Lamna Ditropis Research Articles

Quantification of red myotomal muscle volume and geometry in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis) using T1‐weighted magnetic resonance imaging

T1-weighted magnetic resonance imaging (MRI) in conjunction with image and segmentation analysis (i.e., the process of digitally partitioning tissues based on specified MR image characteristics) was evaluated as a noninvasive alternative for differentiating muscle fiber types and quantifying the amounts of slow, red aerobic muscle in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis). MRI-determinations of red muscle quantity and position made for the mid-body sections of three mako sharks (73.5-110 cm fork length, FL) are in close agreement (within the 95% confidence intervals) with data obtained for the same sections by the conventional dissection method involving serial cross-sectioning and volumetric analyses, and with previously reported findings for this species. The overall distribution of salmon shark red muscle as a function of body fork length was also found to be consistent with previously acquired serial dissection data for this species; however, MR imaging revealed an anterior shift in peak red muscle cross-sectional area corresponding to an increase in body mass. Moreover, MRI facilitated visualization of the intact and anatomically correct relationship of tendon linking the red muscle and the caudal peduncle. This study thus demonstrates that MRI is effective in acquiring high-resolution three-dimensional digital data with high contrast between different fish tissue types. Relative to serial dissection, MRI allows more precise quantification of the position, volume, and other details about the types of muscle within the fish myotome, while conserving specimen structural integrity.

Feeding habits of the blue shark, Prionace glauca, and salmon shark, Lamna ditropis, in the transition region of the Western North Pacific

We describe the feeding habits of 70 blue sharks (Prionace glauca) and 39 salmon sharks (Lamna ditropis) caught at 0–7 m depth at night by research drift gillnets in the transition region of the western North Pacific during April–May of 1999 and 2000. Blue sharks of 50–175 cm total length fed on a large variety of prey species, consisting of 24 species of cephalopods and 16 species of fishes. Salmon sharks of 69–157 cm total length fed on a few prey species, consisting of 10 species of cephalopods and one species of fish. Important prey for the blue sharks were large, non-active, gelatinous, meso- to bathypelagic cephalopods (e.g., Chiroteuthis calyx, Haliphron atlanticus, Histioteuthis dofleini and Belonella borealis) and small myctophid fishes. Important prey for the salmon sharks were mid-sized, active, muscular, epi- to mesopelagic squids (e.g. Gonatopsis borealis, Onychoteuthis borealijaponica and Berryteuthis anonychus). Our results suggest that blue sharks feed on cephalopods mainly during the daytime when they descend to deep water. Salmon sharks may feed opportunistically with no apparent diurnal feeding period. Blue sharks and salmon sharks have sympatric distribution in the transition region in spring; they have different feeding habits and strategies that reduce competition for food resources.

Satellite Tagging and Cardiac Physiology Reveal Niche Expansion in Salmon Sharks

Shark populations are declining globally, yet the movements and habitats of most species are unknown. We used a satellite tag attached to the dorsal fin to track salmon sharks (Lamna ditropis) for up to 3.2 years. Here we show that salmon sharks have a subarctic-to-subtropical niche, ranging from 2 degrees to 24 degrees C, and they spend winter periods in waters as cold as 2 degrees to 8 degrees C. Functional assays and protein gels reveal that the expression of excitation-contraction coupling proteins is enhanced in salmon shark hearts, which may underlie the shark's ability to maintain heart function at cold temperatures and their niche expansion into subarctic seas.

Satellite Tracking Catches Sharks on the Move

The great white shark--once considered a homebody--is proving a transoceanic traveler, according to results published in this week9s issue of Science (p. 100). Another paper (p. 104) documents that a less fearsome cousin called the salmon shark has now shown up in Hawaii, far away from its supposed home in Alaska.

Mammal-like muscles power swimming in a cold-water shark

Effects of temperature on muscle contraction and powering movement are profound, outwardly obvious, and of great consequence to survival. To cope with the effects of environmental temperature fluctuations, endothermic birds and mammals maintain a relatively warm and constant body temperature, whereas most fishes and other vertebrates are ectothermic and conform to their thermal niche, compromising performance at colder temperatures. However, within the fishes the tunas and lamnid sharks deviate from the ectothermic strategy, maintaining elevated core body temperatures that presumably confer physiological advantages for their roles as fast and continuously swimming pelagic predators. Here we show that the salmon shark, a lamnid inhabiting cold, north Pacific waters, has become so specialized for endothermy that its red, aerobic, locomotor muscles, which power continuous swimming, seem mammal-like, functioning only within a markedly elevated temperature range (20-30 degrees C). These muscles are ineffectual if exposed to the cool water temperatures, and when warmed even 10 degrees C above ambient they still produce only 25-50% of the power produced at 26 degrees C. In contrast, the white muscles, powering burst swimming, do not show such a marked thermal dependence and work well across a wide range of temperatures.

