Andrew C. Seitz

Variability in the summer diets of juvenile polar cod (Boreogadus saida) in the northeastern Chukchi and western Beaufort Seas

Polar cod (Boreogadus saida) is an important link between top predators and lower trophic levels in high-latitude marine ecosystems. Previous findings describe differences in its diet throughout the western Arctic; however, the causes of this variation are not well known. This study examined the diets of juvenile polar cod collected via demersal trawling methods over three summers in the northeastern Chukchi Sea (2010–2012) and one summer in the western Beaufort Sea (2011) to determine the amount of variability explained by biological, spatial, and interannual factors. Prey were identified, measured for length, and aggregated by percent mean weight into taxonomically coarse prey categories for analysis. Within seas, variation in juvenile polar cod diet composition was significantly related to body size, latitude, longitude, depth, and interannual (Chukchi Sea only) factors. Canonical correspondence analysis indicated body size was the most important factor contributing to the total variance in juvenile polar cod diet in the Chukchi and Beaufort Seas. Body size-based diet differences between the Chukchi and Beaufort Seas were evaluated using non-metric multidimensional scaling. This method revealed that similar-sized polar cod consumed similar-sized prey in both seas, but their diets were more benthically influenced in the Chukchi Sea and more pelagically influenced in the Beaufort Sea. Juvenile polar cod diet compositions vary by body size and region of inhabitance throughout their distribution. Here, we show that body size was the primary factor explaining variation in the summer diet of juvenile polar cod within the Chukchi and Beaufort Seas.

Toward a national animal telemetry network for aquatic observations in the United States

Animal telemetry is the science of elucidating the movements and behavior of animals in relation to their environment or habitat. Here, we focus on telemetry of aquatic species (marine mammals, sharks, fish, sea birds and turtles) and so are concerned with animal movements and behavior as they move through and above the world’s oceans, coastal rivers, estuaries and great lakes. Animal telemetry devices (“tags”) yield detailed data regarding animal responses to the coupled ocean–atmosphere and physical environment through which they are moving. Animal telemetry has matured and we describe a developing US Animal Telemetry Network (ATN) observing system that monitors aquatic life on a range of temporal and spatial scales that will yield both short- and long-term benefits, fill oceanographic observing and knowledge gaps and advance many of the U.S. National Ocean Policy Priority Objectives. ATN has the potential to create a huge impact for the ocean observing activities undertaken by the U.S. Integrated Ocean Observing System (IOOS) and become a model for establishing additional national-level telemetry networks worldwide.BackgroundTelemetry can provide environmental, behavioral and physiological data in near-real time, or by use of archival tags in which the data are stored or later transmitted to satellites. Aquatic animal species tagged have ranged from 6-g salmon smolts to 150-ton whales. Detailed observations of animal movements and behavior in relation to critical habitats in their aquatic environment have significantly improved our understanding of ecosystem function and dynamics. These observations are critical for sustaining populations, conserving biodiversity and implementing ecosystem-based management through an increased understanding of ecosystem structures, functions, and processes, as well as their importance to ecosystem services and values. Sensors carried by tagged animals have come of age and deliver high-resolution physical oceanographic data at relatively low costs. Animals are particularly adept at helping scientists identify critical habitats, spawning locations, and important oceanographic features (e.g., fronts, eddies and upwelling areas). They also provide important insights into regions of the oceans that are difficult and expensive to monitor (e.g., offshore environments, Arctic). This paper focuses on how to integrate an operational ATN into U.S. IOOS.ResultsThe development of U.S. IOOS initially focused on the acquisition and integration of physical and chemical oceanographic data. With this system now operational, U.S. IOOS is ready to add the acquisition of relevant biological observations, and to enhance the acquisition of physical and chemical oceanographic observations via ATN platforms.ConclusionA U.S. ATN observing system that monitors aquatic life on a range of temporal and spatial scales could yield both short- and long-term benefits, fill oceanographic observing and knowledge gaps, and advance many of the National Ocean Policy Priority Objectives. ATN has the potential to create a huge impact for the ocean observing activities undertaken by IOOS and become a model for establishing additional national-level telemetry networks worldwide.

Ecology of fishes in a high-latitude, turbid river with implications for the impacts of hydrokinetic devices.

