Lamprey (Lampetra fluviatilis and Lampetra planeri) ammocoete habitat associations at regional,catchment and microhabitat scales in Northern Ireland

Abstract – Habitat characteristics associated with lamprey ammocoetes (Lampetra spp.) were investigated at three different spatial scales: regional (Northern Ireland), catchment (Ballinderry River) and microhabitat. At the regional scale, ammocoetes were more abundant in rivers with a pH ≥8.2, while within a catchment, abundance was negatively related to the number of potential lamprey barriers and distance upstream. At the microhabitat scale, at sites where ammocoetes were present, ammocoetes were more abundant where median phi ≥1.94 (very coarse sand), where sediment depth ≥11.5 cm, and where kurtosis was >1.71. This study provides information on habitat associations of lamprey in the UK which may be of use in their conservation, in particular it highlights the negative association of migration barriers with lamprey abundance.     

Laboratory assessment of sea lamprey larvae burrowing performance

Abstract –  To study the burrowing behaviour and performance of larval sea lamprey ( Petromyzon marinus L.), 120 ammocoetes were collected and observed in the laboratory. Burrowing movements of ammocoetes placed in an aquarium with sediments of differing grain size were video recorded. The video was reviewed and, for each larva, the total time spent moving, the number of stops during the burrowing movement, the total time spent stopped and total time elapsed until complete withdrawal below the substrate surface was registered. Smaller ammocoetes had lower burrowing performance than larger individuals, across all substrate types, but the differences were greater in coarser substrates. Additionally, coarser sediment particles increased the time spent on burrowing regardless of larval size.     

Demography of sea lamprey (Petromyzon marinus) ammocoete populations in relation to potential spawning‐migration obstructions

相似文献   

From shallow to deep waters: habitats used by larval lampreys (genus Petromyzon and Lampetra) over a western European basin

Abstract –  Habitat requirements of lamprey ammocoetes (Petromyzon marinus and Lampetra genus) were investigated, for the first time, from shallow to deep waters, at different spatial scales across the Gironde‐Dordogne continuum, thanks to a water suction dredge. Fish‐habitat relationships were assessed through two complementary statistical analyses: habitat‐use curves and habitat suitability models using the Boosted Regression Trees (BRT) technique. Analyses were performed on a small‐size data set that was characterised by the low prevalence of lamprey. The sea lamprey larvae occurred in deeper areas than their Lampetra genus counterparts. ‘Pools’ of 2 m’ depth and more were optimal habitats for the former species. Among the environmental variables retained to model lamprey occurrences, the mesohabitat (a categorical variable) was demonstrated to be highly influential, in terms of fine grain‐size substratum and vegetation cover. These preliminary results suggest that monitoring using the water suction dredge method may contribute to sea lamprey conservation.     

Distribution, growth and transformation timing of larval Geotria australis in New Zealand

Lamprey, Geotria australis, are widely distributed in New Zealand and are common in streams and rivers of the west coast of both islands, the southern tip of the North Island, the Banks Peninsula and the southern coast of the South Island. In fresh water, lamprey are found in association with all substrate types but are most commonly (> 50% of the sample sites) found in association with finer gravels. There is insufficient evidence to determine any change in historically abundant adult spawning migrations. Spawning, back calculated from larval growth rates, probably occurs late November-December, and emergence at 9.63 mm occurs in January. We estimate that, on average, ammocoetes grow 0.068 mm/day throughout the year, and metamorphose and emigrate to sea between January-May, 3.5 years after spawning at 101 mm (SD = 6.7).     

Predation of the juvenile stages of diadromous fish by sea bass (Dicentrarchus labrax) in the tidal reaches of an English chalk stream

• 1. The first incidence of predation by the sea bass (Dicentrarchus labrax) on lamprey ammocoetes and salmonid smolts is reported.
• 2. These preliminary findings suggest that there is a need for further investigation to determine if juvenile diadromous fish form a significant component of the diet of sea bass, and to identify whether the likelihood of enhanced abundance of sea bass in protected nursery areas presents a particular threat to the conservation of Atlantic salmon (Salmo salar).
• 3. This will require further sampling of the stomach contents of sea bass and estimates of the sea bass population in nursery areas to be determined, linked with an assessment of the impact of such predation on the conservation status of particular stocks of diadromous fish. © 2011 Crown copyright. Reproduced with the permission of her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.

