Migratory patterns of anadromous white-spotted charr Salvelinus leucomaenis in Eastern Hokkaido, Japan: The solution to a mystery?

We evaluated the migratory patterns of white-spotted charr in eastern Hokkaido, Japan using: (1) field observation of fish, (2) salinity-recording archival tags, and (3) analysis of otolith Sr and Ca concentrations. Field observations suggest that the majority of anadromous white-spotted charr outmigrate to the sea in spring (April to June) and ascend the river between late summer and autumn (August to November). Salinity records from archival tags revealed a fluctuating pattern consisting of both low and high values within a month, indicating frequent short-term movements between freshwater (including non-natal rivers) and brackish/salt water habitats. Otolith Sr:Ca ratios exhibited a sharp rise at about 40–50% of the otolith radius, which was followed by several spikes consisting of both low and high values, indicating that fish migrated between freshwater and marine environments multiple times during their life history. However, the peaks in Sr:Ca ratios were generally associated with annulus zones on the otolith, indicating that the anadromous migration was generally an annual event.     

Flexible seaward migration of Dolly Varden <Emphasis Type="Italic">Salvelinus malma</Emphasis> in the Shiretoko Peninsula,Hokkaido, Japan

The migratory history of Dolly Varden Salvelinus malma was investigated in 30 streams in the Shiretoko Peninsula, Hokkaido, Japan, which is in the southern part of their distribution. Captured Dolly Varden were classified into two categories by their body coloration: silvery fish were thought to be an anadromous form, and non-silvery fish a fluvial form that remains in freshwater throughout its life. Forty-seven of 1,739 Dolly Varden collected in the spring and ten of 2,126 Dolly Varden collected in the autumn were silvery fish. Twenty silvery fish and 120 non-silvery fish were examined by analysis of otolith Sr:Ca ratio. Three silvery fish from autumn and 15 non-silvery fish had migrated to salt water or brackish water. The other specimens of silvery fish were regarded as smolt or pre-smolt before seaward migration. The present study suggests that Dolly Varden in the Shiretoko Peninsula have a flexible migratory history, where some of the non-silvery fish utilize marine environments while some individuals follow an anadromous life history.     

Diversity of life strategies of pikepech <Emphasis Type="Italic">Sander lucioperca</Emphasis> (L.) in the Lower Volga (by the data of microelement composition of otolithes)

Strontium (Sr) and calcium (Ca) contents and Sr/Ca ratios in otoliths of pikeperch Sander lucioperca have been studied by X-ray fluorescent microanalysis. A sample of 95 specimens from the Lower Volga region are studied. The fish were obtained in a section of the Akhtuba River at a distance of 250–279 km upstream from the Caspian Sea. Some specimens in the sample have low strontium content throughout the otolith. The other fish have increased both Sr content and Sr/Ca ratios in core zones of otolith or near its outer edge: the Sr/Ca ratio is over 6.00 × 10^–3, with a maximum at 10.02 × 10^–3. The fish with a low Sr/Ca ratio live in freshwater and demonstrate a resident life history strategy. Pikeperch that have increased ratios of Sr/Ca in outer zones of otolith demonstrate a migratory life history strategy. These fish leave the freshwater of the Volga and feed in brackish water of the Northern Caspian Sea. Some migratory fish migrate to the sea as underyearlings, stay in a brackish water for 1 year or less, and then return back to fresh water for the rest of its life. The other group migrates back and forth from freshwater to the sea several times during their life. Finally, some fish leave freshwater for 1–2 years, spending this time in the Northern Caspian Sea. The conclusion is that the pikeperch stock in the Lower Volga has a complicated composition and consists of freshwater (residents and rheodromic ones) and migratory (anadromous and semianadromous) fish.     

Life history and migration of Sakhalin taimen, Hucho perryi, caught from Lake Akkeshi in eastern Hokkaido, Japan, as revealed by Sr:Ca ratios of otoliths

Microchemical analysis of the strontium (Sr) and calcium (Ca) ratios of otoliths was conducted to determine the life history and migration of anadromous Sakhalin taimen, Hucho perryi. In 2008 and 2009, 10 specimens were sampled from Lake Akkeshi in eastern Hokkaido, Japan. Our results indicated that some specimens migrated to brackish waters during their early life histories. Because the Sr:Ca ratios of the specimens in this study were all less than those of specimens from Sakhalin Island during a previous study, specimens from Lake Akkeshi may have migrated to brackish water, or may have remained in the ocean for only a short period.     

