Seasonal Migration Patterns Research Articles

Feasibility of Surgically Implanting Acoustic Tags into Pacific Herring

AbstractInternally 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.

Seasonal PCB Bioaccumulation in an Arctic Marine Ecosystem: A Model Analysis Incorporating Lipid Dynamics, Food-Web Productivity and Migration

Primary production and species' lipid contents in Arctic ecosystems are notoriously seasonal. Additionally, seasonal migration patterns of fish may alter prey availability and thus diet. Taking the southern Barents Sea as a study region and PCBs as model contaminants, we examined to what extent each of these factors cause bioaccumulation in fish to change throughout the year. Data on physiology and standing stocks of multiple trophic levels were used to estimated season-specific carbon budgets and by inference also corresponding values for food ingestion and production of cod, capelin, and herring. When combining these values with Arctic lipid dynamics for bioaccumulation model parameter setting, we predicted bioaccumulation factors (BAFs) that were in good agreement with BAFs for cod and capelin observed between 1998 and 2008. BAFs in all fish were 10 times lower in summer than in spring and fall/winter and were mainly driven by lipid dynamics. Trophic magnification factors (TMFs: increase in BAF per unit increase in trophic level as derived from our carbon budgets) were highest for PCB 153 during spring (2.3-2.4) and lowest for PCB 52 in summer and fall/winter (1.5-1.6) and were driven by seasonal shifts in trophic level and lipid dynamics.

Insights on leatherback turtle movements and high use areas in the Southwest Atlantic Ocean

Leatherback sea turtles, Dermochelys coriacea, undertake broad oceanic movements while traveling between breeding and foraging areas. While satellite telemetry has been used to investigate long-term movements and diving patterns of leatherback turtles around the world, behavioral information for this species in the South Atlantic Ocean is limited. Here we present the first data on movements, habitat use and diving behavior of leatherback turtles in the Southwest Atlantic Ocean (SWA). Four leatherback turtles (two females, one male and one subadult) were fitted with satellite relayed data loggers (SRDL) in 2005 and 2006 after being incidentally captured by industrial (high seas pelagic longlines) and artisanal (coastal bottom-set gillnets) Uruguayan fisheries. Turtles tended to remain in the western side of the South Atlantic Ocean where specific areas were frequented, in one instance showing a round-trip migration between temperate and tropical waters. Previously unidentified high use areas were recognized along continental shelf and break waters in the SWA, both in temperate and tropical regions. Leatherback turtles exhibited seasonal migration patterns and displayed marked changes in diving behavior between high use areas. Furthermore, our results highlight the importance of the Rio de la Plata estuary as a key foraging area for D. coriacea in the SWA which should be considered a central focus of attention for future research and conservation efforts.

Resolving the effect of climate change on fish populations

Abstract Rijnsdorp, A. D., Peck, M. A., Engelhard, G. H., Möllmann, C., and Pinnegar, J. K. 2009. Resolving the effect of climate change on fish populations. – ICES Journal of Marine Science, 66: 1570–1583. This paper develops a framework for the study of climate on fish populations based on first principles of physiology, ecology, and available observations. Environmental variables and oceanographic features that are relevant to fish and that are likely to be affected by climate change are reviewed. Working hypotheses are derived from the differences in the expected response of different species groups. A review of published data on Northeast Atlantic fish species representing different biogeographic affinities, habitats, and body size lends support to the hypothesis that global warming results in a shift in abundance and distribution (in patterns of occurrence with latitude and depth) of fish species. Pelagic species exhibit clear changes in seasonal migration patterns related to climate-induced changes in zooplankton productivity. Lusitanian species have increased in recent decades (sprat, anchovy, and horse mackerel), especially at the northern limit of their distribution areas, while Boreal species decreased at the southern limit of their distribution range (cod and plaice), but increased at the northern limit (cod). Although the underlying mechanisms remain uncertain, available evidence suggests climate-related changes in recruitment success to be the key process, stemming from either higher production or survival in the pelagic egg or larval stage, or owing to changes in the quality/quantity of nursery habitats.

Bioalpha, transmission loss and validation of scattering models in biologically intense shallow water environments.

