Adult Sea Lamprey Research Articles

Changes in Spawning Runs of Sea Lamprey (Petromyzon marinus) in Selected Streams of Lake Superior after Chemical Control

During lampricide treatment of a stream, sea lamprey, Petromyzon marinus, that will constitute the spawning run the following spring inhabit the Great Lakes and are not affected by the treatment. However, the number of adults captured at electrical barriers declined as much as 99% in some streams 1 year after chemical treatment. Large declines of adults were noted in streams which were treated late in the year. Streams in which significant populations of larval lampreys survived the chemical treatment, or contained lentic populations, continued to attract adults. Adult sea lampreys could be attracted to sea lamprey ammocoetes in streams or in offshore areas and hence use this as one of a number of clues to determine rivers suitable for spawning.Key words: sea lamprey, olfaction, orientation/homing, spawning migration, habitat alteration (chemical), Petromyzon marinus, lampricides

Changes in Biological Characteristics of the Sea Lamprey (Petromyzon marinus) as Related to Lamprey Abundance, Prey Abundance, and Sea Lamprey Control

Biological characteristics of adult sea lampreys, Petromyzon marinus, in the Great Lakes changed in response to lamprey and prey abundance and the chemical control program. Sea lampreys collected as early as 1947, through 1978, from southern Lake Superior, northwestern Lake Michigan, the Ocqueoc River and Canadian shore of Lake Huron, and the Humber River of Lake Ontario were analyzed. Generally, abundance of sea lampreys peaked in each lake before the chemical control program began. The annual mean lengths and weights were relatively low when lampreys were abundant and increased as the numbers were reduced by the control efforts. As an indication of the change in sea lamprey weight per unit change in length, annual log10 weight on log10 length equations were solved at the arbitrary length of 410 mm. The values were plotted against years for each lake and interpreted with respect to chemical treatment periods. All slopes were negative before the control period and positive thereafter. Sea lamprey lengths and weights were low when fish stocks in the Great Lakes were near depletion. As salmonids again became abundant through stocking, lampreys grew larger. In Lake Superior, where detailed records on lake trout abundance have been available since 1959, a significant relation exists between the changes in the sea lamprey estimated weight values at 410 mm and in lake trout abundance (P < 0.01). Male sea lampreys were the dominant sex when populations of the parasite were high. A shift to a preponderance of females occurred as lamprey abundance declined.Key words: Petromyzon marinus, Salvelinus namaycush, abundance, sex ratio, weight–length relationship, chemical control

Ecological Impacts of Lampricide Treatments on Sea Lamprey (Petromyzon marinus) Ammocoetes and Metamorphosed Individuals

Sea lamprey (Petromyzon marinus) ammocoetes are found in fewer locations now than before lampricide treatments began. Posttreatment reinfestation does not always occur in those tributaries previously infested. Abundance of ammocoetes and transformed individuals has declined in most watersheds with a few exceptions where density-dependent factors may have been influential. Increased growth was related to reduced density. Sex compositions of larval and metamorphosing populations were highly variable during initial lampricide treatments. Females predominated in some streams, males in others. Streams once dominated by males now favor females in residual and reestablished populations of larvae. The shift to femaleness in the larval populations has precipitated a similar shift in adult sea lamprey populations of the upper Great Lakes.Key words: sea lamprey, ammocoetes, transformed, distribution, abundance, growth, sex composition

Proximate Composition of the Adult Anadromous Sea Lamprey, Petromyzon Marinus, in Relation to Feeding, Migration and Reproduction

SUMMARY (1) The large fluctuations in the proximate composition of the muscle, liver, gonad and whole body of various stages in the adult phase of the life cycle of the anadromous sea lamprey have been related to the feeding, migration and reproduction of the animal. (2) Lipid levels were equivalent to only 1.3% of the animal's wet body weight at the end of the 10-month non-trophic period which follows the initiation of metamorphosis. (3) The relative amount of lipid rose by approximately eight times during the subsequent freshwater and marine parasitic phase, before subsequently declining to 40 after the conclusion of the upstream migration and spawning. (4) The data indicate that protein, as well as lipid, is extensively catabolized during the spawning period. (5) The lipid content of the liver is much greater in male than female upstream migrants, whereas the reverse situation is found in the gonads. (6) The increase in the weight of lipid in the ovary during the spawning migration corresponds to a value equivalent to approximately one half of the lipid reduction incurred by the whole animal. (7) Values for glycogen levels in the muscle, liver and gonad vary markedly during the

The distribution of fat in larval, metamorphosing, and young adult anadromous sea lampreys, Petromyzon marinus L.

