Wayne Perryman - Academia.edu (original) (raw)

Papers by Wayne Perryman

Marine Mammal Science, Jun 26, 2015

ABSTRACT Reproductive parameters were estimated and compared for eastern North Pacific population... more ABSTRACT Reproductive parameters were estimated and compared for eastern North Pacific populations of common dolphins using specimen and photogrammetric data. Age and length data for Delphinus capensis and D. delphis specimens recovered as bycatch or strandings were used to estimate the postnatal growth rates needed to estimate age for calves measured in aerial photographs. Bayesian methods propagated uncertainty among models and revealed that the 2009 cohort of calves had birth dates centered on 6 March 2009 for D. capensis and 12 December 2008 for D. delphis. The evidence for discrete calving seasons suggests a mechanism of reproductive isolation has evolved between species. Photogrammetric data and Bayesian methods were also used to estimate the average length at which calves swim independently: 145.1 cm (≈ 11.1 mo) in D. capensis and 140.1 cm (≈ 14.0 mo) in D. delphis, and the proportion of calves (calves/dolphins counted): 0.045 in D. capensis and 0.069 in D. delphis. The latter parameter was converted to an index of calf production (calf/female dolphin) that was >50% lower than pregnancy rates suggesting few births occurred during the study year. Comparisons of regional differences in calf production suggest variability in habitat use patterns within the study area.

Marine Mammal Science, 2013

Molecular assays were used to determine the sex of 1,294 biopsied common dolphins (658 long-beake... more Molecular assays were used to determine the sex of 1,294 biopsied common dolphins (658 long-beaked common dolphins, Delphinus capensis, and 636 short-beaked common dolphins, D. delphis) in the Southern California Bight. Sex ratio differed substantially between the two species; females comprised 241 (36.6%) of D. capensis samples and 410 (64.5%) of D. delphis samples. All biopsies were taken either from a large research ship or from a small, rigid-hull inflatable boat (RHIB) launched from the larger ship. When conducting replicate biopsy effort on the same schools from each vessel/platform ("Tandem Biopsy Sampling"), we found evidence that disproportionately more female D. capensis were biopsied from the RHIB than from the ship but the same was not true for D. delphis. We suspect that these results are driven by bowriding-behavior differences between the two species. Biopsy duration, geographic location, school size, and Julian date were considered as potential covariates with sex ratio; geographic location was the only one to show strong evidence of correlation. This study also presents an alternative to the erroneous practice of comparing sex ratios to a theoretical assumption of parity (i.e., 50:50 sex ratio) when researchers avoid sampling animals paired with calves.

Marine Mammal Science, May 14, 2018

Estimating the number of dolphins in a group is a challenging task. To assess the accuracy and pr... more Estimating the number of dolphins in a group is a challenging task. To assess the accuracy and precision of dolphin group size estimates, observer estimates were compared to counts from large-format vertical aerial photographs. During 11 research cruises, a total of 2,435 size estimates of 434 groups were made by 59 observers. Observer estimates were modeled as a function of the photo count in a hierarchical Bayesian framework. Accuracy varied widely among observers, and somewhat less widely among dolphin species. Most observers tended to underestimate, and the tendency increased with group size. Groups of 25, 50, 100, and 500 were underestimated by <1%, 16%, 27%, and 47%, respectively, on average. Precision of group size estimates was low, and estimates were highly variable among observers for the same group. Predicted true group size, given an observer estimate, was larger than the observer estimate for groups of more than about 25 dolphins. Predicted group size had low precision, with coefficients of variation ranging from 0.7 to 1.9. Studies which depend on group size estimates will be improved if the tendency to underestimate group size and the high uncertainty of group size estimates are included in the analysis.

Marine Mammal Science, Apr 1, 1993

At least four morphologically distinct forms of common dolphins are found in the eastern Pacific.... more At least four morphologically distinct forms of common dolphins are found in the eastern Pacific. We compared length data for common dolphins photographed from the northern, central and southern regions as defined by Perrin et al. (1985) and found significant differences in average length for adult animals (> 150 cm) and for "adult females" defined for our purposes as animals accompanied by calves. Analyses of calculated birth dates for calves demonstrated differences in timing of reproduction between the geographically adjacent forms. Length distributions from aerial photographs and samples collected from the purse seine fishery were strikingly similar. This work demonstrates a new, noninvasive method for obtaining unbiased life history and morphological data.