     

Migration and escapement of silver eel males,Anguilla anguilla,from a southwestern European river

The catadromous life cycle of the European eel encompasses a spawning migration to the Sargasso Sea. Prior to their migration, eels develop a silver coloration being referred to as “silver eels.” Due to the dramatic European eel recruitment decline, it is crucial to quantify silver eel escapement to evaluate the success of measures taken under Eel Management Plans (Regulation EC (1100/2007)). Thus, the percentage of silver eels escaping from the River Mondego (Portugal) was estimated during two consecutive spawning seasons (2014–2016) and their migratory behaviour was studied. Thirty-six male silver eels were tagged with acoustic transmitters and their downstream migration was tracked using automatic receivers deployed at four locations along the river course, from the first impassable obstacle up to the river mouth (67 km). Among the tagged eels, 15 (42%) escaped to the sea. In both years, individuals displayed faster migration speed in the downstream reaches of the river. BRT (“Boosted Regression Trees”) models were used to explain downstream migration and escapement of silver eels. The analyses revealed that the downstream migration is triggered by several environmental variables with water conductivity as the most influential predictor. Escapement of eels from the estuary occurred a few hours after their arrival and was primarily explained by the offshore wind intensity, which promotes a current in the coast that may favour their transport to the open sea. These findings contribute to a better understanding of silver eel migration in southern latitudes and highlight and reinforce the need to monitor spawner escapement.     

Cumulative impacts of habitat fragmentation and the environmental factors affecting upstream migration in the threatened sea lamprey,Petromyzon marinus

1. River ecosystems are often fragmented by artificial structures, such as weirs. For anadromous species, these structures can impede access to upstream spawning sites and ultimately lead to severe population declines.
2. This study focused on the freshwater spawning migration of the sea lamprey, Petromyzon marinus, an anadromous species threatened by habitat fragmentation across its native range. To quantify the cumulative impacts of multiple weirs on upstream-migrating adults, and to explore the environmental factors affecting migratory movements, passive acoustic telemetry was applied to 56 individuals during their spawning migration in the heavily fragmented River Severn basin, UK.
3. While 89% of tagged sea lamprey passed the first weir upstream of the release site on the main river, only 4% passed the fifth weir. For 85% of migrants, the upstream extent of migration was immediately downstream of a weir. Individuals that passed weirs upstream of the release site (n = 50) took 21.6 ± 2.8 days to reach their most upstream location, experiencing cumulative passage times at weirs of 15.7 ± 2.8 days; these delays constituted a median of 84% of total upstream movement times.
4. Multistate models showed that the weir passage rates of sea lamprey in tidal and non-tidal areas increased significantly when downstream river level and discharge were elevated. Upstream-to-downstream changes in direction were frequent downstream of weirs, but rare in unobstructed river sections.
5. The results provided evidence for a cumulative effect of multiple weirs on sea lamprey movements, substantially delaying upstream migrants and limiting their spawning to atypical habitat. The results also demonstrated the crucial roles of high tides and elevated discharge events in enabling weir passage. Although the Severn Estuary features conservation designations for sea lamprey, this study reveals that barriers are inhibiting their upstream migration, a problem that should be addressed to assist sea lamprey conservation.

     

Role of large‐ and fine‐scale variables in predicting catch rates of larval Pacific lamprey in the Willamette Basin,Oregon

Pacific lamprey Entosphenus tridentatus is an anadromous fish native to the Pacific Northwest of the USA. That has declined substantially over the last 40 years. Effective conservation of this species will require an understanding of the habitat requirements for each life history stage. Because its life cycle contains extended freshwater rearing (3–8 years), the larval stage may be a critical factor limiting abundance of Pacific lamprey. The objective of our study was to estimate the influence of barriers and habitat characteristics on the catch‐per‐unit‐effort (CPUE) of larval Pacific lamprey in the Willamette River Basin, Oregon, USA. We sampled lampreys at multiple locations in wadeable streams throughout the basin in 2011–13 and used an information theoretic approach to examine the relative influence of fine‐ and large‐scale predictors of CPUE. Pacific lamprey was observed across the basin, but its relative abundance appeared to be limited by the presence of natural and artificial barriers in some sub‐basins. Lower velocity habitats such as off‐channel areas and pools contained higher densities of larval lamprey; mean Pacific lamprey CPUE in off‐channel habitats was 4 and 32 times greater than in pools and riffles respectively. Restoration and conservation strategies that improve fish passage, enhance natural hydrologic and depositional processes and increase habitat heterogeneity will likely benefit larval Pacific lamprey.     

