The aim of this assessment is to advance our understanding in the spatial ecology of the resident inshore and offshore population of bottlenosedolphins in Golfo Dulce (GD) and Osa Peninsula Waters (OPW). Our approach used niche-based models (Phillips et al., 2006, Thorne et al., 2012,Friedlaender et al., 2011), which provided details of how dolphins use coastal and oceanic habitats, describing the factors that influence theirdistribution in the study area and identifying the critical habitats to be considered for management and conservation. Our analyses indicate severalimportant aspects of the distribution of these two ecotypes of bottlenose dolphins. As expected in the study area, these two ecological races occurin close proximity, but differ in the structural factors of the habitat they occupy. The inshore population uses areas close to the mouths of the riversas critical foraging habitats, being influenced by tidal cycles and seasonal changes in water temperature and salinity. The offshore population inoceanic habitats must rely on prey species found in rare but profitable patches, therefore pelagic dolphins in the open ocean would often need totravel long distances searching for these patches. Distribution models illustrating the difference in habitat use presented in this assessment are keyto effective management of the marine mammals’ diversity in Costa Rica.

The exponent for predicting total body mass from length has been studied in many species and here data on common minke whales from areas in the North Atlantic is added from both Icelandic and Norwegian research catches. The exponent was found to be not significantly different from 3. In addition seasonal changes in body mass and in the parts of blubber, muscle and visceral fat are reported. The exponent for how blubber mass increases with length is lower than 3. In all cases a significant increase over the season was detected, in particular for the mature animals, and also in girth measurements, particularly at the posterior part of the body. Pregnant females had significantly more blubber than other whales. These results agree with studies on blubber thickness measurements and tissue energy content of Icelandic baleen whales and observed changes in the ecosystem around Iceland during the research period.

ABSTRACT
 
 Under the U.S. Marine Mammal Protection Act, bottlenose dolphins [Tursiops truncatus] along the United States Atlantic coast are managed as a series of 17 distinct stocks. To determine the status of each stock, the Potential Biological Removal (PBR) is compared with anthropogenic removals, primarily as a result of fisheries bycatch. Estimates of abundance, with associated measures of variance, are required to generate the PBR for each stock. The objectives of the current study were to estimate abundance for the Southern North Carolina Estuarine System Stock (SNCESS) of bottlenose dolphins and to refine the southern boundary of this stock. To meet these objectives, photo-identification surveys were conducted during the summer and winter of 2014 in estuarine and nearshore coastal waters in southern North Carolina. The surveys extended 25km south of the defined southern stock boundary, along the northern South Carolina coast. One mark and one recapture survey were conducted for each season. Each survey was completed in four or five days and covered over 300km of survey tracklines. Dorsal fin images were processed and managed using FinBase, and only images of suitable quality and distinctiveness were used for estimates of abundance. A three-step decision tree was used to assign each dolphin group to either the SNCESS or an adjacent coastal stock, based on sighting location, ranging patterns derived from matches to photo-identification catalogs, and statistical modeling. Only sightings classified as SNCESS were used to estimate stock abundance. Abundance estimates were calculated using three methods: the Chapman modification to the Lincoln-Petersen method, package Rcapture in Program R, and program MARK 6.2. The most parsimonious estimate was generated using the package Rcapture for program R, with the bias corrected M0 model yielding an estimate of 283 dolphins (CV = 0.33, 95% CI 170-396) in the summer of 2014. The distribution of SNCESS dolphins shifted south in the winter and several individuals were observed up to 70km southwest of the currently recognized southern boundary. The results of this study support the current definition of the SNCESS but suggest revisions to the southern boundary. The SNCESS is the smallest bottlenose dolphin stock off the east coast of the USA and is at risk of population decline as a result of fisheries-related mortality.

