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Stenella attenuata (Gray, 1846). Zool. Voy. H.M.S. "Erebus" and "Terror", 1:44. TYPE LOCALITY: None given, unknown (possibly India, see Gray, 1843). DISTRIBUTION: Worldwide: temperate to tropical waters. STATUS: CITES - Appendix II. SYNONYMS: albirostratus, brevimanus, capensis, consimilis, graffmani, malayanus, pseudodelphis, punctata, velox. COMMENTS: Perrin et al. (1987) revised this species. D. dubius is a nomen nudum (sic dubium] (Perrin et al., 1987). Opinion 1660 of the International Commission on Zoological Nomenclature (1991) conserved attenuata Gray, 1846 and suppressed velox Cuvier, 1839, pseudodelphis Schlegel, 1841, and brevimanus Wagner, 1846., Published as part of James G. Mead & Robert L. Brownell, Jr., 1993, Order Cetacea, pp. 349-364 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 356, DOI: 10.5281/zenodo.7352970

Data from the Mexican purse seiner fleet operating in the eastern Tropical Pacific, for the year 1985-1990, are used to show that the fraction of surface schools of yellowfin tuna Thunnus albacares associated with dolphins (Stenella attenuata and others) increases with sea surface temperature. Possible reasons for this correlation are briefly discussed.

Since the passage of the U. S. Marine Mammal Protection Act, approximately 1.25 million dolphins have been killed incidentally during purse seine fishing operations for yellowfin tuna (Thunnus albacares) in the eastern tropical Pacific Ocean. The three species of pelagic dolphins primarily involved in this fisheries interaction are the spotted dolphin (Stenella attenuata), spinner dolphin (Stenella longirostris), and common dolphin (Delphinus delphis). We review the status of these species relative to stock structure, current population size, levels of fishery-related mortality, and trends in abundance. Abundance estimates have been derived from two sources: data collected by observers on research vessels and data collected by observers on tuna vessels. Estimates of incidental mortality are currently derived only from data collected by observers on tuna vessels. There is no evidence of any significant change in abundance for any of these three species since 1985. However, declines in abundance have been detected over the last 15 yr.

International audience; The aim of this work is an attempt to synthetize the different results of our researches on dolphin's contamination by Hg and their interpretation. It is based on the results obtained following the total Hg determination in several organs of 35 specimens of Stenella coeruleoalba stranded on French Atlantic and Mediterranean coasts and 45 Stenella attenuata captured in the Eastern tropical Pacific. Considering our present knowledge on Hg ecotoxicological processes, the trophic route, via cumulative Hg transfers through the marine trophic network, can be considered as the major contamination route for the dolphins. However, considering the influence of the geographical origin of the individuals it also seems reasonable to assume that the principal contamination source of the high Hg concentrations observed in pelagic dolphins are natural metal deposits.

International audience; Based on a sample of 27 dolphins (Stenella attenuata) captured in the Eastern tropical zone of the Pacific Ocean, this study was carried out to analyze the cadmium accumulation levels and distribution in 12 organs or tissue samples. The average cadmium concentrations were between 0.2 mg Cd · kg−1 in the brain and muscle and 48 mg Cd · kg−1 in the kidneys. For most of organs and tissues the average values were between 1 and 5 mg Cd · kg−1. Kidneys, liver, muscle, and intestine contained almost 85% of the total cadmium burden of all tissues considered in this study. Most of the biological and ecological factors taken into account (age, sex, total weight, and length of the dolphins, weight of the organs, place and date of capture) interacted with the cadmium concentrations and burdens in the collected organs or tissues. Three factors appear to be of prime importance: age, body weight, and geographical location of the area of capture.