We describe the growth of a female gray whale calf (JJ) during her rehabilitation at SeaWorld of ... more We describe the growth of a female gray whale calf (JJ) during her rehabilitation at SeaWorld of San Diego and compare its growth with that of another gray whale calf (Gigi II) previously maintained at SeaWorld of San Diego in 1971-1972. We repeatedly measured JJ's length, girth, and body mass between 11 January 1997 (when she was judged to be 3-7 days old) and 31 March 1998 when she was released. On 11 January 1997, JJ was 4.2 m long, slightly shorter than the average length of freeranging newborn gray whales and weighed 758 kg. However, JJ grew 33% faster during the next 30 weeks than predicted, and was about 1 m longer than Gigi II from six months of age to release. The patterns of growth of both gray whale calves indicated that the rate of increase in body length declined just after weaning. By one year of age, JJ weighed nearly twice as much as Gigi II at the same age. From the best-fit equation, M=(21.4)(G)(L 2), we estimated that JJ weighed 9280 kg when released at 14 months of age.

Bulletin, Southern California Academy of Sciences, Aug 1, 2014

Blubber progesterone levels were measured in biopsy samples and used to predict the pregnancy sta... more Blubber progesterone levels were measured in biopsy samples and used to predict the pregnancy status of 507 female common dolphins (204 long-beaked common dolphins, Delphinus capensis, and 303 short-beaked common dolphins, D. delphis). Samples were collected in the coastal waters of the eastern North Pacific between central California, USA and the southern end of Baja California, Mexico. The percentage of females pregnant was similar between the two species: 22.1% (n = 45) of D. capensis and 28.1% (n = 85) of D. delphis. For both species we found strong geographic patterns in pregnancy, suggesting that some areas were more conducive for pregnant females. A sizable drop in percent pregnant from early (38.8%, n = 133) to late (25.3%, n = 91) autumn was found in D. delphis but not in D. capensis. The potential for sample selectivity was examined via biopsies collected either from a large research ship or from a small, rigid-hull inflatable boat (RHIB) launched from the larger ship. An analysis of "Tandem Biopsy Sampling", replicate biopsy effort on the same schools from each vessel/platform, yielded little evidence that disproportionately more pregnant female common dolphins were biopsied from one platform versus the other. This result plus an analysis of pregnancy status relative to the duration of biopsy operations failed to uncover strong evidence of unaccounted sampling bias with respect to pregnancy state. In total, these results demonstrate the utility of blubber progesterone concentrations to assess pregnancy status in free-ranging cetaceans and they highlight potential factors associated with population-level variation in dolphin pregnancy rates.

Understanding the population consequences of disturbance from operational activities will allow t... more Understanding the population consequences of disturbance from operational activities will allow the US Navy to comply with take limits for protected marine mammals and to design effective mitigation. This is particularly relevant for beaked whales, which are known to be sensitive to anthropogenic noise, including navy sonar. Passive acoustics, controlled exposure experiments and telemetry studies indicate that Blainville's beaked whales (Mesoplodon densirostris, Md) move away from navy sonar sources and are displaced from their regular feeding habitat. Recent assessments of population age structure have led to a hypothesized population consequence of repeated disturbance by sonar at the US Navy's Atlantic Test and Evaluation Center (AUTEC) in the Bahamas, with fewer calves and subadults contributing to lower overall abundance compared to a control population off Abaco Island (~170 km away). Bioenergetics models support the plausibility of this hypothesis, suggesting that beaked whales require relatively high-quality habitat in order to meet their high energy requirements, and that regular displacement from preferred feeding habitats could potentially impact survival and reproduction through compromised body condition. This is of particular concern for lactating females with increased energetic demands, and could indeed result in lower reproductive success, reduced calf survival and negative population consequences. However, empirical data on female body condition and growth of calves is lacking, constraining a direct assessment of whether nutritional stress from disturbance is a realistic mechanism for explaining the apparent population responses.

