Humpback whales Megaptera novaeangliae undertake extensive annual migrations, have complex migratory patterns, and have held several mammalian long-distance movement records. Here, we report on a whale known to feed in the Russian Far East that was sighted in breeding areas on either side of the North Pacific, the Mariana Islands and Mexico, in less than 1 yr (357 d apart). This is the longest published distance (11261 km great-circle route) between 2 unique sightings of a photo-identified humpback whale to date. To understand the context of this movement, we investigated records of whales that had been sighted in Russian feeding areas and Mexican breeding areas using historic and newly available photo-identification data. We found 117 humpback whales documented in both countries between 1998 and 2021, revealing a substantial increase from the only 11 matches that were previously known. These whales exhibited high site fidelity to Mexico, with one-third seen in multiple years, and up to 10 yr. However, we also found that they changed breeding areas more frequently than Mexico whales matched to other feeding areas, illustrating how the Mariana Islands-Mexico movement may have occurred. We document the first complete round-trip migrations between Mexico and Russia, a journey of >16400 km, the longest known migration of Northern Hemisphere humpback whales. Our data demonstrate regular trans-Pacific movements of humpback whales in the North Pacific, highlighting the importance of Mexico for the species ocean-basin-wide and the need for effective local management to aid in the conservation of multiple at-risk distinct population segments.

Indo-Pacific humpback dolphins Sousa chinensis in Hong Kong (HK) waters are part of a large (ca. 2000-2500), but declining, population that occurs in the Pearl River Estuary of southern China. To understand the factors that may influence dolphin densities in 4 different parts of HK, a 25 yr (1996-2020) database containing 66439 km of line-transect survey effort and 4052 dolphin sightings was used. Seventeen variables representing natural and anthropogenic habitat factors were evaluated using generalized additive models (GAMs) to identify the preferred habitat of humpback dolphins in HK waters. In the environmental GAMs, rainfall, salinity, and river discharge were significant factors related to dolphin density, consistent with their observed strong preference for estuarine habitat. Sea surface temperature was also important for one of the 4 subareas. In the anthropogenic GAMs, the only significant variable was the amount of habitat area lost to land reclamation in North Lantau. This finding is consistent with previous hypotheses that heavy coastal engineering in North Lantau has contributed to observed declines in dolphin abundance during the study period. This study provides some of the first quantitative indications of factors that are potentially influencing the density of the animals in various parts of HK. As such, it will be a valuable tool for evaluating and mitigating potential impacts of both natural and anthropogenic factors on the population in the future.

Lethal collisions between ships and whales (‘ship strikes’) are a pressing management issue across the globe, and recent work highlights the need for better information to support collision risk avoidance by mariners. Using a ship-based observer stationed on the bow, we recorded the behavior of humpback whales Megaptera novaeangliae surfacing around large cruise ships transiting Glacier Bay National Park, Alaska, one of the largest marine protected areas in North America. We documented surfacing bouts (i.e. series of surfacings when whales breathe between deeper foraging dives) over 460 h of observation from 65 cruises. We detected few surfacings per bout (mean = 2.9) and observed a moderate within-bout submergence time (median = 20.1 s), showing that whales are unavailable for detection during the majority of their time near the surface. We then used these data to parameterize a modified mark-recapture model to estimate the probability of a whale surfacing before and after first detection by mariners. The estimated probability that a whale surfaced prior to detection was moderate (0.54; 95% credible interval [CRI]: 0.52-0.57), indicating that often, the first detected cue (e.g. a blow or a visible fluke) was not the first cue produced (i.e. available to be detected). The probability that a whale remained near the surface following detection was high (median = 0.87; 95% CRI: 0.85-0.88). This indicates that whales likely remain at risk of collision following detection, enabling mariners to evaluate ship-speed-specific avoidance maneuvers based on initial sighting distances to decrease collision risk.

Belize maintains the largest proportion of the Endangered Antillean manatee Trichechus manatus manatus population in its range, but tourism and boat traffic have increased substantially over the past 3 decades. We utilized 25 yr of Belize Antillean manatee stranding data (1995-2019), 6 aerial surveys (1997, 1999, 2000, 2001, 2002, 2014), and 2 decades of boat registration data to examine: (1) spatial patterns in stranding incidence and risk of watercraft collision; (2) temporal patterns in strandings and registered watercraft; and (3) the relationship between manatee strandings attributed to watercraft collision and watercraft numbers. The number of watercraft collision strandings increased significantly over time, from 1-4 yr-1 in the late 1990s and early 2000s to 10-17 yr-1 in the late 2010s. The per manatee risk of watercraft collision stranding increased across space and time with the number of registered boats. Strandings were greater in areas of high boat traffic, high human population density, and mangrove habitats, particularly in Belize City and Placencia. These results highlight the need to reduce the threat of watercraft collisions to conserve this Endangered subspecies in Belize. Conservation efforts should focus on reducing the number of boats and their speed within zones of high manatee use to reduce mortality due to boat collisions, including establishing additional non-motorized vessel areas, restricted access, and reduced speed zones.