Environmental signature in the otolith elemental fingerprint of the tapertail anchovy, Coilia mystus, from the Changjiang estuary, China

The ontogenetic patterns of habitat use and the migratory history of the tapertail anchovy, Coilia mystus, collected in the Changjiang estuary around Chongming Island, China, were studied by examining the environmental signature in the otolith strontium (Sr) and calcium (Ca) fingerprints using electron probe microanalysis (EPMA). Our results suggest that the migration strategy of C. mystus is much more flexible than supposed in the literature to date. The spring spawning population of C. mystus from the studied area was found to consist of individuals with different migration histories. Although the tapertail anchovy seems to be an anadromous fish that spawns and hatches in a freshwater habitat, it can also use a freshwater environment in non‐spawning seasons. The otolith EPMA of the elemental fingerprint (Sr x‐ray maps and Sr : Ca ratios) is an environmental indicator that can be applied to the migratory ecology of other important diadromous species in China.     

基于耳石微化学的乌苏里白鲑生境履历分析

为了分析乌苏里白鲑(Coregonus ussuriensis Berg)的洄游生态类型及生境履历, 采用X射线电子探针微区分析技术(EPMA)研究了2013年12月、2014年1月黑龙江干流2尾和松花江干流2尾乌苏里白鲑矢耳石的锶(Sr)、钙(Ca)元素微化学特征。定量线分析结果显示, 乌苏里白鲑耳石锶钙比值(Sr/Ca×103)波动显著, 具有对应淡水生活的低值区(小于5), 而且还有对应咸水生活的高值区(大于10), 显示了乌苏里白鲑的溯河洄游履历; 耳石元素面分析结果也显示乌苏里白鲑的淡水-咸水洄游的特征。结合耳石年轮特征分析, 乌苏里白鲑具有年度(季节)洄游特征, 部分群体有规律在淡水-咸水中季节洄游, 不同个体在淡水、咸水之间停留时间存在较大差异。研究表明, 乌苏里白鲑伴随着季节性洄游特征, 具有江海或者淡水-河口之间洄游的履历。     

Morphology,stomach contents and growth of the endangered salmonid,Sakhalin taimen <Emphasis Type="Italic">Hucho perryi</Emphasis>, captured in the Sea of Okhotsk,northern Japan: evidence of an anadromous form

Synopsis We describe a total of 25 anadromous Sakhalin taimen Hucho perryi collected on the coast of Sarufutsu, northern Hokkaido, Japan in June 1997 and 1999. We examined morphology, stomach contents and growth of three anadromous taimen (one male and two females) in detail, which were preserved in good condition. The three taimen were aged and one female still had some eggs retained in her abdomen. The stomach contents of the three taimen consisted of sand lance Ammodytes personatus Girard and sculpin Triglops sp. On the basis of scale analyses, the growth rate of the three taimen was estimated by using the back-calculation method, and the highest rates were observed at young ages. Guanine pigmentation was present at the base of the caudal fin of each taimen and is considered as a potential morphological trait to differentiate anadromous from fluvial specimens. Another anadromous taimen, of which some individuals had reared for more than 3 years in seawater are also reported. For the conservation of this rare and endangered species, their migration route between rivers and sea should be protected     