Scattering and extinction by fish swim bladders are manifestations of the same phenomenon. Scattering causes reverberation from dispersed fish and distinct echoes from fish schools (clutter), and diminishes the magnitude of transmitted signals. The biological extinction coefficient (bioalpha) has been shown to have a large effect on transmission loss (TL) in several biologically intense, shallow water environments, including the Bristol Channel [Weston (1967)], Yellow Sea [Qiu et al. (1999)], Gulf of Lion [Diachok (1999)], and Santa Barbara Channel [Diachok (2005)]. Consequently, models of biological scattering must include the effects of bioalpha on TL in shallow water environments. The objectives of this paper are to review the experimental evidence of the effects of bioalpha on TL, and to describe and demonstrate the effectiveness of an analytical approach to modeling this phenomenon. Since it is not possible at present to predict the effects of bioalpha on TL from first principles (distributions of swim bladder dimensions, spatial distributions of number densities, and timing of diurnal changes in school structures and seasonal migration patterns are only approximately predictable), experiments designed to demonstrate the validity of scattering models in biologically intense, shallow water environments should include concurrent broadband TL measurements during both night and day.

Vertical distribution and seasonal dynamics of mesozooplankton in the Iceland Basin

The abundance and seasonal vertical distribution of dominant zooplankters in the Iceland Basin was studied from data collected on four cruises between November 1996 and June 1997. Copepods were by far the most abundant group, making up ∼70% or more of the mesozooplankton. Two species constituted >90% of the copepod biomass: Calanus finmarchicus and Pareuchaeta norvegica. A seasonal migration pattern was evident in C. finmarchicus, P. norvegica, Oithona spp., and Metridia lucens: from December to February they inhabited the deeper layers, whereas from April to June they were most abundant in the upper layers. The vertical distribution of Pleuromamma robusta was rather similar year round. Oncaea spp. stayed deep during winter, but only a limited part of the population rose to upper waters during the summer. The reproduction of C. finmarchicus took place in May in the surface layers and it was linked to the phytoplankton spring bloom. In contrast, the reproduction of P. norvegica occurred at depth in February and was uncoupled to the spring bloom. Calanus hyperboreus is an expatriate in the Iceland Basin that does not reproduce there. The data on Oithona spp. and Oncaea spp. indicate that the former group reproduces between April and June in the upper layers, whereas the latter appears to reproduce year round at depth. As judged by the incidence of adults of both sexes the reproduction of M. lucens took place in spring and summer. The breeding of P. robusta was probably not confined to a particular season of the year.

The impact of out-migrants and out-migration on the HIV/AIDS epidemic: a case study from south-west India

Seasonal migration may be an important driver of the HIV epidemic in India; however, migrant sexual behaviour data are limited. This study assessed the extent to which migration could explain heterogeneity in HIV prevalence in Bagalkot district, in Karnataka state, India, examining important migration-related risk factors for HIV transmission and implications for prevention. We used mathematical modelling to explore the potential impact of different seasonal migration patterns on HIV prevalence. A deterministic compartmental mathematical model of heterosexually transmitted HIV infection was developed. Six migration scenarios were explored, depending on which population migrated (men/clients only/female sex workers; FSW), and which local population determined the demand for commercial sex while migrants were away. The impact of migration varied substantially across the six migration scenarios. Migration was unlikely to explain heterogeneity in HIV prevalence unless a fraction of all men migrated and local FSW drove the demand for commercial sex. Even with very high-risk migrant sexual behaviour in the migration destination, targeting interventions at 30%-100% of local core groups could prevent a maximum of 12%-40% of new infections (87% effective condoms), from 2004-2015. Targeting migrants locally and at their destination could have up to 1.6-times the impact of targeting migrants only at their destination. Results suggest that core group interventions introduced locally because of the difficulty of reaching migrant populations could still be beneficial. Understanding how local sexual networks change during migration is crucial for understanding the impact of migration on HIV transmission, and for designing HIV preventive interventions.