Quantifying distribution and abundance of predators is an integral part of any ecosystem monitori... more Quantifying distribution and abundance of predators is an integral part of any ecosystem monitoring effort. Antarctica poses many challenges to doing so. Recent advances in the development of Unmanned Aerial Systems (UAS), par- ticularly with vertical take-off and landing (VTOL) aircraft, have provided a new tool for addressing the challenges to estimating abundance of predators. We present preliminary results of a pilot study in the use of VTOLs for estimating abundance of krill-dependent predators. Studies in 2010/11 focused on operations, test flights, estimates of penguin abundance, comparisons to ground counts, and calculating colony area and density. Introduction Aerial photography has become a standard tool in wildlife assessments when scientists are faced with esti- mating the number of animals in large aggregations. Be- cause manned aircraft support is not always available due to cost or logistical constraints, we investigated the ap- plicability of small, unmanned aerial systems (UAS) as an alternative to manned platforms. We felt that there was an open niche for a platform that could be easily carried into the field, operated safely by a team of two people, and could collect images of adequate resolution to sup- port accurate counts of small, aggregated targets in a low contrast environment. To provide the flexibility of operat - ing in rugged terrain or from ships, we required that the aircraft be able to take off and land vertically. To reduce potential disturbance to the sampled populations and risks of pollution from fossil fuels, we restricted our search to platforms powered by batteries. We required that the UAS be capable of conducting missions under direct con- trol of the operator or through a series of predetermined waypoints. Although our primary sampling system was to be single frame images, the aircraft would be required to transmit live video to a ground station to aid in target selection and mission planning. We envisioned these sys- tems as tools for relatively short-range photographic mis- sions requiring endurance on the order of 15 - 45 minutes. After reviewing a wide range of military and commer- cial systems, we decided that the small, electric, multi-rotor copters were the best fit for our needs. These small UAS were designed to be photographic platforms and are excep- tionally stable in flight. Their control systems incorporate input from 3-axis gyros, 3-axis accelerometers, barometric altimeters, and GPS units, making them relatively easy to fly. Because the rotors on these aircraft are directly driven by electric motors and aircraft movements are controlled by simply changing the rotation rate of one of the motors, these aircraft require none of the mechanical linkages and multiple moving parts associated with standard helicopters. In addition, the use of multiple rotors reduces the size and resultant kinetic energy in each blade, making the aircraft safer for both operators and wildlife in case of a mishap. We selected Cape Shirreff, Livingston Island, South Shetland Islands for our field test because the habitat is rugged, remote, and scientists there work with large aggre- gations of penguins and fur seals. Our objectives were to: 1. Test operation of three independent verti-

Marine Mammal Science, Oct 27, 2020

Knowing size-at-age is important for determining food requirements and making inferences about th... more Knowing size-at-age is important for determining food requirements and making inferences about the nutritional status of individuals and their populations. Accurate growth curves are also needed to quantify drug dosages to treat wounded or entangled animals. However, body sizes are often based on small numbers of measured animals that must be improved as new data become available. We updated an

Marine Mammal Science, 2001

Estimates of Steller sea lion (Eumetopias jubatus) pup production are valuable for estimating pop... more Estimates of Steller sea lion (Eumetopias jubatus) pup production are valuable for estimating population trend and size. Currently in Alaska, pups are counted by visiting rookeries, driving older animals into the water, then walking through the rookeries and counting the pups, a highly disruptive procedure. At smaller rookeries, with good vantage points, pups are occasionally counted from the periphery of rookeries without disturbing the sea lions. We evaluated counts made from medium-format, color, aerial photographs as an alternative to drive counts and peripheral counts. Neither the peripheral counts nor the aerial photographic counts disturbed animals on the rookeries. There were strong 1: 1 linear relationships between photographic counts and drive counts ($ = 0.966, P < 0.001) and between photographic counts and peripheral counts (VZ = 0.999, P < 0.001). Precision was similar for all three methods of counting. We suggest that medium-format, color, aerial photography is appropriate for routine surveys of Steller sea lion pups in Alaska because it is not disruprive to the hauled-out sea lions and provides comparable estimates with similar precision to drive and peripheral counts. Large areas can be rapidly surveyed during periods of good weather with a minimum of manpower.