In the Mediterranean, at the end of the 19thcentury, dolphins were identified as pest species for their disruptive actions during some fishing phases. Numerous fishermen organizations asked for permission to hunt dolphins, and the killing of a dolphin was often institutionally favoured by several national laws. We provide a picture of the systematic culling campaigns for dolphins in Italy up to the absolute prohibition of capture, analysing the governmental measures implemented against dolphins, the official number of individuals killed and their value (in Italian liras) in 11 Italian Maritime Compartments from 1927 to 1937. Officially, over 6,700 dolphins were killed in 10 years along the Italian coast and rewards distributed for about 360,160 Italian liras, which, at the current exchange rate, correspond to 355,000 euros, for a contribute of about 52 euros for each dolphin. Considering that the meat was consumed both at the family level or sold, mainly as salted and dried meat, the dolphin hunting could be considered a profitable activity in those years for the fishermen. Due to the scarce information available on the size of the dolphin populations around the Italian coast, it is difficult to estimate the impact of the bounty fishing on the Italian populations during the studied period. Nevertheless,it is possible to hypothesizethat it could have affected all the local recruitment, producing an effect on the local population far from being negligible.

Observations of 37 individual blue whales (Balaenoptera musculus) were recorded off the southern coast of Sri Lanka during the Southwest Monsoon Season (SWM). Sightings were made during a scientific geophysical survey campaign conducted in July and August 2017. Whilst blue whales are regularly recorded on the continental slope of southern Sri Lanka during the Northeast Monsoon Season (NEM) (December - March) and during the two inter-monsoonal periods (March - April and September - October), limited data is available for the SWM (May - September) mostly due to unfavourable weather conditions and very little survey effort. In the northern hemisphere blue whales undertake seasonal migrations from higher latitude feeding grounds to lower latitude breeding and wintering areas. However it has been suggested that a population of blue whales in the Northern India Ocean (NIO) remains in lower latitudes year round taking advantage of the rich upwelling areas off Somalia, southwest Arabia and western Sri Lanka. Data from this study nevertheless support a theory that a certain number of individuals remain off the southern coast off Sri Lanka during the SWM, suggesting that the productivity in this region is sufficient to support their year-round presence. This study therefore fills a knowledge gap regarding the presence and movement of blue whales in the NIO highlighting the importance of data obtained from platforms of opportunity.

The aim of the present study is to trace a diagnosis of Bryde´s whale (Balaenoptera edeni) strandings in jurisdictional Brazilian waters through the compilation of published records and those conveyed in communication channels. During 1972 and 2015, 74 strandings were documented between the states of Rio Grande do Sul and Rio de Janeiro, Bahia and Maranhão. The results point out statistically significant differences between the frequencies of strandings in relation to Brazilian regions (χ² = 103.17), with the highest abundance found for the Southeast region (71.62%). Statistically significant differences were also observed between stranding frequency and sexual maturity (χ² = 12.31), with a higher abundance for sexually mature females(54.25%). No statistically significant difference between the stranding frequency in relation to seasonality (χ² = 2.34) was observed. Regarding sex, no statistically significant difference between stranding frequency for males and females was found (χ²=3.12). A trend of increasing B.edeni strandings was observed from the 1980s onwards, by the use of a simple linear regression. This may be due to population growth of the species, increased monitoring throughout the Brazilian coast, and/or increased anthropogenic threats. Thus,stranding monitoring is important for the adoption of conservation measures for this species, as well as for the determination of regional stocks through genetic analyses.

The Bolivian river dolphin (Inia boliviensis), locally known as bufeo is an endemic species and categorized as Vulnerable in the Red Book of Vertebrates of Bolivia. Despite the fact that the Bolivian river dolphin is the only cetacean in land-locked Bolivia, knowledge about its conservation status and vulnerability to anthropogenic actions is extremely deficient. We report on the rescue and translocation of Bolivian river dolphins trapped in a shrinking segment of the Pailas River, Santa Cruz, Bolivia. Anthropogenic activities to alter the landscape and create agricultural land in the area include significant deforestation and irrigation channel construction and are likely to be a contributory factor causing the entrapment of these Bolivian River dolphins. The dolphins were trapped in shallow water in a 1 km section of river. Dry season water levels were rapidly falling and this section of river dried up completely. We collaborated with several institutions, authorities, and volunteers to translocate 26 Bolivian river dolphins, including calves, juveniles, and pregnant females. The dolphins were captured and transported using well-padded boats and vehicles and released into the Rio Grande. Each dolphin was accompanied by biologists who assured their welfare. No dolphins were injured or died during this process. If habitat degradation continue, it is likely that events in which river dolphins become trapped in South America may happen more frequently in the future.