Annual variability in upstream migration of glass eels in a southern USA coastal watershed

We investigated the environmental factors that affected temporal variability of eel recruitment and upstream migration in a freshwater coastal river along the southeastern US. Glass eels Anguilla rostrata were collected through ichthyoplankton sampling in the lower Roanoke River, North Carolina. Monthly samples were taken from fixed stations from May 2001 through June 2003. There was no evidence of consistent seasonal migration patterns for glass eels in Roanoke River. From May through December in 2001, glass eels were captured only during August. In 2002, glass eels arrived in February and remained in ichthyoplankton samples through October, with the exception of samples from September. Peak catch occurred in March at 4.02 ± 1.2 and declined through June to 0.18 ± 0.07 (#/1,000 m3). By August, the mean density increased to 0.96 ± 0.82 and to 3.59 ± 2.77 by October. In 2003 from January through June, glass eels were captured only during February and March. Glass eels were routinely collected when river discharge rates were 650 m−3 s−1 resulted in no glass eels in our samples. Upstream migration during 2002 was not correlated with water temperature or related to lunar phase. Glass eel freshwater upstream migration was initiated when water temperatures exceeded a threshold range of 10°C to 15°C; however, glass eels continued to migrate when water temperatures approached 30°C. The overall negative effect of river discharge suggests that changes in the water release schedules of upstream hydroelectric facilities during glass eel migration could strongly influence their recruitment success.

Inter‐ and size‐specific patterns of fish seasonal migration between a shallow lake and its streams

Abstract – This study used passive telemetry (passive integrated transponders) to evaluate winter migration in three species of cyprinids (roach (Rutilus rutilus(L.)), white bream (Blicca bjoerkna(L.)) and rudd (Scardinius erythrophthalmus(L.))) and their potential predators (pike (Esox lucius(L.)) and perch (Perca fluviatilis(L.))) between a shallow lake and its streams. Migration patterns were investigated from October to June, and a substantial part of the roach (40%) and white bream (55%) populations tagged in the lake during autumn migrated during winter into the streams, whereas only very few piscivores (<2%) migrated. In contrast to roach and white bream, only few rudd (<6%) migrated, which is likely a consequence of different overwintering strategies, e.g., rudd overwintering in shallow highly structured habitats. Small rudd migrated more than larger rudd, whereas there were no size‐differentiated migration patterns for roach or white bream. Migration of the cyprinid fishes was generally initiated in late October and ended in May, and specific synchronised bursts of migration were observed in December, January and April, suggesting that migration is triggered by one or more proximate environmental cues. The cyprinid fishes generally entered the streams in late afternoon or in the morning, depending on season, but overall migration patterns varied between the three streams. We suggest and discuss that our results have great implications for lake management as well as for the interpretation of seasonal trophic dynamics in shallow lakes.

Spatial and temporal variation of Palaemon adspersus, Palaemon elegans, and Crangon crangon (Decapoda: Caridea) in the southern Black Sea

In order to characterize the seasonal, bathymetric, and spatial distribution of the species, Palaemon adspersus, Palaemon elegans, and Crangon crangon, shrimps were sampled with a beam trawl in four stations at depths between 1 and 30 m from February 2002 to January 2004 on the Sinop Peninsula coasts of the southern Black Sea. One-way analysis of similarity (ANOSIM) results demonstrated that the caridean composition was significantly different ( p < 0.001) between seasons and between sampling areas. No significant relationship of the caridean composition was evident between depth zones ranging from 1 to 30 m. These three carideans occurred together in 28.5% of the sampling occasions. Different seasonal migration pattern was evident for all the three species. Palaemon adspersus migrated inshore during relatively higher water temperatures, whereas C. crangon density decreased in the shallow waters during the same period, and P. elegans population was mostly observed at depth zones of 5–10 m and was only observed in the 30 m depth zone in winter. The abiotic factors that characterize the coexistence of these three carideans were primarily determined by the habitat types and bottom structures.