Seasonal foraging movements and migratory patterns of female Lamna ditropis tagged in Prince William Sound, Alaska

Conventional and electronic tags were used to investigate social segregation, distribution, movements and migrations of salmon sharks Lamna ditropis in Prince William Sound, Alaska. Sixteen salmon sharks were tagged with satellite transmitters and 246 with conventional tags following capture, and were then released in Prince William Sound during summer 1999 to 2001. Most salmon sharks sexed during the study were female (95%), suggesting a high degree of sexual segregation in the region. Salmon sharks congregated at adult Pacific salmon Oncorhynchus spp. migration routes and in bays near Pacific salmon spawning grounds in Prince William Sound during July and August. Adult Pacific salmon were the principal prey in 51 salmon shark stomachs collected during summer months in Prince William Sound, but the fish appeared to be opportunistic predators and consumed sablefish Anoplopoma fimbria, gadids, Pacific herring Clupea pallasi, rockfish Sebastes spp. and squid (Teuthoidea) even when adult Pacific salmon were locally abundant. As Pacific salmon migrations declined in late summer, the salmon sharks dispersed; some continued to forage in Prince William Sound and the Gulf of Alaska into autumn and winter months, while others rapidly moved south‐east thousands of kilometres toward the west coasts of Canada and the U.S. Three movement modes are proposed to explain the movement patterns observed in the Gulf of Alaska and eastern North Pacific Ocean: ‘focal foraging’ movements, ‘foraging dispersals’ and ‘direct migrations’. Patterns of salmon shark movement are possibly explained by spatio‐temporal changes in prey quality and density, an energetic trade‐off between prey availability and water temperature, intra‐specific competition for food and reproductive success. Transmissions from the electronic tags also provided data on depth and water temperatures experienced by the salmon sharks. The fish ranged from the surface to a depth of 668 m, encountered water temperatures from 4·0 to 16·8° C and generally spent the most time above 40 m depth and between 6 and 14° C (60 and 73%, respectively).

Homeothermy in adult salmon sharks, Lamna ditropis

Salmon sharks, Lamna ditropis, belong to a small group of sharks that possess vascular counter-current heat exchangers (retia mirabilia) allowing retention of metabolically generated heat, resulting in elevated body temperatures. The capacity of free-swimming lamnid sharks to regulate rates of heat gain and loss has not been demonstrated. Using acoustic telemetry, we recorded swimming depth and stomach temperature from four free-swimming salmon sharks in Prince William Sound, Alaska. Temperature data were obtained over time periods ranging from 3.8 to 20.7 h. Temperature profiles of the water column were obtained concurrently for use as estimates of ambient temperature. Mean stomach temperature among four individuals tracked ranged from 25.0 to 25.7°C. These sharks defended specific elevated temperatures regardless of changes in ambient temperature, which ranged from about 5–16°C. The maximum observed elevation of stomach temperature over ambient was 21.2°C. Because stomach temperatures were so strictly maintained relative to changes in ambient temperature, a thermal rate coefficient, k, (°C min−1 °C thermal gradient−1) for cooling of 0.053 min−1 was obtained via a `control' experiment with a dead salmon shark. We show that free-swimming adult salmon sharks maintain a specific stomach temperature independent of changes in ambient temperature through a combination of physical and physiological means, and essentially function as homeotherms. This unique ability is probably the underlying factor in the evolutionary niche expansion of salmon sharks into boreal waters and in their ability to actively pursue and capture highly active prey such as salmon.

Isolation and characterization of CXC receptor genes in a range of elasmobranchs

The CXC group of chemokines exert their cellular effects via the CXCR group of G-protein coupled receptors. Six CXCR genes have been identified in humans (CXCR1-6), and homologues to some of these have been isolated from a range of vertebrate species. Here we isolate and characterize CXCR genes from a range of elasmobranch species. One CXCR1/2 gene fragment isolated from Scyliorhinus caniculus (lesser spotted catshark), and two CXCR1/2 copies from each of the elasmobranchs, Cetorhinus maximus (basking shark), Carcharodon carcharias (great white shark), and Raja naevus (cuckoo ray), exhibit high similarity to both CXCR1 and CXCR2. The two copies evident in the cuckoo ray and lamniform sharks provide strong evidence of CXCR1/2 lineage specific duplication in rays and sharks. A CXCR fragment isolated from Lamna ditropis (salmon shark) shows high similarity to a range of CXCR4 genes and strong clustering with CXCR4 gene homologues was apparent during phylogenetic reconstruction.