Variation in acoustic behavior based on school size and species composition was examined for surveys in the eastern tropical Pacific (2000), along the U.S. West Coast (2001), and in the U.S. EEZ surrounding Hawaii (2002). Sounds were monitored using a towed hydrophone array, and vocal schools were defined as those producing any combination of whistles, burst pulses, and/or echolocation clicks. Delphinid schools containing mixed species were consistently more vocal than single species schools. Vocal schools of Stenella attenuata, S. longirostris, Delphinus delphis, and Lissodelphis borealis were significantly larger than non‐vocal schools. Vocal schools of Tursiops truncatus and Grampus griseus were somewhat larger than non‐vocal schools, although this relationship was not significant. There was no relationship between group size and vocal activity for S. coeruleoalba, Steno bredanensis, and Globicephala spp. For species without a strong group size effect, all but T. truncatus were more vocal in the Hawaiian waters. The ability to use acoustic techniques in dolphin population estimation depends on their effectiveness in consistently detecting dolphin schools. This study suggests that small single‐species schools of S. attenuata, S. longirostris, D. delphis, and L. borealis are more likely to be missed during acoustic monitoring in these regions.

Spectral and statistical analyses were used to compare the whistle structure of six species of dolphin; Stenella longirostris, Stenella frontalis, Stenella attenuata, Lagenorhynchus obscurus, Tursiops truncatus, and Sotalia fluviatilis. A consistent pattern existed in the various coefficients of variation calculated for the different species. In general, the frequency variables had the lowest coefficients of variation (cv). The values of cv for maximum frequency were usually the lowest. Compared to other species Tursiops had relatively large coefficients of variation of the frequency variables indicating that the frequencies of Tursiops whistles were more diverse. The other five species had similar frequency ranges which had higher upper frequencies than Tursiops. The results of discriminate analysis indicated that here were significant differences between the whistle structures of the different species, and that these differences were related to taxonomic relations, body size, and habitat. The magnitude ...

The first marine mammal acoustic survey using a towed passive hydrophone array was recently completed. Other cetacean surveys have used static, low‐frequency arrays; the array used is a broadband, mobile system, receiving both baleen and toothed whale signals. For acoustic censusing and tracking (ACT) to become an accepted technique, it’s biases and assumptions must be described. ACT has a number of advantages, including a permanent record of all effort, compared to visual methods which are instantaneous samples, with no permanent record. This record permits measurement of perception and availability biases. A dynamic strip width can be calculated by continuously recording SPL. An area of 154 621 km2 was surveyed in the north central Gulf of Mexico during seven cruises, recording 1431 tapes. Recording effort occurred over 11 997 km of a total transect distance of 12 580 km, corresponding to a 95.4% level of effort; a concurrent visual survey yielded a 48.5% level of effort. A total of 157 contacts from 13 cetacean species were recorded, including 67 sperm whale (Physeter macrocephalus), 22 pantropical spotted dolphin (Stenella attenuata), one baleen whale, 327 unidentified dolphin, and 30 unidentified cetacean contacts. Three‐dimensional distributions were determined for sperm whale and pantropical spotted dolphin. Estimates of cetacean populations were computed based on this effort.

Chromosomes from cultured fibroblasts of two Pacific porpoise species, Stenella attenuata and S. longirostris and one Atlantic species, S. dubia, were compared to test the feasibility of using variation in constitutive heterochromatin and other chromosomal characteristics for analyses of population relationships and defining stocks of endangered porpoises. The G-band karyotypes of the three species were identical except for minor band differences resulting from heterochromatin variation. The nucleolar organizer regions (NORs) were located on the same two pairs of acrocentric chromosomes in all three species, although individual variation occurred in the number of active NORs present. Differences in the distribution and amount of C-band heterochromatin were observed between the three species. Stenella attenuata and S. dubia were very similar in C-band pattern, while S. longirostris was distinctly different. Conspicuous heteromorphism between the C-heterochromatin of the homologs of several pairs of chromosomes was noted in all individuals examined. In addition, variation in the amount of heterochromatin was observed between the four S. attenuata individuals studied. Of the chromosomal characteristics studied, only C-heterochromatin variation holds promise for distinguishing interspecific populations of porpoises. The final decision regarding the feasibility of using C-band heterochromatin to distinguish interspecific populations of porpoises must await comparison of morphologically differing populations within what is currently regarded as a single species.