Development of diets for the intensive culture of Pacific lamprey

The Pacific lamprey Entosphenus tridentatus is an ancestral species of critical importance to the ecosystem and indigenous cultures in the Pacific Northwest. Conservation aquaculture has been proposed as a potential technique to restore Pacific lamprey populations. Intensive culture methods and diets for this species have not been developed. A sixteen week feeding trial tested the effects of seven diet treatments on the survival, growth, fatty acid profile and whole body lipid content of Pacific lamprey ammocoetes. Dietary treatments were: active dry yeast, yeast plus fish oil emulsion, micro‐algae, micro‐algae plus fish oil emulsion, yeast with micro‐algae, yeast with micro‐algae plus fish oil emulsion and yeast with larval fish diet. Each diet was offered to five replicate tanks stocked with 20 ammocoetes that were 51 days post hatch. Survival during the trial was not affected by diet. The greatest length and weight increases were in fish fed diets containing yeast. Growth decreased as the amount of algae in the diet was increased. Lipid retention was significantly higher in fish fed yeast with larval fish diet relative to the other treatments. Feed conversion ratio was lowest in fish fed diets containing yeast. Whole body fatty acid profiles tended to reflect the fatty acid profile of the diet. Percentages of 20:5n‐3 and 22:6n‐3 were significantly higher in fish fed diets containing fish oil emulsion. Overall, yeast with larval fish diet provided the best growth performance in larval Pacific lamprey.     

Climbing success of adult Pacific lamprey on a vertical wetted wall

The ability of adult Pacific lamprey, Entosphenus tridentatus (Gairdner), to climb has enabled development of lamprey‐specific fishways. Sheer vertical climbing elements are needed for these structures when fishway installation space is limited. A 1.6‐m high aluminium wetted wall was built to test Pacific lamprey vertical climbing in relation to flow and three water delivery mechanisms: overflow, upwelling and sidewelling. Passage success and passage times were recorded for individual Pacific lamprey (n = 122). For those that interacted with the structure (n = 104), 94% successfully ascended the wall (76% on their first attempt). Average time from first interaction with the structure to exit ranged from 19.5 to 47.0 min. Success rates and passage times were not significantly affected by flow or water delivery treatments. This indicates that vertical elements can facilitate lamprey passage in the 0.13–3.59 L min^?1 cm^?1 flow range tested and may greatly expand the design alternatives in certain situations.     

Condition assessment of lamprey populations in the Yorkshire Ouse catchment,north‐east England,and the potential influence of physical migration barriers

• 1. River lamprey (Lampetra fluviatilis) and sea lamprey (Petromyzon marinus) are designated features of the River Derwent Special Area of Conservation (SAC) and the Humber Estuary (a possible SAC). This study determined the condition of lamprey populations in the Yorkshire Ouse catchment by assessing the species composition, distribution, abundance and size‐structure of larval (ammocoete) populations in five major tributary rivers (Derwent, Swale, Ure, Nidd and Wharfe).
• 2. According to EU condition assessment criteria, Lampetra populations (assumed to be mostly river lamprey) are at present in favourable condition, with site mean (±SE) densities ranging from 2.7 (±1.2) to 160.3 (±50.5) individuals m^?2 (all river means >2 individuals m^?2), and at least two size (≈age) classes present in optimal microhabitats. By contrast, no sea lamprey larvae were recorded, suggesting that populations of this species are in unfavourable condition.
• 3. Actions to protect and enhance nationally or internationally important stocks must be implemented from at least a catchment perspective, because many of the issues affecting such species are not localized. With respect to lampreys, particular attention should be given to protecting spawning and nursery habitats, improving water quality, reducing impingement at abstraction points, preventing exploitation at spawning grounds and increasing passage at potential physical obstructions.

Copyright © 2007 John Wiley & Sons, Ltd.     

Are lampreys homebodies? Studying ammocoetes with open population models

Larval lampreys (ammocoetes) are assumed to be sedentary and have restricted movements, but their movement is still poorly understood. Using elastomer implants, ammocoetes of two different species of lampreys (Lethenteron appendix and Petromyzon marinus) in two streams were tagged with permanent, unique marks (N = 1035) and resampled once a month from June 2014 until October 2014. Some individuals were recaptured during every sampling event (N = 3, 0.3%). However, most animals were never recaptured after being tagged (N = 700, 67%) or were captured only once (N = 213, 21%). The apparent survival (?) varied in response to time and grouping variables at both sites (0.25–0.86), but the probability of capture (P) did not vary as much (0.41–0.85). Differences were detected between sites, with ? being higher for L. appendix at Dyke Creek, a Genesee River tributary. Whether differences were caused by site‐specific details or species differences is unclear. At Dyke Creek, where age could be partially established from length‐frequency histograms, ? was higher for 1 year old than for older animals. At Oquaga Creek (where P. marinus were captured), ? was highly variable (0.11–0.72) and was lowest in the fall sampling (September–October). The P was similar at both sites (0.5–0.6) and across times and groups, even when it was significant to the model. Understanding the movement of ammocoetes will help conserve and control lampreys.     