As marine traffic increases globally, ship strikes have emerged as a primary threat to many baleen whale populations. Here we predict ship-strike rates for fin whales Balaenoptera physalus and humpback whales Megaptera novaeangliae in the central territorial waters of the Gitga’at First Nation (British Columbia, Canada), which face increases in existing marine traffic as well as new liquified natural gas (LNG) shipping in the next decade. To do so, we utilized Automatic Identification System (AIS) databases, line-transect surveys, shore-based monitoring, whale-borne tags, aerial drone-based focal follows, and iterative simulations. We predict that by 2030, whale encounters will triple for most vessel types, but the change is most extreme for large ships (length >180 m) in prime whale habitat, in which co-occurrences will increase 30-fold. Ship-strike mortalities are projected to increase in the next decade by 2.3× for fin whales and 3.9× for humpback whales, to 2 and 18 deaths yr-1, respectively. These unsustainable losses will likely deplete both species in the coastal region of BC. Models indicate that the largest single source of mortality risk in 2030 will be from the LNG Canada project. Of the mitigation options we evaluated, a 10 knot speed ceiling for all large ships is potentially effective, but the best measure for guaranteed mitigation would be seasonal restrictions on LNG traffic. While certain data gaps remain, particularly with respect to humpback whales, our predictions indicate that shipping trends within Gitga’at waters will impact whale populations at regional levels. We provide our analysis in the R package ‘shipstrike’.

Acoustic telemetry allows for fine-scale, or positional, tracking of fish in localised environments, and advancement in analytical techniques allows for quantifiable patterns in fish movement and behaviour. White sturgeon Acipenser transmontanus in the regulated Upper Columbia River are listed as endangered in Canada due to their considerable decline over the last century. An improved understanding of where, when, and why white sturgeon move in relation to river regulation is important for species recovery. A VEMCO Positioning System was used to collect the positions of white sturgeon in critical habitats immediately downstream of a dam on the Upper Columbia River over a 1 yr period. We applied hidden Markov models and generalised linear mixed models to (1) identify ecologically meaningful movement behaviours within the positions dataset; and (2) investigate the relationships between movement behaviour and biological (sex) and environmental (e.g. discharge, temperature, habitat) factors. Two behaviour states were identified: ‘residential’, characterised by short movements with less frequent turns, and ‘exploratory’, characterised by longer movements with more frequent turns. Water temperature largely influenced the mean weekly probability of a behaviour state, while discharge influenced the spatial distribution of movement behaviours. Changes in movement patterns were also apparent across seasons, with a higher occurrence of residential behaviour in the winter and spring and exploratory behaviour in the summer and fall. Results will help inform species recovery measures, such as overall flow management and optimization of operations to reduce impacts of river regulation.

Alshari et al. (2023; Endang Species Res 50:311-313) were able to collect 3 Fluvitrygon kittipongi specimens from the Pahang River, which were not available to us at the time of our study (Lim & Then 2022; Endang Species Res 48:43-50). The cytochrome c oxidase I (COI) sequences (or haplotypes) of these 3 stingrays were identical to each other but differed from the haplotypes of our Perak River specimens. The result of 100% similarity between COI sequences of our Perak River rays and the eDNA water samples isolated from Pahang River in our study was suggested by Alshari et al. (2023) as DNA contamination in our study, which is plausible. However, further population genetics studies would be necessary to ascertain that the Perak River haplotype does not occur in stingrays of the Pahang River.

Some red-cockaded woodpecker (RCW) Dryobates borealis populations remain understudied. This is notable because management that incorporates population demographics and site characteristics may benefit RCW recovery. The Oakmulgee Ranger District of the Talladega National Forest (Alabama, USA) has no wiregrass Aristida stricta, small forest stand sizes, rolling topography, and contains an understudied RCW population. Our goal in the Oakmulgee was to characterize RCW habitat, possibly identify ways in which habitat differed from other regions, and estimate associations between habitat and reproductive output. We found that 70.2 and 92.5% of sampled stands met recovery standard thresholds for small and large pine basal area (BA) as defined in the United States Fish and Wildlife Service (USFWS) RCW Recovery Plan. While 74.6% of longleaf pine Pinus palustris-dominated stands met the threshold for overstory hardwood canopy composition, 60.0% of loblolly pine P. taeda-dominated stands did not. Few stands met the recommended percentage of herbaceous understory (19.8%) or recommended absence of hardwood midstory. A lower rate of partial brood loss was associated with a greater area of large pines (≥25.4 cm diameter at breast height; DBH), a smaller area of small pines (≥10 and <25.4 cm DBH), a larger area burned in the dormant season, and higher RCW density. In our models, hardwood overstory and midstory did not influence egg or hatchling production. Hardwoods in the Oakmulgee could contribute to unfavorable habitat, as indicated in the USFWS RCW Recovery Plan, as well as relate to variation in habitat across the RCW’s range. Regions of the RCW’s range are understudied, and limited staffing and funding impede advances in understanding and conservation.