Migration dynamics of Pacific herring (Clupea pallasii) and response to spring environmental variability in the southeastern Bering Sea

In the southeastern Bering Sea, Pacific herring (Clupea pallasii) migrate from the Pribilof Islands region where they overwinter, to the Alaska coast where they spawn in spring. The migration sustains a nearshore commercial fishery that targets roe-bearing females just prior to spawning. Herring also are taken as bycatch in groundfish trawl fisheries, where time and area closures in these fisheries are triggered by herring bycatch caps. Using herring bycatch data collected since the 1970s by National Marine Fisheries Service (NMFS) observers aboard groundfish fishing vessels, a retrospective analysis was conducted to describe the seasonal migration pattern of Pacific herring in the southeastern Bering Sea and to study its spatial and temporal variability. Observed changes in herring catch per unit of effort were compared with variability in climate and oceanographic conditions. The seasonal migration is complex, but annual shifts in migration routes and a possible northward shift of the overwintering grounds was identified. Pre-spawning herring aggregated in different areas depending on whether spawning occurred early or late in spring. The thermal structure of the ocean around the ice edge appears to influence herring migration timing and route as well as spawning date. Thus, on the basis of recent changes in sea-ice extent and duration, we suggest that the herring bycatch savings area that was developed from data collected in the 1980s should be revised to reflect prevailing conditions. r 2007 Elsevier Ltd. All rights reserved.

Intercept Telemetry of the Hudson River Striped Bass Resident Contingent: Migration and Homing Patterns

AbstractHudson River striped bass Morone saxatilis show highly variable migration patterns, as observed through past tagging studies and otolith microchemical analyses. Recent studies have shown resident, estuarine, and ocean migratory contingents in the Hudson River. We undertook a directed study to more precisely characterize the seasonal migrations of the resident contingent. Remote biotelemetry was conducted on 12 resident striped bass during a 14‐month period in 2004–2005. All tagged striped bass migrated downriver from October 2004 to January 2005 and returned upriver from March to May 2005. Observed seasonal migration patterns were similar to those expected from previous tagging and otolith microchemistry studies: Directed downriver emigration to brackish‐water overwintering habitats was followed by upriver migration to spring–summer freshwater feeding and spawning habitats. Eight of 12 fish showed directed spring migrations upriver to their original tagging site and were repeatedly located there, indicating strong homing behavior and residence. These very specific patterns of homing indicate that local‐scale effects (e.g., fishing, pollution) can have persistent effects on components of the Hudson River striped bass population.

Harvest trails in Australia: Patterns of seasonal migration in the fruit and vegetable industry

Against a background of declining employment in agriculture, a mobile workforce plays a crucial role in meeting seasonal labour demand in Australia. The dynamics of this labour force have received surprisingly little attention. We situate seasonal migration within the rising diversity of present-day mobility, and capture images of its early history in Australia. Statistical and documentary sources provide a basis to illustrate patterns of demand for seasonal labour and estimate the size of the workforce. Drawing on fieldwork in three case study regions of Queensland, we then seek to establish the composition of the seasonal workforce, identify their motives for undertaking seasonal work, and discover their harvest trails. Combining these data generates a typology that distinguishes key groups. Our results point to a fall in the numbers of Permanent Itinerants compensated by a sharp rise in Retirees and Working Holiday Makers from Overseas, each with distinctive spatial circuits. We argue that consumption motives play a growing role in the dynamics of seasonal labour mobility, and identify an emerging organisational apparatus that shapes and controls the industry. Drawing on the experience of other developed countries with more open labour markets, we anticipate continuing transformation in seasonal labour dynamics.

Winter short‐distance migration of juvenile fish between two floodplain water bodies of the Lower River Rhine

Abstract – During winter, large numbers of juvenile fishes (mainly roach, Rutilus rutilus L.) were observed to migrate at dawn from a floodplain lake into a connected channel, whereas they migrated in the opposite direction at dusk. The diurnal migration pattern was strongly correlated to light intensity. The total number of migrating fish decreased from autumn to spring. Ice coverage and water temperature were the only abiotic factors that affected the seasonal migration pattern significantly. Moonlight, water level, current velocity, rainfall, insolation and wind velocity did not influence the observed migration of juvenile fish. The results are discussed in relation to food availability, predation risk and energy conservation.