There is limited information concerning the cetaceans inhabiting the coastal waters of Mauritius. This document details the sightings of cetaceans encountered during April 2008 – September 2014. Boat-based surveys were conducted throughout the year, primarily focusing on spinner and bottlenose dolphin populations that are important for the local dolphin-watching industry. More than 1246 hours over 749 days of surveys were spent searching for cetaceans. All cetaceans encountered were recorded. During 2013 and 2014, dedicated diversity surveys were conducted and 2443.6km of search effort was covered around the islands. The encounter rate was 0.025 cetacean sightings/km. Over the total study period 13 species were recorded from 1459 sightings. Species included: Megaptera novaeangliae, Stenella longirostris, Tursiops aduncus, Tursiops truncatus, Globicephala macrorhynchus, Stenella attenuata, Physeter macrocephalus, Mesoplodon densirostris, Feresa attenuata, Peponocephala electra, Grampus griseus and Ziphius cavirostris. In addition, there were strandings of Kogia sima and Ziphius cavirostris. The most common species encountered were spinner dolphins, Indo-Pacific bottlenose dolphins, humpback whales and sperm whales. As expected only humpback whales showed any seasonality in monthly encounter rates (Kruskal-Wallis H = 42.39, Hc = 54.25, p < 0.001). The overall Shannon diversity index was 0.58 (95% CI 0.57–0.60) though this ranged between 0.77 in 2009 to 0.25 in 2014. The Shannon index value for the diversity study was 0.83 (95% CI 0.74–0.91). This study demonstrates the richness of the waters around Mauritius and the importance of the area for beaked whales, migrating humpback whales and the presence of resident sperm whales.

Seasonal and interannual (El Niño–La Niña) variations in dolphin distributions in the eastern tropical Pacific Ocean have not been quantified, inspite of an extensive research vessel database. Fisheries observer data from the yellowfin tuna purse-seine fishery, collected year-round from 1986through 2015, were used to construct a binned spatiotemporal dataset of the presence/absence of spotted, spinner and common dolphin schools bymonth and 1° area. Distribution patterns were predicted from generalised additive logistic regression models applied to the binned data, with dynamicpredictors of surface temperature and salinity, thermocline depth and a stratification index. The dolphin taxa, especially common dolphins, showsome niche separation in relation to these variables. Predicted distributions for each taxon showed seasonal and interannual differences. Spottedand spinner dolphins responded to changes in the position and size of the eastern Pacific warm pool and avoided the equatorial cold tongue inSeptember–October and during La Niña. Common dolphins responded to seasonal and interannual changes in the Costa Rica Dome, the cold tongue,and the coastal upwelling habitat along Baja California, Peru and Ecuador. These predicted temporal variations are consistent with changes inpreferred habitat driven by environmental variability.

Given the difficulties and costs often associated with surveying cetaceans, enlisting members of the public to collect data offers a promisingalternative approach. Comparison of cetacean ‘participatory science’ (also known as ‘citizen science’) data with data collected during traditionalscientific studies helps reveal the strengths and weaknesses of a participatory science approach. With a large number of vessel operators on thewater throughout the year, including dolphin-oriented tour boats, the Hawaiian Islands offer an ideal study site to employ such a dual-methodcomparison. The study aimed to enhance understanding of nearshore dolphin distributions relative to bathymetry. Operators of tour and fishingvessels within the shallow Maui Nui basin of the Hawaiian Islands were recruited to report delphinid sightings. Researchers conducted standarddolphin surveys within the same region. The participatory science approach was successful in generating a large sample size of sightings from fivedifferent species. Findings here demonstrate the potential value of participatory science and of using a multimethod approach to infer odontocetedistribution trends relative to bathymetry in areas where both methods are feasible. Important refinements for future projects are highlighted.