A histological study using Sudan Black B has been made of the distribution and relative density of fat in the various regions of the body of larval (ammocoete), metamorphosing, and young adult stages of the anadromous sea lamprey, Petromyzon marinus L., caught in New Brunswick. The principal sites of fat storage are located in and around the fat column, lateral to the notochord, between the notochord and either the cardinal or caudal veins, surrounding the body cavity, beneath the skin, and in the myosepta and the nephric fold. Dense but more restricted sites are present lateral to the nerve cord, between the bundles of muscle fibres, and surrounding the pharyngeal cavity. Fat is most abundant in large ammocoetes captured in May and June and in those displaying the very earliest stages of metamorphosis in July. The amount of fat declines during metamorphosis, but is still abundant in November just prior to the time when the sea lamprey can commence parasitic feeding. Fat was undetectable, however, in nearly every site in those animals in which feeding was delayed until the following May. This study shows that sea lampreys accumulate large amounts of fat at the end of larval life by employing a wide variety of different storage sites. It also demonstrates that the fat in virtually all of these sites may be exhausted when the nontrophic period following the initiation of metamorphosis is of a very long duration.

Trigeminal sensory neurons of the sea lamprey

Intracellular recordings were made from neurons of the trigeminal sensory ganglia of young adult sea lampreys. Receptive fields were mapped, and four classes of sensory cells were identified. Touch cells gave rapidly adapting responses to indentation of the skin. Pressure cells gave slowly adapting responses to indentation of the skin. Pit organ cells gave slowly adapting responses to mechanical stimulation of single lateral line pit organs. Nociceptive cells gave slowly adapting responses to destructive stimuli, such as puncture or burning of the skin. The axons of nociceptive cells had longer refractory periods and slower conduction velocities than did the axons of the other types of cell, indicating that nociceptive cells had smaller diameter axons.

Photokinesis and behavioral thermoregulation in adult sea lampreys (Petromyzon marinus)

AbstractPhotokinetic responses of adult sea lampreys were used to facilitate study of their thermoregulatory behavior in a laboratory thermal gradient. Lampreys swam about actively when room lights were switched on, but attached themselves to the side walls at temperature‐dependent sites in the gradient when lights were turned off. Attachment sites were significantly correlated with temperature (correlation coefficient = 0.73, p < 0.01). Acete mean preferred temperature of five lampreys, previously acclimated at 10°C, was 14.3 ± 3.0 (S.D.) °C. This is the first experimental demonstration of behavioral thermoregulation in this ancient class of jawless vertebrates (Agnatha).

Retinal projections in larval, transforming and adult sea lamprey, Petromyzon marinus.

Unilateral enucleations were performed on larval, transforming and adult sea lampreys. Following 5 to 11 days survival, the animals were sacrificed and the brains were processed using a modified Fink-Heimer technique. In larvae, contralateral optic projections were found to the posterior one-third of the dorsal thalamus, the pretectum, and the optic tectum. No ipsilateral projections were present in the larvae. In enucleated transforming and adult lampreys, degenerating axons were observed in the optic chiasm and bilaterally in the optic tracts. Retinal efferents projected bilaterally to a lateral neuropil region ("tractus opticus") in the posterior one-half of the dorsal thalamus. Contralaterally, a conspicuous dorsomedial cell group (lateral geniculate nucleus) also received a projection. Contralateral projections to the superficial layers of the pretectum and optic tectum were observed. Ipsilateral retinal projections to the pretectum and optic tectum in transforming and adult lampreys were restricted to a small zone at the ventrolateral margins of the pretectum and tectum. The changes in distribution of retinofugal projections during transformation appear to be occurring at the same time that the eye differentiates into its adult form.