Validation of geolocation estimates based on light level and sea surface temperature from electronic tags

Electronic tags have enhanced our understanding of the movements and behavior of pelagic animals by providing position information from the Argos system satellites or by geolocation estimates using light levels and/or sea surface temperatures (SSTs). The ability to geolocate animals that remain submerged is of great value to fisheries management, but the accuracy of these geoloca- tion estimates has to be validated on free-swimming animals. In this paper, we report double-tagging experiments on free-swimming salmon sharks Lamna ditropis and blue sharks Prionace glauca, tagged with satellite telemetry and pop-up satellite tags, which provide a direct comparison between Argos positions and geolocation estimates derived from light levels and SSTs. In addition, the Argos- based pop-up satellite tag endpoints and GPS-based recapture locations of Atlantic bluefin tunas Thunnus thynnus were compared with the last geolocation estimates from pop-up satellite and archival tags. In the double-tagging experiments, the root mean square errors of the light level lon- gitude estimates were 0.89 and 0.55°; while for SST latitude estimates, the root mean square errors were 1.47 and 1.16° for salmon sharks and blue sharks respectively. Geolocation estimates of Atlantic bluefin tuna, using archival data from surgically implanted archival tags or recovered pop-up satel- lite tags, had root mean square errors of 0.78 and 0.90° for light level longitude and SST latitude esti- mates, respectively. Using data transmitted by pop-up satellite tags deployed on Atlantic bluefin tunas, the light level longitude and SST latitude estimates had root mean square errors of 1.30 and 1.89°, respectively. In addition, a series of computer simulations were performed to examine which variables were most likely to influence the accuracy of SST latitude estimates. The simulations indi- cated that the difference between the SST measured by the electronic tag and the remotely sensed SST at a given location was the predominant influence on the accuracy of SST latitude estimates. These results demonstrate that tag-measured SSTs can be used in conjunction with light level data to significantly improve the geolocation estimates from electronic tags.

Variation in lipid classes and fatty acid composition of salmon shark ( Lamna ditropis) liver with season and gender

The influence of season and gender on lipid content, lipid classes, and fatty acid compositions was assessed in livers of salmon shark ( Lamna ditropis), caught in the Pacific Ocean. No significant difference in the hepatosomatic index was noted with season, though the lipid content was significantly higher ( P<0.05) in winter. Triacylglycerol (TAG) was identified as the predominant lipid class (78.5–82.0%), followed by sterol esters (5.7–9.1%) and hydrocarbons (3.4–5.4%). No significant differences were observed in TAG composition with respect to the season or gender. However, diacylglyceryl ether contents were significantly higher ( P<0.05) in winter (3.8–5.3%) than those obtained in summer (1.3–1.1%). Polyunsaturated fatty acids constituted the major fatty acid class of salmon shark total liver lipid and docosahexaenoic acid (C22:6n-3) (22.7–28.4%) was the most abundant fatty acid which was significantly lower ( P<0.05) in winter. These results suggested that lipid characteristics of salmon shark liver were influenced by season, but not by gender.

Orbital rete and red muscle vein anatomy indicate a high degree of endothermy in the brain and eye of the salmon shark

The salmon shark has been ranked as the most endothermic lamnid shark based upon geographical range, extent of slow twitch muscle, supra-hepatic rete size, and limited temperature measurements, yet its anatomy has remained largely undescribed, and measurements of brain or eye temperatures have not been reported. In this study, four specimens are examined to determine if the morphological requirements for warming the brain and eyes are present. A well-developed arterial orbital rete lies within a venous sinus on both sides of the cranium. Cool, oxygenated blood from the gills can pass through the vessels of this exchanger before reaching the brain or eyes. Since venous blood in the sinus flows opposite the arterial blood, counter-current heat exchange can occur. A vein originating in the red swimming muscle likely contributes to the warmth of the venous sinus by supplying blood directly from the warmest region of the shark. Before collecting in the orbital sinus, this red muscle vein bathes the brain in warm blood. These morphological data suggest the salmon shark has a significant capacity to warm the brain and eyes.