Bird migration across the Mediterranean: ringing activities on Capri within the Progetto Piccole Isole

Palearctic-African spring migrants are faced with the challenging crossing of the double ecological barrier of the Sahara Desert and the Mediterranean Sea. Islands represent unique opportunities to stopover and rest during these prolonged endurance flights. To study spring migration across the Mediterranean, the Italian Ringing Centre at INFS has co-ordinated the Progetto Piccole Isole since 1988 with Capri being among the most active stations. Islands are used as stopover sites by huge numbers of birds belonging to a wide range of species and irrespective of physical conditions of migrants. Clearly defined species-specific seasonal migration patterns are observed, and also differential migration of sex and age classes. Wide-front movements over the sea of typical nocturnal migrants occur also during daytime. Physiological studies confirm the importance of the short stopovers observed on the islands, which permit the birds to adjust their metabolic state, rest and rely, in many cases, on easily accessible nectar as an energetically rich food. Strong links with habitats both in Africa and within the Mediterranean confirm the need for internationally coordinated conservation strategies for Palearctic-African migrants.

Seasonal Distribution of Yearling Masu Salmon Released from the Sea of Japan Side of Southwestern Hokkaido, Japan

AbstractWe investigated the seasonal distribution and migration patterns of hatchery‐reared masu salmon Oncorhynchus masou in the area surrounding Hokkaido, the northern island of Japan. From 1993 to 1999, we tagged and released 313,000 yearling masu salmon smolts into the coastal waters of the Sea of Japan adjacent to southwestern Hokkaido. From May of the release year through July of the following year, a total of 1,693 fish were recaptured in the coastal waters of northern Japan. Just after their release, masu salmon juveniles had two migration routes; one group moved northward along the western side of Hokkaido in the Sea of Japan, while the second group passed through the Tsugaru Strait and then moved eastward into the Pacific Ocean. It was estimated that both groups reached the Sea of Okhotsk at 30–40 d postrelease. The summer distribution of tagged fish was unknown because none were recaptured. Young fish appeared in the Sea of Okhotsk again in autumn and then migrated southward, retracing the above two routes. They reached the Tsugaru Strait and Pacific coastal waters ranging from the northeastern Shimokita Peninsula in Honshu to the Iburi district of Hokkaido. Tagged masu salmon juveniles were recaptured in these areas until the following March, which indicates that these sites were the most important overwintering areas. Adult fish rapidly returned to the area of release from April to June. Our results suggest that hatchery masu salmon migrated in the coastal waters of northern Japan within a relatively short period.

Variability in retention of Calanus finmarchicus in the Nordic Seas

Abstract Using a regional ocean circulation model and particle tracking, we have studied the probability of the copepod Calanus finmarchicus being retained within the Nordic Seas' population as a function of its initial location, its vertical migration pattern, and the interannual variability in physical forcing. Defining a retention index in terms of the number of particles remaining within the Nordic Seas divided by the initial number of particles released, we found that spatial location had the greatest effect on the retention index during the study period, 1988–1991. Variability as a result of differences in physical forcing among years and among different seasonal vertical migration patterns had smaller but similar effects. The seasonal vertical migration behaviours with the highest advective loss rates and the most sensitive to interannual physical forcing were those that ascended early and descended late from a shallow summer depth. Average retention within the Nordic Seas was 0.40 after one year in simulations with diffusion and advection, and 0.42 in simulations with advection only. The average retention at the end of the four-year sequence was 0.10 and 0.12 with and without diffusion, respectively. Particles located in the western areas of the Nordic Seas had the highest retention, while those along the Norwegian coast showed little or no retention after four years. Initial location has a larger influence on retention than interannual variability in advective fields. C. finmarchicus offspring tend to reside in areas different from their parents, with different probabilities of retention. This spatial variability in retention rate is also experienced as inter-generational variability by members of the population. Model results suggest that almost all of the C. finmarchicus that are advected into the Barents Sea originate from off the Norwegian coast. Thus, predicting C. finmarchicus inflow into the Barents Sea requires knowledge of their abundance on the Norwegian Shelf.