The bony falx (BF) and bony tentorium (BT) of spotted dolphins (Stenella attenuata) at different growth stages were observed. The BF and BT were observed to have the shape of the entire falx cerebri (FC) and tentorium cerebelli (TC), respectively, in adults, but were not seen in fetuses at all. Partially formed BF and BT were observed in the young. The BF and BT of spotted dolphins are formed by ossification in the FC and TC in the course of aging. Based on age determination by means of dentinal growth layers of the maxillary teeth, the ossification in the FC and TC of spotted dolphins begins by about 1 yr of age, and is completed, except for the passage of nerves and blood vessels, by about 9 yr of age. The BF and BT of spotted dolphins are formed possibly by continual dietary intake of large amounts of calcium, phosphorus and vitamin D.

Multivariate analyses were performed on 36 morphometric and meristic skull measurements taken on 613 spotted dolphins ( Stenella attenuata ) from the eastern tropical Pacific Ocean. Corrections were made to account for sexual dimorphism. Findings extend previous results which indicate sharp demarcation between two stocks: a larger, more robust coastal or inshore form; and a smaller, more terete pelagic or offshore stock. Sample means from 5° latitude-longitude blocks were projected onto principal component I and showed separation of four inshore from 19 offshore blocks, primarily on the basis of size involving most morphometric characters. A second component with high loadings on tooth counts summarized differences of three southern inshore blocks (adjacent to Central America) from a fourth, more northerly block located at the Gulf of California. Cluster analyses provided a similar summary of interblock associations. Principal components and cluster analysis based on individual specimens were also used to identify seven individuals with questionable affinity. The remaining 606 specimens (575 offshore, 31 inshore) were used to generate a discriminant axis and associated classification functions that correctly allocated all specimens. The best character for distinguishing between offshore and inshore specimens is Tooth Width. Classificatory information is provided to enable other researchers to assign unknown specimens.

There are at least two races of spotted dolphin, Stenella attenuata, in the eastern Pacific, based on length, color pattern, and skeletal differences. The coastal form is provisionally called S. attenuata graffmani. The offshore form is distinct from a third, Hawaiian race. Likewise, at least three unnamed races of spinner dolphin, S. longirostris, occur in the eastern Pacific. Length, shape of adult male, color pattern, and cranial differences are used to distinguish a Costa Rican, an eastern, and a whitebelly race. An Hawaiian race is distinct from these. A distributional break may indicate two stocks of the striped dolphin, S. coeruleoalba.

In decalcified and hematoxylin-stained thin section, teeth of sexually mature female spotted dolphins ( Stenella attenuata ) often exhibit a deeply dark-stained layer (DSL) at the boundary of one or more of their annual growth layer groups. We compared DSL counts, made without reproductive information, to the corresponding reproductive condition in 75 females to test five hypotheses concerning the possible significance of DSLs. We found an exclusive association between DSLs and calving events. The teeth of an Hawaiian spinner dolphin, Stenella longirostris , labeled with tetracycline one month after giving birth to a calf in captivity, contained a dentinal DSL near the label. The number of DSLs in the dentine of a female probably indicates the minimum number of calves born to the female. In future studies DSL counts may be useful in estimating birth frequencies, year-specific birth rates, and calf mortality in odontocetes.

A light microscopic investigation of the histological development of the terminal airways of 18 Stenella attenuata and two S. longirostris showed the lungs to be in a glandular stage of development until 3 months postimplantation (p.i.) age. By 3.5 months (p.i.) the lung was at the canalicular stage. At 4 months mesenchymal rings and muscular bands were in a sphincterlike arrangement around terminal bronchioles. At 7 months (p.i.) the alveolar stage occurred. About 8-9 months cartilaginous rings were present and in association with myoelastic sphincters. Their function remains an enigma, even though many hypotheses as to function have been proposed. We suggest that the presence of well-developed sphincters and cartilage in the neonate may give clues to their function as well as offer potential experiments that would not be as suitable in the adult porpoise.