Hydrokinetic devices generate electricity by capturing kinetic energy from flowing water as it moves across or through a rotor, without impounding or diverting the water source. The Tanana River in Alaska, a turbid glacial system, has been selected as a pilot location to evaluate the effects of such a device on fish communities that are highly valued by subsistence, sport, and commercial users. The basic ecology and habitat use of fishes in turbid glacial systems are poorly understood; therefore it is necessary to study the species composition of the fish community and the spatial and temporal patterns of mainstem river use by these fishes to evaluate impacts of a hydrokinetic device. In this document, we provide an overview of existing knowledge of fish ecology in the Tanana River and impacts of hydrokinetic devices on fishes in other river systems. Seventeen fish species are known to inhabit the Tanana River and several may utilize the deepest and fastest section of the channel, the probable deployment location for the hydrokinetic device, as a seasonal migration corridor. Previous studies in clearwater river systems indicate that mortality and injury rates from turbine passage are low. However, the results from these studies may not apply to the Tanana River because of its distinctive physical properties. To rectify this shortcoming, a conceptual framework for a comprehensive fish ecology study is recommended to determine the impacts of hydrokinetic devices on fishes in turbid, glacial rivers.

Feasibility of Surgically Implanting Acoustic Tags into Pacific Herring

Abstract Internally implanted acoustic tags represent a potentially valuable approach to assessing the seasonal migration and distribution patterns of Pacific herring Clupea palasii. We examined the feasibility of implanting two sizes of dummy acoustic tags (9 mm in diameter × 21 mm long, 1.6 g; and 7 mm in diameter × 18 mm long, 0.7 g) in Pacific herring that had been held in captivity for nearly a year and that ranged from 165 to 215 mm in fork length (FL) and from 41.6 to 142.6 g. Relatively low mortality (4%) and tag shedding (4%), as well as growth similar to that observed in control fish after 135 d, indicate that, with proper handling, Pacific herring are amenable to surgical implantation of acoustic tags.

Interannual site fidelity of Pacific halibut: potential utility of protected areas for management of a migratory demersal fish

Interannual site fidelity of Pacific halibut: potential utility of protected areas for management of a migratory demersal fish Julie K. Nielsen* and Andrew C. Seitz College of Fisheries and Ocean Sciences, Department of Fisheries, University of Alaska Fairbanks, 17101 Pt. Lena Loop Rd, Juneau, AK 99801, USA College of Fisheries and Ocean Sciences, Department of Fisheries, University of Alaska Fairbanks, PO Box 757220, Fairbanks, AK 99775-7220, USA *Corresponding author: tel: þ907 723 1469; fax: þ907 796 5447; e-mail: julie.nielsen@gmail.com

Interpreting Lamprey Attacks on Pacific Cod in the Eastern Bering Sea

AbstractAdult anadromous lampreys attack several species targeted by large-scale commercial fisheries in the North Pacific Ocean, and the potential negative impact to these host fishes is not well understood. The Arctic Lamprey Lethenteron camtschaticum and Pacific Lamprey Entosphenus tridentatus are anadromous species that feed in the eastern Bering Sea, and lamprey parasitism is evident on Pacific Cod Gadus macrocephalus near the Bering Slope. To examine this parasitic interaction, we first built models using morphological measurements from lamprey oral discs to predict which lamprey species caused the observed wounds on Pacific Cod. We then examined lamprey wounding rates and explored healing patterns related to the severity and location of lamprey wounds. We scanned 8,746 Pacific Cod for lamprey wounds and found that 4.9% of the cod had at least one wound. Lamprey wound morphology was better predicted by an oral disk model built for Pacific Lamprey than by a similar model built for Arctic Lamprey. The...

A Unique Case of Bilateral Hectocotylization in the North Pacific Giant Octopus (Enteroctopus dofleini)