Identifying sea-run brown trout, Salmo trutta, using Sr : Ca ratios of otolith

 The migratory history of the brown trout, Salmo trutta, collected from Japanese rivers, was examined in terms of strontium (Sr) and calcium (Ca) uptake in the otolith, by means of wavelength dispersive X-ray spectrometry on an electron microprobe. Sea-run (anadromous) and freshwater-resident (nonanadromous) types of S. trutta were found to occur sympatrically. Otolith Sr concentration or Sr : Ca ratios of anadromous S. trutta fluctuated strongly along the life history transect in accordance with the migration (habitat) pattern from sea to freshwater. In contrast, the Sr concentration or the Sr : Ca ratios of nonanadromous fish remained at consistently low levels throughout the otolith. The higher ratios in anadromous S. trutta, in the otolith region from the core to 1500 μm, corresponded to the initial seagoing period, probably reflecting the ambient salinity or the seawater–freshwater gradient in Sr concentration. The findings clearly indicated that otolith Sr : Ca ratios reflected individual life histories, enabling the sea-run S. trutta to be distinguished from the freshwater-resident brown trout. Received: March 18, 2002 / Revised: May 15, 2002 / Accepted: June 5, 2002 Acknowledgments The authors are grateful to Messrs. T. Ikeda, S. Kudo, Y. Miyakoshi, M. Nagata, K. Shimoda, T. Takami, K. Takeuchi, and M. Ueda for their assistance in collecting specimens. This work was supported in part by Grant-in-Aid No. 13760138 from the Ministry of Education, Culture, Sports, Science and Technology, Japan. Correspondence to:Takaomi Arai     

Regional variation in otolith Sr:Ca ratios of African longfinned eel Anguilla mossambica and mottled eel Anguilla marmorata: a challenge to the classic tool for reconstructing migratory histories of fishes

Otolith Sr:Ca ratios of the African longfinned eel Anguilla mossambica and giant mottled eel Anguilla marmorata from nine freshwater sites in four rivers of South Africa were analysed to reconstruct their migratory life histories between freshwater and saltwater habitats. For A. mossambica, the Sr:Ca ratios in the otolith edge differed significantly among rivers and had large effect sizes, but did not differ among sites within a river. Otolith Sr:Ca ratios did not differ among rivers for A. marmorata. When rivers were pooled, the edge Sr:Ca ratios of A. mossambica were not significantly different from those of A. marmorata. According to the river-specific critical Sr:Ca ratio distinguishing freshwater from saltwater residence, most A. mossambica and A. marmorata had saltwater habitat experience after settlement in fresh water. This was primarily during their elver stage or early in the yellow eel stage. During the middle and late yellow eel stage, freshwater residency was preferred and only sporadic visits were made to saltwater habitats. The data also suggest that regional variations in otolith Sr:Ca ratios affect the critical Sr:Ca value and are a challenge for the reconstruction of migratory life histories that should be explicitly considered to avoid bias and uncertainty.     

Variation in migratory history of Dolly Varden in a stream with an artificial dam in the Shiretoko Peninsula,Hokkaido, Japan

The variation of migration patterns in Dolly Varden Salvelinus malma in a stream with an artificial dam (erosion-control-dam) in the Shiretoko Peninsula, Hokkaido Island, Japan, at the southernmost part of its distribution, was examined by otolith Sr:Ca ratio analysis. All specimens from the above-dam area showed consistently low Sr:Ca ratios (<5.0 × 10⁻³) throughout the otolith. In contrast, many specimens from the below-dam area had higher ratios (>5.0 × 10⁻³) throughout the otolith or only at the outer part than do those from the above-dam area. This higher ratio is probably due to salinity effects. Specimen from the below-dam area could be divided into three types: (1) Consistently low Sr:Ca ratios throughout the otolith, being freshwater residents. (2) Low Sr:Ca ratios around the inner part of the otolith, and thereafter higher ratios toward the outer part, being typically anadromous. (3) Relatively higher Sr:Ca ratios throughout many or in some parts of the otolith, indicating that these have migrated from the freshwater to brackish water or seawater from the early life stage. These findings suggest that Dolly Varden has a high degree of plasticity in its migratory behavior.     

洞庭湖中是否存在溯河洄游型刀鲚

利用电子探针微区分析(EPMA)技术, 分析了2018年8月采自湖南省岳阳市洞庭湖畔水产市场2尾刀鲚(Coilia nasus)干制个体的矢耳石中锶和钙微化学特征。定量线分析结果显示, 2尾样本的耳石锶钙比值(Sr/Ca×1000)波动显著, 从耳石核心到边缘可分别出现对应淡水生境的锶钙比值<3的低值区, 对应于半咸水生境的3—7高值区和再次为对应于淡水生境<3的低值区。面分布分析结果更直观显示两尾刀鲚个体的耳石从核心到边缘对应于不同盐度生境的锶含量变化图谱, 即从耳石核心到边缘可分别出现对应于淡水生境的蓝色区域, 对应长江口外半咸水生境的黄绿色区域和再次对应于淡水生境的蓝色区域。这种淡水-半咸水-淡水的生境转换显示出了上述个体的典型溯河洄游生活史“履历”。研究显示目前距长江河口约1400 km的洞庭湖中仍可能存在溯河洄游型刀鲚个体。     

