Adult survival and reproduction in an Argentine bottlenose dolphin population: The science needed for its conservation

Several small populations of bottlenose dolphins (Tursiops truncatus) are known to inhabit the Atlantic coast of Argentina, however, apparently with little exchange between them. The study population in Bahia San Antonio (San Matías Gulf, province of Río Negro) appears to be one of the southernmost populations (42°S/65°W). Adult survival and calving rates are critical for the survival of this population. Boat-based photo-identification surveys between 2008 and 2011 were used for a mark-recapture analysis of the survival of 35 distinctly marked adults. Survey trips in September 2008 (n=9), August 2009 (n=10), September 2010 (n=6) and in September 2011 (n=6) were used as secondary periods for a Pollock’s Robust Design analysis within MARK. The population was assumed to be closed within the secondary periods, and model selection indicated random migrations (rather than Markovian or No migration) outside the secondary periods. Adult survival was very high. Calving interval was calculated for 14 reproductive females with 28 calves since 2006 with the average being 3.5 ± 1.03 years. Assuming a population size of approximately 100 individuals, the minimum annual birth rate is 4.7% per year. Of the 28 calves, 3 are presumed to have died within the first 2-3 years of life, whereas 14 are known to have survived that period. Although bottlenose dolphins occur further south along the Argentine coast, the study population appears to be the most southerly stable population after the neighboring Valdez population was recently reported to be vanishing. Interactions with fishing and contamination appear to be the most likely impacts on adult survival and reproduction. So far, our results indicate a relatively small population with apparently healthy birth and survival rates

Development and validation of an environmental DNA protocol to detect an invasive Caribbean freshwater fish, the guppy (Poecilia reticulata)

I.S. and C.D.S. contributed to study conception and design. I.S. secured funding for assay development, testing, and field survey work. I.S., K.-A.B., and S.B. conducted field surveys in Jamaica; I.S. and J.L.W. oversaw collection of positive and negative control samples in Oklahoma. Assay design was undertaken by E.D.H. DNA extractions, in vitro assay tests, and assessment of assay performance was overseen by S.N.S. Data analysis and summary of qPCR screening results was performed by S.N.S. and C.D.S., with contributions from J.L.W. The first draft of the manuscript was written by S.N.S., with contributions and reviews by C.D.S., I.S., J.L.W., E.D.H., K.-A.B., and S.B. All authors read and approved the final manuscript.We describe the development and validation of a qPCR assay to detect Poecilia reticulata, a highly invasive species of freshwater fish invasive to the Caribbean islands, through environmental DNA (eDNA) sampling. Originating from Trinidad, this species is invasive and detrimental to countless native tropical fish communities. A qPCR assay, consisting of a set of primers and a fluorescent probe, amplifying a 214 base pair target region of the mitochondrial Cytochrome B gene was designed for P. reticulata from existing DNA sequence data. The assay was assessed for target specificity, with no evidence of amplification in closely related or sympatrically distributed non-target species. In vitro tests indicate that the assay consistently detects P. reticulata down to concentrations of 2.0 × 10−5 ng/μl. The developed assay provides a new, practical tool for monitoring freshwater habitats throughout the Caribbean, allowing for early and rapid detection of invasive fish species of conservation concern.This research was supported by the University of Oklahoma, the Sam Noble Oklahoma Museum of Natural History, and the University of the West Indies, Mona Campus. Research was conducted in accordance with field permits in Jamaica (NEPA#18/27) and the University of Oklahoma Institutional Animal Care and Use Committee (IACUC) protocols R17-031 and R19-006. The authors thank M. Gordon, H. Bennett, E. Bennett and S.-M. Bennett-Monroe for field and laboratory assistance. Funding support for this work was provided by the University of Oklahoma and the Sam Noble Oklahoma Museum of Natural History to C.D.S and I.S.Ye

Demographics of the disappearing bottlenose dolphin in Argentina: a common species on its way out?

Populations of the once common bottlenose dolphin (Tursiops truncatus) in Argentina have precipitously declined throughout the country in the past decades. Unfortunately, local declines of common species are easily overlooked when establishing priorities for conservation. In this study, demographics of what may well be the last remaining resident population in the country were assessed using mark-recapture analysis (Pollock's Robust Design) of a photo-identification dataset collected during 2006-2011 in Bahía San Antonio (Patagonia, Argentina). Total abundance, corrected for unmarked individuals, ranged from 40 (95%CI: 16.1-98.8) to 83 (95%CI = 45.8-151.8) individuals and showed a decrease over the years. Adult survival rates varied between 0.97 (± 0.037 SE) and 0.99 (± 0.010 SE). Average calving interval equalled 3.5 ± 1.03 years, with 3.5 births/year in the entire population and a minimum annual birth rate of 4.2%. However, data suggest that calves may have been born and lost before being documented, underestimating birth rate, calf mortality, and possibly the number of reproductive females. Either way, the recruitment rate of calves appears to be insufficient to support the size of the population. This population is relatively small and declining. Considering the disappearance of populations north and south of the study area, an incessant decline will have severe consequences for the continuous existence of this species in Argentina, indicating an urgent need for serious conservation efforts. This study provides insight into how the failure to recognize local population declines can threaten the national (and eventually the international) status of a common species like the bottlenose dolphin