The freshwater biology of adult anadromous Sea lampreys Petromyzon marinus

The lengths, weights and condition factors of young adult lampreys caught feeding on Gaspereau, Alosa pseudoharengus. Shad, Alosa sapidissima, and White suckers, Catostomus commersoni, in the lake‐like extensions of the St. John River system during May, suggest that many lampreys do not feed in the nine to ten months following the initiation of metamorphosis in mid‐July. The mean lengths (d‐95% confidence limits) of individuals taken in four samples between May 13 and 29 did not differ significantly and ranged from 132‐7± 2‐81 to 135‐7 ±3‐71 mm. A significant increase in mean condition factor from II15 to 1‐353 during this time indicates that the short period spent feeding in May enables the animal to replenish its food reserves prior to its downstream migration. Since several of the 81 feeding adults caught between the latter part of June and mid‐July, at a point 140 km from the estuary of the St. John, were still attached to spawning‐run Atlantic salmon, Salmo salar, this teleost host had probably been responsible for their transport upstream. The wide range in their length (156‐403 mm), together with the presence in the lakes in May of a few young adults larger than those which have only just started feeding, suggest that the time of onset of the parasitic phase is variable but may generally commence in either the late autumn or in the spring. Scarring on salmon due to lamprey attack was predominantly (84%) on the ventral surface between the operculum and caudal peduncle. Over 35 % of the salmon examined in June 1975 had been attacked, more of these attacks being on the right side of the body of both males (59‐6%) and females (49‐8%) than on either the left (20‐2 and 23‐7 %) or both sides (20‐2 and 26‐5 %). While lamprey attacks may cause some mortality among the smaller teleosts, any effect on salmon is probably indirect through causing increased susceptibility to infection and stress. The ability of adult anadromous Sea lampreys to feed and grow in fresh water demonstrates the relative ease with which landlocked forms could have been evolved in response to extreme environmental changes. This evolutionary step has involved a decline in the ability to osmoregulate in high salinities and a reduction in body size and fecundity, the adaptive significances of which are discussed. Data on upstream migrants indicate that males and females undergo length reductions of at least 11 and 15 % respectively between the time of their entry into fresh water and the completion of spawning.

Morphology of the gills of larval and parasitic adult sea lamprey, Petromyzon marinus L.

The general morphology of the gills is similar in larval (ammocoetes) and parasitic adult sea lampreys, Petromyzon marinus, despite different methods of ventilation necessitated by their feeding habits. The gill lamellae are supported by randomly-distributed pillar cells which enclose blood spaces and collagen columns. The distribution of these cells in lampreys is different from that of higher fishes and it may be inefficient for respiratory exchange. The presence of cytoplasmic microfilaments suggests that these cells have the ability to reduce the lamellar blood spaces through contraction. Marginal channels at the tips of the lamellae are lined only by endothelial cells. The thickness of the water-blood pathway in lampreys falls within the range described for higher fishes, with the most efficient gas exchange likely occuring at the lamellar tips where only a single layer of epithelial cells is present. The abrupt increase in height of the epithelium near the lamellar bases in adults, compared to the gradual transition in height along the lamellae in ammocoetes, is perhaps reflective of higher oxygen requirements during the parasitic stage. The consistent appearance of wide, lateral intercellular spaces within the respiratory epithelium of lampreys indicates possible involvement of these spaces in transport. Mucous secretion appears to be an important function of the superficial platelet cells in ammocoetes. "Mitochondria-rich" and "mitochondria-poor" superficial cells are observed in both ammocoetes and adults, with the mitochondria-rich cells more prevalent toward the lamellar bases. The possibility that at least some of these cells may be involved in absorption is discussed. Mitochondria-rich cells in the interlamellar region are morphologically different in ammocoetes and adults but all possess an abundance of smooth endoplasmic reticulum and hence resemble "chloride cells" of higher fishes. The similarity of these cells in the parasitic adult lamprey to chloride cells of marine fishes may reflect the potential of the adult lamprey to osmoregulate in salt water. A scarcity of these cells in ammocoetes and their resemblance to chloride cells in freshwater fishes may reflect the restriction of larval lampreys to a freshwater habitat.

