Carl R. Schilt

Cooperative societies in three- dimensional space: On the origins of aggregations, flocks, and schools, with special reference to dolphins and fish

Abstract In three-dimensional open space habits, and to a lesser degree open terrestrial habitats, cooperative groupings of animals have repeatedly evolved. These cooperative systems have been observed in a wide variety of animal taxa, ranging from sea urchins to cetaceans. Various attempts have been made to relate the origins of such patterns to kin or altruism theory. An evolutionary stable strategy appears to be involved. We propose a graded series of group structures of increasing complexity by means of which three-dimensional groupings could have evolved without recourse to either group selection or even necessarily kin selection or reciprocal altruism. These structures are asocial and social aggregations , and polarized schools . Social aggregations and polarized schools allow cooperative feeding and avoidance of predation. They confer three predation-related advantages over living alone for animals in open environments: (1) the dilution effect of large prey numbers relative to those of predators, (2) the encounter effect, which provides some protection from searching predators, and (3) the confusion effect by means of which visual tracking by a predator is confounded. We suggest that the gaze stabilization system of the visual system is involved in the most advanced version of the confusion effect. In polarized schools members sense and react to each other, forming a sensory integration system (SIS). This system allows detection and transmission of information across a school, flock, or herd in three dimensions. Because members watch beyond their immediate neighbors the transmission of such group reactions can greatly exceed the reaction speed of individual members, or any predator. Because the confusion effect and the SIS depend upon uniformity of behavior the polarized school is uncommonly difficult and perhaps impossible to cheat against. We perceive this as a key factor in the establishment of the evolutionarily stable strategy of schooling. Polarized schools and aggregations are considered as the extremes of a behavioral continuum. Because in daytime the polarized school is a safer place to be and because the aggregation allows more freedom of movement for such activities as food finding, groups in open space oscillate between the these extremes during varying levels of predation. The social complexity of fish schools seems modest whereas dolphin schools show the complexities of fairly typical mammalian organization. Occupancy of open space by both oceanic dolphins and schooling fish seems to have fostered promiscuous mating. In both open water fish and mammals elements of a cooperative disposition occur, which involves both cooperation and suppression of some aspects of individuality. Such dispositional elements allow the automatic support of a cooperative society. Dolphin schools, which during daytime rest or danger react like fish schools, express typical mammalian organization at other times. Dolphin echolocation has probably allowed the expression of mammalian behavior patterns at sea because it confers a major advantage over shark predators. The expression of mammalian social complexity may have required both kin and reciprocal altruistic patterns in different species.

Responses of Blueback Herring to High-Frequency Sound and Implications for Reducing Entrainment at Hydropower Dams

Abstract Low- and high-frequency sounds were tested as a means of repelling blueback herring Alosa aestivalis in confined-area and open-water experiments. Confined-area tests were performed by analyzing the response of blueback herring in floating net-pens to sounds differing in frequency, sound pressure levels (SPLs, given in decibels [dB] in reference to l.0 μPa), and pulse width. Highfrequency sounds between 110 and 140 kHz, at SPLs above 180 dB (at 1.0 m from the transducer) and at various pulse widths, elicited statistically significant (P < 0.05) avoidance responses by blueback herring. A reduced response was observed at sound frequencies of 100 and 150 kHz. Low-frequency sounds between 0.1 and 1 kHz at SPLs of 160–175 dB (at 1.0 m from the transducer) elicited only short-term startle responses. Field tests were performed at Richard B. Russell Dam (on the Savannah River at the Georgia-South Carolina border) to evaluate candidate transducers and amplifiers. In field evaluations a single high-frequenc...

Hydroacoustic evaluation of fish passage through Bonneville Dam in 2000

The Portland District of the U.S. Army Corps of Engineers requested that the Pacific Northwest National Laboratory (PNNL) conduct fish-passage studies at Bonneville Dam in 2004. These studies support the Portland Districts goal of maximizing fish-passage efficiency (FPE) and obtaining 95% survival for juvenile salmon passing Bonneville Dam. Major passage routes include 10 turbines and a sluiceway at Powerhouse 1 (B1), an 18-bay spillway, and eight turbines and a sluiceway at Powerhouse 2 (B2). In this report, we present results of four studies related to juvenile salmonid passage at Bonneville Dam. The studies were conducted between April 15 and July 15, 2004, encompassing most of the spring and summer migrations. Studies included evaluations of (1) Project fish passage efficiency and other major passage metrics, (2) B2 fish guidance efficiency and gap loss, (3) smolt approach and fate at the B2 Corner Collector (B2CC), and (4) B2 vertical barrier screen head differential.

Vibration of otolithlike scatterers due to low frequency harmonic wave excitation in water.

Otoliths may be approximated as hard objects moving in an acoustic medium in response to arriving sounds. We modeled how parameters of sound such as frequency and direction could be encoded from the motion of the otoliths. Prior numerical models predicted harmonic oscillation (rocking) of scatterers suspended in an acoustic medium when exposed to planar harmonic waves. Because of the potential for the angular oscillation to produce additional information about the sound source, the simulated rocking motions were studied using an additional numerical model. The number of scatterers, their spatial arrangements, shapes, and the characteristics of the incident sound waves were varied. The results were analyzed and will be presented. [Work supported by the Office Naval Research.]

Natural modes of vibration in the auditory system of a teleost.