Behavioural ecology and population structure of Hector's dolphin (Cephalorhynchus hectori)

xiv, 168 leaves :ill., maps ; 30 cm. Includes bibliographical references. University of Otago department: Marine Science.Aspects of social structure, behavioural ecology, and population biology of Hector's dolphin (Cephalorhynchus hectori) were studied. Especially information on ranging behaviour and group composition of this species were scarce albeit important for its conservation. Fieldwork was carried out in seven study areas along the east and west coasts of the South Island of New Zealand between November 1993 and January 1998 from a small boat. Individual Hector's dolphin were sighted and resighted using photo-identification. Habitat selection of Hector's dolphins was investigated using three environmental parameters: water depth, underwater clarity, and sea surface temperature. A resource selection function was applied to discern used from unused sites. The dolphins were found significantly more often in warm, shallow, and murky waters. The temperature effect, however, was regarded to be an artefact, as dolphins were suspected to have left the nearshore habitat in winter moving farther offshore in similar surface temperatures. In spring and early summer, Hector's dolphin exploited a short-term food source preying on small migrating fish on the surface. White-fronted terns (Sterna striata) associated with dolphins profiting from the dolphins' foraging. Summer home ranges of 32 adult individuals with more than ten sightings around Banks Peninsula between 1985 and 1997 were about 10-60 km long alongshore. Individuals showed high site-fidelity for up to twelve consecutive summers but were never resighted in these near-shore home ranges in winter. The general decrease in nearshore densities in winter was interpreted as a consequence of home ranges being shifted offshore in winter. The complete lack of observed movements over 60-600 km within the study period made any alongshore migration unlikely. The inshore-offshore movement was confirmed within Akaroa Harbour, Banks Peninsula, between November and April. A Monte Carlo randomisation test was developed on data sets from two populations (Banks Peninsula and Porpoise Bay). Association patterns were described for dyads in three other populations (Kaikoura, Moeraki, and Jackson Bay). Most associations were weak and did not differ significantly from randomness. This confirmed earlier findings that Hector's dolphin have a "fission-fusion society". A combined stereo-photogrammetry and underwater-video system was developed and used at close range to measure the length (age) and determine the gender of bow-riding individuals. The system could be used only in calm sea conditions and hence provided limited data. Gompertz growth functions were computed for males and females from a small set of measurements from dead individuals. The majority of bow-riding individuals proved to be immature or subadult. Mark-recapture and a Cormack-Jolly-Seber model were used to estimate the mean annual adult survival rates for Hector's dolphin in the same four areas to be 70-100%. Mean calving interval and calf mortality were estimated to be 2.2 years and at least 36% within the first six month using data from all study areas

Behavioural ecology and population structure of Hector's dolphin (Cephalorhynchus hectori)

xiv, 168 leaves :ill., maps ; 30 cm. Includes bibliographical references. University of Otago department: Marine Science.Aspects of social structure, behavioural ecology, and population biology of Hector's dolphin (Cephalorhynchus hectori) were studied. Especially information on ranging behaviour and group composition of this species were scarce albeit important for its conservation. Fieldwork was carried out in seven study areas along the east and west coasts of the South Island of New Zealand between November 1993 and January 1998 from a small boat. Individual Hector's dolphin were sighted and resighted using photo-identification. Habitat selection of Hector's dolphins was investigated using three environmental parameters: water depth, underwater clarity, and sea surface temperature. A resource selection function was applied to discern used from unused sites. The dolphins were found significantly more often in warm, shallow, and murky waters. The temperature effect, however, was regarded to be an artefact, as dolphins were suspected to have left the nearshore habitat in winter moving farther offshore in similar surface temperatures. In spring and early summer, Hector's dolphin exploited a short-term food source preying on small migrating fish on the surface. White-fronted terns (Sterna striata) associated with dolphins profiting from the dolphins' foraging. Summer home ranges of 32 adult individuals with more than ten sightings around Banks Peninsula between 1985 and 1997 were about 10-60 km long alongshore. Individuals showed high site-fidelity for up to twelve consecutive summers but were never resighted in these near-shore home ranges in winter. The general decrease in nearshore densities in winter was interpreted as a consequence of home ranges being shifted offshore in winter. The complete lack of observed movements over 60-600 km within the study period made any alongshore migration unlikely. The inshore-offshore movement was confirmed within Akaroa Harbour, Banks Peninsula, between November and April. A Monte Carlo randomisation test was developed on data sets from two populations (Banks Peninsula and Porpoise Bay). Association patterns were described for dyads in three other populations (Kaikoura, Moeraki, and Jackson Bay). Most associations were weak and did not differ significantly from randomness. This confirmed earlier findings that Hector's dolphin have a "fission-fusion society". A combined stereo-photogrammetry and underwater-video system was developed and used at close range to measure the length (age) and determine the gender of bow-riding individuals. The system could be used only in calm sea conditions and hence provided limited data. Gompertz growth functions were computed for males and females from a small set of measurements from dead individuals. The majority of bow-riding individuals proved to be immature or subadult. Mark-recapture and a Cormack-Jolly-Seber model were used to estimate the mean annual adult survival rates for Hector's dolphin in the same four areas to be 70-100%. Mean calving interval and calf mortality were estimated to be 2.2 years and at least 36% within the first six month using data from all study areas

Total abundance estimates with 95%CI for the study area of 2009, 2010 and 2011, corrected for the proportion of unmarked individuals in the population.

<p>Total abundance estimates with 95%CI for the study area of 2009, 2010 and 2011, corrected for the proportion of unmarked individuals in the population.</p

Seasonal abundance estimates of bottlenose dolphins in the study area.

<p>N: abundance estimate of marked individuals, SE: standard error, Proportion of marked dolphins: seasonal average (±SD) of the proportion of marked individuals in the dolphin groups encountered, N_total: total abundance estimate (marked and unmarked individuals).</p><p>Seasonal abundance estimates of bottlenose dolphins in the study area.</p

Hours of photo-identification survey effort over the different seasons (in brackets the number of additional opportunistic photo-identification surveys).

<p>Hours of photo-identification survey effort over the different seasons (in brackets the number of additional opportunistic photo-identification surveys).</p