Life-history information regarding most cephalopod species is somewhat scarce, and information relating anatomical anomalies of cephalopods is even more limited. For octopus species, the few anomalies that have been reported include: arm bifurcations (Smith, 1907; Okada, 1965; Gonzalez & Guerra, 2006), fourtharm hectocotylus (Robson, 1929), hexapody (Toll & Binger, 1991), septapody (Gleadall, 1989), decapody (Toll & Binger, 1991), and double hectocotylization (Robson, 1929; Palacio, 1973). Most male octopus have a modified third right arm or hectocotylus that is specialized for passing sperm packets to females. The tip of this specialized arm, known as a ligula, is spoon-shaped bearing a seminal groove ending in a rounded calamus. There are only three species of octopus that typically have the hectocotylized arm on the third left arm instead of the third right: Scaeurgus unicirrhus, Euaxoctopus panamensis and Pteroctopus tetracirrhus (Palacio, 1973). In over one hundred years of research, double hectocotylization has been reported in only six individual cases in six different species of octopus including: Eledone cirrhosa (by Appellof, 1892), Octopus briareus (by Robson, 1929), Octopus vulgaris (by Palacio, 1973), Octopus selene (by Palacio, 1973), Octopus chierchiae (by Roy Caldwell, personal communication) and Octopus minor (by Higashide et al., 2007). In each case, the third right arm was hectocotylized, along with an additional arm from the right side of the body (unilateral hectocotylization) or a left arm (bilateral hectocotylization). mentation of double hectocotylization for the Enteroctopus dofleini cephalopod having double hectocotylization not including either the third right or left arm. MALACOLOGIA, 2013, 56(1 2): 297 300

Robin N. Gibson (Ed.), Flatfishes: Biology and Exploitation

Flatfishes are one of the more notable orders of vertebrates on the planet. Over 700 species occupy freshwater, estuarine, and saltwater habitats, spanning from the equator to the poles. Their bilateral asymmetry, following a radical metamorphosis as juveniles, as well as their uncanny ability to camouflage themselves by perfectly matching the substrate on which they are living, allowed them to diversify and occupy the niche of a benthic predator. In addition to these unique biological characteristics, flatfishes provide an important source of protein, up to 25% of global groundfish landings, to people around the world via industrial, artisanal and subsistence fisheries. ‘‘Flatfishes: biology and exploitation,’’ edited by Robin Gibson, is an up-to-date and thorough compilation of what is known about the order Pleuronectiformes. The book consists of an excellent introduction by the editor and fourteen chapters written by 27 internationally renowned experts in the fields of flatfish biology and fisheries. The contents can be roughly divided into three sections. The first part covers systematics and distribution, the second part deals with biology, including reproduction, early life history, recruitment, age and growth, trophic ecology, and behavior and the third part describes exploitation of flatfishes including major fisheries, aquaculture and stock enhancement. This book will be a valuable resource for a variety of people in the fields of fish and fisheries biology. The writing style and target audience is consistent among chapters and should be accessible to undergraduate students and professional researchers alike. At 416 pages, the book does not exhaustively cover every detail of flatfishes, but rather summarizes the current state-of-knowledge accomplished through a century of research. However, the real value of the book lies in the thorough reviews of published research and the comprehensive lists of references at the end of each chapter. In addition to the knowledge presented specifically about flatfishes, there are several concise descriptions of fundamental concepts in fisheries biology that will be useful to beginners in the field. There were a few minor shortcomings in this book that I feel should have been addressed to increase the book’s impact as a key reference on flatfishes. First, a chapter specifically devoted to the biology of metamorphosis, a key characteristic that separates flatfishes from other teleosts, was missing. Recently, there have been major advances in the knowledge of hormonal changes that mediate metamorphosis and the imaging technology for viewing these anatomical changes. I am quite surprised that these were not incorporated into the book. Second, there was a strong bias on commercially valuable north temperate A. C. Seitz (&) School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, PO Box 7577220, Fairbanks, AK 99775-7220, USA e-mail: aseitz@ims.uaf.edu

Characterizing the Juvenile Fish Community in Turbid Alaskan Rivers to Assess Potential Interactions with Hydrokinetic Devices

AbstractInstallation of hydrokinetic power-generating devices is currently being considered for the Yukon and Tanana rivers, two large and glacially turbid rivers in Alaska. We sampled downstream-migrating fish along the margins of both rivers, a middle island in the Yukon River, and mid-channel in the Tanana River in order to assess the temporal and spatial patterns of movement by resident and anadromous fishes and hence the potential for fish interactions with hydrokinetic devices. Results suggest that (1) river margins in the Yukon and Tanana rivers are primarily utilized by resident freshwater species, (2) the mid-channel is utilized by Pacific salmon Oncorhynchus spp. smolts, and (3) only Chum Salmon O. keta smolts utilize both river margin and mid-channel areas. Some species exhibited distinct peaks and trends in downstream migration timing, including Longnose Suckers Catostomus catostomus, whitefishes (Coregoninae), Arctic Grayling Thymallus arcticus, Lake Chub Couesius plumbeus, Chinook Salmon O. ...