states) and socialize (27%), and it is not a travel corridor for accessing other favorable sites (traveling = 5%). Dolphin behavior varied significantly based on time of day, group size, calf presence, and general boat presence. When boats were present, the proportion of time dolphins spent socializing and foraging was significantly less than expected by chance. Swimming speeds increased significantly in the presence of small recreational boats, dolphin-watching tour boats, shrimp trawlers, and when tour boats and shrimp trawlers were both present. Reorientation rate increased significantly in the presence of tour boats and trawlers. Dolphin behavioral responses to vessel presence may result in decreased energy consumption due to disrupted foraging activity. Without proper management, the observed behavioral changes may be detrimental to individuals within this population in the short term, with potential long-term consequences to health and survivorship. [ABSTRACT FROM AUTHOR]

In the early 1970s. Roger Payne and colleagues developed a non-invasive, shore-based method for collecting data on free-ranging marine mammals in their natural environments. By using a theodolite, or surveyor's transit, they were able to collect data on nearshore marine mammal movement patterns, habitat use, and behavior without any disruption to the animals. As technology advanced, theodolite data collection progressed from analog machines requiring manual data entry to digital equipment linked to computer software that facilitated data management and automated calculations of marine mammal positional information. There are limitations associated with theodolite use, and concurrent data collection methods can contribute information that may not be possible with shore-based research alone. Since the first published research in 1978 using a theodolite to describe the behavioral ecology of dolphins off Argentina, at least 46 species of marine mammals in 36 countries have been tracked by theodolite, and the method continues to be used globally to contribute to non-invasive marine mammal research, conservation, and management. [ABSTRACT FROM AUTHOR]

The article discusses the use of underwater passive acoustic monitoring (PAM) and theodolite tracking to study Indo-Pacific humpback dolphin behavior and sound production. The PAM and shore-based theodolite tracking findings are compared. It is noted that three Ecological Acoustic Recorders (EARs) were deployed on the monitoring site of Lung Kwu Tan (LKT).

The yelkouan shearwater Puffinus yelkouan is endemic to the Mediterranean and Black Seas, and classified as Vulnerable in the IUCN Red List. Information on the species’ distribution and habitat use in the eastern Mediterranean is scant, and only a few studies were based on direct visual observations in offshore waters. Here, we provide information on 1) the occurrence of yelkouan shearwaters within a 3000 km² study area off the region of Veneto, Italy, in the northwestern Adriatic Sea, based on visual surveys conducted from small boats between April and October 2018-2022 (effort: 169 days, 23,836 km), and 2) the geographic, bathymetric and oceanographic variables likely to drive the species’ offshore distribution. Yelkouan shearwaters (238 sightings, 916 individuals) were observed in waters 9-33 m deep, between 2 and 24 km from the coast. Individual counts ranged between 1 and 100, with 95% of the encounters having less than 10 individuals. An Explainable Boosting Machine model-a machine learning technique based on generalized additive models-selected chlorophyll a as the most important variable to explain the species’ occurrence, followed by distance from the coast, and bottom depth. The model indicated a higher occurrence in waters with chlorophyll a less than ~2.3 mg/m³, farther than ~15 km from the coast, and deeper than ~22 m. The effects of SST, salinity, and day of the year were less clear. This study provides insight into the offshore distribution of yelkouan shearwaters, within one of the Mediterranean areas most exposed to cumulative human threats. [ABSTRACT FROM AUTHOR]

Humpback dolphins (genus Sousa) use shallow, near-shore waters throughout their range. This coastal distribution makes them vulnerable to recreational and commercial disturbances, especially near heavily populated and industrialized areas. Most research focusing on Sousa and human activities has emphasized direct impacts and threats, involving injury and death, with relatively little focus on indirect effects on dolphins, such as changes in behaviour that may lead to deleterious effects. Understanding behaviour is important in resolving human-wildlife conflict and is an important component of conservation. This chapter gives an overview of animal behavioural responses to human activity with examples from diverse taxa; reviews the scientific literature on behavioural responses of humpback dolphins to human activity throughout their range, including marine vessel traffic, dolphin tourism, cetacean-fishery interactions, noise pollution, and habitat alteration; and highlights information and data gaps for future humpback dolphin research to better inform behaviour-based management decisions that contribute to conservation efforts. [ABSTRACT FROM AUTHOR]

The article discusses the impact of vessel traffic on movements of Sousa chinensis in Lantau Island, Hong Kong. It is evident that human-related recreation and commercial disturbances affect marine mammals with near-shore distributions. It has been informed that Sousa chinensis are protected under the Wild Animals Protection Ordinance and a code of conduct for vessels in Hong Kong.