Fishes are diverse in hearing systems and anatomy. Doing actual bioacoustic experiments with even one species, candidate sound, and acoustic environment is difficult to conduct and to generalize. Our modeling approach, if properly carried out and validated, will enable us to do virtual bioacoustic experiments that will enhance knowledge of biophysical phenomena with economy of time and resources. We present preliminary results of a project that extends to fishes our finite‐element modeling methods, which have been used to investigate marine mammal bioacoustics. These methods involve obtaining appropriate specimens, scanning them with x‐ray CT, measuring elasticity of tissues, and constructing a finite‐element model. Then we simulate the interactions between selected anthropogenic sounds and the model of the fish. Here we introduce vibrational analysis with fishes, simulating the resonant frequencies of the otoliths and surrounding structures in a large sciaenid fish (the white seabass, Atractoscion nobili...

Directional responses of blueback herring to ultrasonic pulses

Adult blueback herring (Alosa aestivalis) have been found to be directionally responsive to very high (118 kHz fundamental) pulsed sounds. The experiments were conducted in a pen containing filtered fresh water. Fish responses were videotaped. Fish usually only flinched in response to the onset of continuous wave stimuli. They usually moved immediately away from the source of short repetitive impulse sounds (duration from around 20 cycles to about four ms and less than 174 dB re 1 mPa at the nearest fish). Although a variety of pulse repetition rates were tested, no clear effect of that variable on fish response was apparent within the limits set by the experimental design. Sounds of similar frequency (120 kHz fundamental, 4 ms pulse duration, 5 Hz repetition rate) but over 200 dB re 1 mPa at the nearest fish also produced a behavioral response which sometimes resulted in the fish moving quickly away from the sound source but always included a dramatic and immediate coalescing into a tight school, as is o...

Anatomy of a Northeastern Pacific Ocean Sciaenid Fish, the White Weakfish (Atractoscion nobilis)

Anatomy of a Northeastern Pacific Ocean Sciaenid Fish, the White Weakfish (Atractoscion nobilis) Carl Schilt, Bigleaf Science Services, North Bonneville, WA and Ted Cranford, San Diego State University, San Diego, CA. The bony fish family Sciaenidae, commonly called the croakers, grunts, and drums, are as bioacoustically interesting as their names suggest. Although the anatomy and bioacoustics of some North Atlantic Ocean forms have been investigated, those of the Pacific Ocean are less-well studied. The white weakfish (or white seabass, Atractoscion nobilis) is a near-shore marine sciaenid of the West Coast of North America and is the target of sport and commercial fisheries and the subject of a substantial stock enhancement program. Two fresh post-mortem specimens of the white weakfish were subjected to CT scanning on two different spatial scales. The full body of the larger animal, about 1 m long total length (TL), was scanned at a 0.625 mm voxel size whereas the head of a much smaller specimen (about ...

ESTABLISHING THE BOUNDARY CONDITIONS FOR EXPERIMENTS ON THE EFFECTS OF ANTHROPOGENIC SOUND ON FISH AND INVERTEBRATE ANIMALS

Espmark, Y., & Langvatn, R. (1985). Development and habituation of cardiac and behavioral responses in young red deer calves (Cervus elaphus) exposed to alarm stimuli. J. Mammal. 66, 702-711. McCauley, R. D., Fewtrell, J., Duncan, A. J., Jenner, C., Jenner, M. N., Penrose, J. D., Prince, R. I. T., Adhitya, A., Murdoch, J., & McCabe, K. (2000). Marine seismic surveys: a study of environmental implications. APPEA J. 40, 692-708. Wells, R. S. (2003). Dolphin social complexity: lessons from long-term study and life history. In Animal Social Complexity: Intelligence, Culture, and Individualized Societies (Ed. F. B. M. de Waal and P. L. Tyack), pp. 32-56. Cambridge, MA: Harvard University Press.

Ultrasound hearing and response in alosine herrings: A short history of the pure and applied research to date

In the early 1990s it was reported that downstream‐migrating American shad (Alosa sapidissima) avoided a sonar‐sampling beam with fundamental frequency over 150 kHz. Since then there has been a considerable body of laboratory and field work to determine which fishes have such hearing capacity, what the hearing limits are, what the hearing mechanisms may be, what might have led to selection for such capacity, and the utility of such stimuli to control the local distributions of fishes with such ultrasonic hearing. So far it seems that ultrasonic click aversion is limited to one subfamily of primarily anadromous herrings (family Clupeidae; subfamily Alosinae). The capacity to hear very high clicks and the propensity to swim away from the stimulus direction has led to experiments in shad protection, especially in hydropower and other industrial environments, which have been promising. This talk will review the history of both the pure and applied science on alosine herring ultrasound response and suggest pos...

Synthesis of Biological Reports on Juvenile Fish Passage and Survival at Bonneville Dam through 2005

This report describes a review of available literature on juvenile salmonid passage at Bonneville Dam from 1939 through 2005. Studies of interest included project-wide fish-passage efficiency (FPE) studies by radio telemetry and fixed-aspect hydroacoustics, fish survival studies (direct and indirect), FGE studies, powerhouse and unit (by netting, hydroacoustics, and radio telemetry), predation studies in the forebay and tailrace, behavioral studies on forebay approach and egress, and surface-bypass studies. The FPE effort will include a review of available distribution data (horizontal, diel, and vertical) for juvenile salmon. This study does not repeat the results of previous review and synthesis studies but cites them. Where no previous review exists for a subject area, all reports were reviewed and synthesized. The report includes an annotated bibliography summarizing each of the documents reviewed and a DVD disk containing all of the original papers and reports along with an HTML index to the documents.