Timing Of Spawning Migrations Research Articles

Reproduction, biometric patterns of pink salmon and effect of commercial fishery on the runs of the species on the south of the north-eastern coast of Sakhalin Island in 2021

Purpose: to present up-to-date data on the dynamics of the spawning run, reproduction conditions and biometric characteristics of pink salmon in three reference watercourses in the southern part of the north-eastern coast of Sakhalin Island, as well as analysis of impact of commercial fishing on the spawning run and distribution of spawners within spawning grounds. Methods: common methods of ichthyological research were applied to collect and process field data. Data were synthesized in MS Excel, analysis and visualization were carried out in MS Excel and Statistica. Scientific novelty: results of monitoring of pink salmon in the southern part of the north-eastern coast of Sakhalin are presented. Despite the intensive commercial fishery in this area, there are no other data on the dynamics of pink salmon runs, density of breeders on spawning grounds, and biometric characteristics of spawners, except for those presented in this paper. Result: data on the timing of spawning migration, distribution of pink salmon within spawning grounds and degree of occupation of spawning grounds, temporal structure of spawning run; bio-metric characteristics of pink salmon are presented. Assessment of the influence of commercial fishing on the dynamics of spawning run and distribution of pink salmon within spawning grounds is discussed. Practical relevance: the presented data is an integral part of information supply of fishery research of the most widespread species of Pacific salmon - pink salmon, which forms the basis of salmon fishery in the Sakhalin Region. Also, the presented data is applicable for preparation of scientifically-based recommendations for optimizing the fishing pressure.

Differences in spawning migration timing and mortality between males and females of the pelagic goby Gymnogobius isaza in Lake Biwa, central Japan

Differences in spawning migration timing and mortality between males and females of the pelagic goby Gymnogobius isaza in Lake Biwa, central Japan

Individual variation in spawning migration timing in a salmonid fish-Exploring roles of environmental and social cues.

Describing and explaining patterns of individual animal behaviors in situ, and their repeatability over the annual cycle, is an emerging field in ecology owing largely to advances in tagging technology. We describe individual movements of adult Sakhalin taimen Parahucho perryi, an endangered salmonid fish, in the headwaters of a river in northern Japan during the spring spawning season over 2 years. Migration timing, separated into stages prior to, during, and following the spawning period, was found to be more consistent and repeatable for females than males. We hypothesized that the observed coordinated movement within seasons, and repeatability in migration timing across seasons, could result from (1) individual-specific responsiveness resulting from endogenous, biological traits that are mediated by environmental factors, or (2) social interactions among comigrating individuals. We found that water temperature and water level experienced by fish near the river mouth approximately a week before arrival at the spawning ground explained variability in run timing between years for females but not males. We found no evidence of conspecific attraction or repulsion resulting from social interactions among the spawners and post-spawners. We conclude that individual-specific responsiveness to environmental cues was the likely mechanism underpinning the observed migration timing and movement patterns.

Biological characteristics of Pacific salmon spawners of the Paramushir Island and Shumshu Island in 2021

The purpose of these studies is to obtaining up-to-date information on the dynamics of spawning migration and the quality indicators of Pacific salmon on the Paramushir and Shumshu Islands (Northern Kuril Islands). Methods used: the work was carried out in accordance with the methods generally accepted in fisheries research. Scientific originality: for the first time in the last decade, data were collected on the dynamics of anadromous migration and on the biological parameters of the Pacific salmon of the Northern Kuriles. Result: up-to-date information on the timing of spawning migration and quality indicators of pacific salmon of the Northern Kuril Islands in 2021 is presented. Information about the temporal structure of the spawning stream has been obtained. Practical significance: the results will be used in the preparation of materials substantiating the forecasted volumes of pacific salmon catches in subsequent years, as well as in regulating the fishing of pacific salmon in the Northern Kuril Islands.

Temporal segregation in spawning between native Yellowstone cutthroat trout and introduced rainbow trout

AbstractHybridisation with introduced taxa poses a threat to native fish populations. Mechanisms of reproductive isolation can limit or prevent hybridisation between closely related species. Understanding how these mechanisms interact between the same species across geographically distinct occurrences of secondary contact, and how regional factors influence them, can inform our understanding of hybridisation as a threat and management actions to mitigate this threat. We used data collected on adult fish migration timing and approximate emergence timing of subsequent juvenile fish paired with genomic data to assess whether temporal isolation in the timing of spawning exists between Yellowstone cutthroat trout, rainbow trout and hybrids in the North Fork Shoshone River drainage in northwest Wyoming. We found evidence that Yellowstone cutthroat trout spawn, on average, two to four weeks later than rainbow trout and hybrids and two environmental covariates related to water temperature and discharge were associated with differences in spawning migration timing. Despite statistical support for Yellowstone cutthroat trout spawning later, disproportionately high numbers of rainbow trout and hybrids, paired with extended spawning seasons, lead to substantial overlap between all genotypes. Our results provide further evidence of temporal segregation in the timing of spawning as a mechanism of reproductive isolation between closely related species, but substantial spawning overlap suggests temporal segregation alone will not be enough to curtail hybridisation in conservation populations.