The article presents a study on underwater recording stethoscope for dolphin rehabilitation and diagnosis in Texas. It is stated that the device is based on omnidirectional hydrophone submerged underwater to listen, amplify, and record sounds arising from the internal organs of marine mammals. The device is used in rehabilitative care in Texas Marine Mammal Stranding Network (TMMSN) on several marine mammals including melon-headed whale, bottlenose dolphin, and rough-toothed dolphin

Fewer than 200 Indo-Pacific humpback dolphins (Sousa chinensis) occur in Hong Kong waters (though these are part of a much larger population in the Pearl River Estuary), with a decrease in the past about 10 years. They have partially overlapping individual ranges (mean = 100 km2), and two partially overlapping communities. Seasonal occurrence is higher in June-November than December-May, approximate wet and dry monsoon seasons, respectively. Group sizes tend to average three dolphins, a decrease from the past decade. Feeding often occurs in abruptly changing water depths and off rocky natural shores. The area immediately north of Hong Kong International Airport is largely used for travelling between locations to the west, east and further north. The area around Lung Kwu Chau Island in northwest Hong Kong is a "hot spot" for foraging and socializing. The area off Fan Lau, southwest Lantau Island, is largely used for foraging. A former foraging "hot spot" was located around the Brothers Islands east of the airport, now reduced, possibly due to increases in high-speed ferries (HSFs) and other activities. Sound recordings of dolphins from bottom-mounted hydrophones suggest that northwestern Hong Kong waters are used more at night than in daytime. Sexual activity and calving occur throughout the year, with a peak in late spring to autumn (wet monsoon season). Humpback dolphins communicate acoustically with each other and probably passively listen to prey in murky waters, and anthropogenic noises may be masking communication and affecting prey location. Increasing sounds of shipping, HSFs and industrial activities are likely to alter dolphin habitat use patterns and overall behaviours beyond the present already affected status. [ABSTRACT FROM AUTHOR]

The article reports on the observation of mother and calve behavior among dusky dolphins via the use of an unmanned aerial vehicle (UAV). Particular attention was given to swimming speed, inter-adult distance, and respiration and suckling rates in the area between the Kaikoura Peninsula and the Haumuri Bluffs, New Zealand.

Harmful algal blooms produced by the phytoplankton species Karenia brevis and its associated neurotoxin, brevetoxin (PbTx), occur throughout the Gulf of Mexico and have had devastating impacts on co-occurring populations of bottlenose dolphins (Tursiops truncatus), an important marine sentinel species. The majority of documented impacts, however, are from the eastern Gulf of Mexico, with a critical lack of information on the degree and frequency of PbTx exposure in bottlenose dolphins from Texas coastal waters. This study documents PbTx exposure in Texas bottlenose dolphins between 2007 and 2017 and their association with co-occurring K. brevis blooms. PbTx was detected in 60% (n = 112) of the animals tested. Liver tissue samples had the highest frequency of detection (62%), followed by feces (41.4%) and gastric contents (30.4%). PbTx was not detected in urine or intestinal tissue. The concentration ranges of PbTx detected in feces (1.2–216, mean 38.4 ng/g), gastric contents (3.3–1016, mean 158 ng/g) and liver (0.6–52.4, mean 8.5 ng/g) samples were an order of magnitude less than values reported for Florida dolphins for the same sample types. The proportion of dolphins recovered within 4 weeks of a bloom that tested positive for PbTx ('Bloom' group; 75%) was significantly higher compared to those that were recovered 5–8 weeks after termination of a bloom ('Post-Bloom' group; 36%; p = 0.004). The proportion of PbTx-positive animals with no observed bloom association ('Baseline' group; 60%) was also significantly greater than the Post-Bloom group (p = 0.012). No significant difference in proportion of PbTx-positive animals was detected between Bloom and Baseline groups (p = 0.242). No significant differences in liver PbTx concentrations were observed between any pairwise combinations of the 3 exposure groups (p = 0.261). Overall, these findings suggest persistent PbTx exposure for many individuals in these populations, although the health impacts of such exposure are not known. • First long-term dataset of brevetoxins in Texas marine mammals. • Establishment of baseline brevetoxin levels and frequency of toxin positive animals in the Texas dolphin population. • Dolphins sampled during blooms and non-bloom periods were toxin-positive more often than those sampled after blooms. • Brevetoxin exposure in Texas dolphins appears to be persistent and chronic. [ABSTRACT FROM AUTHOR]