Vestibulo-ocular reflexes in the adult sea lamprey

Vestibulo-ocular reflexes were elicited in isolated preparations of small adult sea lampreys (Petromyzon marinus). Mechanical stimulation of the labyrinths or electrical stimulation of the vestibular nerves produced stereotyped, conjugated eye movements (Table 1) and appropriate electrical activities in individual extraocular muscles (Fig. 1). No inhibition of discharges in motor nerves was observed during stimulation of opposing reflexes. Likewise, nystagmus was never seen during continued stimulation. The primitive eye reflexes of the lamprey probably correspond to the simple excitatory pathways from single ampullae to individual eye muscles of higher vertebrates.

Radioautography of Presumptive Interrenal Cells in the Sea Lamprey After 3H‐cholesterol Injection

Abstract Radioautography demonstrates that the injection of 3H‐cholesterol into larval and adult sea lamprey, Petromyzon marinus L., results in labelling of their presumptive interrenal cells. This localization of cholesterol and/or its metabolites is: (1) further evidence for the homology of these cells with adrenocortical cells of higher vertebrates and (2) a suggestion of the possibility that these cells in lampreys are able to absorb cholesterol for utilization in corticosteroid synthesis.

Steroid formation in the larval and parasitic adult sea lamprey, Petromyzon marinus L

Presumptive adrenocortical tissue (PAT) from all known sites in parasitic adults or larval sea lamprey, Petromyzon marinus L., were incubated with [4- 14C]progesterone in a buffered medium with an NADPH generating system. Testicular tissue from parasitic adults was similarly incubated. PAT from both parasitic adults and larvae formed 11-deoxycortisol (S), 17α-hydroxyprogesterone (17αOHP), and androstene dione (AD) but no cortisol (F) cortisone (E), corticosterone (B), 11-deoxycorticosterone (DOC), or testosterone (T) were formed. Therefore PAT may be lacking in 11β-hydroxylase activity but does contain 17α- and 21-hydroxylase and 20-desmolase activities. Testicular tissue failed to produce F, E, B, S, T, 17αOHP, or AD. However, testicular tissue did form DOC indicating the presence of 21-hydroxylase activity. After the 4-hr incubations, histological examination indicated that the PAT and testicular tissue were normal in appearance.

In vitro incubations of presumptive adrenocortical cells from the opisthonephros of the adult sea lamprey, Petromyzon marinus

Presumptive adrenocortical cells from the glomus region of the opisthonephros of the sea lamprey, Petromyzon marinus, were incubated with [4- 14C] progesterone, cholesterol, 11-deoxycortisol, and 11-deoxycorticosterone in a buffered medium for 4 hr with an NADPH generating system. After extraction and chromatographic purification of the incubation media, a considerable amount of 14C radioactivity was observed in the cortisol, corticosterone, cortisone, and 17α-hydroxyprogesterone areas in several of the incubations. Following the addition of the appropriate authentic tritium labeled steroid and further purification by chromatography and recrystallization the formation of 17α-hydroxyprogesterone was confirmed from progesterone. The formation of progesterone from cholesterol may also have occurred but definitive evidence was lacking. Cortisol, cortisone, 11-deoxycortisol, and 11-deoxycorticosterone were not detected in these incubations.

Sex Ratios and Lengths of Adult Sea Lampreys (Petromyzon marinus) from a Lake Ontario Tributary

The mean lengths of adult males and females of the sea lamprey (Petromyzon marinus) migrating into the Humber River from Lake Ontario in each of the years 1968–1972 varied little, and were similar to those found by other workers in recently established populations in the upper lakes. In contrast, the ratio of males to females, which lay within the narrow range of 1:1 to 1.26:1, was similar to those reported for long-established populations.

Effects of mammalian corticotrophin on the ultrastructure of presumptive interrenal cells in the opisthonephros of the lamprey, Petromyzon marinus L.

AbstractThe administration of mammalian corticotrophin to larvae and adult sea lamprey, Petromyzon marinus L., results in changes in fine structure of cells within presumptive interrenal tissue located in the opisthonephric kidneys. Compared to controls, stimulated cells show increases in the volume of smooth endoplasmic reticulum, mitochondria, and the Golgi apparatus with an accompanying decrease in numbers of lipid droplets. In addition, the plasma membrane near a perivascular space is commonly highly folded. Mitochondria are often of unusual configuration and possess “puffs” and the cristae are more tubular than in controls. The enlarged Golgi apparatus is accompanied by large numbers of coated vesicles.The morphological features of corticotrophin‐stimulated presumptive interrenal cells of lampreys closely resemble the appearance of adrenocortical cells of mammals and the interrenal cells of other vertebrates after similar stimulation. These results suggest that these cells in lampreys and adrenocortical cells are likely homologs.

