FIADHLÚRA

Lifestylesof theBY ANNE SUNDERMANN

Brown trout and its saltwater sibling the sea trout are incredibly successful in Irish waters. Resident since the post-Ice Age period (about 14,000 years ago) when glacial melt created viable fresh and brackish waterways in Ireland, members of the salmonid species Salmo trutta are an incredibly adaptable and important fish. All modern S. trutta in Ireland are born in freshwater, where they develop into fry. When S. trutta fry reach a certain age, they reach a developmental decision point: stay close to home and enjoy the comforts of a freshwater lifestyle or head out and make a life on the high seas for a season or two of growth and maturation (known as the anadromous path). Regardless, all must return to a freshwater base to spawn.

The resident freshwater juveniles (primarily male) are found in almost every waterway on the island and may stay resident in their natal waterway or migrate locally. They are not selective in diet and live in healthy numbers in various locations from mountain rivers and lakes to brackish coastal streams and bays. Their colouring remains the speckled brown, darker or lighter to blend with surroundings. Brown trout spawn in

the last quarter of the year, preferring moderate to highquality waters. e ashier sea trout young, usually female, undergo a process known as smolti cation, which adapts the sh to a marine environment. As they develop, the fry, now parr, undergo profound physical, developmental and behavioural changes that allow it to survive in seawater, including larger size, and organ-level re nements of osmotic function, particularly in gills and kidneys. During smolti cation the parr release guanine (a foundational base of DNA) which causes the sh’s scales to take on a silvery sheen, the signature look of the sea trout juvenile (now known as a smolt).

In autumn, sea trout return to freshwater to spawn. ese large (0.5-2kg) females wait o shore and in small coastal waterways for optimal conditions to run upstream and deposit their eggs on gravel bars. Overwintering sea trout gather in bays and along the Irish coastline. Research shows

BROWN & SEA

TROUT

that small coastal streams may be critical to the abundance and robustness of sea trout populations.

After a period of growth and maturation, the silvery sea trout reach a second juncture: return to sea after spawning or wait until the next spring. Some return shortly after spawning, however most overwinter in freshwater and migrate to sea in March and April.

SEA CHANGES The “should I stay or should I go” evolutionary path is not one taken lightly, and requires significant investment by an organism. Salmo trutta’s use of these alternative migratory tactics is based on a combination of genetics, sex, environment, and available resources. Female trout are more likely to migrate and, with more food resources at their disposal, generally grow larger than the resident males.

Migration, or anadromy, uses up a considerable amount of energy. Metabolism, the process by which an organism breaks down food resources to provide resources (energy) for evolutionary tactics like migration, also comes into play when determining the life path of S. trutta. The liver is a key organ in terms of metabolic function, so it makes sense that scientists have found differences in liver gene expression between migrant and resident populations.

HIERARCHY OF NEEDS In addition to the physiological and evolutionary pressures created by anadromy, food and shelter needs are also stressors on S. trutta populations. Brown trout feed primarily on invertebrates that live in the river or lake, including mayfly, caddis fly, and stone flies. Sea trout require a protein-rich diet, feeding on shrimp and sand eels in addition to their freshwater diet.

Trout habitats and food sources are increasingly under stress from man-made threats, including climate changes. More extreme weather conditions lead to low flow and, conversely, flooding. Smaller coastal waterways are important sources of shelter and food to both resident and migratory trout, but are easily degraded. Unfortunately, they receive little official protection, save for the Water Framework Directive, which seeks to improve the ecology of Ireland’s surface waters, groundwater, and coastal waters.

Freshwater spawning habitats are easily damaged by human activities, eliminating pools and gravel bars, which are important habitats for both resident and migratory trout and their food sources. The availability of food is an important factor in the migration decision, and the numbers of migratory fish increase with low food availability.

The fallout from climate change is likely the most significant threat to brown and sea trout populations. Rising air and water temperatures will certainly have a negative impact on this cold water-loving species. Altered weather patterns create periods of low stream flow in spring and summer, while more frequent and intense extreme rain events will scour the waterways in autumn and winter, potentially disrupting breeding cycles.