Temperature Measurements from Salmon Sharks,Lamna ditropis,in Alaskan Waters

Abstract Salmon sharks, Lamna ditropis, occur only in the North Pacific Ocean. These large sharks can grow to 250 cm total length and weigh 220 kg. They are endothermic, and previous investigators reported red muscle temperatures of 8–11 C above ambient water temperature. We recorded red muscle temperatures up to 15.6 C above ambient, along with additional muscle and organ temperatures.

Shark bycatch in the Japanese high seas squid driftnet fishery in the North Pacific Ocean

From the late 1970s to 1992, large-scale pelagic driftnet fisheries in the North Pacific targeted flying squid ( Ommastrephes bartrami), tunas and billfishes. In the late 1980s, cooperative multinational scientific observer programs began on Japanese, South Korean, and Taiwanese driftnet fleets fishing in international waters. These programs resulted in some of the most comprehensive data on the distribution and abundance of epipelagic species in the North Pacific transition region. Eleven elasmobranch taxa were sighted by observers in the Japanese flying squid driftnet fishery. Blue sharks accounted for 93.7% of the elasmobranch bycatch in 1990 and 1991. In 1991, observers collected biological data on a limited number of shark and fish species, including blue shark ( Prionace glauca) and salmon shark ( Lamna ditropis). Canada experimented with a flying squid driftnet fishery in coastal waters near British Columbia beginning in 1979 but it was terminated in 1987 because of unacceptable levels of bycatch. Blue shark and salmon shark CPUEs were an order of magnitude higher in the coastal Canadian experimental driftnet fishery than in the high seas squid driftnet fishery. The average size of blue sharks in coastal catches was larger than sharks caught in the high seas fishery. The seasonal pattern of CPUE in the Japanese squid driftnet fishery was consistent with the seasonal location of the fleet and the subtropical–subarctic ecological gradient that polarizes salmon and blue sharks. Errors-in-variables regression equations are provided to convert among total length, eye-fork length, and precaudal length measurements.

Distribution of Pelagic Elasmobranchs Caught by Salmon Research Gillnets in the North Pacific

The distribution of pelagic elasmobranchs was analyzed using bycatch data from the high seas salmon surveys by research gillnets from 1981 to 1991 in the North Pacific Ocean and the Bering Sea. Five species of sharks and one stingray were reported. Blue and salmon sharks and spiny dogfish were dominant and constituted 98% of the total shark catch. It is considered that the research area includes the southern part of the distribution for spiny dogfish and salmon sharks and the northern part of that for blue, shortfin mako, cookiecutter sharks and pelagic stingrays. These elasmobranchs showed spa tial segregation by species in distribution according to oceanographic conditions. Intraspecific sexual and growth dependent segregations were also confirmed. Length frequency distributions of blue and salmon sharks suggest that their nursery grounds exist around the transitional domain of the subarctic boundary. The Japanese high-seas salmon fishery ceased in 1992 af ter some 40 years of industrial fishing from 1952 because of international concern about the impact of this fishery upon the oceanic ecosystem. The Fisheries Agency of Japan has conducted salmon research for the rational use of salmon stocks for a long time. It also started bycatch research in the 1970 s using several research vessels. Bycatch research data collected by the research vessels of Hokkaido University and chartered vessels for scientific research from 1981 to 1991 were used for the present analy sis. The research area is widely distributed from 35?N 63°N from the northern coast of Japan to the Gulf of Alaska and the Bering Sea. The spatial distribution and migration of pelagic elas mobranchs are still poorly known, although several sur veys were conducted in the North Pacific Ocean.1-6) Many of those studies partly described their distributions and migrations due to the limitation of research area, season and gear selectivity. Therefore, more detailed biological and ecological information is necessary for the conserva tion and stock management of pelagic elasmobranchs. This paper describes the distribution of pelagic sharks and rays in the North Pacific, north of the subarctic boundary.

Effect of soaking time on catch-per-unit-effort of major species taken in the Japanese squid driftnet fishery in 1990

We made a preliminary analysis of the effect of soaking time on the catch of the Japanese squid driftnet fishery in the central North Pacific in 1990. In a typical fishing operation, eight or nine net sections (each 4–7 km long) were used. Net retrievals began from the last section deployed. The soaking time for each section ranged from approximately 5 to 19 h, based on 993 fishing operations by 75 vessels monitored by scientific observers from Canada, Japan and the USA. The relationship between soaking time (indexed by section retrieval order number) and average catch in number per net panel or tan (catch-per-unit-effort, CPUE) revealed three patterns depending on the species entangled. These patterns included: (1) positive relationship between CPUE and soaking time throughout the sections (blue shark and salmon shark); (2) positive relationship within the first three to six sections, which were probably retrieved during the night and dawn, but constant or slightly decreased CPUE in later sections retrieved in day time (neon flying squid, Pacific pomfret, seabirds); (3) negative relationship (pelagic armorhead). These different patterns were considered to represent primarily the behavior of species, diel vertical migration or diel feeding activity, and secondly drop out from the nets and predation.

