Search

The Western North-Pacific (WNP) gray whale feeding grounds are off the northeastern coast of Sakhalin Island, Russia and is comprised of a nearshore and offshore component that can be distinguished by both depth and location. Spatial movements of gray whales within their foraging grounds were examined based on 13 years of opportunistic vessel and shore-based photo-identification surveys. Site fidelity was assessed by examining annual return and resighting rates. Lagged Identification Rates (LIR) analyses were conducted to estimate the residency and transitional movement patterns within the two components of their feeding grounds. In total 243 individuals were identified from 2002–2014, among these were 94 calves. The annual return rate over the period 2002–2014 was 72%, excluding 35 calves only seen one year. Approximately 20% of the individuals identified from 2002–2010 were seen every year after their initial sighting (including eight individuals that returned for 13 consecutive years). The majority (239) of the WNP whales were observed in the nearshore area while only half (122) were found in the deeper offshore area. Within a foraging season, there was a significantly higher probability of gray whales moving from the nearshore to the offshore area. No mother-calf pairs, calves or yearlings were observed in the offshore area, which was increasingly used by mature animals. The annual return rates, and population growth rates that are primarily a result of calf production with little evidence of immigration, suggest that this population is demographically self-contained and that both the nearshore and offshore Sakhalin feeding grounds are critically important areas for their summer annual foraging activities. The nearshore habitat is also important for mother-calf pairs, younger individuals, and recently weaned calves. Nearshore feeding could also be energetically less costly compared to foraging in the deeper offshore habitat and provide more protection from predators, such as killer whales. [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]

In coastal waters of the Pearl River Delta (PRD) region, the Indo-Pacific humpback dolphin (Sousa chinensis) is thought to number approximately 2500 individuals. Given these figures, the putative PRD population may appear strong enough to resist demographic stochasticity and environmental pressures. However, living in close proximity to the world's busiest seaport/airport and several densely populated urban centres with major coastal infrastructural developments comes with challenges to the long-term survival of these animals. There are few other small cetacean populations that face the range and intensity of human-induced pressures as those present in the PRD and current protection measures are severely inadequate. Recent mark-recapture analyses of the animals in Hong Kong waters indicate that in the past two decades the population parameters have not been well understood, and spatial analyses show that only a very small proportion of the dolphins' key habitats are given any form of protection. All current marine protected areas within the PRD fail to meet a minimum habitat requirement that could facilitate the population's long-term persistence. Demographic models indicate a continuous decline of 2.5% per annum, a rate at which the population is likely to drop below the demographic threshold within two generations and lose 74% of the current numbers within the lifespan of three generations. In Hong Kong, the case of humpback dolphins represents a particularly explicit example of inadequate management where a complete revision of the fundamental approach to conservation management is urgently needed. [ABSTRACT FROM AUTHOR]

Marine seismic surveys, which use loud, primarily low-frequency sound to penetrate the sea floor, are known to disturb and could harm marine life. The use of these surveys for conventional and alternative offshore energy development as well as research is expanding. Given their proliferation and potential for negative environmental impact, there is a growing need for systematic planning and operational standards to eliminate or at least minimize impacts, especially when surveys occur in sensitive areas. Mitigating immediate impacts is obviously critical, but monitoring for short- as well as long-term effects and impacts is also needed. Regulatory requirements for both mitigation and monitoring vary widely from one country or jurisdiction to another. Historically, most have focused on acute effects but share a common objective of minimizing potential adverse impacts. Specific examples in different areas are given to illustrate general approaches for predicting, minimizing, and measuring impacts for operations in essentially any marine environment. The critical elements of a robust mitigation and monitoring plan for responsibly conducting marine seismic surveys include obtaining baseline ecological data; substantial advance planning, communication, and critical review; integrated acoustic and visual monitoring during operations; and systematic analysis of results to inform future planning and mitigation. [ABSTRACT FROM AUTHOR]