Projections of individual axons in lamprey spinal cord determined by tracings through serial sections.

AbstractThe brain and spinal cord of one adult sea lamprey, Petromyzon marinus, 12 cm in length, were fixed in glutaraldehyde and osmium, stained in toluidine blue, embedded in Araldite, and sectioned serially at 5 μ. Over 50 large axons were traced through the spinal cord to their probable cells of origin.The axon of one giant interneuron was followed from the posterior spinal cord rostrally into the lateral medulla of the brain.A formerly unrecognized pair of Müller axons was found to originate from the reticular cells I2.An unusual feature of some Müller axons was their migration out of the ventral columns and their subsequent branching.

Structure and distribution of interstitial cells (presumptive interrenal cells) in the opisthonephric kidneys of larval and adult sea lamprey, Petromyzon marinus L

The opisthonephric kidneys of larval and adult sea lamprey, Petromyzon marinus L., possess diffusely arranged interstitial cells having all the morphological features of steroid-secreting cells, namely abundant smooth endoplasmic reticulum, lipid droplets, and mitochondria with vesiculate to tubular cristae. The kidney does not show any 3β-hydroxysteroid dehydrogenase activity but the cells are sudanophilic and stain with Nile blue. These cells are always closely associated to the arterial circulation and can be found within the renal corpuscle and among the kidney tubules. Morphological evidence suggests a resemblance to interrenal cells of other vertebrates. Lack of any demonstration of 3β-hydroxysteroid dehydrogenase activity may be explained by the fact that only small numbers of cells are normally present in lampreys. The evolutionary implications of these findings are discussed in relation to the distribution of interrenal tissue in other vertebrates.

Intertubular circulation in the opisthonephric kidneys of adult and larval sea lamprey, Petromyzon marinus L.

AbstractThe opisthonephric kidneys of both larval and adult Petromyzon marinus lack a renal portal system. The tubules are supplied with arterial blood from the glomus through a system of efferent arterioles, capillaries, and sinusoids with the latter draining into the venous system. The adult kidney possesses a more complex and larger system of sinusoids than ammocoetes and these sinusoids reach the venous system through large subcapsular sinuses. Paralleling of tubules with sinusoids and arterioles in the ventral portion of the adult kidney resembles the association of the vasa recta with the tubules of the renal medulla in the mammalian kidney. This may suggest a mechanism important to tubular transport in adult lampreys. The intertubular tissue of ammocoetes is infiltrated with haemopoietic tissue while large numbers of phagocytes within the adult sinusoids may be involved in the destruction of blood cells.

The opisthonephric kidney of the sea lamprey of the Great Lakes, Petromyzon marinus L. IV. Intermediate, distal, and collecting segments of the adult.

AbstractBoth short and long intermediate segments are found in the opisthonephric kidney of the adult sea lamprey and they possess morphologically distinct cell types. Wide lateral intercellular spaces appear between both the cuboidal cells of short segments and the squamous cells of long segments. Periodically the epithelium of the long segment is reduced in thickness providing for a close relationship between the interstitium and the tubular fluid. These features indicate that the segment may be involved in urine formation.The distal segment is divisible into two distinct portions: a straight pars recta and a twisted pars convoluta. The cuboidal cells of the pars recta and the columnar cells of the pars convoluta are characterized by abundant smooth endoplasmic reticulum and mitochondria, features reminiscent of cells involved in ion transport. Multivesicular bodies, coated vesicles, and dense apical tubules suggest that cells of both regions may also be involved in endocytosis.The cells of the collecting segment have few organelles but they possess a cytoskeleton of coarse filaments and wide intercellular spaces.The parallel arrangement of the intermediate, distal, and collecting segments and of the blood vessels within the adult kidney is suggestive of a functional unit similar to that found in the medulla of the mammalian kidney.