Instream size segregation and density of Geotria australis ammocoetes in two New Zealand streams

Geotria australis occurred almost to the upstream limit of detectable discharge in two New Zealand streams. The length, and consequently age, of larvae differed over the course of the stream and smallest animals - presumed to be age 0 - predominated upstream. Metamorphosing larvae (mean length 99.5 mm) typically occurred in downstream reaches, where flows were higher and substrate was coarser. We estimated that annual larval survival was 47% for age 0 to 1 and 77% for age 1 to 2. Differences in the relation between length and weight occurred both between years within a stream and between streams; thus, we assume growth is generally variable. The density of ammocoetes in New Zealand streams ranged from 0 to 104 m^?2 and was significantly related to substrate type and depth in a multiple linear regression model. Because of the predictable nature of lamprey distribution and abundance, we believe it should be possible to estimate the absolute abundance of ammocoetes in a catchment with only a limited assessment of substrate properties.     

A simple method for assessing minimum flows in regulated rivers: the case of sea lamprey reproduction

• 1. The sea lamprey (Petromyzon marinus) is an anadromous species that occurs in some large Iberian rivers, such as the Tagus, and their tributaries. The sea lamprey populations of the River Tagus are threatened by habitat loss and overexploitation, which means that conservation measures, including maintenance of the spawning grounds, are urgent. Habitat loss is mainly due to hydroelectric and flood‐control dams that have affected the migration and spawning habitats of anadromous species. The main objective of this study was to use a simple, cost‐effective method to assess a minimum instream flow for the regulated River Tagus. The method used was based on the wetted perimeter–discharge relationship, but accounted for the habitat requirements of spawning sea lampreys.
• 2. In 1998, a habitat survey was conducted along a 30 km segment of the River Tagus downstream from Belver Dam (the first impassable obstacle for fish movements), a stretch that includes potential habitats for spawning sea lampreys. Four spawning areas were identified, and in each one a representative reach was selected along which to collect elevation and geo‐positional data. For a range of flows from 0 to 50 m³ s^?1, hydraulic modelling and studies of spawning habitat availability were conducted, both for each reach and for the total wetted area of the four reaches.
• 3. The availability of spawning habitat was limited by flow. Results showed that the present minimum flow downstream from Belver Dam (8 m³ s^?1) is insufficient to ensure suitable habitat conditions in a significant part of the segment studied; gains in wetted usable area were more substantial with discharges of up to 20 m³ s^?1, and thus a minimum flow of 10–20 m³ s^?1 was recommended. Potential spawning habitat could be improved by increasing instream flow to at least 50 m³ s^?1. The impacts of the Belver release regime on anadromous species are discussed and a more ‘ecologically oriented’ form of water management is suggested

. Copyright © 2004 John Wiley & Sons, Ltd.     

Abiotic triggers for sea and river lamprey spawning migration and juvenile outmigration in the River Rhine,Germany

The activity patterns of migrating lampreys (sea lamprey Petromyzon marinus and river lamprey Lampetra fluviatilis) are poorly understood. This study uses extensive screening data from the cooling water intake of a nuclear power plant on the River Rhine, Germany, gathered on 1308 days over 46 consecutive months between 2011 and 2014. More than 34,000 lampreys were retrieved, of which the great majority (99.9%) were outmigrating nonfeeding postmetamorphic individuals. The main factors controlling outmigration were season, water temperature and river discharge. The bulk of downstream migration was observed each year in spring at water temperatures between 9 and 12°C, with earlier migrations during significant discharge peaks between December and February. The migration activity of postmetamorphic individuals declined during summer and autumn, regardless of discharge. Turbidity increased the occurrence of postmetamorphic lampreys and supported diurnal migration, which accounted for nearly 20% of all lamprey records. In winter, outmigrating individuals of both species exhibited significantly longer body lengths than those detected during other seasons. Haematophagus postmetamorphic sea lampreys were also retrieved (n = 28) and represent the most upstream records of parasitically feeding sea lamprey detected thus far. Adult lampreys migrating upstream were found mainly in spring, but in very low numbers, indicating high prespawning mortalities. The study points to a challenging future for the protection of lampreys in this area: the long duration and the round‐the‐clock nature of the observed migration demand flexible solutions to realise safe operational windows for water intake stations and to minimise impacts on juvenile lampreys.     