Genetic Diversity of Stellate Sturgeon in the Lower Danube River: The Impact of Habitat Contraction upon a Critically Endangered Population

One of the last wild populations of the critically endangered stellate sturgeon (Acipenser stellatus) survives in the Danube River. Limited knowledge about the genetic structure, ecology, and evolution of this species led to poor and inconsistent management decisions with an increased risk for species extinction in the wild. Here we show the results of genetic structure screening of the Danube River wild population over 12 years timespan. Our research does not bring evidence of population recovery. No genetic structuring was identified at the mitochondrial level concerning spawning migration timing, sampling locations, and developmental stages. Eleven maternal lineages were revealed based on restriction fragment lengths analysis of the D-loop region, with one haplotype as the most frequent. While this could be the result of a massive restocking activity using a reduced number of spawners, our data does not support it. The selection of mitochondrial haplotypes under the pressure of habitat contraction and the narrower range of temperature variation since dams’ construction on the river could explain the observed distribution. Several factors of managerial concern are discussed. Our results provide baseline data on the mtDNA diversity in a critically endangered species of exceptionally high socioeconomic and conservation interest.

Homogenization of the timing of chum salmon returns in relation to hatchery transplantation

The timing of migration and breeding is an important aspect in the study of the migratory ecology of fishes. This timing in fish is generally determined by both genetic and environmental factors but is also subject to anthropogenic selection. Hatchery transplantation practices, where hatchery fish are produced from returned adult salmon and then transplanted into several rivers, have been going on for over 30 years in the southern part of Hokkaido Island, Japan. In this study, I compared the inter-river variation in timing of spawning migration in chum salmon to examine the effects of hatchery transplantation on the timing of migration. There was less inter-river variation in the timing of spawning migration in transplanted rivers than in non-transplanted rivers. This result suggests that hatchery transplantation homogenizes the timing of spawning migration in chum salmon. Changes to other resource management tools, such as promoting natural spawning and/or hatchery releases using local fishes, may be important to preserve diversity in the timing of migration.

Seasonal timing of reproductive migrations in adfluvial bull trout: an assessment of sex, spawning experience, population density, and environmental factors

Using individual tags combined with a fish fence operated at the mouth of Smith-Dorrien Creek, the primary spawning habitat for Lower Kananaskis Lake bull trout (Salvelinus confluentus), we approximated a complete census of the spawning population from 1996 to 2000 to assess whether timing of upstream and downstream spawning migrations varied with extrinsic and intrinsic factors. The timing of both upstream and downstream migrations varied with sex, previous spawning experience, density, and temperature. Inferred spawning duration based on the predicted upstream and downstream migration dates indicated that experienced female spawners spent the least amount of time upstream and first-time spawners spent the most time upstream. No consistent differences in upstream migration timing were observed between non-repetitive and repetitive spawners. We suggest that variations in spawning migration timing observed in Lower Kananaskis Lake may be linked to environmental factors that influence upstream swimming ability and acquisition and expenditure of energy with respect to reproduction.

Influence of rainfall, hydrological fluctuations, and lunar phase on spawning migration timing of the Neotropical fish Prochilodus costatus

The arrival of the rains and the hydrological changes they cause are essential in the reproductive cycle of Neotropical migratory fishes, but their association with the onset of migration is still poorly understood. This study aimed to determine the role played by rainfall, hydrological changes, and the lunar cycle as triggers for migration of Prochilodus costatus (Prochilodontidae) in the upper Sao Francisco River, Brazil. In total, 132 individuals were fitted with radiotelemetry transmitters over three consecutive spawning seasons. Spawning migration began with the onset of the rains from late September to mid-December. Individuals exhibited a strong preference for initiating migration at the beginning of the rainy season, when river discharge is low, in days with positive changes in water level, and at times of new or waxing moon. The fraction of the population that initiates migration each year appears to be dependent on rainfall, indicating that P. costatus may be a partial migrant. The results show that P. costatus and, possibly, other migratory Neotropical fish, rely on different but interconnected environmental cues to trigger their spawning migration, ensuring that individuals migrate in time to reach their spawning grounds and find appropriate environmental conditions for spawning.