Study on the bile salt, sodium scymnol sulfate, from Rhizoprionodon acutus. IV. Structures of chimaerol and sodium chimaerol sulfate in the bile of Lamna ditropis and Rhizoprionodon acutus.

Sodium chimaerol sulfate (1) was isolated from the bile of Lamna ditropis and Rhizoprionodon acutus by chromatography on silica gel and Sephadex LH-20, together with sodium scymnol sulfates, (24R,25S)- and (24R,25R)-(+)-3 alpha,7 alpha,12 alpha,24,26-pentahydroxy-5 beta-cholestan-27-yl sodium sulfates (3 and 4) and 3, respectively. On acid hydrolysis, compound 1 afforded chimaerol (2), which was identified as (24R,25R)-(+)-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,26-pentol by direct comparison with an authentic sample, prepared by reduction of (24R,25S)-(+)-24,26-epoxy-5 beta-cholestane-3 alpha,7 alpha,12 alpha,27-tetrol (5) with LiAlH4. The structure of 1 was concluded to be (24R,25R)-(+)-3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestan-26-yl sodium sulfate, based on the chemical transformation and spectral data.

Body temperature of the salmon shark, Lamna ditropis

The salmon shark, Lamna ditropis Hubbs and Follett, is a streamlined, pelagic predator capable of rapid swimming locomotion, very similar to its close relative, the Atlantic porbeagle, Lamna nasus (Bonnaterre). The porbeagle is warm-bodied, maintaining deep body temperatures 7–11 °C above those of the surface water from which they are captured (Carey &amp; Teal, 1969a). Presumably, Lamna ditropis is also warm-bodied. Opportunities to measure temperatures of salmon sharks occurred on 2, 4 and 5 September 1979, when one of us (D.R.) hooked and landed three salmon sharks while hand-trolling for salmon. The sharks were all caught near Cape Edgecumbe, about 60 km from Sitka, Alaska (57° 6´N, 135° 55´ W) at a depth of 12–40 m.

Mortality of seabirds and fish in a lost salmon driftnet

Abstract Large numbers of seabirds have been killed in offshore salmon driftnets. Mortality of seabirds occurs not only in the nets being fished but also in lost or discarded gear. In 1978, we recovered ninety-nine seabirds of five species, two salmon sharks, one ragfish and over two hundred chum and silver salmon from a lost salmon dirftnet in the western North Pacific. Our observations indicate that such nets may be a hazard to marine organisms for extended periods on time.

ニベリン条虫 &lt;i&gt;Nybelinia surmenicola&lt;/i&gt; の成虫と生活史について(Cestoda: Trypanorhyncha: Tentaculariidae)

The adult of Nybelinia surmenicola OKADA in DOLLFUS, 1929 (Cestoda: Trypanorhyncha: Tentaculariidae) is described and illustrated for the first time. The sample was obtained from the stomach of the salmon shark, Lamna ditropis HUBBS et FOLLETT, taken in the Bering Sea. A morphological comparison is briefly made of the cestode specimens in different developmental stages colected from the euphausiids, squid, walleye pollock and salmon shark, and a possible life-history of N. surmenicola is discussed.

ネズミザメ筋肉油の脂肪酸組成

The components of fatty acids in the muscle oil of salmon shark, Lamna ditropis HUBBS and FOLLETT (Nedzumizame, in Japanese), were analysed qualitatively by gasliquid chromatography using two different columns (polar: DEGS, non-polar: APL). It is inferred that iso acids (18:0, 20:0, 22:0), anteiso acids (20:0, 22:0), methylbranched acid (24:0) and 24:2 acid exist in this oil among the other common fatty acids in sea water fish (saturated normal: 14, 16, 17, 18, 19, 20, 21, 22, 23, 24; unsaturated normal: 14:1, 16:1, 16:2, 18:1, 18:2, 18:3, 20:1, 20:2, 20:3, 22:1, 22:2, 22:3, 24:1).