基于耳石微化学的长江安徽和县江段刀鲚生境履历重建

为了解长江刀鲚(Coilia nasus)的“生境履历”, 利用电子探针微区分析技术研究了2015年5月17日在长江安徽和县江段捕获的刀鲚短颌鲚与长颌鲚类型耳石Sr和Ca微化学特征。短颌鲚的耳石Sr/Ca值变化动态为2类, 一类比值稳定在2.00左右(1.65±0.87—2.03±0.96), 反映了其纯淡水的生境履历; 另一类比值波动显著, 不仅具有对应淡水生境的低值(2.39±1.18—2.63±0.85), 还具有对应半咸水生境的高值(3.22±1.17—3.29±1.14), 显现了其江海生活的生境履历。长颌鲚耳石的Sr/Ca值均波动显著, 同时具有对应淡水生境的低值(1.35±1.07—2.37±1.04)和半咸水、海水生境的高值(3.47±1.09—8.35±1.25), 表现了其均为溯河洄游的生境履历。Sr面分析结果也与上述Sr/Ca值的结果相印证。长江安徽和县江段刀鲚资源组成复杂, 群体可由纯淡水型和江海生活型的个体共同组成。     

Otolith Sr:Ca and Ba:Ca may give inconsistent indications of estuarine habitat use for American eels (<Emphasis Type="Italic">Anguilla rostrata</Emphasis>)

Temporal patterns in otolith Sr:Ca and Ba:Ca ratio values of American eels Anguilla rostrata from two sites in western Newfoundland gave insight into the use of freshwater and saline habitats. Mean Sr:Ca and Ba:Ca values at the core zone did not differ between sites, indicative of a common oceanic origin. At the otolith edge, representing continental life, both Sr:Ca and Ba:Ca values varied between sites consistent with ambient element:Ca ratio values and salinity, with typically higher Sr:Ca and lower Ba:Ca values in saline than in fresh waters. Most eels (73%) from Muddy Hole, an estuarine site, were evaluated as estuarine residents while most (70%) eels from Castors River, a freshwater site, were evaluated as freshwater residents, with the remaining eels from each site evaluated as inter-habitat migrants. An otolith element:Ca critical value appropriate for distinguishing between fresh and saline water residence is fundamental for estimating the proportion of eel residence in freshwater and their subsequent classification into habitat residence groups. Such classification is moderately robust to the critical value selected. For inter-habitat migrants, moderate otolith Sr:Ca values between the elver check and otolith edge suggestive of estuarine residence may coincide with Ba:Ca values suggestive of freshwater residence. No general critical value for separating fresh and estuarine habitats was found for otolith Ba:Ca. Otolith Ba:Ca temporal patterns may assist the use of Sr:Ca in the evaluation of historical habitat residence and inter-habitat movement but the use of otolith Ba:Ca values should be applied cautiously for American eels and perhaps of other estuarine/freshwater migratory fishes.     

Migration flexibility between freshwater and marine habitats of the pond smelt Hypomesus nipponensis

The life histories of the pond smelt Hypomesus nipponensis collected from Japanese fresh waters and brackish (sea) waters were studied by examining the strontium (Sr) and calcium (Ca) concentrations in their otoliths. The Sr:Ca ratios in the otoliths changed with the salinity of the habitat. The pond smelt living in a freshwater environment showed consistently low Sr:Ca ratios throughout the otolith, averaging 1·2–1·3 × 10⁻³. These samples were identified as a standard freshwater type. In contrast, fish collected from the intertidal zone showed higher otolith Sr:Ca ratios than those in the standard freshwater type, and the ratios fluctuated along the growth phase. In addition to the two representative life‐history types of H. nipponensis , i. e . freshwater and anadromous life‐history types, other pond smelts were found to have an estuarine resident life history‐type with no freshwater phase, indicating that the pond smelt has a flexible migration strategy with a high degree of behavioural plasticity and an ability to utilize the full range of salinity in its life history.     