We analyzed 4 meristic and 32 morphometric cranial traits of 612 adult specimens of spotted dolphins (Stenella attenuata) from the eastern tropical Pacific Ocean for sexual dimorphism. Eleven 5” latitude/longitude blocks with five or more of each sex were assessed with a two-way ANOVA for sex and geographic differences. Interaction between these two factors was found for six measurements, suggesting that the degree of sexual dimorphism varies geographically for a few characters (although in no discernible geographic pattern). Sexual dimorphism was demonstrated for 23 of the 36 characters, with differences ranging from 0.00 to 5.88 percent. Females characteristically had a longer rostrum, while males generally had larger skulls overall. In terms of number of characters, the extent of sexual dimorphism demonstrated for skulls of spotted dolphins goes considerably beyond that shown for any other small delphine. A discriminant function involving a combination of 10 characters enabled us to identify correctly the sex of more than 75 percent of the specimens. A procedure for correcting specimen measurements is outlined that would enable an investigator to combine male and female specimens in geographic variation studies. A term (zwitter) is proposed for use when referring to specimens where measurements have been corrected to take into account differences between the sexes. When studying morphological variation within a species, it can be important and informative to apportion variability into geographic and non-geographic components. Genetically controlled, non-geographic variation manifests itself in several ways, each of which may have distinct evolutionary implications. Sexual

The composition and quantity of free short-chain acids in the milk of whales Stenella attenuata and the composition of short-and long-chain acids in their milk lipids were studied. The content of lipids in the milk was about 19.7%, the REICHERT-MEISSL value about 6.1, and the content of free short-chain acids about 3.1 meq/l. Acetic, propionic, isobutyric, isovaleric, and n-enamthic acids were usually present in free form. Acetic acid was the most dominate, followed by n-enanthic and isovaleric acids. Other acids were detected in trace amounts. A series of short-chain straight acids from acetic acid to n-capric acid and a series of short-chain branched acids from isobutyric acid to isoenanthic acid were usually detected in milk lipids. Generally, actic acid was the most abundant, the straight-chain acids from proponic acid to n-capric acid were present in nearly equal amounts, but branched-chain acids were few. Long-chain branched acids in milk lipids were also prewent only in small amounts. Iso-17:0 acid showed the maximum concentration among the odd-numbered iso acids and iso-18:0 acid among the even-numbered iso acids. Few anteiso acids and few iso acids with carbon number lower than 13 were detected.

The spotted dolphin (Stenella attenuata), a species commonly associated with the tuna fishery, is widely distributed in the eastern tropical Pacific Ocean (ETP). Geographic patterns in morphological characteristics of this dolphin were evaluated for 36 skull measurements of 574 museum specimens allocated to 5° latitude-longitude blocks. A strong subdivision between northern and southern offshore populations was demonstrated using principal components, canonical variates and cluster (UPGMA and function-point) analyses of block means derived from standardized, sex-adjusted measurements. Classification functions derived from a stepwise multiple discriminant analysis correctly identified more than 87 percent of the specimens as being from either a northern or southern locality. These results support recognition of southern spotted dolphins as a separate management stock. Dolphins from a sample representing a far-western locality show similarities with those from the south. Patterns of geographic variation in morphology were evaluated using Mantel tests and matrix correlations; 17 of the 36 characters showed regional patterning and 18 exhibited local patterning. Morphological trends were also assessed with respect to 14 oceanographic measures that characterize environmental variability in the ETP. In general, clinal variation in morphology mirrors a north-south trend found in several environmental variables. Overall, the most striking associations between morphological and environmental variables involved Solar Insolation (Jan.). Sea surface temperatures also exhibited a strong association with morphological variables; the highest correspondence was found between width of the temporal fossa and sea surface temperature in July. In addition, the thickness of the oxygen minimum layer exhibited a pattern of variation that was statistically associated with 58 percent of the skull characters. The geographic patterns found for cranial morphology and environmental measures are strongly clinal and in general congruent, suggesting that oceanographic conditions in part determine trends in morphological characteristics of spotted dolphins.