Using the Spectacled Bear as a Conservation Tool in the Condor Bioreserve, Ecuador

Conservation organizations in the Condor Bioreserve (CBR) in northern Ecuador use the spectacled bear (Tremarctos ornatus) as a surrogate species to focus conservation efforts. However, the utility of single-species management has been questioned in recent scientific literature, making it appropriate to review the spectacled bear's efficacy as a conservation tool. The spectacled bear does not enjoy unqualified public support in CBR and surroundings, suggesting that it may not be appropriate as a flagship species. It may be more effective as a keystone species; its diet and migratory habits suggest that it may have a significant impact on plant community structure through fruit dispersal. However, more research is needed in this arena before drawing any conclusions. The spectacled bear is perhaps most appropriate as an umbrella species because of its large home range, which encompasses at least two ecosystem types: páramo and montane forest. Traditionally, the concept of the umbrella species has stressed minimum area requirements, but the spectacled bear may be a more effective umbrella species if its dispersal requirements and seasonal migration patterns are also addressed. Eco-Ciencia, an Ecuadorian research organization, recently constructed a habitat model for spectacled bear. They are uniquely positioned to address issues of habitat connectivity both within and between the protected areas of CBR. In doing so, they could influence future zoning decisions in and around CBR, an area that is experiencing rapid population growth. This could improve conservation efforts for spectacled bear and other species.

Seasonal migration patterns of female sika deer in eastern Hokkaido, Japan

Fifty‐seven female sika deer (Cervus nippon yesoensis), captured at the wintering area in the Shiranuka Hills in eastern Hokkaido, Japan, were radio‐tracked during 1997–2001 to examine the factors affecting seasonal migration at the individual‐landscape level. Ten of the 57 deers migrated between low‐altitude summer home ranges and intermediate‐altitude winter home ranges (the upward migrants). Twenty‐nine migrated between high‐altitude summer home ranges and intermediate‐altitude winter home ranges (the downward migrants). Twelve used the intermediate‐altitude home ranges all year round (the non‐migrants). The remaining six were unknown. The summer home ranges of deer were widely scattered over an area of 5734 km2. Migration distances ranged between 7.2 and 101.7 km. Deer showed high site fidelities to their seasonal home ranges. The upward migrants wintered in areas of less snow, higher quality of bamboo grass, and more coniferous cover than their summer home ranges. The downward migrants wintered in areas of less snow, higher quality of bamboo grass, higher winter temperature, and more southern slopes, but less coniferous cover than their summer home ranges. The non‐migrants used year‐round ranges with little snow, high quality of bamboo grass, and sufficient coniferous cover. We suggest that snow cover and bamboo grass are the factors affecting seasonal migration of the population and that coniferous cover is another factor for the upward migration.

Protein sequence database methods.

Seasonal migration pattern of owls at Bukowo-Kopań station (N Poland) in 2000-2003 Data were collected at the Operation Baltic stations and included over 2000 owls caught and ringed at Bukowo-Kopań station in autumns 2000-2003. Birds were caught with raptor nets, ringed and measured according to the Operation Baltic standards. The Long-eared Owl (Asio otus) is the most numerous migrant at Polish coast of the Baltic Sea. Migration of this species has wave-like pattern with few nights of very high owl numbers after nights without these birds. Amount of migrants changes decidedly from year to year. This is a result of fluctuations associated with small mammal populations dynamics. Other owl species pass Bukowo-Kopań station in rather low numbers. We can distinguish two groups of owl species according to terms of passage peaks. Both the Short-eared Owl (Asio flammeus) and the Barn Owl (Tyto alba) migrate in the highest numbers generally at the same time as the Long-eared Owl, i.e. at the beginning of November. Correlation is in most cases statistically significant. On the contrary, the migration pattern of the Tengmalm's Owl (Aegolius funereus) is conspicuously different. Passage maximum of this species occurs at the beginning of October and by 25 October the passage is almost finished. But even then individuals that migrate later are caught during the same migration peaks as the Long-eared Owl. Obtained results indicate that the passage of different owls is similar to the most numerous and typical migrant species - the Long-eared Owl. Other species choose the same nights for passage, which suggests that some common factors influencing owl migration exist.