Members of Salmo trutta are classic examples of the dexterity of species as they evolve to meet varying environmental conditions, with changes ranging from behaviour to body size to chemical adaptations that allow survival in brackish and high-salinity waters. According to Ken Whelan, our leading authority on the subject, “sea trout and their close relatives the estuarine or slob trout, are amongst the most adaptable of our fish species in Ireland. But as shown by the almost complete loss of individual populations of western sea trout, arising from the impacts of sea lice originating from salmon farms, the continued presence of these magical creatures cannot be taken for granted!” As real as their successes are, the snowballing effect of human intervention leave S. trutta populations vulnerable.

Garraíodóireacht Gheimhridh

le Cáit Nic Lochlainn

Meantán gorm

Ar lá geimhridh, má fhéachann tú amach d’fhuinneog, b’fhéidir nach bhfeicfidh tú mórán ag tarlú i do gháirdín. Agus go minic bíonn an aimsir ró-fhuar le go leor ama a chaitheamh amuigh faoin spéir.

Ach is cuid riachtanach den saolré an tsíocháin agus an tost.

Tá tréimhse díomhaoin an-riachtanach do go leor síolta, agus ar ndóigh d’ainmhithe, feithidí, agus plandaí.

Cé go bhfuil cuma marbh ar an radharc a fheiceann tú, tá go leor ag tarlú faoi thalamh: is féidir le do gháirdín a bheith ina mhicreascóp de cheantar na tuaithe.

Is tearmann riachtanach é an gairdín bruachbhailte do go leor créatúir; agus is féidir leis bheith ina thearmann bithéagsúlacht.

Cé go bhfuil sé níos lú ná páirc, is féidir leat leagan beag den fhiadhulra a fheiscint in aice baile. Ma ta crainn, claí, paiste féir agus beagán uisce ann, beidh tús maith déanta agat ar gharraí "fiáin".

Is é an rud is mó ná gan a bheith róslachtmhar! Lig don dúlra a saibhreas a scaipeadh - is féidir leat slacht a chur ar, nuair a thagann la ‘le Pádraig!

In ionad na gclaí a fheicimid faoin tuaith, is féidir le na toir foscadh agus bia a thairiscint:

Tá caora fós ar go leor dár bplandaí fiáine dúchasacha - mar shampla, cuileann, eidhneán, caorann, droigheann dubh, iúir, coll; Tá siad seo go léir dathúil i ngairdín freisin.

Ba chóir go bhfágfar na féara fiáine gan stró gan gearradh, ós rud é go bhfuil a gceann síolta donn tirim mar bhia do go leor speiceas agus suíomhanna codlata geimhridh d’fheithidí.

Agus cé nach bhfuil sruthán nó loch ag a bhformhór ina ngairdín, tá lochán simplí an-úsáideach: uisce le hól d’ainmhithe, ar ndóigh - ach folctha freisin d’éin chun a gcuid cleití a ní. Tá cleití glana níos clumhach agus níos teo.

Agus b’fhéidir go gcaithfidh na froganna fireann an an gheimhridh i mbun locháin - ag geimhreadh sna teochtaí fuara. Beidh na baineannaigh i bhfolach i measc chairn lomán, agus i bhféar fada tais.

Fiú amháin i gcoirnéil seid nó sna bearnaí idir brící i mballa, féadfaidh féileacáin codladh trí na míonna fuara - cosúil le tortaí beaga agus peacóga srl. Déan iarracht gan cur isteach orthu.

Caitheann damháin alla, leamhain agus go leor feithidí an aimsir fhuar i bhfoirm larbha, pupae, nó braislí uibheacha: ná déan iad a mharú le díograis iomarcach!

Agus má aimsíonn tú go bhfuil an dorchadas agus na teochtaí fuara dubhach agus codlatach fiú do dhaoine, cuir i gcuimhne duit féin go bhfásann an féar ó lár mhí Feabhra - agus braitheann go leor plandaí ní amháin ar theocht ach ar uaireanta an lae freisin. Ta an lá ag dul chun síneadh!

Breathnaigh agus taifead taifid náisiúnta sonraí bithéagsúlachta d’Éirinn má fheiceann tú aon speiceas neamhchoiteanta.