In order to ascertain the origin and function of iso-valeric acid in dolphin oil, the fatty acid composition of oil obtained from Stenella attenuata was studied by gasliquid chromatography, especially with the consideration of the differences occurring in various parts of the body but also in the various stages of development. The results obtained are as follows: 1) Degrees of unsaturation of blubber oils of the foetus and nurseling were remarkably lower than that of the adult. 2) The content of short-chain fatty acids (C2-C6) varied according to the stage of development and the part of the body. 3) Most of the short-chain fatty acids consisted of iso-valeric acid in the adult, but in the nurseling or foetus, iso-butyric acid or n-butyric acid was also adundant, next to iso-valeric acid. 4) Long-chain fatty acids (C10-C22) contained many branched-chain fatty acids of the iso-series, which were the most abundant in jaw oil of the adult and nurseling and in head oil of the foetus. The content of branched-chain fatty acids of the iso-series in blubber oil was poor in all stages. 5) Of the branched-chain fatty acids of the iso-series, iso 15:0 was highest in the adult, and iso 16:0 was equal to or higher than iso 15:0 in the nurseling and foetus.

Previous work has determined the age distribution from a sample of spotted dolphins (Stenella attenuata) killed in the eastern Pacific tuna purse-seine fishery. In this paper we examine the usefulness of this age distribution for estimating natural mortality rates. The observed agedistribution has a deficiency of individuals from 5-15 years and cannot represent a stable age distribution. Sampling bias and errors in age interpretation are examined as possible causes of the "dip" in the observed age structure. Natural mortality rates are estimated for the 15+ age classes based on the assumption that these are sampled representatively. The resulting annual survival rate

Stenella attenuata (Gray, 1846). Zool. Voy. H.M.S. "Erebus” and "Terror,” 1:44. TYPE LOCALITY: Unknown. DISTRIBUTION: Tropical waters of Indian, Pacific, and Atlantic Oceans. COMMENT: Includes frontalis, graffmani, and dubia; see Rice, 1977:8. Includes malayana; see Perrin, 1975, Bull. Scripps Inst. Oceanogr. Univ. Calif., 21: 1 -206, but also see Rice, 1977:13. The taxonomy of the spotted dolphins (frontalis, dubia, attenuata, and plagiodon) remains to be resolved (WFP). The presently recognized nominal forms (frontalis, attenuata, and plagiodon) will probably prove to be two species of spotted dolphins; frontalis is probably conspecific with either attenuata (JGM), or plagiodon (WFP); dubia (including asthenops and crotaphyscus), used by Hershkovitz, 1966:31, may belong to either of the two probable species (WFP and RLB; DWR; JGM). Hershkovitz, 1966:31, argued that dubia is a prior name for attenuata. See Hall, 1981:882-883, for additional discussion. PROTECTED STATUS: CITES - Appendix II as Order Cetacea. ISIS NUMBER: 5301411002013002001 as S. dubia., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Cetacea, pp. 290-304 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 296, DOI: 10.5281/zenodo.7352983, {"references":["Rice, D. W. 1977. A list of the marine mammals of the world. Third ed. NOAA Technical Report, NMFS SSRF- 711: 1 - 15.","Perrin, W. F. 1975. Variation of spotted and spinner porpoise (genus Stenella) in the eastern tropical Pacific and Hawaii. Bulletin of the Scripps Institution of Oceanography, 21: 1 - 206.","Hall, E. R. 1981. The mammals of North America. Second ed. John Wiley and Sons, New York, 1: 1 - 600 + 90, 2: 601 - 1181 + 90."]}