Sea lamprey avoid areas scented with conspecific tissue extract in Michigan streams

Three in‐stream experiments were conducted to determine whether sea lamprey, Petromyzon marinus L., tissue extract (alarm cue) and 2‐phenylethylamine hydrochloride (PEA HCl, a putative predator cue) influenced the distribution of migrating adult sea lamprey. Experiments evaluated sea lamprey movement when an odour was applied to (1) a tributary of a larger stream; and (2) half of a stream channel. Fewer sea lamprey entered the tributary and side of the river scented with sea lamprey tissue extract compared to the control treatment. Sea lamprey did not avoid the tributary and side of the river scented with PEA HCl. A final laboratory experiment found no difference in the avoidance response of sea lamprey to PEA HCl mixed with river water vs PEA HCl mixed with water from Lake Huron. As such, the lack of sea lamprey response to PEA HCl in the stream was unlikely to have been caused by the presence of the river water. Rather, the difference between laboratory and field results may be attributed to the complexity of the physical environment.     

An increase in the concentration of hepatic iron during the metamorphosis of the lamprey Geotria australis is accompanied by increased superoxide dismutase activity

The concentration of total non-haem iron and its ferritin iron component, and the activity of the enzyme superoxide dismutase (SOD), were measured in the livers of ammocoetes, metamorphosing animals (stages 1–7) and recently metamorphosed downstream migrants of the lamprey Geotria australis. Total non-haem iron in the liver rose significantly from 0.15–0.55 μg.mg wet weight⁻¹ in ammocoetes and metamorphosing stages 1–3 to 2.2–2.9 μg.mg⁻¹ in stages 5–7 and to 8.8 μg.mg⁻¹ in downstream migrants. The comparable values for ferritin iron were 0.06–0.26, 1.4–2.0, and 5.3 μg.mg⁻¹. Superoxide dismutase activity fell sharply from 0.39 μg.mg⁻¹ in large ammocoetes to between 0.07 μg.mg⁻¹ in stage 1 and 0.15 μg.mg⁻¹ in stage 6, before rising significantly to 0.26 μg.mg⁻¹ in stage 7 and 0.35 μg.mg⁻¹ in downstream migrants. The sharp fall in SOD activity at the beginning of metamorphosis is assumed to be related to the marked decline in plasma iron which occurs at the onset of this non-trophic phase in the life cycle. It is proposed that the subsequent increase in SOD activity in the liver of G. australis with increasing iron represents a mechanism aimed at reducing the potentially toxic effects of iron accumulation. This view is consistent with the significant and positive correlation found between both total non-haem and ferritin iron and SOD activity in the liver of non-trophic animals.     

Migration pattern of shirauo Salangichthys microdon Bleeker, in the Ishikari River system and adjacent nearshore sea area, Japan, as estimated by otolith microchemistry analysis

ABSTRACT:   The purpose of the present paper was to reveal the migration pattern of shirauo Salangichthys microdon Bleeker, in the Ishikari River system and its adjacent coastal sea areas. To this end, the strontium–calcium (Sr:Ca) ratios of the otoliths of 98 individuals were examined. Profiles of the Sr:Ca ratios during the life history after hatching in the estuary of the Ishikari River fell into two different patterns. One was characterized by a high (slightly fluctuating) Sr:Ca ratio throughout the life history; the other was characterized by an initial high Sr:Ca ratio followed by a lower value later in life. The former pattern was considered to be that of estuary–sea residents and the latter that of upstream migrants. Most upstream migrants migrated upstream once, although several did it twice. Back-calculated body lengths during the upstream and seaward migrations of the upstream migrants varied widely from 6.4 mm to 39.8 mm and from 13.5 mm to 79.4 mm, respectively. These findings suggest that estuary–sea residents and upstream migrants co-occurred spatiotemporally, and suggest a wide variation in migration patterns in the shirauo's life history.     

Upstream migration of the anadromous sea lamprey (Petromyzon marinus Linnaeus, 1758) in a highly impounded river: Impact of low‐head obstacles and fisheries

相似文献