Flexible Life History Strategies of Ninespine Sticklebacks,Genus <Emphasis Type="BoldItalic">Pungitius</Emphasis>

Synopsis We studied the life histories of the ninespine sticklebacks, Pungitius pungitius and Pungitius tymensis, collected from Japanese freshwater and brackish (sea) water habitats by examining the strontium (Sr) and calcium (Ca) concentrations in their otoliths. The Sr:Ca ratios in the otoliths changed with the salinity of the habitat regardless of identification as freshwater or brackish water type based on morphological characteristics. The ninespine sticklebacks living in a freshwater environment showed consistently low Sr:Ca ratios throughout the otolith. These samples were identified as a standard freshwater type. In contrast, all freshwater-type fishes collected from the intertidal zone showed higher otolith Sr:Ca ratios than those in the standard freshwater type, and the ratios fluctuated with the growth phase. All brackish water-type fishes collected in the intertidal zone showed the highest otolith Sr:Ca ratio throughout the otolith. In the present study, besides the two representative life history types of P. pungitius, i.e., freshwater and brackish water life history types, other sticklebacks had an anadromous life history type. These findings clearly indicate that the ninespine stickleback has a flexible migration strategy with a high degree of behavioral plasticity and an ability to utilize the full range of salinity in its life history.     

Migratory history of the threespine stickleback Gasterosteus aculeatus

 The migratory history of two highly divergent forms (the Japan Sea and Pacific Ocean forms) of the threespine stickleback Gasterosteus aculeatus collected from Japanese brackish water (seawater) and freshwater was studied by examining strontium (Sr) and calcium (Ca) concentrations in their otoliths using wavelength dispersive X-ray spectrometry on an electron microprobe. The Sr : Ca ratios in the otoliths changed with salinity of the habitat. The otolith Sr : Ca ratios of the freshwater resident-type samples of the Pacific Ocean form showed consistently low Sr : Ca ratios, averaging 0.85–0.96 × 10⁻³ from the core to the edge. In contrast, the otolith Sr : Ca ratios of the anadromous type of both the Japan Sea and Pacific Ocean forms fluctuated strongly along the life history transects in accordance with their migration patterns from seawater to freshwater. The higher ratios in the anadromous type, averaging 5.4 × 10⁻³, in the otolith region from the core to 200 μm, corresponded to the seagoing period, suggesting that otolith Sr : Ca ratios are affected by ambient water salinity. These findings clearly indicate that otolith Sr : Ca ratios reflect individual life histories, and that these two highly divergent forms of stickleback have a flexible migration strategy. Received: May 23, 2002 / Revised: July 29, 2002 / Accepted: August 19, 2002 Acknowledgments We are grateful to Dr. S. Mori of Gifu Keizai University, and Miss M. Yamada and Messrs. M. Kume and T. Kitamura of Hokkaido University, for their assistance in sampling. This work was supported in part by Grant-in-Aid No. 13760138 from the Ministry of Education, Culture, Sports, Science and Technology, Japan. Correspondence to:Takaomi Arai     

Migratory history of the spotted flagtail, <Emphasis Type="Italic">Kuhlia marginata</Emphasis>

The spotted flagtail, Kuhlia marginata (Kuhliidae) is commonly found in streams throughout the Ryukyu Archipelago, including Okinawa Island, Japan. Although it has been suggested that they spawn at sea, little is known about their migratory history. The aim of the study was to clarify their migration history based on otolith microchemistry analysis, size composition and the gonadal development of fish collected from the Genka River on Okinawa Island. All strontium/calcium (Sr/Ca) ratios of otoliths remained high around their cores, and then dropped rapidly at some distance from the core. The estimated standard length corresponding to decreases correlated with the size of new recruits collected in the river (ca. 20 mm in standard length: SL). Multiple increases, the sign for migrations into the high saline area, were recognized intermittently around the otolith margin. As the estimated SL at these increases in the Sr/Ca ratio occurred above the minimum maturation size (female: 95.5 mm SL; male: 83.5 mm SL), such multiple increases in Sr/Ca ratios were caused by spawning migration. Therefore, we conclude that the catadromous pattern of K. marginata is as follows; this species grows in the sea during the early life stage until ca. 20 mm SL and then grow in the freshwater area until maturation, before they migrate again to the sea for spawning. Sr/Ca ratio profiles also suggested that a large number of males did not return to the freshwater area after spawning, whereas females might spawn several times during their lives around the inshore area.     

