Do Eurasian minnows (Phoxinus phoxinus L.) inhabiting brackish water enter fresh water to reproduce: Evidence from a study on otolith microchemistry          下载免费PDF全文

Roland Svirgsden  Mehis Rohtla  Anu Albert  Imre Taal  Lauri Saks  Aare Verliin  Markus Vetemaa 《Ecology of Freshwater Fish》2018,27(1):89-97

Dynamics of coastal fish assemblages in the Baltic Sea are still rather poorly understood. In particular, little information is available on migrations and movements of the small‐bodied littoral fish species like Eurasian minnow (Phoxinus phoxinus L.). Minnow is considered typically as a river and lake species, but it also inhabits brackish coastal waters of the Baltic Sea. In this study, we investigated movement patterns of brackish water inhabiting minnows using otolith microchemistry. Fish were collected from four different sites (from two bays and two stream mouths) around Saaremaa Island. The results indicated that at least three distinct migration patterns exist: (i) seawater residency, (ii) fast springtime migrations to fresh water or to bays with lower salinities (areas near stream mouths) and (iii) prolonged migrations to fresh water (some cases overwintering in streams). Migration patterns listed above were not evenly distributed among sites, and some individuals did not migrate to fresh water in every year. None of the analysed fish were freshwater residents. Additionally, potentially ontogenetic effects on Mn and Sr concentrations were observed in the otolith core regions, which may have important implications for the interpretation of otolith chemistry data. The overall findings of this study demonstrate that much more complex migration patterns exists in brackish water inhabiting minnow populations than previously thought and at least some individuals do enter freshwater to reproduce.  相似文献   

Parr dispersal between streams via a marine environment: A novel mechanism behind straying for anadromous brown trout?          下载免费PDF全文

Imre Taal  Mehis Rohtla  Lauri Saks  Martin Kesler  Kristiina Jürgens  Roland Svirgsden  Lagle Matetski  Aare Verliin  Päärn Paiste  Markus Vetemaa 《Ecology of Freshwater Fish》2018,27(1):209-215

Otolith Sr:Ca profiles demonstrated that juvenile anadromous brown trout (ABT) Salmo trutta may descend to the brackish waters of the Baltic Sea from their natal streams as parr or fry and then migrate into non‐natal streams before transforming into smolt. To our knowledge, no such published documentation exists for ABT. The ecological significance of this life‐history strategy is presently not clear. However, stream shifting through the marine environment should to be considered with regard to stock management and the assessment and restoration of salmonid populations and their potential habitats.  相似文献   

Life‐history characteristics of ide Leuciscus idus in the Eastern Baltic Sea          下载免费PDF全文

M. Rohtla  R. Svirgsden  I. Taal  L. Saks  R. Eschbaum  M. Vetemaa 《Fisheries Management and Ecology》2015,22(3):239-248

Otolith Sr:Ca and Ba:Ca profiles were used in parallel with age data to investigate the life‐history characteristics of ide, Leuciscus idus (L.) (n = 111), in the Väinameri Sea, West Estonia. Sr:Ca profiles were more variable and useful than Ba:Ca profiles. Flexible life‐history patterns were observed within and among the three study sites. Most of the individuals (72%) hatched in semi‐enclosed bays that are fresh water during spring spawning but are often flooded with brackish water during other seasons. The importance of lotic spawning varied among sites and was the highest (88%) in Matsalu Bay, moderate in Saunja Bay (33%) and lowest (0%) in Käina Bay. Young of the year emigrated from natal sites and entered the sea within the first summer; 95% did so during the first month post‐hatch. Juvenile ide undertook non‐spawning, freshwater migrations in the following spring; however, the reasons behind this phenomenon remain unknown. As the importance of lotic spawning has significantly decreased and multiple historically important ide spawning rivers lack anadromous runs altogether, it is suggested that actions should be taken to aid the recovery of those imperilled spawning stocks.  相似文献   

Do sea trout Salmo trutta parr surveys monitor the densities of anadromous or resident maternal origin parr,or both?          下载免费PDF全文

M. Rohtla  L. Matetski  R. Svirgsden  M. Kesler  I. Taal  A. Saura  M. Vaittinen  M. Vetemaa 《Fisheries Management and Ecology》2017,24(2):156-162

Brown trout Salmo trutta L. parr were sampled from 21 Estonian and three Finnish streams to investigate whether national sea trout parr surveys sample the progeny of anadromous or resident maternal parents. Otolith Sr:Ca core values were used and validated as a tool for distinguishing between the progeny of the two forms. In Estonia (n = 283), 92% of the parr were the progeny of anadromous maternal parents, and 8% were the progeny of resident maternal parents, whereas in Finland (n = 24), the respective proportions were 79% and 21%. Variation in the maximum otolith Sr:Ca core values among progeny of anadromous maternal parents indicated that some adult females may enter fresh waters several months before spawning. It was concluded that easily accessible locations situated up to 30 km from the sea largely contain progeny of sea trout, whereas sites with poor connectivity with the sea can be dominated by progeny of resident trout. This study demonstrated that the method applied provided an effective means to distinguish between the progeny of sea trout and resident brown trout.  相似文献