The journal of cetacean research and management, Feb 15, 2023

Geographic variations in size and proportions of blue whales (Balaenoptera musculus) were investi... more Geographic variations in size and proportions of blue whales (Balaenoptera musculus) were investigated using length data acquired from whaling records and aerial photogrammetric surveys. Results showed that blue whales found in the eastern Pacific off Central and North America are significantly shorter (by approximately 2m) than blue whales found at higher latitudes in the North Pacific. Results support the occurrence of a morphologically distinct eastern North Pacific (ENP) blue whale population which migrates in spring/summer from warm waters off Central America and Mexico to temperate feeding grounds along the west coast of North America. Southern Hemisphere blue whales sampled with vertical aerial photogrammetry off northern Peru and the Galapagos Islands were similar in size to the ENP blue whales. However, the population affinity of these southern blue whales remains uncertain. No length data were available for blue whales formerly captured off southern Japan and Korea. Nonetheless, a history of diminishing fishery catches and a lack of any recent sightings suggests that these whales were members of a geographic population that is now severely depleted or extinct. Based on comparisons of total length, length of rostrum and length of tail region, ENP blue whales were found to be morphologically similar to the 'pygmy' blue whale (B.m. brevicauda) described from the Kerguelen Island region of the southern Indian Ocean. 'Antarctic' blue whales (B.m. intermedia) from the Southern Ocean were found to be statistically significantly larger than their conspecifics at high latitudes in the North Pacific. These results support the hypotheses that blue whales that migrate from warm seas to cold feeding grounds in high latitudes are larger than those whose distributions are limited to low and mid-latitudes. Differences in morphology may reflect selective pressure on populations to adapt physiologically to energy demands associated with different migration, environmental and ecological regimes. As some of the results come from populations located far apart in different oceans, questions remain concerning the continuity of populations within and among ocean basins. Consequently, research using fishery data and approaches such as photogrammetry, telemetry, acoustics and molecular genetic analysis should be continued to better understand the worldwide blue whale population structure.

Frontiers in Marine Science, Mar 11, 2021

Journal of unmanned vehicle systems, Mar 1, 2016

Aerial imagery is the most effective method National Marine Fisheries Service (NMFS) uses to asse... more Aerial imagery is the most effective method National Marine Fisheries Service (NMFS) uses to assess abundance of Steller sea lions (Eumetopias jubatus). These images are traditionally captured from occupied aircraft, but the long distances between airfields along the 1,900 km Aleutian Island chain, inclement weather during the survey season, and dangerous winds at sites adjacent to cliffs severely limit flying opportunities. Due to the pressing need for current trend information for a population in persistent decline we turned to a small unoccupied aircraft system (UAS), an APH-22 hexacopter. Our primary objective was to supplement traditional aerial surveys during the annual abundance survey. The second objective was to test whether the resolution of images captured with the hexacopter were adequate for sighting permanently marked individuals. From June-July 2014, NMFS biologists based on a research vessel assessed sites from Attu Island to the Delarof Islands (n = 23), surveying sites from land (n = 12) and with the hexacopter (n = 11). Simultaneously, Traditional aerial surveys were conducted east of the Delarof Islands (n = 172). This combined approach enabled us to conduct the most complete survey of adult, juvenile, and newborn Steller sea lions in the Aleutian Islands since the 1970s. Images collected also allowed for us to identify alphanumeric permanent marks on individuals as small as juveniles. With this successful implementation of UAS, NMFS plans to use the hexacopter to supplement future surveys.

Journal of Mammalogy, Oct 19, 2012

Body growth of North Atlantic right whales (Eubalaena glacialis) was described from measurements ... more Body growth of North Atlantic right whales (Eubalaena glacialis) was described from measurements of knownage live and dead individuals to gain insights into the nutritional needs and life-history strategies of this endangered species. Body lengths from 154 individuals revealed that calves more than doubled in size and attained three-fourths of asymptotic adult size by the time they had weaned at 12 months. Calves gained on average~1.7 cm and~34 kg per day while nursing during this extremely rapid growth phase. Mean predicted lengths and body mass were 4.2 m and 1.1 metric tons (mt) at birth, 10.3 m and 13.5 mt at weaning, and 13.6 m and 29.6 mt when fully grown. Growth of right whales was best described using a 2-phased Gompertz growth model and could not be fit using any of the single continuous growth models commonly used for other mammals. Rapid growth during dependency may minimize the risk of predation and maximize calf survival. Rapid calf growth also may maximize development of the mouth and baleen to optimize foraging efficiency of juveniles at the time of weaning, as well as improve reproductive fitness by reducing the age at which sexual maturity is attained. However, transferring the amount of energy needed to support the rapid postnatal growth of North Atlantic right whales may ultimately affect the intervals between pregnancies (.3 years) of mature females.