Incorporation of strontium into otoliths of an estuarine fish

Patterns of Sr/Ca variability in fish otoliths have been widely applied as tracers of movement between freshwater and marine habitats, with the assumption that low salinity habitats correspond to lower otolith levels of Sr/Ca. On the other hand, fluvial estuaries can contain steep gradients in Sr/Ca, and in some estuaries, freshwater values of Sr/Ca can exceed marine values, which are relatively constant across marine habitats. Therefore, to interpret Sr/Ca variability in otoliths of fish that move through estuaries, information is needed about both the incorporation of strontium into otoliths and the nature of the gradient of Sr/Ca in the water. We conducted four experiments to evaluate the incorporation of strontium into fish otoliths under estuarine conditions, using white perch (Morone americana) as a model estuarine fish. One laboratory and the two field experiments tested the relationship between Sr/Ca in the otolith and that in the water. A fourth experiment investigated the effect of salinity, independently of the water chemistry (Sr was manipulated while maintaining a constant salinity and Ca level). All four experiments supported a direct relationship between Sr/Ca in the otolith and the water, across a range of estuarine salinities. Results also indicated that the incorporation of strontium into otoliths of estuarine fishes should be constant across broad gradients of Sr/Ca in estuarine waters. While the experiments supported past applications of tracing estuarine and diadromous movements with otolith Sr/Ca chronologies, we emphasize the need to understand the underlying nature of Sr/Ca gradients in estuaries, which may limit or confound reconstructions of estuarine habitat use.     

The migratory history of anadromous and non-anadromous tapertail anchovy Coilia nasus in the Yangtze River Estuary revealed by the otolith Sr:Ca ratio

The migratory history of tapertail anchovy Coilia nasus in the Yangtze River Estuary, China was investigated using otolith Sr:Ca ratios and two-dimensional images of the Sr level from an X-ray electron probe microanalyzer (EPMA). The results showed that 17 of the 22 young-of-the-year (YOY) specimens had low Sr:Ca ratios (1.2–2.4?×?10^?3;1.5?±?0.3?×?10^?3) at the central otolith area, indicating their riverine origin and initial freshwater residence. In addition, 11 of the 14 adult specimens had low Sr:Ca ratios (1.3–2.2?×?10^?3; 1.7?±?0.4?×?10^?3) at the central otolith area but showed alternating changes between high (>4.0?×?10^?3) and low (<2.5?×?10^?3) values outside of this region, reflecting their riverine origin and the migration between freshwater and estuarine habitats. These 28 specimens represented the anadromous population in this region. The other 5 YOY specimens had high Sr:Ca ratios (3.6–5.9?×?10^?3; 4.8?±?0.8?×?10^?3) throughout the life history. Similarly, the other 3 adult specimens had high Sr:Ca ratios (4.0–5.7?×?10^?3; 4.8?±?0.7?×?10^?3) at the central otolith area but showed alternating changes between low and high values outside this region, suggesting that estuarine-origin non-anadromous individuals occurred in this region. The average of the otolith Sr:Ca ratios and Sr level mapping along the life-history transects could be used as a scalar for charting the migratory history of the tapertail anchovy in the Yangtze River Estuary: <2.0?×?10^?3 for freshwater residence and 3.5–6.0?×?10^?3 for estuarine residence.     

Occurrence of the non-anadromous life history in the shirauo, Salangichthys microdon

Strontium (Sr) and calcium (Ca) concentrations in the otoliths of the shirauo, Salangichthys microdon, collected from Japanese coastal waters were examined by wavelength‐dispersive X‐ray spectrometry on an electron microprobe. The otolith Sr : Ca ratios gradually increased from 15.7?19.7 × 10^?3 around the core to 32.8?39.4 × 10^?3 around the edge of otoliths, with no transition point from the low Sr : Ca ratio phase to the high phase. The fluctuation pattern of otolith Sr : Ca ratios was different from the anadromous form reported in a previous study. The evidence indicates that the fish do not necessarily migrate into freshwater during the growth phase.