Corresponding long-term shifts in stream temperature and invasive fish migration

By investigating historic trapping records of invasive sea lamprey (Petromyzon marinus) throughout tributaries to the Laurentian Great Lakes, we found that upstream spawning migration timing was highly correlated with stream temperatures over large spatial and temporal scales. Furthermore, several streams in our study exceeded a critical spring thermal threshold (i.e., 15 °C) and experienced peak spawning migration up to 30 days earlier than in the 1980s, whereas others were relatively unchanged. Streams exhibiting warming trends and earlier migration were spatially clustered and generally found on the leeward side of the Great Lakes where the lakes most affect local climate. These findings highlight that all streams are not equally impacted by climate change and represent, to our knowledge, the first observation linking long-term changes in stream temperatures to shifts in migration timing of an invasive fish. Earlier sea lamprey migration in Great Lakes tributaries may improve young of the year growth and survival but not limit their spatial distribution, making sea lamprey control more challenging.

Temporal spawning migration patterns of landlocked Atlantic salmon (Salmo salar) in a constructed stream

AbstractLandlocked Atlantic salmon (ouananiche, Salmo salar) spawning migration timing varies throughout its range and is influenced by a variety of environmental variables. This study examined the spawning migration time of landlocked Atlantic salmon in a small (4 ha) constructed stream linked to a large reservoir (32,600 ha) in Newfoundland, Canada. Salmon use of the stream was passively monitored using Passive Integrated Transponder (PIT) Tags from 2006 to 2012. Of the salmon tagged throughout the reservoir, 48% entered the stream during the spawning season and remained there for 18–36 days from late September to November before they returned to the reservoir. Most fish entered the stream at dusk (32%). The lunar cycle influenced the timing of migration each year. Mean stream discharge (cubic metres per second) influenced migration timing in some years, and water temperature appeared to have minimal impact on migration timing. Twenty per cent of fish migrated to the stream in multiple years and 51% of these individuals appeared to use the stream on a biennial or alternate year cycle. These results demonstrate that small constructed streams can attract salmon from throughout a large reservoir and can provide valuable habitat in areas where spawning habitat is limited.

Different timing of spawning migration of sexes in Honmoroko Gnathopogon caerulescens from Lake Biwa to the Ibanaiko Lagoon, Japan

Different timing of spawning migration of sexes in Honmoroko <i>Gnathopogon caerulescens</i> from Lake Biwa to the Ibanaiko Lagoon, Japan

A tool to identify pink salmon ( Oncorhynchus gorbuscha) × Chinook salmon ( O. tshawytscha) hybrids in the St. Marys River, Michigan–Ontario

The first putative hybrid between pink salmon ( Oncorhynchus gorbuscha) and Chinook salmon ( O. tshawytscha) in the Laurentian Great Lakes was reported in 1992. Since that time, many St. Marys River anglers have reported catching hybrid ‘pinook’ salmon, but their true identity was often undetermined. Although Great Lakes populations of pink and Chinook salmon exhibit similar life history strategies to their Pacific coast counterparts, temporal and spatial overlap of spawning activities in the St. Marys River has made hybridization between these species common. We examined meristic and morphometric data from pink, Chinook and hybrid salmon captured in the St. Marys River during spawning migrations from 1999 to 2002. In addition, we determined spawning migration timing, size structure, age-at-maturity, and sex ratios for pink salmon, Chinook salmon and their hybrids. Spawning migrations of hybrid salmon were composed primarily (93%) of male fish. Peak migration for hybrids (20–30 September) was intermediate to peak migrations for the parent species (pink salmon: 10–19 September, Chinook salmon: 01–10 October). Hybrid salmon were intermediate for most meristic and morphometric characters examined. Using meristic and morphometric data, multivariate models were built and tested to determine the utility of using these data to aid in the identification of hybrids and the parent species. The result was an easy-to-use identification tool that requires counts of only four characters (lateral line scales, gill rakers, branchiostegal rays, and mandibular teeth) to identify pink salmon, Chinook salmon, and their hybrids.