This paper is an account of preparation and examination techniques and criteria used to estimate age in decalcified and stained tooth thin sections from spinner and spotted dolphins. A dentinal growth layer group (GLG),composed of two thin light and two thicker dark-stained layers, is deposited annually. The GLG component layers are variably visible, but the "ideal" pattern and successive thinning of dentinal GLGs are used as a guide to determine GLG limits. Age-specific thicknesses of dentinal GLGs found in Hawaiian spinner dolphin teeth seem to be applicable to teeth of spotted dolphins and can be used as an aid in locating GLG boundaries. Cementa1 GLGs are composed of a dark-stained and alightly stained layer and usually aredeposited at a rate of one per year, but may be deposited every other year or two or three times per year. Two slightly different methods of counting dentinal GLGs are presented, along with guidelines for determining whetherdentinal or cementa1 GLG counts provide the best estimate of age for a specimen. (PDF contains 23 pages.)

Chromosomes were prepared from skin fibroblast cultures of animals killed in the Pacific Ocean and identified by Dr. W. Perrin, La Jolla, California. Stock cultures of the females are frozen, the female karyotype is prepared with ASG technique. Previous Stenella sp. karyotypes studied by Kulu were also 2n=44.

SYNOPSIS The histological structure of the reniculus is described for the first time in the cetacean forms Delphinaptera leucas, Delphinus bairdi, Stenella styx, Stenella attenuata and Sousa plumbea. A sporta perimedullaris musculosa is shown to be present in all. A common pattern of renicular vascular arrangements is described and renicular venous return is shown to be effected by alternative renicular and perirenicular pathways. Such pathways constitute the sole radicles of the renal vein and no “wandering” veins emerge from the kidney surface.

Two specimens of Stenella attenuata, trained to chase a winchtowed lure, reached a top speed of 11.03 meters per second (21.4 knots) in 2.0 seconds. The maximum power output, occurring 1.5 seconds after the start, was calculated from measured values of acceleration and drag coefficient. The maximum power output per unit body weight was 50 percent greater than for human athletes. The measured drag coefficient, obtained from periods of coasting, was approximately the same as that of an equivalent rigid body with a near-turbulent boundary layer.

Aerial surveys were conducted off the coasts of Mexico and Central America during January and February 1974 to estimate sizes of porpoise populations (Stenella attenuata, S. longirostris, and Delphinus delphis) involved with the yellowfin tuna (Thunnus albacares). Line-transect techniques were used to obtain density estimates of approximately 1.1 schools/1,000 km2 (CV = 15%) for all 3 species of porpoises combined. Density estimates by species were derived, and have formed the primary basis for management of the incidental kill of porpoise by the purse-seine fleet from 1974 to 1980. J. WILDL. MANAGE. 45(3):650-657 The purse-seine fishery for tuna in the eastern tropical Pacific Ocean uses several species of porpoises (or dolphins) as indicators of the presence of tuna schools (Perrin 1968, 1969). In the process of netting tuna, many porpoises are killed. Since 1968, the National Marine Fisheries Service (NMFS) has conducted a program of research into the population biology of the major porpoise species to assess the impact of this incidental mortality on the porpoise populations (Perrin et al. 1976, Smith 1979). Knowledge of the size of the impacted porpoise populations is an important component in estimating the impact of the incidental kill by the fishery. This information can be used with estimates of reproductive rates and numbers of porpoises killed to determine present status and estimate the effects of future levels of incidental kill (Smith 1979). This paper describes the use of line-transect sampling theory (Seber 1973) in obtaining estimates of abundance of the porpoise populations involved in this fishery. This study was funded by the Southwest Fisheries Center, La Jolla, California. Many individuals were involved in completing this study, most notably E. Barham as field-party chief. The field party consisted of J. Coe, T. Belleau, W. Evans, J. O'Conner, and T. Smith. G. Stauffer collaborated closely in initial aspects of the study design, and S. Clark assisted with some of the preliminary data analysis. I thank these and others for their assistance and support.