Previously spawned Atlantic salmon ascend a large subarctic river earlier than their maiden counterparts

Spawning migration timing of maiden Atlantic salmon Salmo salar and previous spawners was analysed in the catches in 1989–2004 in the large subarctic River Teno in the northernmost parts of Finland and Norway. The hypothesis was that the migration timing of previous spawners and their maiden counterparts is similar, with the migration timing similar between sexes. In most cases, however, previous spawners were observed to migrate into the River Teno and its tributaries earlier than their maiden counterparts. The difference in run timing was especially evident between maiden one‐sea‐winter (1SW) Atlantic salmon and the corresponding group of previous spawners [1S1, 1 year at sea (1) followed by first spawning (S) and reconditioning period of 1 year (1) at sea and second spawning run] for both sexes in the River Teno and in its two tributaries. The same was also evident between 2SW maiden and 2S1 previous spawning female Atlantic salmon in the River Teno. Females showed earlier spawning migration than males both in previous spawners and maiden Atlantic salmon. Different maiden sea‐age classes also showed differences in run timing as multi‐sea‐winter fish (2–4SW) ascended earlier than 1SW fish but the timing of 1S1 and 2S1 previous spawning females coincided. The results suggest that run timing of Atlantic salmon may not be strictly genetically fixed as previous spawners ascend earlier than they did on their first spawning migration as maiden fish, and indicated that the closeness of the reconditioning area of postspawners to the river of origin resulted in an early ascent. Run timing of different sea‐age groups has major management implications if the populations are heavily exploited with numerous fishing methods in different periods of the fishing season, as in the River Teno system.

The timing of spawning migration: implications of environmental variation, life history, and sex

During 1960–2002, the arrival times of all spawning male and female Atlantic salmon (Salmo salar L., 1758) and brown trout (Salmo trutta L., 1758) entering Dalälven River were recorded. To study the role of environmental variation in spawning migration timing, we used long-term temperature (river and sea) and river discharge data. For salmon, the spawning migration peak was strongly correlated with mean monthly sea and river temperatures during spring: salmon arrived earlier when temperatures were higher and later when temperatures were lower. River discharge explained little of the variation in migration timing. Female salmon migration showed a stronger correlation with temperature than male salmon migration, and female salmon arrived ≈18 days earlier than males. Trout showed a larger variation in their spawning migration, but river and sea temperatures and river discharge explained little of the variation. Trout females arrived ≈7 days earlier than males. The sea and river temperatures were highly correlated during the spawning migration, indicating that large climate processes determine the temperature regimes in the Baltic Sea and its tributaries. Time of arrival at the river was not correlated with ovulation date; a female salmon or brown trout arriving late could ovulate almost immediately, whereas a female arriving early could wait to ovulate.

Timing of Adult Migration and Stock Structure for Sockeye Salmon in Bear Lake, Alaska

AbstractSockeye salmon Oncorhynchus nerka returning to the Bear Lake system on the Alaska Peninsula exhibit a bimodal pattern of adult spawning migration timing produced by early and late migrants. We examined, by field observation of tagged adults, the relationship between adult migration date, breeding site, and breeding date for sockeye salmon returning to Bear Lake to assess stock structure within the system and determine whether distinct populations were segregated as they passed through the commercial fishery. Observed tag recoveries documented that (1) early and late migrants breed in different locations, (2) early migrants breed earlier in the reproductive season than late migrants (i.e., the chronological order of spawning followed the adult migration order), and (3) the adult migration has three major temporal components rather than two. Bear Lake's sockeye salmon population complex is composed of at least seven distinct spawning populations that display substantial temporal separation as they enter freshwater. The low level of abundance at the middle of the season is misleading; it is predominated by a single, discrete population rather than being merely a low point between two peaks. Given the brief (14‐km), low‐gradient migration from the Bering Sea to Bear Lake, the populations are probably segregated as they pass through the commercial fishery and thus the temporal distribution of fishery openings has the potential for disproportionate exploitation and reduction of representation by some genotypes.

Spawning of anadromous rainbow trout, Oncorhynchus mykiss (Walbaum): a threat to sea trout, Salmo trutta L., populations?

Interference competition for territorial space and food resources between progeny of anadromous brown trout, i.e., sea trout, Salmo trutta L., and non-indigenous anadromous rainbow trout, Oncorhynchus mykiss, was studied in stream channels under laboratory conditions. In addition, the two anadromous species were compared by measurements of fecundity, egg size, alevin size, growth rate, and timing of spawning migration. Competition was mediated through migration of sea trout parr out of the stream channels and the results suggest a negative influence on the sea trout in terms of displacement further downstream in the channels and lowered specific growth rate when fish of equal size were tested together. Given the size advantages normally found, caused by differences in spawning period, sea trout parr held their positions in the stream channels while the smaller rainbow trout parr moved out of the system or stayed in areas where sea trout were absent. This study was initiated because an increasing number of ascending rainbow trout was reported in many streams on Gotland. Spawning rainbow trout have been observed to have destroyed sea trout spawning redds. Despite rainbow trout spawning in many streams, only one descendant from these anadromous rainbow trout has been found to date.